Hand Nerve Injury - Compression - Brachial plexus Flashcards
Which of the following is the most likely site of entrapment of the posterior interosseous nerve in the forearm?
(A) Arcade of Frohse
(B) Arcade of Struthers
(C) Band of Osborne
(D) Lacertus fibrosis
(E) Ligament of Struthers
The correct response is Option A.
Nerves of the upper extremity are prone to entrapment in areas of tight passage or at sharp inflection points. The site or level of compression defines the sensory and motor findings. The median nerve can become entrapped proximally in the arm by the ligament of Struthers, which is a dense band that can form between the supracondylar humeral process and the medial epicondyle. More distally, the median nerve can become entrapped beneath the lacertus fibrosis, which is a dense fascial sheet that extends proximally to the biceps tendon from the antebrachial fascia.
The ulnar nerve exits the arm in the medial intermuscular septum. Fascial folds in this area are known as the arcade of Struthers and can pinch the nerve, especially following anterior transposition. As the ulnar nerve passes through the cubital tunnel, a constricting band can form. This band, known as the band of Osborne, must be released during neuroplasty.
The radial nerve exits the arm after passing posterior to the humerus. It divides into the superficial and deep branches; the deep branch of the radial nerve, also known as the posterior interosseous nerve, can become entrapped, typically due to a fascial band over the supinator called the arcade of Frohse. The radial nerve here can also be compromised by vascular leashes, the edge of the extensor carpi radialis brevis, the edge of the proximal supinator, and the edge of the distal supinator. Proximal compression leads to weakness of extension of the wrist, finger, and thumb, often with radial deviation of the wrist because the extensor carpi radialis longus tendon is innervated proximally.
The pronator syndrome can be differentiated from anterior interosseous nerve syndrome by:
A) The lack of motor findings in the pronator syndrome
B) The lack of pain in the anterior interosseous nerve syndrome
C) The loss of sensibility associated with the pronator syndrome but not the anterior interosseous nerve syndrome.
D) EMG
E) Phalen’s test
Correct answer is option C.
The pronator syndrome can be distinguished from the anterior interosseous nerve syndrome by the loss of sensibility in the distribution of the median nerve, which is not a part of the anterior interosseous nerve syndrome. While motor findings are more common in the anterior interosseous nerve syndrome, they can occur in advanced pronator syndrome. Both syndromes will demonstrate pain in the proximal forearm and abnormal EMG findings in the majority of cases. Approximately one-third of anterior interosseous nerve syndromes occur spontaneously. Other causes are traumatic events, anatomic variation, infections, iatrogenesis, or forearm mass compression. Anterior interosseous nerve palsy has been described with vaccinations and pregnancy also.
A 24-year-old man has a 2.5-cm gap in the distal digital nerve of the dominant right index finger after cutting the finger while using a saw. Which of the following donor nerves is most appropriate for autografting?
(A) Dorsal branch of the ulnar nerve
(B) Medial antebrachial cutaneous nerve
(C) Superficial radial nerve
(D) Sural nerve
(E) Terminal branch of the posterior interosseus nerve
The correct response is Option E.
Selection of an appropriate nerve graft depends on the length, diameter, and function required from the graft. In addition, sensory loss at the donor site should not present a functional problem.
In this patient, the terminal branch of the posterior interosseous nerve will best match the required specifications for replacement of the severed digital nerve. The posterior interosseous nerve can be found deep to the extensor tendons at the level of the wrist. It lies in the floor of the fourth extensor compartment on the radial side, ulnar and deep to the extensor pollicis longus tendon and muscle. The terminal branch is frequently harvested for digital nerve defects because one fascicular strand can be transferred to replace a single digital fascicle. Because it is an articular branch of the nerve, there is no associated sensory deficit.
All of the other sources can be used for grafting but are inferior to the terminal branch of the posterior interosseous nerve for the replacement of a digital nerve. Although the dorsal branch of the ulnar nerve can provide approximately 15 cm of nerve for grafting, harvest of this branch is associated with numbness on the dorsoulnar aspect of the hand. Harvest of the lateral and medial antebrachial cutaneous nerves can be associated with significant donor site morbidity. This is a less favored site for grafting due to the large amount of interfascicular tissue surrounding the nerves. The superficial radial nerve provides an excellent source for graft material, with minimal epineural tissue and tightly packed fascicles, and is best used for nerve reconstruction in a patient with a pre-existing lesion of the high
and posterior to the lateral malleolus in the ankle and can provide as much as 40 cm of nerve for grafting.
An upper trunk (C5-C6) brachial plexus injury is most likely to result in dysfunction of which of the following muscles?
A) Biceps
B) Flexor carpi ulnaris
C) Pectoralis minor
D) Trapezius
E) Triceps
The correct response is Option C.
Upper trunk brachial plexus injuries are associated with the classic “waiter’s tip” posture: the shoulder is adducted and internally rotated at rest. The elbow is extended, the forearm is pronated, and the wrist and digits are held in flexion. Impacted nerves include the axillary, musculocutaneous, and suprascapular nerves. The musculocutaneous nerve innervates the biceps and brachialis muscle. Loss of function of these muscles results in deficits of elbow flexion and forearm supination.
The flexor carpi ulnaris is innervated by the ulnar nerve, which originates from the medial cord of the brachial plexus and carries innervation from C8-T1.
The pectoralis minor is innervated by the medial pectoral nerve from the medial cord of the plexus and carries nerve fibers from C8 and T1.
The trapezius is innervated by the spinal accessory nerve (cranial nerve XI).
The triceps is innervated by the radial nerve, which originates from the posterior cord of the brachial plexus and has contributions from C5-T1.
Sites of ulnar compression at the elbow (cubital tunnel syndrome) include:
A) Osborne’s ligament
B) Transverse carpal ligament
C) Medial collateral ligament
D) Superior ulnar collateral artery
E) Lacertus fibrosis
Correct answer is option A.
Cubital tunnel syndrome, ulnar nerve compression at elbow, is the second most common peripheral nerve entrapment syndrome. Typically, there is a progressive worsening of symptoms related to compression of the ulnar nerve at the elbow. These symptoms begin with medial elbow pain and paresthesias in the ring and small fingers. Patients may complain of difficulty placing the affected hand into a pants pocket due to abduction for the small finger (Wartenberg’s sign). Symptoms progress to clumsiness and eventually to constant numbness with weakness and atrophy of the intrinsic muscles of the hand.
On examination findings of Tinel’s sign over cubital tunnel, reproduction of symptoms with elbow flexion/compression suggest cubital tunnel syndrome. Patients may have other ulnar nerve findings. There are many potential structures which can compress the ulnar nerve at the elbow. The ulnar nerve is most commonly compressed by the cubital tunnel retinaculum also known as Osborne’s ligament, which runs from the medial epicondyle to the olecranon. An anomalous muscle, the anconeus epitrochlaris, may also contribute to compression beneath the cubital tunnel retinaculum. The fascia of the flexor carpi ulnaris and the proximal fascia of the flexor digitorum superficialis may also compress the nerve distally. A prominent medial head of the triceps and the medial intermuscular septum may both contribute to compression just proximal to the medial epicondyle; the intermuscular septum is more commonly problematic when incompletely excised at the time of a transposition procedure. Finally, the Arcade of Struthers which is inconsistently present, is formed by a fascial connection between the medial intermuscular septum and triceps fascia the internal brachial ligament and may contribute to compression well proximal to the medial epicondyle. In short, the ulnar nerve can be compressed at the elbow at the point at which the ulnar nerve pierces the medial intermuscular septum, Arcade of Struthers, Anconeus muscle, Osborne’s fascia and the medial epicondyle, and the deep flexor pronator aponeurosis.
A 21 year-old woman who rows regularly with her university’s crew rowing club comes to the office because she has had pain on movement of the right thumb as well as pain and swelling of the distal forearm for the past month. She has not sustained trauma to the hand or arm. Physical examination shows tenderness and crepitus 4 cm proximal to the wrist and over the distal and radial aspects of the forearm. Slight discomfort is noted on ulnar deviation of the wrist with the thumb clasped in the palm. No grinding or crepitance of the thumb carpometacarpal joint is noted. Which of the following is the most appropriate initial step in management of this patient’s condition?
(A) Injection of a corticosteroid into the first dorsal compartment
(B) Injection of a corticosteroid into the third dorsal compartment
(C) Splinting of the carpometacarpal joint of the thumb
(D) Splinting of the wrist in extension
(E) Observation
The correct response is Option D.
The patient described has findings consistent with intersection syndrome, a tenosynovitis of the second dorsal compartment (common radial wrist extensors) associated with pain and swelling of the muscle bellies of the abductor pollicis longus (APL) and extensor pollicis brevis (EPB), 4 cm proximal to the wrist joint (ie, where the muscle bellies of APL and EPB cross extensor carpi radialis longus and extensor carpi radialis brevis). As in other stenotic conditions of the hand and wrist, it is associated with repetitive motions of the wrist and is frequently seen in athletes, especially rowers and weightlifters. Initial nonoperative treatment consists of rest, nonsteroidal anti-inflammatory drugs (NSAIDs), splinting of the wrist in 15 degrees of extension, and, in some patients, injection of a corticosteroid into the second dorsal compartment. For those with persistent pain, surgical release of the second dorsal compartment beginning at the wrist and extending proximal to the area of swelling may be necessary.
De Quervain disease, a tenosynovitis of the first dorsal compartment, presents with wrist pain on the radial side aggravated by movement of the thumb, most often in women aged 40 €“60 years. Local tenderness and swelling 1 to 2 cm proximal to the radial styloid and knifelike pain on Finklestein test (clasped thumb in palm while wrist is ulnarly deviated) is diagnostic. In mild cases, rest, NSAIDs, and splinting of the wrist in gentle extension and the thumb widely abducted may be successful. Injection of a corticosteroid into the first dorsal compartment may be successful in 50% €“80% of patients following one or two injections. If nonsurgical modalities are unsuccessful, then surgical release of the first dorsal compartment is successful, if variations of this compartment are appreciated and addressed.
Tenosynovitis of the extensor pollicis longus (third dorsal compartment) is rare but requires early diagnosis and urgent operative treatment to prevent tendon rupture, a complication rarely seen with de Quervain disease, trigger finger, or trigger thumb. It presents with pain, swelling, tenderness, and often crepitus at Lister €™s tubercle. Surgical treatment consists of third dorsal compartment release and tendon transposition radial to Lister €™s tubercle. Injection of a corticosteroid is rarely indicated.
Degenerative arthritis of the thumb most frequently affects the carpometacarpal joint. Diagnosis can be made by a positive grind test (ie, crepitations elicited with axial loading combined with the rotation of the thumb metacarpal), and confirmed with radiographs that show destruction of the articular surface and joint space. Early-stage disease may be treated with rest, splinting, NSAIDs, and thenar strengthening. If this fails to relieve pain, then ligament reconstruction may be performed, based on the extent of joint surface destruction. As the patient progresses to end-stage degeneration of the carpometacarpal joint, carpometacarpal arthrodesis, trapezium hemiprosthesis, ligament reconstruction-tendon interposition arthroplasty, or hemi- or complete trapeziectomy may be appropriate management.
Targeted muscle reinnervation allows for increased type of which of the following prosthetic controls for an above-elbow amputee?
A) Cable
B) Electromyographic
C) Passive
D) Switch
The correct response is Option B.
Upper limb amputation is a devastating loss, more so than lower limb amputation. The level of amputation portends increased functional loss, i.e., forearm-level amputees maintain more functional capacity than above-elbow amputees. Many patients with upper extremity amputations rely on their prosthetic for daily functional demands. Patients with an above-elbow amputation have less muscles to exert control of a prosthetic, which makes multiple simple movements difficult and compound movements especially challenging.
There are multiple types of prostheses for the upper extremity. There are passive prosthetics, which are frequently cosmetic but may allow for a stable post for the other extremity. Functional prosthetics are body-powered (via cable controls) or externally powered (myoelectric, switch control). Body-powered prostheses use the remnant body motions through a harness (i.e., scapular and humeral motion for a transhumeral amputee) via cable to control motion and the force of a terminal device. These are simple devices that do not require as much maintenance and have more longevity, but they are limited in terms of functionality.
Myoelectric prostheses use the remnant muscle contractions via electromyographic (EMG) capture for prosthetic control. The more independent discrete electromyographic signals there are, the more potential functional options of the prosthetic there are. If there are minimal/limited EMG sensor options, then switch control can be used. Switch control is when small switches are turned on/off to increase control for separate components of a prosthetic. Switch control can be combined with myoelectric control to increase functionality for higher level amputees. For example, a transhumeral-level amputee can use switch control to position the elbow, while EMG signals from the biceps and triceps control wrist/hand motion.
Targeted muscle reinnervation (TMR) uses nerve transfers to “hyperreinnervate” muscles to allow for increased distinct electromyographic signals as well as increased amplification of signals, increasing control sites for prosthetic functionality. A good example is using residual peripheral nerves of transhumeral amputees, such as the median, radial, and ulnar nerves, to increase independent control of each biceps and triceps head as well as brachialis. TMR therefore allows for increased EMG control of a myoelectric prosthetic.
Histologic evaluation of nerves after TMR compared to neuroma demonstrate which of the following?
A) Increased myelinated fiber cross-sectional area
B) Increased myelinated fiber counts
C) Increased fibrous tissue
D) Increased S100 staining
E) Biphasic cellularity
Correct answer is option A.
A histologic study of neuroma and nerves after TMR in a rabbit model demonstrated that compared to neuroma, nerves after TMR demonstrated a more grossly normal appearing architecture and increased myelinated fiber cross-sectional area. Myelinated fiber counts were significantly decreased after TMR when compared to neuroma and were more similar to control nerves. Increased fibrous tissue and S100 staining are common histologic findings of traumatic neuromas. Biphashic cellularity is a histologic finding seen in schwannomas.
A 42-year-old woman comes to the office for evaluation of a severely painful mass on the upper right arm and numbness in the right forearm six months after undergoing decompression neuroplasty with submuscular transposition. This procedure was performed for progressively worsening compression of the dominant ulnar nerve at the elbow. She developed severe complex regional pain syndrome two weeks after the procedure. Physical examination shows a 0.5-cm mass proximal and central to the medial epicondyle that is adherent to the skin and extremely sensitive. Examination shows decreased sensation to light touch over the ulnar volar forearm. Following excision of the neuroma, which of the following is the most appropriate next step in management?
(A) Medial epicondylectomy
(B) Nerve stump implantation
(C) Stress occupational therapy program
(D) Topical lidocaine patch
(E) Ulnar nerve vein wrap
The correct response is Option B.
The ulnar nerve neuroplasty is complicated by complex regional pain syndrome (CRPS) with an associated nerve injury. The medial antebrachial cutaneous nerve (MABC) of the forearm originates from the medial cord of the brachial plexus (shown in the diagram below). The MABC derives from the C8 and T1 roots. In the mid arm, the MABC and the basilic vein pierce the deep fascia and provide sensation to the overlying ulnar volar forearm skin. The MABC can be injured during ulnar nerve at the elbow neuroplasty. If CRPS develops from an identifiable nerve injury, resolution is best achieved by identifying and correcting the nerve injury. In the scenario described, excision and tensionless implantation into adjacent muscle or bone is the most appropriate option.
Medial epicondylectomy would not address the primary MABC neuroma, nor would wrapping the ulnar nerve with a vein graft. A stress occupational therapy program can be useful in CRPS without an identifiable nerve injury. With the injury described, however, the pain more likely would worsen. Topical transdermal anesthetic patches can alleviate but not resolve the nerve pain.
A 23-year-old man is brought to the emergency department after sustaining a single gunshot wound to the right upper arm. Physical examination shows a high radial nerve palsy. Which of the following is the most appropriate first step in management of potential nerve injury?
A ) Immediate surgical exploration and primary nerve repair if nerve is lacerated
B ) Immediate surgical exploration and repair with a nerve graft if nerve is lacerated
C ) Immediate surgical exploration, resection of devitalized nerve, and suture tagging of nerve ends for delayed repair
D ) Observation with electromyography six weeks after injury followed by exploration and repair if no return of function
E ) Observation with electromyography six months after injury followed by exploration and repair if no return of function
The correct response is Option D.
In general, nerve injuries associated with open wounds should be explored and repaired early. If the nerve injury resulted from a relatively clean laceration or wound, it should be explored and repaired immediately. Crush or significant soft-tissue injury prohibits early nerve repair until the extent of devitalized tissue can be determined and the soft-tissue repair is stable.
Although gunshot wounds are technically open injuries, they should be treated as closed or blunt nerve trauma because the etiology of the trauma is predominately heat and shock. The majority of nerve dysfunction spontaneously recovers after gunshot wounds. Thus, the most logical first step in treatment is observation for at least six weeks at which time electrodiagnostic studies can be undertaken.
If there is not complete clinical return of function within six weeks, electrodiagnostic studies should be performed for baseline function and repeated at 12 weeks if clinical return of function is still not complete. If electromyography does demonstrate motor unit potentials, expectant management should be continued as full function should return. Electrodiagnostic studies should not be delayed for six months because long-term function is significantly decreased if nerve repair is delayed longer than three months.
Lack of clinical or electrical evidence of reinnervation at three months requires surgical exploration. A nerve that has been completely divided or fails to conduct intraoperatively should be managed with resection of scar tissue and repair of the nerve gap with an interpositional nerve graft. An in-continuity lesion should undergo neurolysis of nonfunctioning nerve units and nerve grafting. The functioning units can remain intact.
A 20-year-old man is undergoing nerve grafting for reconstruction of a 2-cm digital nerve gap. During operative exploration, the distal aspect of the posterior interosseous nerve is identified initially beneath the extensor tendons of the fourth compartment of the forearm. As the nerve is dissected proximally, it courses beneath which of the following muscles?
(A) Brachioradialis
(B) Extensor digitorum communis
(C) Extensor digitorum quinti
(D) Extensor indicis proprius
(E) Extensor pollicis longus
The correct response is Option E.
The terminal branch of the posterior interosseous nerve is a good source of nerve for grafting of small distal gaps of the digital nerves because it leaves no cutaneous sensory loss at the donor site. This nerve branch can be found at the floor of the fourth compartment, beneath the extensor digitorum communis and extensor indicis proprius muscles, but travels more proximally beneath the extensor pollicis longus muscle. The posterior interosseous nerve does not traverse deep to the extensor digital quinti. The superficial radial nerve travels beneath the brachioradialis muscle and emerges at the wrist.
A 34-year-old man has radial nerve palsy six months after undergoing open reduction and plate fixation of a fracture of the humeral diaphysis. The integrity of the radial nerve was confirmed at the time of the initial injury. Which of the following is the most appropriate next step in management?
(A) Dynamic extension splinting
(B) Injection of a corticosteroid
(C) Tendon transfers
(D) Interpositional nerve grafting
(E) Neurolysis
The correct response is Option C.
In patients with high radial nerve palsy, the primary goal is restoration of extension of the wrist, fingers, and thumb. If the nerve was intact at the time of the initial surgery and there is subsequently no return of function six months later, further improvement is unlikely, and tendon transfers are indicated at this time.
Transfer of the pronator teres to the extensor carpi radialis brevis is frequently performed to recover wrist extension. To regain finger extension, the flexor carpi radialis, flexor carpi ulnaris, or flexor digitorum superficialis of the long or ring fingers is transferred into the distal extensor digitorum communis tendons. Transfers to regain thumb extension include the palmaris longus or flexor carpi radialis to the extensor pollicis longus. Additionally, some surgeons advocate end-to-side tendon transfers.
The extensor carpi radialis brevis cannot be transferred to the extensor digitorum communis because it is also affected by the radial nerve palsy. Transfer of the flexor digitorum profundus tendon of the long finger is associated with significant loss of function at the donor site.
Splinting is not indicated in a patient who has persistent radial nerve palsy six months after the initial procedure.
Injection of a corticosteroid is inappropriate treatment of radial nerve palsy.
Because the nerve is shown to be intact, the presence of a neuroma in continuity may be inhibiting the reinnervation process. EMG should be performed to determine the potential for nerve grafting or neurolysis in this patient. However, most nerve grafting procedures in adults provide only limited improvement in motor and sensory functions six months after denervation.
A 50-year-old woman previously diagnosed with left forearm compression neuropathy of the superficial radial nerve comes to the office for examination. The patient has not responded to 7 months of conservative management which consisted of NSAID therapy, steroid injection, a trial of splinting, and activity modification. Operative treatment is planned. Fascial release between which of the following two tendons is most appropriate in this patient?
A) Abductor pollicis longus and extensor pollicis brevis
B) Brachioradialis and extensor carpi radialis longus
C) Extensor carpi radialis longus and extensor carpi radialis brevis
D) Flexor carpi radialis and abductor pollicis longus
E) Flexor carpi radialis and brachioradialis
The correct response is Option B.
Superficial radial nerve compression of the forearm occurs most frequently at the posterior border of the brachioradialis where the nerve transitions from a deeper, subfascial position to a more superficial, subcutaneous location. Also known as Wartenberg syndrome, patients may present with pain, numbness, or tingling over the dorsal radial hand radiating to the dorsal thumb and index finger.
Symptoms of superficial radial nerve compression may be confused with symptoms of de Quervain’s tenosynovitis. In addition, both conditions may coexist simultaneously.
Patients diagnosed with superficial radial nerve compression are initially treated conservatively since this approach is successful in relieving symptoms in the majority of cases. Conservative management consists of rest, splinting, removal of external compression source (such as a tight wristwatch band, bracelet, or handcuffs), and nonsteroidal anti-inflammatory medications.
Surgery is indicated when conservative measures fail. Surgical decompression involves release of the fascia between the brachioradialis and extensor carpi radialis longus tendons. It is at this interval that the nerve transitions from deep to superficial and prone to compression. The other responses do not reflect the correct surgical anatomy of this condition.
A 48-year-old woman has numbness and paresthesia of the right hand 2 years after mastectomy and radiation therapy. She reports no pain or night waking. Symptoms have not improved with cock-up wrist splints or injection of a corticosteroid into the carpal tunnel. Physical examination shows swelling and weakness of the right arm, most prominently in the C5-C6 distribution; no varicosities, stasis ulcers, dermatitis, or symptoms of Horner syndrome are noted. Allen test is normal. Electromyography shows myokymia. CT scan shows diffuse swelling but no mass. Which of the following is the most likely diagnosis?
A ) Acute ischemic injury
B ) Carpal tunnel syndrome
C ) Chronic venous insufficiency
D ) Radiation-induced brachial plexopathy
E ) Tumor recurrence
The correct response is Option D.
The most likely diagnosis is radiation-induced brachial plexopathy, which can occur when radiation therapy is directed at the chest, axillary region, thoracic outlet, or neck. The incidence is 1.8 to 4.9% of those patients receiving radiation therapy to the above areas and is most common in patients with underlying breast or lung carcinoma. Patients often have sensory symptoms, with swelling and a generalized weakness of the arm. Eighteen percent of patients have pain in the shoulder, wrist, or hand. The neurologic findings are most prominent in the C5-C6 distribution. The lymphatic-vascular system may show prominent lymphedema of the involved extremity without cyanotic or dusky features. There should be no disturbance of arterial or venous circulation in the involved extremity and no changes in the limb to suggest venous insufficiency (ie, varicosities, stasis ulcers, or dermatitis). The Allen test should be normal. Horner syndrome is not present in patients with radiation-induced brachial plexopathy.
Eighty percent of patients with tumor infiltration into the brachial plexus come to the office because of pain in the shoulder, upper arm, elbow, and ring and little fingers. Symptoms progress to atrophy and weakness of the C7-T1 distribution with persistent pain and occasional Horner syndrome. CT scan shows a discrete mass with circumscribed tissue infiltration. Electromyography shows segmental slowing.
Patients with acute ischemic injury have symptoms of paresthesia in the C5-C6 nerve distribution and acute, nonprogressive weakness and sensory loss. CT angiography would
demonstrate subclavian artery segmental obstruction. Electromyography shows segmental slowing.
Patients with carpal tunnel syndrome often have night waking and experience a period of symptomatic relief after injection of a corticosteroid into the carpal tunnel.
Chronic venous insufficiency does not typically have neurologic sequela.
A 29-year-old man is brought to the emergency department because of a deep laceration of the medial right arm at the elbow. Examination shows complete loss of ulnar nerve function to the right hand. During exploration in the operating room, complete transection of the ulnar nerve at the elbow with a 3-cm nerve gap after debridement is noted. Which of the following procedures is most likely to result in the earliest recovery of intrinsic muscle function in this patient’s hand?
A) Anterior interosseous nerve transfer
B) Cable grafting with nerve allografting
C) Cable grafting with sural nerve grafting
D) Primary repair with the elbow in flexion
E) Ulnar nerve transposition and primary repair
The correct response is Option A.
The most appropriate answer is transfer of the anterior interosseous nerve to the motor branch of the ulnar nerve in the distal forearm. Ulnar nerve injuries are especially debilitating with loss of grip and claw hand deformity. High ulnar nerve injuries are considered to be anything proximal to the innervation of the flexor carpi ulnaris and flexor digitorum profundus muscles at or near the elbow. This includes the elbow, upper arm, and brachial plexus.
The prognosis for recovery of intrinsic hand function is poor in high ulnar nerve injuries 30 to 35 cm proximal to the hypothenar eminence. This is due to the length of time required for nerve regeneration, and the motor endplate degeneration that occurs during this time. High ulnar nerve injuries will exceed the approximately 18-month window for regeneration in order to achieve meaningful muscle recovery.
The theory behind nerve transfer surgery is to take an expendable donor nerve and use the fascicles to restore function to a more critically injured nerve. The anastamosis for an AIN-to-ulnar nerve transfer is 8 to 10 cm proximal to the wrist crease and greatly decreases the amount of distance and therefore time required for reinnervation of intrinsic hand muscles. Although the anterior interosseous nerve contains 75% of the axons of the deep motor branch of the ulnar nerve, meaningful recovery of intrinsic muscle function can be expected. The anastamosis for the transfer can be done in an end:end or end:side technique. End-to-side nerve transfer is indicated in partial nerve injuries or lower nerve injuries where primary repair of the injured nerve is possible and one can expect some contribution of nerve fibers from the native nerve.
Primary repair of any nerve injury under tension or that requires extreme joint flexion is not indicated. This results in tension at the repair site, internal scarring, possible flexion contracture, and a poor result. Anterior transposition of the ulnar nerve may be performed in some instances but is reported to gain only 1 cm of length from the proximal nerve. This is not enough to bridge the gap in this scenario.
Any attempt at primary repair of a nerve injury with a 3-cm gap would require nerve grafting. In a mixed nerve, multiple cables of nerve graft are recommended in an attempt to topographically reconnect the sensory and motor fascicular bundles. The current gold standard for nerve repair in adults is autograft. The most common donor nerves are the sural nerve and medial antebrachial cutaneous nerve.
Processed nerve allograft has become a viable alternative to autograft nerve. The allograft nerve is processed and decellularized but maintains the microstructure of the nerve tissue including the fascicular anatomy and microvasculature. The allograft is rapidly revascularized without the donor site morbidity associated with autograft. The RANGER study has demonstrated S3 and M4 or above recovery in 86% of repairs using allograft nerve in gaps up to 5 cm. This question specifically asks about the most rapid recovery of motor function, which should occur with a nerve transfer.
A 24-year-old man comes to the office because of a brachial plexus injury sustained in a motorcycle accident. Nerve transfer to the biceps for restoration of elbow flexion is planned. Which of the following fascicles or nerves is the most appropriate donor for the transfer?
A) Distal spinal accessory nerve
B) Flexor carpi ulnaris fascicle of the ulnar nerve
C) Medial pectoral nerve
D) Palmaris longus fascicle of the median nerve
E) Thoracodorsal nerve
The correct response is Option B.
Adult upper trunk brachial plexus injuries result in significant disability. Several surgical treatment strategies exist, including nerve grafting, nerve transfers, and a combination of both approaches.
The flexor carpi ulnaris (FCU) fascicle of the ulnar nerve to biceps transfer was first described by Oberlin et al in 1994. Generally, the donor nerve with the largest caliber and the greatest number of motor axons should be used for elbow flexion. The other suggested nerve transfer options are also possibilities, but are not as preferable as the FCU fascicle transfer. MacKinnon has advocated transfer of the FCU fascicle of the ulnar nerve to the biceps and FCR fascicle of the median nerve to the brachialis to maximize recovery of elbow flexion.
A 25-year-old man comes to clinic because he has increasing severe pain in the hand three days after undergoing open reduction of a fracture of the distal radius. Physical examination shows extreme swelling of the hand. Which of the following clinical findings is most likely to confirm the suspected diagnosis of compartment syndrome in the hand of this patient?
(A) Diminished sensation on the dorsum of the hand
(B) Pain on active flexion and extension of the fingers
(C) Pain on passive adduction and abduction of the fingers
(D) Pain on passive extension and flexion of the wrist
(E) Pain on passive flexion and extension of the fingers
The correct response is Option C.
The diagnosis of compartment syndrome is primarily a clinical one based on muscle and nerve ischemia. It is possible to measure intracompartment pressure, but the decision to perform a fasciotomy should be based on a high degree of suspicion, close observation of the patient, and clear understanding of the etiology.
Compartment syndrome ischemia may be severe and still not affect the color and temperature of the fingers. The distal pulses are rarely obliterated by compartment swelling, even though muscle and nerve circulation is minimal. The hallmark of muscle and nerve ischemia is pain. The pain is persistent, progressive, and unrelieved by immobilization. Accentuation of the pain by passive muscle stretching is the most reliable clinical test for making the diagnosis of compartment syndrome.
In performing the passive stretch test, one simply stretches the muscle or muscles in the compartment in question, and this should cause severe pain. There are ten compartments of the hand. The intrinsic compartments of the hand are tested by passively abducting and adducting the fingers while keeping the metacarpophalangeal joints in full extension and the proximal interphalangeal joints in flexion. If this maneuver causes a marked increase in pain, the test is diagnostically significant. The adductor compartment to the thumb can be tested by simply pulling the thumb into palmar abduction and thereby stretching the adductor muscle. The thenar muscles are tested by radial abduction of the thumb and the hypothenar muscles by adducting the little finger. Passive or active finger motion can elicit pain seen with other conditions such as flexor tendon infections or injuries, and this is a later and less specific finding.
Diminished sensation is the second most important finding and indicates nerve ischemia as it passes through the affected compartment. The third most important finding is weakness and/or diminished muscle function. Also, palpation of the closed compartments in the hand for tenseness and tenderness should confirm the diagnosis.
A 35-year-old man sustains a laceration of the volar aspect of the left index finger at the level of the mid phalanx while using a knife. There is smooth flexion and extension of the proximal interphalangeal and distal interphalangeal joints. Examination of the fingertip shows good color and capillary refill. Two-point discrimination is 5 mm on the ulnar aspect of the fingertip but is absent on stimulation of the radial aspect. On exploration, a laceration involving 45% of the cross-sectional area of the flexor digitorum profundus (FDP) tendon is noted. The radial digital nerve and artery are transected. The ulnar neurovascular bundle is intact. In addition to repair of the radial digital nerve, which of the following is the most appropriate management?
A) Immediate protected mobilization
B) Repair of the FDP tendon with core and epitendinous sutures and splint immobilization for two weeks followed by protected mobilization
C) Repair of the FDP tendon with core sutures and splint immobilization for two weeks followed by protected mobilization
D) Repair of the FDP tendon with epitendinous sutures and splint immobilization for four weeks followed by protected mobilization
E) Splint immobilization for four weeks followed by protected mobilization
Correct answer is A.
Tendon lacerations of less than 60% of the cross-sectional area of the tendon do not require repair. Attempts to repair the tendon may weaken it. Triggering may occur if the distal or proximal cut edge of the tendon catches on adjacent pulleys. If triggering occurs, trimming the cut edges of tendon, partial or complete pulley release, and repair of the flexor sheath can be performed. In cases of persistent triggering that persists despite these measures, the tendon can be repaired. In the absence of triggering, the tendon does not require treatment. Protected mobilization is performed to promote tendon gliding and strengthening. Despite early recommendations for several weeks of immobilization following digital nerve repair, the outcomes of digital nerve function following immediate protected mobilization are not statistically different than those managed with immobilization.
A 52-year-old man presents for evaluation of a claw deformity of the right ring and small fingers. Medical history includes an unrepaired low ulnar nerve injury sustained 30 years ago. Which of the following is the most likely pathophysiology of this patient’s deformity?
A) Unbalanced abductor digit minimi muscle
B) Unbalanced median and ulnar innervated intrinsic muscles
C) Weak thenar muscles
D) Weak ulnar innervated extrinsic flexor muscles
E) Weak ulnar innervated intrinsic muscles
The correct response is Option E.
Clawing after ulnar nerve injury includes hyperextension of the metacarpophalangeal (MCP) joints and flexion of the interphalangeal (IP) joints. The pathophysiology includes paralysis of the interossei and third and fourth lumbricals. Unopposed long extensors cause the metacarpophalangeal joints to fall into extension while the long flexors pull the proximal interphalangeal joints into flexion. This posture is the classical ‘claw hand.’
A 13-year-old boy is brought to the office because he has difficulty opening his hand and extending his fingers. History includes release of the forearm compartments to treat a pulseless hand following a supracondylar humerus fracture 2 years ago. On physical examination, passive extension of the fingers is restricted when the wrist is fully extended; it improves with full wrist flexion. Which of the following muscles is the most likely cause of the limitation described?
A) Flexor carpi radialis
B) Flexor carpi ulnaris
C) Flexor digitorum profundus
D) Flexor digitorum superficialis
E) Lumbricals
The correct response is Option C.
The most likely cause of the restricted finger extension described is fibrosis of the flexor digitorum profundus muscle. The patient exhibits Volkmann ischemic contracture as a complication of late treatment (over 24 hours from the time of initial ischemia) of arterial compromise associated with the fracture. The muscle groups at the greatest risk during these ischemic episodes are within the deep flexor compartment of the forearm. This risk occurs because the arterial supply is relatively distant from the usual site of occlusion and because this compartment is relatively less distensible. In the scenario described, the flexor digitorum profundus and flexor pollicis longus are at the greatest risk.
Superficial muscle groups such as the flexor carpi radialis, flexor carpi ulnaris, and the flexor digitorum superficialis typically recover some function and do not lead to contractures in the forearm. Likewise, the small muscles of the hand, such as the lumbricals, tend to be less severely injured than the deep compartment of the forearm.
A 54-year-old woman comes to the office because of a 6-year history of weakness and numbness of the left hand. Physical examination shows decreased sensation in the thumb, index, long, and ring fingers. No other sensory abnormalities are noted. Examination of which of the following muscles is most likely to confirm a diagnosis?
A ) Abductor pollicis brevis
B ) Adductor pollicis
C ) First dorsal interosseous
D ) Flexor digiti minimi
E ) Flexor pollicis brevis
The correct response is Option A.
The examination of the patient described suggests an injury or compression neuropathy of the median nerve. The only intrinsic muscle innervated by the median nerve (recurrent branch) that can be reliably tested separately from the ulnar intrinsic muscles is the abductor pollicis brevis. The adductor pollicis, first dorsal interosseous, and flexor digiti minimi are all completely innervated by the ulnar nerve. The flexor pollicis brevis muscle has dual innervation from both the ulnar (deep head) and median (superficial head) nerves.
A 23-year-old man sustained a complete laceration of the ulnar nerve at the level of the elbow four weeks ago when he was stabbed in the nondominant forearm with a knife. After surgical nerve preparation, a 2-cm gap is present. Which of the following is the most appropriate next step in management?
(A) Use of a vein conduit
(B) Tendon transfers
(C) Mobilization of the nerve 15 cm proximally and distally
(D) Sural nerve grafting
(E) Ulnar nerve transposition
The correct response is Option E.
In this 23-year-old man who has a 2-cm nerve gap after sustaining a clean laceration of the ulnar nerve at the elbow four weeks ago, the most appropriate next step in management is transposition of the ulnar nerve. Because transposition of this nerve at the elbow provides as much as 4 cm of length, it is recommended in this patient in whom primary coaptation cannot be performed because of nerve retraction.
Ulnar nerve transposition may yield as much as 3 cm of length when performed in the arm, 2 cm of length at the forearm, and 1 to 2 cm of length at the distal forearm and wrist. Transposition is also appropriate for repair of median and high radial nerve injuries.
Vein conduits should only be considered if direct repair and transposition are not options.
Tendon transfers alone do not restore sensory function, and are recommended for late reconstruction only when nerve repair is no longer an option.
Extensive mobilization of the ulnar nerve into the mid forearm may cause devascularization and injury to distal nerve branches and ultimately worsen functional outcome.
Sural nerve grafting may be considered if transposition of the ulnar nerve results in tension following nerve coaptation.
A 33-year-old woman comes to the office because of volar numbness of the right thumb, index, long finger, and palm for the past 4 months. Medical history includes no abnormalities. Physical examination shows weakness of the palmar abduction of the thumb and interphalangeal joint flexion of the thumb. Percussion tenderness over the volar aspect of the wrist does not reproduce symptoms. Passive flexion of the wrist does not reproduce symptoms. Which of the following is the most likely diagnosis?
A) Anterior interosseous syndrome
B) Carpal tunnel syndrome
C) Cubital tunnel syndrome
D) Posterior interosseous syndrome
E) Pronator syndrome
The correct response is Option E.
Pronator syndrome is a compression neuropathy of the median nerve in the proximal forearm. Paresthesias in the palm and the median nerve–innervated fingers of the thumb along with weakness of the flexor pollicis longus muscle are classic findings in pronator syndrome. Pronator syndrome can be differentiated from carpal tunnel syndrome by sensory symptoms and numbness occurring in the palm, which is innervated by the palmar cutaneous branch of the median nerve. This branch comes off the proper median nerve proximal to the carpal tunnel. Findings of weakness of the flexor pollicis longus muscle and often the flexor digitorum profundus muscle to the index finger are often seen in pronator syndrome. Anterior interosseous syndrome is a motor-only compression of the median nerve in the proximal forearm; sensory findings are not present. Cubital tunnel syndrome or ulnar nerve compression at the elbow presents with sensory findings in the small and ring fingers and may also affect the interosseous muscles. Posterior interosseous syndrome affects the extensor muscles in the forearm and is not the pathologic lesion described in the scenario.
A 51-year-old truck driver comes to the hand clinic because he has had constant burning pain in the left arm since he injured the left wrist while loading a truck two weeks ago. Since the injury, avoiding use of the wrist and wearing an immobilization splint on the wrist have not relieved the pain. On physical examination, the left hand, wrist, and forearm are swollen and mildly mottled. The wrist is extremely sensitive to touch. Range of motion of the left wrist and forearm is significantly decreased. Which of the following findings is most likely on additional evaluation of this patient?
(A) Decreased resting sweat output
(B) Decreased temperature readings on thermography
(C) Increased leukocyte count
(D) Increased uptake on a three-phase bone scan
(E) Osteoporosis on plain radiographs
The correct response is option D.
This patient’s clinical picture is consistent with early complex regional pain syndrome (CRPS) type I, formerly referred to as reflex sympathetic dystrophy (RSD). A reliable adjunctive tool in confirming the clinical diagnosis is the third phase of a three-phase bone scan. For the scan to be considered indicative of CRPS, the third phase typically shows diffuse increased periarticular activity in the involved joints. Increased uptake is variable in children. In time, results of the three-phase bone scan return to normal.
Radiographic evidence of osteoporosis secondary to CRPS, historically referred to as Sudeck atrophy, does not appear until the third to fifth week of the syndrome. Sudeck atrophy typically demonstrates diffuse osteopenia, juxtacortical demineralization, and subchondral erosions or cysts. This Alag@ in radiographic changes is explained by the fact that calcium content must be altered by 30% to 50% before becoming evident on conventional plain radiographs. The radiographic features of rapid bone loss include visible demineralization with patchy, subchondral, or subperiosteal osteoporosis, metaphyseal banding, and profound bone loss. Despite the osteoporosis, fractures are uncommon.
Other available diagnostic tools include thermography and resting sweat output. Thermography is an indirect method of measuring blood flow to an extremity. Patients with CRPS typically show elevated temperature readings on thermography indicative of increased local blood flow. Resting sweat output quantifies abnormal autonomic system activity by measuring the amount of resting sweat that occurs on the extremity. Patients with CRPS have elevated autonomic system activity and, therefore, demonstrate increased resting sweat output.
Leukocyte count is not helpful in confirming the diagnosis of CRPS.
A 17-year-old girl comes to the office because she has persistent wrist drop and weakness of digit extension three weeks after she fractured the intraarticular distal portion of the radius while snowboarding. Open reduction and internal fixation was performed under general anesthesia. A wide-cuff, pneumatic tourniquet was placed over cast padding; inflation pressure was 100 mmHg over the patient’s systolic blood pressure. Reduction was difficult, and tourniquet time was 180 minutes. Use of which of the following interventions is most likely to have decreased the risk of this complication?
A) Elastic stocking rather than cast padding beneath the tourniquet
B) Esmarch bandage as the tourniquet
C) Narrow width tourniquet cuff
D) Standard inflation pressure of 250 mmHg
E) Tourniquet deflation/reperfusion period
Correct answer is option E.
The intervention most likely to decrease the incidence of nerve palsy in the patient described is providing a period of tourniquet deflation (“breather period”) during which tissue acidosis may reequilibrate.
Despite advances in equipment and technique, complications from tourniquet use in upper extremity surgery still occur. The most common problems involve either neurologic or skin complications. Experimental studies suggest that most neurologic sequelae appear to be related to prolonged ischemia, high local tourniquet pressure, or some combination of the two.
Both elastic stockings and cast padding have been shown to decrease skin complications from tourniquet use; neither has been shown to have any effect on neurologic complications.
Esmarch bandages, although effective as tourniquets, provide unpredictable levels of pressure on the arm and have consequently been replaced by automated cuffs and pumps.
Wide tourniquets, with ratios of cuff width to arm circumference greater than 0.5:1, have been shown to achieve hemostasis at lower pressures than narrow cuffs.
Although many surgeons reflexively set upper extremity tourniquets at 250 mmHg, the optimal inflation pressure to minimize risk and maximize hemostasis appears to vary widely depending on body habitus, type of anesthesia, and comorbidities such as hypertension.
A 6-month-old boy who sustained a brachial plexus injury during delivery is brought for evaluation. On examination, the left elbow is held in extension and arm is positioned in internal rotation. He has active flexion of the fingers and wrist. Extension of the fingers and wrist is weak; anti-gravity test of the elbow extension discloses weakness. There is no active elbow flexion or shoulder abduction; Horner’s sign is absent. Which of the following structures is most likely injured?
A) C7 roots
B) C8-T1 roots
C) Lateral cord
D) Posterior cord
E) Upper trunk
The correct response is Option E.
The infant has the classic manifestations of an upper trunk (C5-6), or Erb’s, palsy (weak or absent elbow flexion, shoulder abduction and external rotation, relatively preserved elbow extension and distal wrist/hand flexion). The “waiter’s tip” posture of the affected extremity indicates relative sparing of lower root (C8-T1) function. Isolated injury to the C7 root is uncommon and would primarily affect radial nerve innervated muscles such as the wrist and finger extensors, and forearm pronation. Injury to the posterior cord also effects radial nerve innervated muscles and would not alter biceps or deltoid function as observed in this child. Lateral cord damage would result in weak or absent biceps and pectoral function, but would not diminish deltoid or periscapular muscle activity.
A 55-year-old man with bilateral carpal tunnel syndrome comes to the outpatient surgical unit for elective surgical intervention of the dominant right hand. He will be the tenth procedure of the day for the surgeon performing the operation. The surgeon favors an open technique; he has performed 150 carpal tunnel operations since finishing his hand fellowship 3 years ago. Which of the following is most likely to increase the risk of wrong-site surgery?
A) The elective nature of the procedure
B) Only one surgeon is involved in the operation
C) The procedure will be performed using an open technique
D) The surgeon has a high volume of cases scheduled for the same day
E) The surgeon has only been practicing independently for 3 years
The correct response is Option D.
The term ?wrong-site surgery? includes surgery on the wrong organ or extremity, the wrong patient, or the wrong vertebral level. This error can result in disastrous outcomes for the patient, as well as the institution and professionals involved. Traditionally, these errors have been considered ?sentinel events? that require a root cause analysis to define the hazards that triggered the event. Fortunately, wrong-site surgery is rare; however, the true incidence is unknown and appears to be increasing. Attempts to quantify the true incidence of wrong-site surgery are limited by underreporting to The Joint Commission and the often covert nature of these events caused by liability concerns. One review has estimated an incidence rate of one wrong-site surgery per 100,000 operations. This rate was 4 times higher among hand surgeons, however, with an estimated one in five hand surgeons predicted to perform a wrong-site surgery in their career.
A Joint Commission review of a series of sentinel events identified a number of factors contributing to the increased risk of wrong-site surgery, such as emergency cases; unusual physical characteristics, including morbid obesity or physical deformity; unusual time pressures to start or complete the procedure; unusual equipment or setup in the operating room; multiple surgeons involved in the case; and multiple procedures being performed during a single surgical visit. A large series of wrong-site hand surgeries showed an increased rate of wrong-site surgery with increasing surgeon age and experience, and a direct correlation with increasing surgical case volumes.
While more than one factor was often identified after a root cause analysis, the majority involved a breakdown in communication between the surgical team and the patient and his or her family.
While it seems that something as simple as operating on the correct side would be intuitive, in reality, the enormous pressures of time and patient volume in the current health care environment set up surgeons for an eventual system failure. Review of the factors noted above demonstrates that the major component in preventing wrong-site surgery is effective communication between surgeon and patient, and the surgeon bears the ultimate responsibility of assuring that this level of communication exists.
Current Joint Commission requirements include a preoperative verification, site marking, and a ?time out? in the operating room. One recent study of malpractice claims after wrong-site surgery showed that two thirds of wrong-site surgeries could have been prevented by an effective site-verification protocol. Recommendations for effective site verification include the following:
Site marking by the surgeon with initials or “yes.”
Preoperative verification process: verification of patient identity, site, side, and procedure confirmed by two members of the health care team, including the surgeon. The informed consent should be compared with the operating room schedule. A “time out” before incision will then provide a final confirmation of the appropriate procedure and site. A specific, detailed protocol to define this process that involves clear recommendations for specific behaviors is more likely to be followed than general or ambiguous recommendations.
Inconsistencies: any inconsistencies or uncertainties about the correct operative site should be resolved by the surgeon with agreement by the patient and nursing staff. Specific and explicit protocols should be in place to address the manner in which these uncertainties are resolved.
The informed consent must specify laterality and attempt to localize multiple structures if surgery will be performed in multiple locations.
A newborn who sustained a traction injury to the shoulder during delivery because of the use of forceps has complete palsy of the left upper extremity. Surgical intervention is indicated if there is no spontaneous biceps recovery by what age?
A ) 6 weeks
B ) 6 months
C ) 18 months
D ) 24 months
E ) 36 months
The correct response is Option B.
Most experts will perform surgery on infants who are between 3 and 6 months of age. At 3 months of age, if biceps function is absent, there is a poor prognosis. Early on, 92% will recover spontaneously. If biceps function is noted, surgery is not recommended. At 3 months of age, the child is retested by electromyography if there is no biceps function, although there is poor correlation with final results. The final evaluation is cervical myelography.
A 29-year-old man who is a laborer presents with significant pain of the nondominant left hand. Medical history includes a laceration of the ring and small fingers palmarly over the proximal phalanx 1 year ago. At the time of the injury, he underwent repair of the flexor digitorum profundus to the small finger and direct repair of the ulnar digital nerve to the ring finger. All other nerves were intact. On examination, the patient reports pain over the nerve repair site that interferes with work-related tasks. There is no sensation distal to the repair. Positive Tinel sign over the ulnar extent of the scar on the ring finger is noted. Which of the following surgical techniques is most appropriate in this patient?
A) Excision of neuroma alone
B) Excision of neuroma and nerve implantation into bone
C) Excision of neuroma and nerve repair with allograft
D) External and internal neurolysis of the neuroma in continuity
E) Targeted muscle reinnervation or nerve transfer to nearby motor nerve
The correct response is Option C.
Injuries to the extremities are extremely common, and with the close proximity of the digital nerve to the palmar surface of the digits, these nerves are commonly lacerated. Initial treatment includes primary repair or grafting, depending on the extent of injury and the ability to perform direct repair with minimal tension. Despite repair, patients may develop neuroma in continuity and fail to recover meaningful sensation distal to the level of injury.
In this scenario, the patient has developed a neuroma in continuity at the site of digital nerve repair. Many treatment options exist for the treatment of neuroma in the extremities where the distal nerve target is present. These include: direct repair, the use of a nerve conduit, allograft, or autograft. Where the distal nerve target is absent, as with amputation, techniques to limit or treat neuroma include: excision alone, excision with amputation into muscle or bone, nerve graft to nowhere, nerve capping, centro-central coaptation, end to side neurorrhaphy, targeted muscle reinnervation (nerve transfer), or regenerative peripheral nerve interface (RPNI).
In the study by Moran et al., where authors retrospectively reviewed 127 patients following surgery for symptomatic neuroma, they found that patients who underwent neuroma excision followed by repair had significantly lower DASH scores, compared with implantation into muscle or bone or with simple excision alone (p = 0.03).
Lans et al. demonstrated that patients who underwent neuroma excision followed by repair/reconstruction had lower numeric rating pain scores, lower PROMIS pain interference scores, and higher PROMIS upper extremity scores.
While targeted muscle reinnvervation is a useful technique to prevent or treat neuroma pain, it is more commonly performed in the setting of amputation.
A 45-year-old woman has pain and numbness in the right hand and forearm. There are no motor disturbances. Semmes-Weinstein monofilament testing shows decreased sensation in the index and long fingers, thumb, and palm. Phalen’s and Tinel’s signs are negative over the carpal tunnel.
These findings are most consistent with which of the following?
(A) Anterior interosseous syndrome
(B) C5 cervical radiculopathy
(C) Carpal tunnel syndrome
(D) Cubital tunnel syndrome
(E) Pronator syndrome
The correct response is Option E.
Although the sensory and motor deficits of carpal tunnel syndrome and pronator syndrome are similar, the sensory deficit within the palmar cutaneous region best differentiates pronator syndrome from carpal tunnel syndrome. This patient has findings consistent with pronator syndrome, or compression of the median nerve within the proximal
forearm. Sites of potential entrapment of the median nerve include the ligament of Struthers in the distal arm, the lacertus fibrosis at the level of the elbow, the pronator teres muscle, and the arch of the flexor digitorum superficialis muscle. Although symptoms are similar to carpal tunnel syndrome, sensory findings typically occur more proximally. Symptoms can be reproduced with active elbow flexion with the elbow in pronation, resisted elbow flexion, or resisted pronation with flexion of the wrist. Phalen’s sign is negative in most patients with pronator syndrome.
Anterior interosseous syndrome results from compression of the anterior interosseous branch of the median nerve in the forearm. Affected patients have poorly defined pain in the forearm and weakness of the profundus tendon of the index finger and the flexor pollicis longus tendon but no sensory deficit. Cervical radiculopathy at C5 is characterized by radicular-type pain in the lateral aspect of the upper arm and forearm. Cubital tunnel syndrome is caused by entrapment of the ulnar nerve in the region of the elbow. Affected patients have sensory deficits in the small finger and ulnar aspect of the ring finger.
Which of the following is an expected outcome after TMR?
A) Improved prosthetic control
B) Increased phantom limb pain
C) Increased residual limb pain
D) Increased opiod consumption
E) Increased DASH score
Correct answer is option A.
TMR has been shown in clinical studies to improve prosthetic control with regard to the time required to complete standardized tasks. Phantom limb pain, residual limb pain and opiod consumption were all reduced in patients treated with TMR versus those treated with standard surgical amputation techniques including transection under traction. DASH scores have been shown to improve (decrease) following TMR.
Which of the following diagnostic findings is most consistent with a recovering motor nerve injury?
A) Decreased motor unit potential amplitude
B) Decreased motor unit recruitment
C) Fibrillation potentials
D) Nascent potentials
E) Positive sharp waves
The correct response is Option D.
Electrical studies of a recovering nerve injury would show nascent potentials. This finding usually precedes the onset of clinically evident voluntary movement in the muscles innervated by the injured nerve. Nascent potentials appear several months after injury and result from axonal regeneration. Decreased motor unit potential amplitude, fibrillation potentials, positive sharp waves, and decreased motor unit recruitment are possible diagnostic findings in the setting of a nerve injury, but they are not indicative of recovery. Nerve lesions that spontaneously recover are usually treated nonsurgically, whereas those without recovery are explored and reconstructed. As a general rule, nerve regrowth occurs at approximately 1 inch per month or 1 millimeter per day. Motor endplates degrade at about 1% per week, hence the maximum length that a nerve can grow to restore motor function is approximately 13 to 18 inches. Repairs at the brachial plexus level rarely result in the recovery of any intrinsic muscle function. Sensory end organs, however, remain viable and can be reinnervated even after many years.
A 32-year-old man is brought to the emergency department after sustaining a crush injury to the right forearm when the arm became caught in a machine. On physical examination, there is severe tenseness over the arm. The patient has pain in the forearm with passive motion of the fingers. Radiographs show no evidence of fracture. Doppler ultrasonography shows weak signals over the radial artery. Which of the following is the most appropriate management?
(A) Angiography and infusion of tissue plasminogen activator
(B) Escharotomy in the emergency department
(C) Fasciotomy under general anesthesia
(D) Hyperbaric oxygen therapy
(E) Observation and intravenous administration of fluids
The correct response is Option C.
The most appropriate management of this patient is fasciotomy under general anesthesia. These findings are consistent with compartment syndrome, which is compromise of circulation and tissue perfusion resulting from increased pressure within functional compartments. This condition is characterized by pain, pallor, paresthesia, and pulselessness. Because ischemia typically becomes irreversible after eight hours, treatment should not be deferred until these findings are noted because they often occur late. Compartment pressures can be measured using a hand-held pressure-monitoring device, calibrated manometer, or blood pressure cuff. Various incisions can be used for the fasciotomy procedure, but the carpal tunnel must be released, and three compartments of the forearm (volar compartment, dorsal compartment, and mobile wad) must be released superficially and deeply.
Because this patient has findings consistent with compartment syndrome, surgery should be performed urgently to prevent or minimize the complications resulting from increasing compartment pressures. Prolonged ischemia can lead to muscle necrosis and nerve injury. In the alert, competent patient, the diagnosis of compartment syndrome can be made on clinical examination alone. Pain accentuated by passive stretching of the involved muscle compartment is the hallmark of this condition. Pain on passive motion is the most consistent early sign. Swelling or tenseness of the affected compartments may also be noted.
In patients who have sustained head trauma or spinal cord injuries, compartment pressures may need to be measured. Compartment pressures greater than 30 mmHg, or greater than 20 mmHg in a patient with hypotension, are diagnostic. Distal pulses and perfusion are typically unaffected soon after injury because the radial arteries pass adjacent to and between the muscle compartments. Sensation may be normal or diminished. Diminished neurovascular status is often a late finding.
The most appropriate next step is fasciotomy to decompress the involved muscle compartments. Because collateral circulation is retained to a greater extent in the muscle periphery, profound ischemia is more likely to be noted in the central portion of the muscle belly. The flexor digitorum profundus, flexor pollicis longus, flexor digitorum superficialis, and pronator teres will be affected most significantly, and the wrist flexors and extensors and the brachioradialis muscle usually sustain more moderate damage.
Observation and intravenous administration of fluids are inappropriate in a patient with suspected compartment syndrome. Any delay in decompression will only worsen tissue necrosis. Hyperbaric oxygen therapy has been shown to be beneficial in patients with compartment syndrome but does not replace fasciotomy as the treatment of choice. Angiography and infusion of tissue plasminogen activator (TPA) are indicated in patients with arterial thrombosis or embolization. Escharotomies are typically performed in the emergency department for removal of circumferential eschar in burn patients.
A 51-year-old woman is evaluated because of numbness and tingling of the dorsal and palmar aspects of the left hand, extending to the ring and little fingers, with worsening symptoms at night. Physical examination shows weakness of finger abduction in the hand. Which of the following is the most likely electrodiagnostic finding?
A) Decreased median conduction velocity from above elbow to wrist
B) Decreased ulnar conduction velocity from above elbow to wrist
C) Decreased ulnar conduction velocity from below elbow to wrist
D) Prolonged median sensory latency from wrist to digit
E) Prolonged ulnar sensory latency from wrist to digit
The correct response is Option B.
This patient exhibits symptoms of ulnar nerve compression at the cubital tunnel. Cubital tunnel syndrome is characterized by numbness and tingling in the ulnar nerve distribution (ulnar side of hand, involving little finger and ulnar half of ring finger) and can lead to intrinsic weakness. Compression occurs at the level of the elbow, with slowing of nerve conduction across the area of compression. Electrodiagnostic findings in ulnar nerve compression consist of decreased ulnar conduction velocity in the segment from above elbow to the wrist. Comparison of conduction velocities between above elbow to wrist and below elbow to wrist may show a difference, with nerve conduction being faster when measured from below the elbow, as the area of compression is not traversed. Conduction velocities from below elbow to wrist should not be affected. Ulnar nerve compression at the cubital tunnel can be distinguished from compression at the Guyon canal, as symptoms in the dorsal hand are not involved during nerve compression at the Guyon canal (at the level of the wrist), because the dorsal sensory branch of the ulnar nerve branches proximal to the wrist.
Prolonged median sensory latency from wrist to digit is seen in carpal tunnel syndrome.
A 21-year-old man comes to the office because he has had absence of sensation of the right thumb since he underwent repair of the digital nerve on the opposition side of the digit one year ago. On physical examination, Tinel sign is absent at the surgical scar. After surgical exploration and debridement of the thumb, a 3-cm nerve gap is noted. Which of the following is the most appropriate method of digital reconstruction?
A) Mobilization of the free nerve ends and primary repair
B) Polyglycolic acid tube conduit
C) Posterior interosseous nerve grafts
D) Radial sensory nerve graft
E) Vein conduit
Correct answer is C.
Repair or reconstruction of a digital nerve requires a tensionless technique. With tension, repair of the nerve will cause scarring and form a neuroma. If the gap is too large, a graft or conduit is required for a tensionless reconstruction.
The terminal posterior interosseous nerve graft is ideal because it provides a nerve with similar caliber for the repair.
Harvesting of this nerve avoids a donor deficit because at the level of the distal forearm wrist it only provides for wrist sensation.
Large nerve defects should not be reconstructed with vein or polyglycolic acid tube conduits.
The radial sensory nerve is too large in diameter. Additionally, the sensory loss would be more problematic and would risk a painful neuroma.
A 30-year-old man is evaluated after sustaining a laceration of the left ulnar nerve at the level of the mid humerus. Exploration and direct repair of the ulnar nerve are performed immediately. Which of the following interventions is most likely to result in optimal recovery of hand function?
A) Anterior interosseus nerve transfer to the ulnar nerve
B) Dynamic splinting
C) Electrical stimulation of the ulnar nerve
D) Flexor digitorum superficialis tendon transfer to the A2 pulley
E) Wrist extensor tendon transfer to the lumbricals
The correct response is Option A.
High ulnar nerve injuries are plagued by poor recovery of intrinsic function even when the nerves are repaired under optimal conditions. To maximize recovery and restore intrinsic function in the hand, one of the most effective interventions is transfer of the motor branch of the anterior interosseus nerve to the motor branch of the ulnar nerve at the wrist. Recently, this has been shown to also be useful as a “babysitter” transfer, potentially retaining motor endplates in the small muscles of the hand while a primarily repaired ulnar nerve regenerates.
Dynamic splinting has played a role in radial palsies and is frequently employed to overcome joint contractures that are not fixed (with a hard endpoint). This would not assist in hand recovery in this setting.
Electrical stimulation performed by a hand therapist helps in retraining innervated muscles but will not improve function in the denervated small muscles of the hand.
Tendon transfers have been the mainstay of functional restoration when nerve repair is not possible and/or the timeframe that has elapsed is great enough to make successful reinnervation of the target muscles unlikely. Both the wrist extensor-to-lumbrical transfer and the flexor digitorum superficialis transfer have been used to correct the “clawing” associated with ulnar palsies.
A 35-year-old woman has pain in the medial elbow and numbness and tingling of the ring and little fingers. Her symptoms are exacerbated by flexing the elbow with the forearm in supination. The most likely cause of this patient’s findings is nerve entrapment within which of the following structures?
(A) Arcade of Frohse
(B) Arcade of Struthers
(C) Lacertus fibrosis
(D) Leash of Henry
(E) Ligament of Struthers
The correct response is Option B.
This patient has cubital tunnel syndrome, or compression of the ulnar nerve at the level of the elbow. Characteristic findings include numbness in the dorsoulnar aspect of the hand, in the little finger, and in the ulnar aspect of the ring finger, as well as weakness of the ulnar extrinsic and intrinsic muscles. Although there are several potential sites of nerve entrapment, it is most likely to occur within the arcade of Struthers. This is a group of fascial bands from the medial intermuscular septum that can entrap the nerve, such as following anterior transposition. Another potential site of entrapment is the band of Osborne, which constricts the ulnar nerve as it passes through the cubital tunnel. Release of this band is critical during neuroplasty.
Entrapment of the deep branch of the radial nerve, or posterior interosseous nerve, can occur at the arcade of Frohse, which is a fascial band located along the supinator muscle in the forearm, or at the vascular leash of Henry, which is a sling of radial recurrent vessels that crosses the radial nerve.
The lacertus fibrosus, a dense sheet of aponeurotic fascia that extends from the biceps tendon to the flexor muscle mass, is a potential site of entrapment of the median nerve at the level of the elbow. This nerve can also become entrapped more proximally by the ligament of Struthers, which forms between the supracondylar humeral process and the medial epicondyle.
A 65-year-old man with tetraplegia to the level of C5-6 has the forearm supination deformity shown in the photograph above. On examination, the supination deformity can be passively corrected. In order to relieve the deformity and improve arm function, which of the following is the most appropriate management?
(A) Release of the biceps tendon
(B) Redirecting the brachioradialis tendon into the flexor carpi ulnaris tendon
(C) Redirecting the biceps tendon through the interosseous membrane
(D) Transfer of the triceps tendon to the biceps tendon
(E) Transfer of the biceps tendon to the brachialis tendon
The correct response is Option C.
In order to permanently correct this patient’s supination deformity and improve arm function, the biceps tendon should be redirected through the interosseous membrane. The supination deformity shown in the photograph is common to patients who have C5-6 tetraplegia, but the resting hand position results in loss of function and a displeasing aesthetic appearance. Functional improvement can be achieved by performing a tendon transfer to place the hand in a pronated position (eg, a palm-down position on a table top). This will improve the current aesthetic appearance and allow further tendon transfers to potentially establish key pinch. Because the biceps tendon is the strongest supinator in the forearm, it can be redirected through the interosseous membrane, then reattached to itself to establish forearm pronation. Redirecting the tendon insertion will convert a supinator tendon into a pronator tendon.
Release of the biceps tendon will impair elbow flexion and further weaken upper extremity strength. The brachioradialis tendon, which is the strongest elbow flexor, inserts into the ulna and does not influence supination and pronation in the forearm. Transferring the triceps to the biceps or the biceps to the brachioradialis will not correct the supination deformity.
A 30-year-old woman comes to the emergency department after cutting herself with a kitchen knife. Surgical exploration shows that the median nerve had been cut at the distal forearm. The distal nerve is relatively fixed, but the proximal nerve has been lifted and twisted. Immediate repair is planned. The motor fibers of the proximal nerve end are most likely in which of the following locations relative to the sensory fibers?
A ) Dorsal and radial
B ) Dorsal and ulnar
C ) Volar and radial
D ) Volar and ulnar
The correct response is Option C.
At the level of the distal forearm, the median nerve is a mixed nerve comprised of both motor (20%) and sensory (80%) fibers. The motor fibers become the thenar branch, which innervates the abductor pollicis brevis (AbPB), opponens pollicis (OP), and flexor pollicis brevis (FPB). The FPB is located distal to the AbPB and OP and also has innervation from the ulnar nerve, which is why patients with median nerve injuries can sometimes still bring the thumb to the little finger. The thenar nerve can be injured with a carpal tunnel release procedure. After coursing into the carpal tunnel, these median nerve motor fibers leave the median nerve volar and radial to the sensory fibers of the median nerve through a variety of branching patterns.
When patients have clean-cut injuries to nerves, the nerves can be repaired primarily. In a contaminated, dirty wound caused by a crush and mutilating injury, it can be difficult to determine the nonviable nerve required for debridement before repair. In the scenario described, the nerve ends are labeled with a permanent suture for later identification and repair at a second stage. In general, sensory-only nerves can be repaired by epineurial approximation, and group fascicular repair can be considered for mixed nerves.
A 50-year-old woman has paresthesias of the right thumb six hours after undergoing anatomic open reduction and rigid internal fixation of a fracture of the right distal radius. The pain, numbness, and weakness are worsening. Which of the following is the most appropriate next step in management?
(A) Application of ice and elevation of the extremity
(B) Semmes-Weinstein monofilament testing
(C) Open carpal tunnel release
(D) Release of Guyon’s canal
(E) Surgical exploration of the fracture site
The correct response is Option C.
In this patient who has acute carpal tunnel syndrome, the most appropriate management is open release of the carpal tunnel. Acute carpal tunnel syndrome can occur following injury, infection, or hemorrhage. Although appropriate reduction and stabilization of the fracture should typically be followed by rehabilitation of the soft tissues and wrist joint, open decompression of the median nerve in the carpal canal is the only logical next step in a patient who has developed acute carpal tunnel syndrome. Limited exposure techniques are contraindicated in patients with fractures.
Although application of ice and elevation of the extremity are part of normal fracture management, this course would be inadequate in a patient who has acute compression of the median nerve. Semmes-Weinstein monofilament testing will provide objective evidence of median nerve pathology but will not relieve the pain, numbness, and weakness. Release of Guyon’s canal is appropriate for those patients who require decompression of the ulnar nerve at the wrist. Surgical exploration is recommended for definitive management of fractures not associated with carpal tunnel syndrome or other complications, and may not even be necessary in patients with simple fractures.
A 20-year-old woman presents for repair of a significant degloving injury to her dominant right thumb. During the soft-tissue repair, a 4-cm defect is noted in the radial proper digital nerve. Which of the following is the most appropriate technique for nerve repair?
A) Autologous nerve graft
B) Autologous vein graft
C) Collagen conduit
D) Nerve transposition
The correct response is Option A.
For nerve gaps 3 cm or longer that are not amenable to repair, peripheral nerve grafts are the most reliable choice. Proper microsurgical nerve repair requires meticulous, atraumatic technique with appropriate magnification, instrumentation, and sutures. Primary repair is recommended when a tension-free anastomosis is possible. In this case, primary repair is not possible, even with nerve mobilization or transposition. Use of these autologous grafts is limited by donor site supply and morbidity, loss of sensation, and possible neuroma formation.
Various nerve conduits such as silicone tubes, biologic tubes such as vein grafts, and biodegradable conduits such as collagen or polyglycolic acid are limited to small diameter nerves with shorter nerve gaps (2 to 3 cm). There appears to be no significant regeneration beyond 3 cm. Nerve transpositions are not performed for digital nerve repair.
A 37-year-old man has severe pain, swelling, and discoloration of the right hand one month after sustaining a crush injury to the dorsal aspect of the hand. A 4-cm laceration was repaired at the time of injury; there were no fractures or tendon injuries. On examination, the hand is swollen and stiff.
These findings are most consistent with which of the following conditions?
(A) Osteomyelitis
(B) Posttraumatic arthritis
(C) Reflex sympathetic dystrophy
(D) Secretan’s disorder
(E) Suppurative tenosynovitis
The correct response is Option C.
This patient’s findings are most consistent with reflex sympathetic dystrophy (RSD) or complex regional pain syndrome (CRPS), which manifests as a progressive or complex pain syndrome. Severe pain, swelling, stiffness, and
discoloration of the affected part are characteristic. These changes are thought to result from vasomotor instability of the sympathetic nervous system. Hyperhidrosis, osteoporosis, and trophic changes may also occur. The stages of reflex sympathetic dystrophy are acute, subacute, and chronic.
Osteomyelitis is a bone infection that develops secondary to an adjacent wound, joint, or tenosynovial infection. Osteomyelitis can also arise from blood-borne pathogens.
Patients with posttraumatic arthritis have joint pain, stiffness, and swelling that develop following intra-articular injury; however, the pain is typically less severe than in patients with RSD.
Secretan’s disorder or peritendinous fibrosis is often associated with minor work-related trauma. It is characterized by edema of the dorsal aspect of the hand and factitious lymphedema of the hand. This condition is typically not associated with the severe pain of RSD.
Suppurative tenosynovitis is characterized by fusiform swelling, tenderness along the flexor tendon sheath, and increased pain with passive extension or semiflexed positioning of the finger.
A neonate has C5-6 brachial plexus palsy at birth. Complete recovery of function is most likely in this patient if some activity is demonstrated in the deltoid and biceps muscles by how many months of age?
(A) 2
(B) 4
(C) 6
(D) 8
(E) 12
The correct response is Option A.
In neonates who have brachial plexus palsy at birth, neurologic outcome correlates directly with the severity of the brachial plexus injury. The evaluation and management of brachial plexus palsy remains somewhat controversial. A recognition of the natural history of this condition, along with more uniform evaluation procedures, has resulted in better care of affected neonates. One author recommends using the rate of biceps recovery as an indication for early operative exploration of the brachial plexus. However, the course of biceps recovery over time has been shown to incorrectly predict outcome in 13% of patients. A more complete evaluation of elbow flexion and extension of the wrist, finger, and thumb seems to be more predictive of outcome.
Nevertheless, those infants with C5-6 injuries who begin to exhibit some function of the deltoid and biceps muscles by age 2 months will most likely have normal arm function. In contrast, infants who do not exhibit strong biceps contractions by age 6 months will likely not ultimately attain completely normal arm function.
A 44-year-old woman is evaluated because of a 6-month history of pain in her right upper chest and back, intermittent coolness in her right hand, and numbness and tingling of her right ring and little fingers. Results of the Adson test show a decreased radial pulse on the affected side, and the Roos test reproduces the patient’s symptoms on the affected side. Which of the following is the most appropriate next step?
A) Decompression of ulnar nerve at elbow
B) Noninvasive vascular study and electrodiagnostics
C) Resection of anterior and middle scalene muscles
D) Transaxillary resection of first rib
E) Observation
The correct response is Option B.
Three kinds of surgical procedures are employed to treat thoracic outlet compression syndrome (TOCS): transaxillary resection of the first rib, transcervical anterior and medial scalenectomies, and combined transaxillary first rib resection with immediate anterior and medial scalenectomies. This is the most complete procedure for total decompression of the thoracic outlet region. Because 70% of cases have soft-tissue involvement as the etiology of TOCS, current treatment includes transcervical anterior and middle scalenectomy in most TOCS cases.
Prior to any surgery, patients are treated conservatively with an exercise program for TOCS involving scalene stretching, first rib intercostal relaxation, nerve gliding, muscle relaxants, and pain patches for painful myofascial trigger points. Unfortunately, these conservative treatment modalities may yield only limited temporary help.
TOCS is usually classified in two groups. A neurogenic group comprises nearly 90% of all cases. This group usually has upper extremity pain, numbness, and tingling. A true vascular group comprises 10% of cases. Approximately 50% of patients still complain of coldness in the extremity. Approximately 40 to 50% of TOCS cases have concomitant peripheral nerve compression symptoms. Simple distal decompression of nerves will not usually lead to near-complete resolution of symptoms in cases of true TOCS.
There are two tissue groups that cause TOCS: soft tissue and osseous structures. The soft-tissue group includes anterior and middle scalene and their sheath, ligaments, and bands. This group comprises at least 70% of all TOCS cases because of congenital and acquired changes in the soft tissues. The osseous group comprises 30% or less of all TOCS cases and includes cervical rib, changes in the first rib, and clavicle due to injury.
Because TOCS can present with several different findings (including vascular and neurological compromise), it is advisable to work up these findings prior to committing to a treatment course. Noninvasive vascular studies and electrodiagnostics is the most reasonable first step in working up and treating these patients.
Volkmann ischemic contracture occurs when forearm compartment pressure is above 30 mmHg for a minimum of approximately how many hours?
A ) Less than 2
B ) 3-5
C ) 6-12
D ) 18-24
E ) Greater than 24
The correct response is Option C.
Permanent neuromuscular damage occurs at 12 hours, leading to subsequent Volkmann contracture. Timeline of ischemia, shown experimentally, is capillary endothelial damage at 3 hours; partially reversible muscle and nerve injury occurs at 6 hours.
Non-operative management for carpal tunnel syndrome includes splinting the wrist in which position?
A) Extension
B) Volarflexion
C) Radial deviation
D) Ulnar deviation
E) Neutral
Correct answer is option E.
Non-operative treatment options for carpal tunnel syndrome attempt to decrease the pressure around the median nerve. Nighttime splints of the wrists, attempt to reduce the pressure within the carpal canal by preventing flexion and extension postures. Oral anti-inflammatory agents are used to reduce swelling in the canal and for their analgesic effect. Activity modification may also help avoid symptom-provoking movements.
In short, measures that have been described for the non-operative treatment of carpal tunnel syndrome include non-steroidal anti-inflammatory medications, rest, splinting, steroid injection, diuretics, vitamin B6, magnets, and ergonomic changes of work environment.
A Froment sign is created by retained function of which of the following muscles?
A) Adductor pollicis
B) Extensor pollicis brevis
C) Extensor pollicis longus
D) Flexor pollicis brevis
E) Flexor pollicis longus
The correct response is Option E.
Ulnar nerve injuries are particularly devastating and have significant sensory and motor functional consequences. Proximal to the elbow, the expected motor deficits include absence of the flexor carpi ulnaris, the flexor digitorum profundus to the middle/ring/small fingers, the hypothenar muscles (opponens digiti minimi, abductor digiti minimi, flexor digiti minimi brevis), the third and fourth lumbrical muscles, the dorsal and palmar interosseous muscles, the adductor pollicis, and the deep head of the flexor pollicis brevis. A Froment sign is observed when the patient attempts to pinch but is unable to activate the adductor pollicis (ulnar innervated) and compensates by activating the flexor pollicis longus by flexing the interphalangeal joint (median nerve innervated). Extensor pollicis longus (EPL), extensor pollicis brevis (EPB), and flexor pollicis brevis (FPB) are not involved in the thumb interphalangeal joint flexion that produces Froment sign.
A 30-year-old man undergoes evaluation of a stab wound to the left upper extremity. A photograph is shown. Examination shows that the injured nerve is completely transected. Supination is weak, and he cannot flex his elbow in a supinated position. Which of the following areas is most likely to be insensate?
A) Dorsal little finger
B) Index finger pad
C) Posterior arm
D) Radial forearm
E) Thumb pad
The correct response is Option D.
The patient has an injury to the musculocutaneous nerve. This nerve provides motor axons to the brachialis, biceps brachii, and coracobrachialis. Patients with a musculocutaneous nerve transection cannot flex the elbow when supinated; the brachioradialis would provide some elbow flexion in a pronated position. The biceps brachii is the strongest supinator of the forearm, so patients with this injury have weak supination. The musculocutaneous nerve also provides sensory axons to the lateral brachial and lateral antebrachial cutaneous nerves. Patients with transection of this nerve would be insensate on the lateral arm and the radial side of the forearm.
Sensation to the posterior arm is provided by the posterior brachial cutaneous nerve, a branch of the radial nerve.
Sensation to the thumb pad is provided by the median nerve.
Sensation to the dorsal little finger proximally is provided by the dorsal sensory branch of the ulnar nerve and distally by the ulnar and radial proper digital nerves, branches of the ulnar nerve.
Sensation to the index finger pad is provided by the median nerve.
A 52-year-old man comes to the office because he has had a clinical diagnosis of carpal tunnel syndrome including numbness and dysesthesia of the thumb, index, and long fingers of both hands for the past four months. He says his symptoms worsen at night and when his wrist position changes while driving. Electrodiagnostic studies show delayed motor and sensory latencies and slowed conduction velocity at the wrist, indicating a conduction block of the median nerve. This block is most likely caused by localized nerve ischemia that results in which of the following?
A ) Blocking of calcium channels
B ) Failure to maintain the resting nerve potential at −30 mV
C ) Opening of sodium channels
D ) Prevention of nerve membrane depolarization
E ) Thickening of the myelin sheath
The correct response is Option D.
Local nerve ischemia prevents depolarization. A charge is maintained across the axon membrane with the interior of the axon having a charge of −90 mV. When the resting membrane potential reaches −50 mV, the membrane depolarizes. Since there is a relatively greater concentration of K+ ions on the inside of the axon, there is a slow leak of K+ ions, which causes the inside of the axon to become less negative. The ATP-dependent pump imports K+ and exports Na+, maintaining the normal resting membrane potential at −90 mV. Maintenance of this ionic charge separation across the membrane requires energy, and the mechanism stops when the energy supply is interrupted, as with local ischemia. This is one of the mechanisms for conduction block that occurs with nerve compression. Various membrane channels consist of proteins embedded in the phospholipid membrane bilayer that allow passage of Na+, Ca2+, and K+ ions. With chronic nerve compression, the myelin sheath disintegrates and saltatory conduction between nodes of Ranvier ceases.
A 42-year-old woman comes to the office for evaluation of a severely painful mass on the upper right arm and numbness in the right forearm six months after undergoing decompression neuroplasty with submuscular transposition. This procedure was performed for progressively worsening compression of the dominant ulnar nerve at the elbow. She developed severe complex regional pain syndrome two weeks after the procedure. Physical examination shows a 0.5-cm mass proximal and central to the medial epicondyle that is adherent to the skin and extremely sensitive. Examination shows decreased sensation to light touch over the ulnar volar forearm. Following excision of the neuroma, which of the following is the most appropriate next step in management?
A) Medial epicondylectomy
B) Nerve stump implantation
C) Stress occupational therapy program
D) Topical lidocaine patch
E) Ulnar nerve vein wrap
Correct answer is B.
The ulnar nerve neuroplasty is complicated by complex regional pain syndrome (CRPS) with an associated nerve injury. The medial antebrachial cutaneous nerve (MABC) of the forearm originates from the medial cord of the brachial plexus (shown in the diagram). The MABC derives from the C8 and T1 roots. In the mid arm, the MABC and the basilic vein pierce the deep fascia and provide sensation to the overlying ulnar volar forearm skin. The MABC can be injured during ulnar nerve at the elbow neuroplasty. If CRPS develops from an identifiable nerve injury, resolution is best achieved by identifying and correcting the nerve injury. In the scenario described, excision and tensionless implantation into adjacent muscle or bone is the most appropriate option.
Medial epicondylectomy would not address the primary MABC neuroma, nor would wrapping the ulnar nerve with a vein graft. A stress occupational therapy program can be useful in CRPS without an identifiable nerve injury. With the injury described, however, the pain more likely would worsen.
Topical transdermal anesthetic patches can alleviate but not resolve the nerve pain.
A 15-year-old girl has absence of sensation of the long finger and radial side of the ring finger 18 months after undergoing operative repair of a partial injury to the median nerve in the wrist. Sensation is normal in the thumb, index, and small fingers and in the ulnar side of the ring finger. An intraoperative photograph is shown above.
Which of the following is the most appropriate management?
(A) Internal neurolysis of the median nerve
(B) Excision of the neuroma only
(C) Excision of the neuroma and epineural repair
(D) Excision of the neuroma and sural nerve grafting
(E) Resection of the median nerve and epineural repair
The correct response is Option D.
In this patient who has a neuroma in-continuity, the most appropriate management is excision followed by sural nerve grafting. Neuroma in-continuity is often difficult to diagnose and treat. Serial clinical examination and electrodiagnostic testing are essential for diagnosis. Although operative exploration can improve hand function and result in a good outcome, the functional fascicles that lie adjacent to the neuroma are at risk for injury. Nerve conduction velocity studies should be performed intraoperatively to identify the nonfunctioning fascicles that lead into
and out of the neuroma. The surgeon should take great care during excision of the neuroma to avoid damaging the functional fascicles. Following excision, autogenous grafting with a donor nerve such as the sural nerve should be performed.
Internal neurolysis would not re-establish the continuity of the involved fascicles. Simple excision of the neuroma will result in recurrence. Excision and epineural repair would place excessive tension on the neurorrhaphy and potentially lead to the development of another neuroma. Resection of the median nerve is an excessive procedure that would eliminate the functional portion of the nerve.
A 65-year-old man presents to the office with symptoms and examination findings consistent with bilateral carpal tunnel syndrome. Medical history includes recent rupture of the left biceps tendon and several trigger fingers. Biopsy of the tenosynovium is performed during carpal tunnel release and the pathology report shows a positive Congo red stain. Which of the following diagnoses is most likely and should prompt further consultation?
A) Amyloidosis
B) Diabetes mellitus
C) Fibromyalgia
D) Malingering
E) Rheumatoid arthritis
The correct response is Option A.
A recent study showed that 10% of men over 50 years old and women over 60 years old with bilateral carpal tunnel syndrome had positive tenosynovial biopsies for amyloid. This can be a devastating disease if left to affect the heart or other organs and can be diagnosed with a simple biopsy during carpal tunnel release. Other findings suggestive of amyloidosis include a spontaneous biceps rupture, trigger finger, and spinal stenosis.
Patients with diabetes and rheumatoid disease have a higher incidence of carpal tunnel syndrome than the general population but the mention of biceps rupture points to the diagnosis of amyloidosis. Fibromyalgia and malingering have not been shown to be related to carpal tunnel syndrome.
The most common cause of the pronator syndrome is considered to be compression of the median nerve by:
A) The fibrous arch of the superficialis muscle
B) The lacertus fibrosus
C) The supinator muscle
D) Tendinous bands within the pronator muscle
E) Arcade of Frohse
Correct answer is option D.
Compression of the median nerve in the proximal forearm occurs by four structures, the fibrous arch of the superficialis muscle, the lacertus fibrosus (bicipital aponeurosis), Ligament of Struthers and the tendinous bands within the pronator teres muscle. Of these the fibrous bands within the pronator are considered most common. The supinator muscle is involved in compression of the posterior interosseous nerve.
A 36-year-old man has pain in the forearm and paresthesia in the hand that are exacerbated with activity. He also has decreased sensation and paresthesia in the radial side of the palm, at the base of the thenar eminence, in the thumb, index, and long fingers, and along the radial side of the ring finger.
These findings are most consistent with which of the following syndromes?
(A) Anterior interosseus syndrome
(B) Carpal tunnel syndrome
(C) Cubital tunnel syndrome
(D) Pronator syndrome
(E) Radial tunnel syndrome
The correct response is Option D.
This 36-year-old man has findings consistent with pronator syndrome, or proximal compression neuropathy of the median nerve. The median nerve may be entrapped beneath the supracondylar process and ligament of Struthers in the distal third of the humerus or at the lacertus fibrosis, the pronator teres muscle, or the arch of the flexor digitorum superficialis muscle.
Functional testing can be used to determine the site of compression. Compression at the ligament of Struthers is indicated by exacerbation of symptoms with flexion of the elbow against resistance. In patients who have compression of the median nerve at the lacertus fibrosis, symptoms are exacerbated by active flexion of the elbow with the forearm in pronation. Patients who have pain with resisted pronation of the forearm during wrist flexion should undergo surgical exploration of the median nerve where it passes through the pronator teres muscle. However, if resisted flexion of the superficialis muscle of the long finger exacerbates symptoms, the superficialis arch should be inspected carefully during surgical exploration.
Electrodiagnostic studies can be used to confirm the diagnosis and determine the level and severity of nerve injury.
Release of the median nerve is appropriate management. During the procedure, the median nerve should be explored starting at a point 5 cm proximal to the elbow and continuing distally. Each of the potential sites of compression should be carefully divided to ensure that the nerve is adequately released.
Patients with anterior interosseous syndrome have poorly defined pain in the proximal forearm that is relieved with rest. They also have weakness or paralysis of the flexor digitorum profundus tendon of the index and long fingers, flexor pollicis longus tendon, and pronator quadratus muscle.
Carpal tunnel syndrome is the most common compression neuropathy of the upper extremity. It is characterized by pain, especially at night, and numbness and weakness in the distribution of the median nerve at the wrist. Numbness in the region innervated by the palmar cutaneous nerve is uncommon.
Cubital tunnel syndrome, or entrapment of the ulnar nerve at the elbow, manifests as pain over the medial aspect of the proximal forearm. Numbness is noted in the dorsoulnar aspect of the hand, small finger, and ulnar aspect of the ring finger. Weakness can be demonstrated in the flexor digitorum profundus tendons of the ring and small fingers and in the ulnar intrinsic tendons, especially the first dorsal interosseous and abductor digiti minimi tendons.
Patients with radial tunnel syndrome have aching pain localized just below the elbow in the extensor mass and along the course of the radial nerve. Although there are four potential sites of compression within the radial tunnel, most patients have entrapment at the arcade of Frohse, which forms a ligamentous band over the deep radial nerve as the nerve enters the supinator muscle. Radial tunnel syndrome manifests as pain rather than specific numbness or weakness.
A 68-year-old man who is undergoing gadolinium-enhanced MRI for evaluation of chronic headaches has the onset of excruciating pain in the forearm after extravasation of approximately 250 mL of gadolinium into the forearm. Which of the following is the most appropriate next step?
(A) CT scan
(B) Measurement of compartment pressures
(C) Plain radiographs
(D) Pulse oximetry
(E) Ultrasonography
The correct response is Option B.
This patient who has sustained an extravasation injury during administration of radiologic contrast is at increased risk for compartment syndrome; therefore, the most appropriate next step is measurement of compartment pressures. Low-pressure extravasation injuries have been shown to occur with administration of contrast material. Because most contrast solutions contain nonionic, water-soluble materials, toxicity is typically less of a problem than with high-pressure injection injuries, which typically involve industrial chemicals or chemotherapeutic agents. However, high-osmolarity solutions are associated with an increased risk for local toxicity and may contribute to local tissue necrosis, especially if they are administered using automated high-pressure injection pumps. Because extravasation of more than 100 mL of contrast material has been associated with an increased incidence of compartment syndrome, compartment pressures should be measured, particularly because this patient has excruciating pain, which is the hallmark of compartment syndrome. Decompressive fasciotomy is indicated if the patient is normotensive and has compartment pressures greater than 30 mmHg, or if the patient is hypotensive and has compartment pressures greater than 20 mmHg.
The volar, dorsal, and mobile wad compartments are contained in the forearm; these compartments have been shown to be interconnected (in contrast to the compartments in the lower extremity). Because of these interconnections, release of the volar compartment alone may release the dorsal and mobile wad compartments sufficiently, and fasciotomy of the dorsal and mobile wad compartments may not be necessary. However, this is not an absolute occurrence. Release of the dorsal compartment has also been shown to decrease pressure in the mobile wad compartment. The flexor tendons are contained within the volar compartment. The dorsal compartment contains all of the extensor tendons, with the exception of the extensor carpi radialis brevis and longus, which are contained (along with the brachioradialis tendon) within the mobile wad compartment.
Pulse oximetry is useful for evaluating loss of perfusion, which is a late deficit in patients with compartment syndrome. Ultrasonography, plain radiographs, and CT scans are not helpful in establishing the diagnosis of compartment syndrome and would be unnecessary in any patient with symptoms of compartment syndrome who has increased compartment pressures.
What percentage of patients have symptomatic neuromas (moderate to severe residual limb pain) after transhumeral level amputation?
A) <20%
B) 20-40%
C) 41-60%
D) 61-80%
E) >80%
Correct answer is option B.
All transected nerves will form a neuroma, however not all of these become symptomatic. Several retrospective studies of upper limb amputation have demonstrated a 25-30% incidence of symptomatic neuroma causing moderate to severe residual limb pain. In studies of isolated finger amputation, the incidence is much lower (6-8%). Although the reason for this is unknow it is thought to be related to the size of the injured nerve.
A 69-year-old woman with type 2 diabetes mellitus is referred to the office because she has compression of the ulnar nerve at the right wrist secondary to an extrinsic burn scar contracture (shown). Physical examination shows weakness of the first dorsal interosseous muscle. Allen test shows perfusion of the hand predominantly by the radial artery. Surgical management includes neurolysis of the ulnar nerve at Guyon’s canal, with identification of the sensory and deep motor branches as shown. Which of the following is the most appropriate technique for coverage of the exposed ulnar nerve?
(A) Adjacent tissue rearrangement of the previously grafted skin
(B) Adipofascial turnover flap with repeat skin grafting
(C) Reverse posterior interosseous fasciocutaneous flap
(D) Reverse radial forearm fasciocutaneous flap
(E) Staged, pedicled groin flap
The correct response is Option C.
In this patient who is undergoing ulnar nerve decompression in the distal forearm and wrist, coverage with supple, vascularized tissue will decrease the risk of recurrent contracture and nerve compression.
Adjacent tissue rearrangement of the previously grafted skin will not address the underlying pathophysiology of the scar contracture. An adipofascial turnover flap based on the ulnar artery is not technically possible (because of perforator disruption from the neurolysis), whereas an adipofascial turnover flap based on the radial artery would not be reliable because of the zone of injury in the distal forearm. A staged, pedicled groin flap is relatively contraindicated, given the patient’s age and the potential development of severe stiffness of the hand. A reverse radial forearm flap requires sacrifice of the radial artery, jeopardizing perfusion of the hand.
The photographs shown below depict a reverse posterior interosseus flap. Based on the posterior interosseous vessels between the fifth and sixth dorsal compartments of the forearm, a reverse posterior interosseous flap can support a large skin paddle (18 _ 8 cm), easily reach the distal metacarpals, and include muscle and bone if needed. Donor site morbidity is negligible. In a clinical series of 80 patients who underwent distal coverage of hand and wrist defects with a reverse posterior interosseous flap, only four flaps were unsuccessful due to ischemia.
Free tissue transfer would be an acceptable alternative to a pedicled flap, but this was not listed as a possible option.
Which of these signs or symptoms should drive early surgical intervention?
A) Anesthesia of the small finger
B) Pain on the medial side of the forearm
C) Positive percussion test of the ulnar nerve at the elbow
D) The presence of intrinsic wasting
E) Failure of pillow splint
Correct answer is option D.
Entrapment syndromes of the ulnar nerve at the elbow generally present with pain out the medial side of the elbow. This may be accompanied by sensor disturbances involving the ulnar one and one-half fingers. Physical examination will demonstrate a positive percussion test over the ulnar nerve or a positive elbow flexion test with increased numbness in the distribution of the ulnar nerve with full flexion of the elbow. None of these, however is considered an indication for early operative intervention, but the presence of intrinsic wasting is considered an indication for early operative intervention.
The Jones transfer for radial nerve palsy, specifically flexor carpi ulnaris to extensor digitorum communis III-V, is most likely to have which of the following significant disadvantages?
A) Difficulty of dissection
B) Inappropriate excursion of donor tendon
C) Indirect line of pull requiring pulley creation
D) Poor synergy
E) Unacceptable postoperative rupture rate
The correct response is Option B.
Although the Jones transfers were practiced for years, there were significant disadvantages that led to them falling out of favor. Among the disadvantages are loss of flexor carpi ulnaris (FCU) as an important ulnar wrist stabilizer and weakness in flexion/ulnar deviation, which is a very important wrist motion. Additionally, the short excursion of FCU is inadequate to fully extend the fingers when transferred to extensor digitorum communis (EDC).
Subsequent modifications to the Jones technique by Boyes and others found better alternatives to the use of FCU. Standard Boyes transfers are:
PT to ECRL and ECRB
FCR to EPL and ABL
FDS-III to EDC (via interosseous membrane)
FDS-IV to EPL and EIP (via interosseous membrane)
A right-handed 34-year-old man has been unable to flex the distal interphalangeal joint of the right index finger and interphalangeal joint of the thumb for the past six months. There is no history of trauma. Physical examination shows normal two-point discrimination of the right hand; the muscles innervated by the ulnar nerve are unaffected.
Which of the following is the most likely cause of these symptoms?
(A) Anterior interosseus syndrome
(B) Cubital tunnel syndrome
(C) Posterior interosseous syndrome
(D) Pronator syndrome
(E) Radial tunnel syndrome
The correct response is Option A.
The most likely diagnosis is anterior interosseous syndrome (also known as Kiloh-Nevin syndrome). This condition is characterized by absence of function of motor units innervated by the anterior interosseous nerve. These motor units include the flexor pollicis longus tendon, the profundus tendons to the index and long fingers, and the pronator quadratus muscle. In affected patients, there is absence of flexion of the interphalangeal joint of the thumb and distal interphalangeal joints of the index and long fingers and weakness of pronation with the elbow in flexion. Anterior interosseous syndrome results in pure motor deficits; there are no sensory abnormalities.
In patients with this condition, the anterior interosseus nerve may be compressed within the tendinous bands (the deep head of the pronator teres tendon, origin of the flexor digitorum superficialis tendon of the ring finger, and origin of the flexor carpi ulnaris tendon) or accessory muscles (anomalous band connecting the flexor digitorum superficialis tendon to the flexor digitorum profundus, accessory flexor pollicis longus, and palmaris profundus tendons). Other causes include vascular anomalies (thrombosis of ulnar collateral vessels or an aberrant radial artery), bicipital bursa, trauma, fractures, or compression resulting from intravenous devices.
Cubital tunnel syndrome, or compression of the ulnar nerve at the elbow, results in sensory deficits of the ring and small fingers and the dorsoulnar aspect of the hand and motor deficits in the intrinsic and extrinsic muscles innervated by the ulnar nerve. Posterior interosseous syndrome is similar to anterior interosseous syndrome in that it also causes pure motor deficits without sensory findings. Affected patients have weakness in the muscles of the wrist and extensors of the thumb and fingers. Compression of the median nerve by the pronator muscle is unlikely because this patient does not have changes in sensation. Compression of the radial nerve in the radial tunnel primarily results in pain in the distribution of the radial nerve.
A 26-year-old man comes to the office 4 weeks after injuring his left shoulder while snowboarding. Physical examination shows limited abduction and forward flexion of the shoulder to 30 degrees. No additional abnormalities are noted. From which of the following areas of the brachial plexus does the affected nerve most likely arise?
A) Lateral cord
B) Lower trunk
C) Medial cord
D) Posterior cord
The correct response is Option D.
The axillary nerve (ventral rami of C5 and C6) arises from the posterior cord of the brachial plexus, giving off muscular branches to teres minor and deltoid. It also innervates the shoulder joint and the skin over the deltoid. Its close proximity to the inferior shoulder capsule as it courses on the anteroinferior border of the subscapularis and then through the quadrangular space, puts it at risk for injury.
The axillary nerve is most commonly injured during orthopedic surgeries such as shoulder arthroscopy, and open reduction and internal fixation (ORIF) of the proximal humerus, in which case, it is most commonly the result of closed traction injury. It can also be seen in the setting of an anterior glenohumeral joint dislocation or proximal humerus fracture, or as the result of a direct blow to the superior aspect of the shoulder. The majority of nerve injuries are temporary neurapraxias, which typically resolve within 6 to 12 months of injury; however, permanent nerve deficit can occur, requiring surgical intervention in the form of decompression, or reconstruction with nerve graft or nerve transfer from the radial nerve.
The lateral cord receives contribution from C5, C6, and C7 roots, and contributes to the musculocutaneous and median nerves. The medial cord receives contribution from C8 and T1 roots, and contributes to the median and ulnar nerves. There are no superior or anterior cords within the brachial plexus.
A 40-year-old construction worker comes to the office because he is unable to extend the left thumb (shown) six months after he sustained a saw injury to the dorsal aspect of the left mid forearm. At the time of the injury, the wound was washed and the skin was repaired in the emergency department. On physical examination, the patient is able to extend the wrist and fingers. No contractures are noted and all joints are supple. Which of the following is the most appropriate management at this time?
(A) Direct repair of the extensor pollicis longus tendon
(B) Transfer of the brachioradialis tendon to the extensor pollicis longus tendon
(C) Transfer of the extensor indicis proprius tendon to the extensor pollicis longus tendon
(D) Tenodesis of the extensor pollicis longus tendon to the extensor digitorum communis of the index finger
(E) Repair of the extensor pollicis longus tendon with intercalated tendon grafting
The correct response is Option C.
The extensor indicis proprius (EIP) is an independent extensor tendon to the index finger, which provides overlapping function with the extensor digitorum communis (EDC). The EIP can be transferred to provide independent thumb extension. Proximity of the EIP to the extensor pollicis longus (EPL) in addition to tendon length, which allows for a strong Pulvertaft weave, also favors the EIP-to-EPL tendon transfer. The EIP is located ulnar to the EDC of the index finger at the metacarpophalangeal (MP) joint. Its integrity must be verified before transfer by having the patient extend the index finger while holding the adjacent digits in flexion.
Direct repair with an intercalated tendon graft is not possible because of longstanding contracture, fibrosis, and foreshortening of the proximal muscle belly six months after injury. Therefore, direct repair of the EPL tendon and repair of the EPL tendon with intercalated tendon grafting are incorrect.
Tenodesis of the EPL to EDC of the index finger would improve thumb extension; however, thumb extension would not be independent of finger extension. This makes tenodesis of the EPL tendon to the EDC of the index finger less desirable than EIP-to-EPL tendon transfer.
Brachioradialis-to-EPL tendon transfer would also improve thumb extension; however, range of motion would be lost because the excursion of the brachioradialis is only 1 to 2 cm compared with an excursion of 3 to 5 cm for the EIP. This makes transfer of the brachioradialis tendon to the PEL tendon less desirable than EIP-to-EPL tendon transfer.
A 35-year-old, right-hand–dominant man presents with a 4-month history of right upper extremity weakness. The patient reports a history of sudden onset shoulder pain that began without trauma. The pain improved, but he has developed difficulty abducting the shoulder, externally rotating the shoulder, and flexing the elbow. MRI shows hourglass constrictions of the brachial plexus. Electrodiagnostic studies demonstrate the involvement of multiple peripheral nerves. Which of the following is the most likely diagnosis?
A) Brachial plexus avulsion
B) Guillain-Barré syndrome
C) Parsonage-Turner syndrome
D) Rotator cuff injury
E) Transverse myelitis
The correct response is Option C.
Acute brachial neuritis, also known as neuralgic amyotrophy or Parsonage-Turner syndrome, is an uncommon but well-recognized clinical entity. Patients characteristically present with acute-onset unilateral severe shoulder and/or arm pain that radiates, followed by progressive weakness and atrophy of the muscles in the shoulder girdle and arm. Pain is the initial symptom for 90% of patients. The etiology of the syndrome is thought to be idiopathic; however, it has been reported in various clinical situations, including post surgery, post infection, during pregnancy, during vigorous exercise, post trauma, and post vaccination. Patients exhibit significant variability in presentation regarding nerve involvement, muscle involvement, the extent of recovery, and recurrence. Diagnosis is made by clinical examination and supported by electrodiagnostic studies and imaging. Electrodiagnostic studies show multiple peripheral nerve lesions, rather than a brachial plexus localization. Parsonage-Turner syndrome is considered self-limited and is often managed conservatively; however, recovery may be protracted and incomplete, and a large percentage of patients never fully recover (30%). Surgical exploration has become more common for patients who do not show clinical or electrodiagnostic signs of recovery after several months. Nerve imaging will demonstrate hourglass constrictions, which are neurolysed at the time of exploration, sometimes in conjunction with nerve transfer.
These patients usually have full shoulder range of motion; additionally, imaging does not correlate with rotator cuff injury.
Avulsion of the brachial plexus would have a prodrome of trauma, and diagnosis would point to root involvement as opposed to more distal nerve pathology.
Guillain-Barré syndrome is usually preceded by infection or other immune stimulation that induces an aberrant autoimmune response targeting peripheral nerves and their spinal roots. These patients traditionally present with symmetric acute flaccid paralysis that can progress to respiratory failure.
Transverse myelitis describes a heterogeneous group of inflammatory disorders that are characterized by acute or subacute motor, sensory, and autonomic (bladder, bowel, and sexual) spinal cord dysfunction (traditionally bilateral), which does not correlate with this patient’s presentation.
A 20 year old man comes to the office after he sustained transection of the ulnar nerve of the left arm during a rollover motor vehicle accident. Physical examination shows a 5-cm transverse laceration in the proximal ulnar aspect of his left forearm. A photograph of the laceration after suture removal is shown. Microscope-assisted epineural repair of the transection is performed. As function is restored over time, which of the following movements will most likely be last to return?
(A) Abduction of the small finger
(B) Adduction of the thumb
(C) Flexion of the metacarpophalangeal joint of the small finger
(D) Flexion of the proximal interphalangeal joint of the small finger
(E) Ulnar €‘sided flexion of the wrist
The correct response is Option B.
The ulnar nerve is the terminal portion of the medial cord of the brachial plexus, after the medial head of the median nerve has separated from it, with fibers from C8-T1. It initially lies medial to the axillary artery and then to the brachial artery as it travels distally in the upper arm. It pierces the intermuscular septum and then follows the medial head of the triceps muscle to the groove between the olecranon process and the medial epicondyle. It gives off no branches in the arm. After the ulnar nerve passes through the cubital tunnel, it gives off articular branches and branches to the flexor carpi ulnaris (FCU) and the medial half of the flexor digitorum profundus (FDP). It travels between the two heads of the FCU and continues into the forearm between this muscle and the FDP.
In the distal half of the forearm, it is joined on its lateral side by the ulnar artery. Proximal to the wrist, the nerve gives off the dorsal sensory branch, providing sensation to the dorsal wrist and ulnar aspect of the hand. The ulnar nerve continues into the hand via Guyon €™s canal, where it splits into a superficial sensory branch and a deep motor branch. The superficial branch supplies the palmaris brevis and the skin of the hypothenar eminence and digital nerves to the small and ulnar side of the ring finger. The motor branch passes between the abductor digiti minimi (ADM) and the flexor digiti minimi (FDM), with the deep branch of the ulnar artery, perforates the opponens digiti minimi and follows the deep volar arch across the interossei, and finally innervates the adductor pollicis (AD) and the deep head of the flexor pollicis brevis.
Based on its path, ulnar €‘sided flexion of the wrist (FCU) would be expected early, followed by abduction of the small finger (ADM) and flexion of the metacarpophalangeal joint (FDM). Interosseus muscle function would manifest as ability to abduct and adduct the fingers, followed last by adduction of the thumb (AD). Flexion of the proximal interphalangeal joints of the fingers is a function of the flexor digitorum superficialis, which is innervated by the median nerve.
An otherwise healthy 58-year-old man comes to the office because of numbness of all fingers of the left hand. He says he first noticed symptoms after a cross-country drive 6 weeks ago. On physical examination, the thumb, index, and long fingers show sensitivity to the 2.83 Semmes-Weinstein monofilament. The ring and little fingers show sensitivity to the 3.22 monofilament. The little finger is held in an abducted position. Abductor pollicis brevis muscle strength is normal. First dorsal interosseous muscle strength is diminished. Which of the following anatomical structures is the most likely cause of these findings?
A) Arcade of Frohse
B) Lacertus fibrosus
C) Ligament of Struthers
D) Osborne ligament
E) Transverse carpal ligament
The correct response is Option D.
This scenario depicts a patient with ulnar nerve compression. Often patients who present with compression neuropathies give a history of numbness of all fingers; however, careful physical examination will show sensory abnormalities only in the anatomical location of the compression. The patient has weakness of the ulnar nerve innervated intrinsic muscles, the first dorsal interosseous muscle, but retains strength in the abductor pollicis brevis muscle. The diagnosis of ulnar nerve compression is suggested. The most common sight of ulnar nerve compression is at the elbow. The anatomical causes of all the nerve compression at the elbow are the arcade of Struthers, the medial intramuscular septum, the bony cubital tunnel, Osborne ligament, an anconeus epitrochlearis muscle, and the origin of the flexor carpi ulnaris muscle. The ligament of Struthers, lacertus fibrosus and the transverse carpal ligament are anatomical sites of compression of the median nerve. The arcade of Frohse is a site of compression of the radial nerve.
A 35-year-old woman who underwent surgical release of the first dorsal compartment 8 months ago is evaluated because of severe pain over the anatomical snuffbox of the right hand since the surgery. Physical examination shows focal tenderness over the region of the first dorsal compartment, a Tinel sign at the surgical scar, and numbness distal to the surgical scar. Medication includes gabapentin since the pain began, and the patient has attempted desensitization in hand therapy. Which of the following is the most appropriate next step in management?
A) Exploration silicone capping of the palmar cutaneous nerve
B) Initiation of oral pregabalin therapy
C) Iontophoresis with dexamethasone
D) Neurolysis and intramuscular placement of the superficial radial nerve
E) Phenol injection into the scar and compression glove therapy
The correct response is Option D.
One potential complication from surgical treatment of de Quervain disease (first dorsal compartment release) is injury to branches of the radial sensory nerve. When such injury is suspected, treatment should consist of exploration and, if possible, repair of the injured nerve branch. When this is not possible, multiple surgical options are available; transposition of the injured radial sensory nerve into the brachioradialis has been one of the commonly employed treatment strategies. Alternatives include transposition of the nerve into bone or a vein, nerve stripping, and coverage of the injured nerve with vascularized tissue.
Both gabapentin and pregabalin are useful medical interventions for nerve pain. General guidelines suggest proceeding with surgical treatment for suspected neuromas if no improvement occurs after 6 months of oral therapy.
Iontophoresis with corticosteroids has no proven efficacy for neuroma therapy. Phenol has been employed for stump neuromas and for Morton’s neuromas; however, there is no evidence to support its use in non-amputation neuroma treatment.
Silicone capping, once advocated for treatment of end-neuromas, has fallen out of favor because of poor pain relief results and displacement/migration of the caps.
A 44-year-old accountant has difficulty extending the middle and ring fingers of the right hand. On examination, there is weakness with extension of the fingers, and thumb. There is no sensory deficit. This patient’s findings are most consistent with…
A) anterior interosseous nerve syndrome
B) lateral epicondylitis
C) posterior interosseous nerve syndrome
D) Wartenberg’s syndrome
Correct answer is option C.
This patient has findings consistent with posterior interosseous nerve syndrome, which is initially characterized by weakness and pain in the forearm in the absence of sensory loss. Other findings include weakness of extension of the metacarpophalangeal joints of the fingers and interphalangeal joint of the thumb, as well as weakness of thumb abduction and wrist extension. Because the innervation of the extensor carpi radialis longus tendon lies above the elbow and is thus not affected, the wrist often deviates radially. Anterior interosseous nerve compression is from compression or neuritis of the anterior interosseous motor branch of the median nerve the results in difficulty with thumb interphalangeal joint and index finger distal interphalangeal joint, unable to make an O. Lateral epicondylitis is characterized by sharp pain at the epicondyle that is exacerbated with passive flexion of the wrist and fingers with the elbow in extension. Injection of a corticosteroid may produce relief. Although patients with lateral epicondylitis may have positive findings on middle finger testing, severe pain with passive stretch is more typical.
Radial tunnel syndrome involves compression of the radial nerve and results in chronic, aching pain in the area of the lateral humerus, elbow, extensor mass, and dorsal wrist. In addition, patients have tenderness over the mobile wad. Severe pain is elicited on middle finger testing. Weakness is not characteristic. Wartenberg’s syndrome, or radial sensory nerve entrapment, is characterized by pain and/or paresthesias over the dorsoradial aspect of the hand and wrist. Tinel’s sign will be positive along the course of the nerve, and the patient will have paresthesias with the forearm in hyperpronation and the wrist in neutral. Because the motor branch of the radial nerve divides more proximally, weakness is not seen.
Risk of development of complex regional pain syndrome is increased by injury to each of the following structures EXCEPT
(A) abdomen
(B) brain
(C) peripheral nerves
(D) spinal cord
(E) upper extremities
The correct response is Option A.
In patients with complex regional pain syndrome, an initial noxious or painful event results in pain that is disproportionate to the initial event and cannot be linked to any specific pathologic process. Features of the condition include spontaneous pain, allodynia, and hyperesthesia that cannot be accounted for by injury to a single peripheral nerve, edema, changes to the skin or blood flow, or any other condition. Conditions that place patients at risk for complex regional pain syndrome include fractures of the distal radius as well as injuries of the upper extremities, spinal cord, brain, and peripheral nerves.
A 17-year-old boy is brought to the emergency department 5 hours after he sustained a stab wound to the left dorsal forearm. On physical examination, he is unable to extend the thumb and metacarpophalangeal joints. Exploration of the wound for repair of a presumed nerve injury is planned. Proper exposure of the nerve is between which of the following muscle groups?
A) Brachialis and triceps
B) Brachioradialis and extensor carpi radialis longus (ECRL)
C) Extensor carpi radialis brevis (ECRB) and ECRL
D) Extensor digitorum communis and ECRB
E) Flexor carpi radialis and pronator teres
The correct response is Option D.
Inability to extend the thumb and metacarpophalangeal joints generally suggests an injury to the radial nerve. Wrist extension can be preserved because of the preservation of the extensor carpi radialis longus muscle innervation. In the forearm, the radial nerve can be best approached directly between the extensor digitorum communis and the extensor carpi radialis brevis muscles. The approach between the brachialis and triceps muscles can identify the radial nerve in the upper arm. The interval between the flexor carpi radialis and pronator teres approaches the median nerve.
A 48-year-old dock worker has effort-associated carpal tunnel syndrome. Which of the following muscles is the most likely cause?
(A) Abductor digiti quinti
(B) Adductor pollicis
(C) Lumbrical
(D) Palmaris brevis
(E) Third volar interosseus
The correct response is Option C.
The lumbrical muscles, which aid in flexion of the metacarpophalangeal joints, typically originate from the radial side of the flexor digitorum profundus tendons, with the exception of the third lumbrical, which originates from the ulnar side of the long finger and radial side of the ring finger. These muscles insert into the radial sagittal band and also assist in extension of the interphalangeal joints. Because the lumbrical muscles rest within the carpal canal during grip functions and can become edematous with prolonged use, carpal tunnel syndrome may be aggravated in patients with muscular hands.
Each lumbrical muscle is innervated by the same source as its flexor digitorum profundus tendon of origin. The median nerve supplies innervation to the first and second lumbricals, and the ulnar nerve supplies the third and fourth lumbricals.
None of the other intrinsic muscles pass within the carpal canal.
A 22-year-old man comes to the office for initial evaluation 24 months after he sustained an injury to the radial nerve secondary to a fracture of the humerus. He has had no improvement in function of the radial nerve during this time. Which of the following is the most appropriate management of this patient=s nerve injury?
(A) Exploration and repair of the radial nerve at the spiral groove
(B) Free innervated muscle flap transfer
(C) Repair of radial nerve with a nerve graft
(D) Tendon transfers
(E) Vascularized nerve graft reconstruction
The correct response is Option D.
The onset of radial nerve palsy in this patient was 24 months ago; therefore, the most appropriate management is tendon transfers to the radial innervated structures that extend the wrist, fingers, and thumb. Wrist extension can be improved with transfer of the pronator teres to the extensor carpi radialis brevis. Finger extension can be improved with transfer of the flexor carpi ulnaris or radialis to the extensor digitorum communis tendons. Thumb extension can be improved with transfer of the palmaris longus to the extensor pollicis longus.
Because the patient has waited so long for treatment, nerve repair is unlikely to achieve recovery of muscle function. After 24 months, the motor end plates atrophy and cannot be reinnervated. When repair of a nerve injury is delayed for an extended period, grafting is usually required for repair. Free innervated muscle flap reconstruction can be considered for necrosis of the flexor compartment in a patient who has had compartment syndrome. Vascularized nerve graft reconstruction is not likely to improve this patient’s hand function.
Twenty-four months after nerve injury, loss at the sensory receptors and motor end plate is severe. Additionally, the time course for recovery of the motor units would require another 6 to 12 months.
A 58-year-old woman who is a pianist comes to the office because she has had increasing clumsiness of the right hand for the past four months. She says the awkward movement of her hand makes it difficult for her to play the piano. Physical examination shows marked atrophy of the first dorsal interosseous muscle. Two-point discrimination is 3 to 4 mm in all fingers. The most likely cause of these findings is nerve compression at which of the following sites?
(A) Arcade of Struthers
(B) Carpal tunnel
(C) Guyon canal
(D) Ligament of Struthers
(E) Osborne ligament
The correct response is Option C.
Isolated intrinsic motor weakness is most often a result of compression of the motor branch of the ulnar nerve with the ulnar tunnel, also referred to as the Guyon canal. The ulnar tunnel is divided into three zones. Within zone 2 of the ulnar tunnel, the deep motor branch passes around the hook of the hamate and between the pisohamate ligament and the fibrous arch of the flexor digiti minimi. The motor branch goes on to innervate the abductor digiti minimi, the flexor digiti minimi, the opponens digiti minimi, the small and ring lumbricals, the palmar and dorsal interosseous muscles, the adductor pollicis, and the deep head of the flexor pollicis brevis muscle. The terminal portion of the nerve innervates the first dorsal interosseous muscle. Causes for compression include ganglion, hamate hook fracture, lipoma, and hypothenar hammer syndrome.
Although isolated motor nerve compression can occur, the ulnar nerve is most commonly compressed at the level of the elbow, which is referred to as cubital tunnel syndrome. Cubital tunnel syndrome classically presents with sensory changes within the small and ring finger followed by weakness in the intrinsic muscles and, in severe cases, weakness of the profundus tendon to the small and ring finger. Surgical release in cases of cubital tunnel syndrome involves release of the Osborne ligament as well as the arcade of Struthers.
The carpal tunnel is the most common site of median nerve compression and is not the most common site of compression in this scenario. The ligament of Struthers may be involved in median nerve compression at the level of the elbow.
A 37-year-old woman presents for evaluation of a laceration to the mid humerus that she sustained in a motor vehicle collision. On examination, the patient is unable to extend the wrist, fingers, or thumb. Surgical exploration shows complete radial nerve transection; the median/ulnar nerves are intact. Direct neurorrhaphy is performed after debridement and mobilization of the nerve ends. Which of the following is the last muscle to be reinnervated during nerve recovery?
A) Abductor pollicis brevis
B) Abductor pollicis longus
C) Brachioradialis
D) Extensor carpi radialis brevis
E) Extensor indicis proprius
The correct response is Option E.
Radial nerve injuries may occur in the setting of humeral fractures, and transection is most common in the setting of an open injury. The most important components of functional recovery following radial nerve injury include wrist, finger, and thumb extension. The order of reinnervation of the radial-innervated muscles is most commonly brachioradialis, extensor carpi radialis longus, supinator, extensor carpi radialis brevis, extensor digitorum communis, extensor carpi ulnaris, extensor digiti quinti, abductor pollicis longus, extensor pollicis longus, extensor pollicis brevis, and extensor indicis proprius. The abductor pollicis brevis is innervated by the median nerve via the thenar motor branch.
A 28-year-old man comes to the office for evaluation of the nondominant left arm 12 weeks after he sustained a traction injury while working with heavy farm machinery. Physical examination shows complete loss of motor function in the ulnar nerve distribution, loss of sensation at the medial arm and forearm, and mild weakness of the left pectoralis major muscle. Nerve conduction testing of the ulnar nerve shows loss of motor conduction, but sensory conduction is intact. Which of the following is the most likely level of brachial plexus injury?
(A) Anterior cord
(B) Posterior cord
(C) Postganglionic root
(D) Preganglionic root
(E) Terminal branch
The correct response is Option D.
This patient has an avulsion injury to the lower roots of the brachial plexus. From proximal to distal, the levels of the brachial plexus are determined by its branching pattern and progress from spinal nerve roots (C5-T1), to trunks, to divisions, to cords, and to terminal branches. Loss of ulnar nerve function indicates damage to the ulnar nerve itself, the medial cord, or the contributing C7, C8, and T1 roots. Loss of medial arm and forearm sensation indicate loss of the medial brachial and medial antebrachial cutaneous nerves, and weakness of the pectoralis muscle indicates loss of the medial pectoral nerve, which innervates the sternocostal head. The lateral pectoral nerve, which is intact in this case, innervates both the clavicular and sternocostal heads and maintains function of the pectoralis major muscle. Loss of motor conductivity with maintenance of sensory conductivity on nerve conduction testing indicates a disruption at the preganglionic nerve root level, with preservation of continuity between the sensory cell bodies in the dorsal root ganglion, the peripheral axons and the peripheral sensory organs, thus preventing Wallerian degeneration of the sensory neurons. The motor neuron cell bodies, however, are located in the ventral horn of the spinal cord, and are separated from their peripheral axons, leading to degeneration and loss of conductivity.
Disruption at the postganglionic nerve root level would result in separation of both sensory and motor cell bodies from their respective peripheral axons and subsequent degeneration. This would lead to loss of both motor and sensory conductivity on nerve conduction testing. Disruptions at the trunk level, cord level, or branch level would also lead to the same results. In addition, loss at the terminal branch level (ulnar nerve in this case), distal to the cord level, would preserve the medial brachial nerve and medial antebrachial nerve, and thus, sensation at the medial arm and forearm.
An 8-year-old boy sustains a near complete amputation through the midportion of the nondominant left arm. Examination shows a significantly comminuted fracture of the humerus. On intraoperative exploration, the median and radial nerves are transected and retracted. The proximal and distal ends of each nerve are visualized; however, following debridement of the affected nerve areas and mobilization of the nerves, there is a 5-cm gap between the nerve ends.
Following reestablishment of arterial and venous flow, which of the following is the most appropriate management of the nerve injuries?
(A) Delayed reconstruction following healing and stabilization of the humerus fracture
(B) Use of absorbable polyglycolic acid conduits to bridge the gap between nerve endings
(C) Sural nerve cable grafting to bridge the gap between nerve endings
(D) Transfer of the ipsilateral intercostal nerves to the distal ends of the radial and median nerves
(E) Humeral shortening with primary repair of the proximal and distal nerve ends
The correct response is Option E.
Following reestablishment of arterial and venous flow, the most appropriate next step is humeral shortening with primary repair of the proximal and distal nerve ends. Nerve repair should ideally be performed as a primary end-to-end repair without tension; in patients with bone comminution, the bone can be shortened within limits to alleviate tension. Shoulder abduction will increase median nerve length by 2.5 cm and ulnar nerve length by 2 cm; elbow flexion will increase the length of both the median and ulnar nerves by an additional 4 cm.
Delayed reconstruction will ultimately be more difficult because the injured nerves will have become retracted and scarred, and mobilization will be limited.
Absorbable polyglycolic acid conduits have been used successfully in bridging digital nerve gaps of 4 mm or less. However, success has not been reported with the use of this material for repair of major peripheral nerves.
Non-interfascicular nerve cable grafts do not optimize fascicle-to-fascicle opposition and thus provide poor results; interfascicular nerve grafts are now used instead. Results seen with nerve grafting are typically less satisfactory than primary repair, especially in older patients. Interfascicular sural nerve grafts can be used in patients in whom humeral shortening is not an option.
Nerve transfer is inappropriate in this patient because the proximal, median, and radial nerves can be repaired instead. Likewise, a neurotization procedure, which involves embedding of the distal end of a nerve in continuity with the spinal cord directly into a recipient muscle, is also not indicated because the distal nerve ends are available for use.
A 25-year-old right-hand dominant man is brought to the emergency department after sustaining a stab wound to the right arm in a bar fight. Physical examination shows a 2 × 1-cm laceration over the antecubital fossa. He is unable to flex the interphalangeal joint of the thumb and the proximal interphalangeal joint of the index finger. Which of the following nerves is most likely injured?
A) Lateral antebrachial cutaneous
B) Median
C) Musculocutaneous
D) Radial
E) Ulnar
The correct response is Option B.
Median nerve palsy is marked by the inability to oppose the thumb or flex the thumb at the interphalangeal joint. The inability to flex the index finger at the proximal interphalangeal joint is also noted. The lateral antebrachial cutaneous nerve provides sensory innervation to the lateral aspect of the arm. The median antebrachial cutaneous nerve innervates the skin of the anterior and middle surfaces of the forearm to the level of the wrist. This nerve does not innervate any muscles. Radial nerve palsy is marked by the inability to extend the fingers, thumb, and wrist. Patients with radial nerve palsies have difficulty grasping objects. The results of tendon transfers to restore function in patients with radial nerve palsies are among the best and most predictable outcomes. Ulnar nerve palsy symptoms include a ?claw? deformity, with flexion deformities of the ring and little fingers. In later stages, profound muscle wasting of the both hypothenar eminence and the first web space is seen.
A patient has complete C5 tetraplegia after sustaining a spinal cord injury. During reconstructive procedures in this patient, restoration of which of the following is most useful functionally?
(A) Digit extension
(B) Digit flexion
(C) Elbow extension
(D) Key pinch
(E) Wrist extension
The correct response is Option C.
Reconstruction after spinal cord injury is based on the level of injury and the muscles that are available for transfer. Because many spinal cord injuries are not complete, testing of individual muscles is essential to determine the most appropriate management. The International Classification for Surgery of the Hand in Tetraplegia, a 10-point scale ranging from 0 to 9, is the most widely used tool to determine functional reconstruction. In a patient with a complete C5 tetraplegia, the Group 0 designation indicates that no muscles suitable for transfer below the elbow are available. In patients with this classification, the most useful reconstruction involves restoration of the elbow extension. Elbow flexion and extension, along with shoulder strength, can enable the tetraplegic patient to propel a wheelchair, to transfer from bed, and to shift the body weight to prevent pressure ulcers. The most commonly prescribed transfers are the deltoid-to-triceps transfer and the biceps-to-triceps transfer.
Reconstruction procedures that restore digital extension and flexion, key pinch, and wrist extension are useful in patients with lower-level spinal cord injury.
A 57-year-old woman comes to the office because of burning pain and stiffness of the right hand 8 weeks after closed treatment of a distal radius fracture. The patient reports that she has had difficulty sleeping and continues to have discomfort despite taking narcotics. On physical examination, the hand is shiny, swollen, and warm, and finger range of motion is decreased. There is hypersensitivity to light touch. X-ray studies show good alignment of the fracture. Electrodiagnostic testing shows no abnormalities. Bone scan shows increased periarticular uptake. Which of the following is the most appropriate diagnosis?
A) Complex regional pain syndrome
B) Factitious disorder
C) Midpalmar space abscess
D) Opioid addiction
E) Pain catastrophizing
The correct response is Option A.
The most appropriate diagnosis is reflex sympathetic dystrophy, or complex regional pain syndrome (CRPS) type I. This patient exhibits symptoms consistent with CRPS, which is a form of severe neuropathic pain. The diagnosis of CRPS involves history, physical examination, and diagnostic testing. In addition to pain out of proportion, other features must be present. These can include changes in blood flow, altered temperature perceptions, sudomotor activity, edema, and pigmentation changes. Although no specific test is pathognomonic, triple-phase bone scans are helpful in adding credence to the diagnosis. First- and second-phase bone scans may show asymmetric flow and autonomic dysfunction, while the third phase demonstrates increased periarticular uptake in multiple joints of the affected extremity.
CRPS is divided into two types. Type I occurs without identifiable nerve involvement (also known as reflex sympathetic dystrophy), and Type II has identifiable nerve involvement (causalgia). It is more common in smokers and in women. Pain in CRPS can be either sympathetically mediated or sympathetically independent. This condition is characterized by persistent pain, cold intolerance, autonomic dysfunction, and trophic changes. Patients may show swelling, stiffness, difficulty sleeping, and persistent pain out of proportion to the normal postoperative/post-injury course that may be incompletely relieved by narcotics.
A variety of treatment modalities have been employed in addressing CRPS. These range from therapy modalities such as range of motion, stress loading, and desensitization to pharmacologic interventions with anticonvulsants or antidepressants. Stellate ganglion blocks or autonomic nerve blocks may be helpful in sympathetically mediated pain, and nerve stimulation (either transcutaneous or at the spinal cord level) can also be employed. Often multiple modalities are used concurrently and in sequence. Peripheral nerve decompression may be helpful in resolving symptoms related to CRPS type II.
Factitious disorder can occur when there is potential for secondary gain, but would not present with physiological symptoms.
Although opioid addiction can be a source of pain complaints in an attempt to acquire additional narcotics, the patient exhibits physiological changes that are unable to be mimicked.
Pain catastrophizing is a maladaptive behavioral response to pain that can be a risk factor for prolonged pain after trauma.
A midpalmar space abscess would be unlikely after a closed distal radius fracture. It would also not be likely to have trophic skin changes or changes in a bone scan as seen in this patient.
An 18-year-old man presents for follow-up evaluation 8 weeks after he sustained a penetrating injury to the posterior medial right elbow and a complete transection of the ulnar nerve in the cubital tunnel. At this time, which of the following are the most likely Sunderland/Mackinnon injury grade and electromyogram/nerve conduction findings in this patient?
The correct response is Option D.
Nerve injuries are graded using the Sunderland/Mackinnon classification. Grade I injuries involve neurapraxia and are expected to recover completely; grades II to IV injuries involve increasing disruption of the perineurium and endoneurium (with expectation for a variable degree of spontaneous recovery); grade V injuries represent neurotmesis, or complete transection of the nerve. Grade VI injuries represent combined injuries in which more than one grade of injury exists within the same segment of damaged nerve. After a complete nerve transection and progression of Wallerian degeneration, patients develop fibrillations and sharp waves and progressive decrease in the compound motor action potential.
A 34-year-old man is brought to the emergency department one hour after sustaining a 7 cm laceration to the left wrist during a suicide attempt. The patient is unconscious but breathing. Physical examination shows a clean, linear radial laceration. Pulsatile arterial bleeding from the wound is noted. A tourniquet is applied to the upper left arm and inflated to 250 mmHg of pressure. Three hours later, the tourniquet is released, and the patient is brought to the operating room. The artery is ligated, and the tendons are repaired. Surgical exploration shows no nerve laceration. The next day, the patient has no sensation or motor function in the left hand. After three days, normal function returns. Which of the following Sunderland grades is the most appropriate classification for this injury?
(A) I
(B) II
(C) III
(D) IV
(E) V
The correct response is Option A.
Nerve injuries can be classified with a system that was first described by Seddon and modified by Sunderland. The table below summarizes these nerve injury classifications. The nerve injury described is classified as Sunderland grade I. Rapid nerve recovery is likely. The patient described had the tourniquet in place for longer than the generally accepted recommended period. Studies have shown that tourniquets should be released after two hours of use. Because of the prolonged use in the scenario described, the patient has sustained neurapraxia. When a tourniquet is used, the nerves and muscles are susceptible to injury. The nerves are particularly sensitive to pressure injury. Two-hour use is a guideline; if additional time is needed, it is generally thought that five minutes of reperfusion is necessary for every 30 minutes of tourniquet time.
A Sunderland grade I injury corresponds with neurapraxia. Complete recovery is expected. A grade II injury corresponds with axonotmesis and slow but complete recovery. Sunderland III, IV, and V injuries do not recover spontaneously. Axonotmesis and neurotmesis occur with Wallerian degeneration; therefore, significant regeneration often takes place only after surgery.
After TMR for patients with transhumeral amputation what muscle typically provides an elbow extension signal for the prosthesis?
A) Lateral head of the biceps
B) Medial head of the biceps
C) Lateral head of the triceps
D) Long head of the triceps
E) Latissimus dorsi
Correct answer is option D.
Nerve transfers for TMR after transhumeral are well-established and include median nerve to medial head of the biceps for “hand close” and radial nerve to lateral head of the triceps for “hand open”. The native innervation to the lateral head of the biceps and the long head of the triceps are preserved for elbow flexion and elbow extension signals respectively.
A 40-year-old, right-hand–dominant man comes to the office because of minimal sensation in the tips of the digits of the right hand and severe pain in the volar aspect of the right wrist. He sustained lacerations of the median and ulnar nerves, radial and ulnar arteries, and all volar flexor tendons 11 months ago when he punched a window. Each of the structures was repaired primarily within hours of injury. On examination, the hand is well perfused. Percussion at the location of the dot in the photograph shown produces severe, painful paresthesia, which radiate distally. Sharp touch sensation is minimally present at the tips of the thumb, index, and long fingers and the radial side of the ring finger; light touch sensation is absent. Which of the following is the most appropriate next step in treatment?
A) Administration of tacrolimus
B) Excision repair with a sural graftbr> C) Neurolysis and conduit wrap
D) Reassessment in 3 months
E) Transfer of the extensor indicis proprius
The correct response is Option B.
The patient has a neuroma of the median nerve after laceration and repair. At 11 months out from injury, he would be expected to have improving light touch at the fingertips. The combination of this and the severe pain with percussion of the volar wrist indicates that very few axons have crossed the repair site. Observing the patient for additional time is unlikely to yield improved recovery. At surgical exploration, the patient had a large neuroma at the repair site. A photograph is shown.
Tacrolimus is an immune modulating agent commonly used in solid organ transplants. It has been investigated in animals and clinical trials in humans and shown some effectiveness in improving nerve regeneration across the repair. It is not currently used in humans outside of clinical trials. Also, in all trials of tacrolimus use, the medication was started at the time of repair, not 11 months later.
Nerve conduits have been used to repair short-gap nerve injuries. Although there are reports of successful nerve regeneration of gaps greater than the original indication of 1.5 cm, a gap of 6 cm is well beyond the limits of what a conduit can bridge.
Transfer of the extensor indicis proprius tendon would restore thumb opposition and use a tendon not involved in the original injury. However, this would not address the patient’s principal complaint of pain and lack of sensation.
After TMR for patients with transhumeral amputation what muscle typically provides a hand close signal for the prosthesis?
A) Lateral head of the biceps
B) Medial head of the biceps
C) Lateral head of the triceps
D) Long head of the triceps
E) Medial head of the triceps
Correct answer is option B.
Nerve transfers for TMR after transhumeral are well-established and include median nerve to medial head of the biceps for “hand close” and radial nerve to lateral head of the triceps for “hand open”. The native innervation to the lateral head of the biceps and the long head of the triceps are preserved for elbow flexion and elbow extension signals respectively.
An 18-year-old man comes to the office because he has “drooping” of the right shoulder and inability to abduct it beyond 30 degrees. He underwent exploration and vascular repair 4 months ago after sustaining a stab wound to the right side of the neck. Photographs are shown. Which of the following surgical transfer techniques is most likely to restore deltoid function in this patient?
A) C5 to C6 nerve root
B) Intercostal to musculocutaneous nerve
C) Partial ulnar nerve to musculocutaneous nerve
D) Radial nerve fascicle to axillary nerve
E) Suprascapular to axillary nerve
The correct response is Option D.
Of the nerve transfers listed, only the transfer of a triceps branch to the axillary nerve will restore innervation to the deltoid muscle and provide shoulder abduction. Although debate remains over whether nerve graft repair (if possible) or nerve transfer provides better outcomes for shoulder abduction, both techniques are frequently employed in the setting of upper trunk brachial plexus injury.
The location of the injury (based on scar and mechanism) makes the injury likely distal to the nerve roots; in addition, root to root transfers are not typically part of the brachial plexus reconstruction ladder.
The suprascapular nerve is often the recipient nerve for partial transfers from cranial nerve XI (spinal accessory nerve) in order to provide shoulder stability. In this pattern of injury and based on the photos demonstrating atrophy of the supraspinatus and infraspinatus, the suprascapular nerve could not act as a donor nerve.
Intercostal nerve and partial ulnar nerve transfers to the musculocutaneous nerve are both frequently used to restore elbow flexion in the setting of upper trunk injuries.
In anterior interosseous nerve syndrome…
A) The median nerve is compressed
B) The site of compression is between the superficial and deep heads of the pronator teres.
C) The site of compression is at the level of the pronator quadratus muscle.
D) The ulnar nerve is compressed
Correct answer is option B.
Anterior interosseous nerve syndrome results when the anterior interosseous nerve is compressed between the superficial and deep heads of the pronator teres. The FDS arch and the fibromuscular bands in the distal forearm are other sites of compression. Additionally several variants accessory muscle have been noted: anomalous heads of the PT, the accessory head of the FPL (Gantzer’s muscle), which occurs in two-thirds of limb, the Palmaris profundus and the flexor carpi radialis brevis.
Surgical treatment consists of releasing the deep head of the pronator teres as well as the flexor fascia at this level. The deep head of the pronator teres is then sutured to the superficial head of the pronator teres. Neither the median nerve nor the pronator quadratus muscle is involved in this condition.
A 20-year-old man comes to the office after he sustained transection of the ulnar nerve of the left arm during a rollover motor vehicle accident. Physical examination shows a 5-cm transverse laceration in the proximal ulnar aspect of his left forearm. A photograph of the laceration after suture removal is shown. Microscope-assisted epineural repair of the transection is performed. As function is restored over time, which of the following movements will most likely be last to return?
A) Abduction of the small finger
B) Adduction of the thumb
C) Flexion of the metacarpophalangeal joint of the small finger
D) Flexion of the proximal interphalangeal joint of the small finger
E) Ulnar sided flexion of the wrist
Correct answer is option B.
The ulnar nerve is the terminal portion of the medial cord of the brachial plexus, after the medial head of the median nerve has separated from it, with fibers from C8–T1. It initially lies medial to the axillary artery and then to the brachial artery as it travels distally in the upper arm. It pierces the intermuscular septum and then follows the medial head of the triceps muscle to the groove between the olecranon process and the medial epicondyle. It gives off no branches in the arm. After the ulnar nerve passes through the cubital tunnel, it gives off articular branches and branches to the flexor carpi ulnaris (FCU) and the medial half of the flexor digitorum profundus (FDP). It travels between the two heads of the FCU and continues into the forearm between this muscle and the FDP.
In the distal half of the forearm, it is joined on its lateral side by the ulnar artery. Proximal to the wrist, the nerve gives off the dorsal sensory branch, providing sensation to the dorsal wrist and ulnar aspect of the hand. The ulnar nerve continues into the hand via Guyon’s canal, where it splits into a superficial sensory branch and a deep motor branch. The superficial branch supplies the palmaris brevis and the skin of the hypothenar eminence and digital nerves to the small and ulnar side of the ring finger. The motor branch passes between the abductor digiti minimi (ADM) and the flexor digiti minimi (FDM), with the deep branch of the ulnar artery, perforates the opponens digiti minimi and follows the deep volar arch across the interossei, and finally innervates the adductor pollicis (AD) and the deep head of the flexor pollicis brevis.
Based on its path, ulnar sided flexion of the wrist (FCU) would be expected early, followed by abduction of the small finger (ADM) and flexion of the metacarpophalangeal joint (FDM). Interosseus muscle function would manifest as ability to abduct and adduct the fingers, followed last by adduction of the thumb (AD). Flexion of the proximal interphalangeal joints of the fingers is a function of the flexor digitorum superficialis, which is innervated by the median nerve.
A 65-year-old woman undergoes open reduction and internal fixation for the injury displayed in the x-ray study shown. Six weeks postoperatively, she has diffuse swelling, stiffness, and pain of the right upper extremity. Her skin appears shiny, and she has changes in the patterns of both hair and perspiration in the right upper extremity when compared with the left upper extremity. After injury, treatment with which of the following would most likely have decreased her risk for this complication?
A) Amitriptyline
B) Ascorbic acid
C) Gabapentin
D) Prednisone
E) Pregabalin
The correct response is Option B.
Complex regional pain syndrome (CRPS) is chronic pain that persists in the absence of ongoing cellular damage and is characterized by autonomic dysfunction, trophic changes, and impaired function. In the perioperative period, the physiologic consequences of CRPS in the upper extremity contribute to or create one or more of the following: clinically significant osteopenia, delayed bony healing or nonunion, joint stiffness, tendon adhesions, arthrofibrosis, pseudo-Dupuytren palmar fibrosis, swelling, and atrophy. The reported incidence of CRPS is 5.5 to 26.2 per 100,000 person-years, and the prevalence is reported as 20.7 per 100,000 person-years. Women are more frequently affected than men, with a ratio of 3:1 to 4:1; the upper extremity is involved more frequently than the lower extremity; and fracture is the most common causative event. Incidence of CRPS after distal radius fracture has been reported to be between 22 and 39%.
In a double-blind, prospective, multicenter trial by Zollinger et al., 416 patients with 427 wrist fractures were studied for the effects of prophylactic vitamin C (ascorbic acid) on the risk of subsequent development of CRPS. Administration of 500 mg vitamin C daily was found to significantly decrease the incidence of CRPS in patients with distal radius fracture. The authors recommend treatment for 50 days.
The other four medications listed have all been reported for the treatment of patients diagnosed with CRPS. None have been reported to decrease the incidence of CRPS when used prophylactically.
A 15-year-old boy presents with a history of a traumatic laceration to the dominant right wrist after punching a window 4 weeks ago. He has numbness and weakness in the median nerve distribution. On operative exploration of the wound, there is a complete transection of the median nerve and a 4-cm gap between the proximal and distal ends. Which of the following is the best method of nerve reconstruction?
A) Polyglycolic acid nerve tube placement
B) Saphenous vein grafting
C) Sural nerve grafting
D) Transposition of the median nerve and primary nerve coaptation
The correct response is Option C.
The best method of nerve reconstruction is sural nerve grafting. An autologous sural nerve graft is the best choice for a nerve gap of 3 cm or greater. Multiple cables would likely be required to reconstruct the entire diameter of the median nerve and restore sensory and motor function.
Transposition of the median nerve and primary nerve coaptation is incorrect since the nerve gap is too large for a tension-free nerve repair, even with transposition of the median nerve at the wrist.
Saphenous vein grafting is incorrect since the size of the nerve defect warrants nerve grafting rather than vein grafting. Vein grafting could be used for an associated vascular injury of this size to the radial or ulnar artery.
Polyglycolic acid (PGA) nerve tube placement would be more appropriate for a nerve gap less than 3 cm. This serves as a scaffold for nerve regeneration. The indications for nerve allograft reconstruction are expanding the subject of ongoing research.
A 37-year-old man is brought to the emergency department five hours after he sustained the injury to the right forearm (shown) when he was mauled by a dog. Physical examination shows complete transection of the median nerve and radial and ulnar arteries. After revascularization, which of the following is the most appropriate management?
(A) Placement of a vacuum-assisted closure device
(B) Escharotomy
(C) Epimysiotomy
(D) Fasciotomy
(E) Split-thickness skin grafting
The correct response is Option D.
The photograph above shows a severe injury of the forearm to the radial and ulnar arteries and the median nerve. The most urgent care needed for this patient is to reestablish the blood supply to the extremity. Muscles can tolerate ischemia for up to four hours, but after six hours, the effect becomes irreversible and tissue loss is greater. With this level of arterial occlusion, restoration of the circulation may produce post-ischemia swelling and initiate a compartment syndrome. Prophylactic fasciotomy is recommended if ischemia time of four to six hours is present before arterial repair. Although compartment pressures can be measured with a commercially available tissue pressure monitor or an infusion technique, these monitoring techniques do not replace the need for fasciotomy with prolonged ischemia. The goal of management is to limit reperfusion injury — not to document compartment pressures. Fasciotomies should be performed in the forearm and over the intrinsic muscles of the hand. The serpentine incision starting from the carpal tunnel running proximally is generally made over the volar forearm with a straight-line incision over the dorsal forearm. Four incisions are generally necessary to release the intrinsic muscles and the thenar and hypothenar muscles. Digital fasciotomies are generally not necessary; however, if there is a significant degree of clinical swelling, fasciotomies are performed along the midaxial line of the fingers and thumb. Epimysiotomy is a procedure during which the muscle covering is stripped from the muscle. This is generally not required. Escharotomy is a procedure during which the skin is incised after a burn injury; it has no role in the treatment of vascular compartment syndrome.
A 24-year-old man is brought to the emergency department 5 hours after being involved in a motorcycle collision. The patient reports worsening pain of the left forearm despite previous opioid administration. On physical examination, the left radial pulse is easily palpable. Hypoesthesia in a median nerve distribution is noted in the left hand. Active motion of wrist and fingers is present but is minimal and limited by pain. Passive wrist motion produces intense pain in the left forearm. X-ray study of the left upper extremity shows no fracture, and remaining trauma workup is negative. A photograph is shown. Which of the following is the most appropriate next step in management?
A) Carpal tunnel release
B) Forearm fasciotomy
C) Local wound care until demarcation of tissue loss
D) Splinting and observation
E) Wound debridement and skin grafting
The correct response is Option B.
This patient presents with acute compartment syndrome (ACS) in the left forearm after blunt soft tissue trauma. The most appropriate next step in management is emergent forearm fasciotomy for decompression.
The diagnosis of ACS in the extremities should be based on clinical presentation and progress. Signs and symptoms commonly evolve over a few hours after the initial traumatic event, especially after fluid resuscitation. Occasionally, the patient’s initial presentation may raise strong suspicion and warrant immediate decompression. ACS in the extremities may develop from soft tissue injury without a fracture in up to 30% of cases.
The commonly accepted clinical findings suggestive of ACS (rest pain, pain on passive motion, paresthesia, and paresis) have been shown to have high specificity but low sensitivity, rendering them a poor predictive value. Paresis/paralysis and other signs of arterial obstruction (pulselessness, pallor, pain out of proportion) are thought to be particularly late findings. Therefore, physicians should have a high level of suspicion for ACS in any case of limb trauma associated with excessive pain and paresthesia. Measurement of compartment pressures may be of diagnostic assistance in equivocal cases, especially when the patient is unable to communicate.
Carpal tunnel release is an important component of a forearm fasciotomy; however, it is not sufficient decompression alone. Emergent decompressive fasciotomy should precede wound debridement, demarcation of tissue loss, and splinting of the extremity. Skin grafting of the wounds (including the skin incisions for fasciotomy) may or may not be needed after resolution of limb edema.
A 24-year-old man comes to the office because he says the ring and little fingers of his right hand “catch” when he puts his hand in his pocket and that he “pokes” himself in the eye when washing his face. History includes repair of a complete transection of the right ulnar nerve at the wrist 1 year ago. On physical examination, he is unable to extend the interphalangeal joints of the ring and little fingers when the metacarpophalangeal joints are flexed. Photographs are shown. Which of the following tendon transfers is the most appropriate management?
A) Extensor indicis proprius (EIP) to adductor
B) EIP to extensor digiti minimi
C) EIP to first dorsal interosseous
D) Flexor digitorum superficialis (FDS) of the little finger to A2 pulley
E) FDS of the little finger to lateral band
The correct response is Option E.
Of the tendon transfer choices offered, only the FDS transfer to the lateral band (of both the ring and little fingers) will correct the loss of interphalangeal joint extension described, thereby diminishing the tendency for the flexed/abducted finger to catch on pocket edges.
The clinical scenario and photographs demonstrate failure of the intrinsic muscle function to return following a low ulnar nerve repair. The deformities demonstrated include ulnar clawing of the little finger primarily, abduction of the little finger (Wartenberg sign), hyperflexion of the interphalangeal joint of the thumb, and atrophy of the intrinsics (especially notable in the hypothenar eminence on the lateral view). Of these deformities, the patient is bothered primarily by the little finger deformity.
Correction of clawing can be achieved actively or passively. Patients who can extend the interphalangeal joints while hyperextension of the metacarpophalangeal joints is blocked (Bouvier test) can achieve correction of clawing with active or passive transfers. Active transfers attempt to re-create the normal function of the intrinsics by directing pull through the lateral bands. Passive transfers re-create the intrinsic function of metacarpophalangeal joint flexion (similar to externally blocking hyperextension) but do not extend the interphalangeal joints.
EIP transfers are useful for correction of the lateral pinch functions of the intrinsic minus hand. An EIP transfer to the adductor tendon re-creates the thumb component of lateral pinch, while the EIP transfer to the first dorsal interosseous tendon would improve the index function in pinch.
EIP transfer to the extensor digiti minimi is one method used to reduce hyperabduction of the little finger. This would not correct the flexion deformity at the level of the proximal interphalangeal joint.
FDS transfer to the A2 pulley provides a passive transfer, which, based on the patient’s inability to extend the interphalangeal joints during the Bouvier test, would not correct the deformity.
A 20-year-old man comes for evaluation 9 months after sustaining a stab wound to the left proximal upper arm. He did not seek medical attention at the time of the injury. Physical examination shows that he is unable to flex the left elbow with the forearm supinated. He is insensate to the lateral aspect of the upper arm and forearm. In addition to the ulnar nerve transfer to the biceps, which of the following nerve transfers is most appropriate to address this patient’s motor deficit?
A) Median nerve to brachialis
B) Musculocutaneous nerve to brachioradialis
C) Posterior interosseous nerve to triceps
D) Radial nerve to pronator teres
E) Ulnar nerve to flexor carpi radialis
The correct response is Option A.
The patient described has sustained a laceration of the musculocutaneous nerve. With this injury, the patient would be able to flex the elbow with the forearm in a pronated position using the brachioradialis, which is innervated by the radial nerve.
Due to the proximal level and amount of time that has passed since the injury, repair with grafting of the musculocutaneous nerve may not be advisable as the axons may not reach the motor end plates of the biceps and brachialis muscles before degeneration.
Use of fascicles from the median nerve, ulnar nerve, and both nerves has been described to restore elbow flexion. Fascicles are transferred distally in the upper arm directly to the nerve branch to the brachialis and/or biceps muscle. Distal coaptation allows donor axons to reach the target muscles more rapidly, and is more appropriate for this patient whose status is nearly 1 year post injury. A fascicle from the ulnar nerve was transferred to the nerve to the biceps (blue dot) and a fascicle from the median nerve was transferred to the nerve to the brachialis (green dot).
The musculocutaneous nerve is injured and cannot be used as a donor. The posterior interosseous nerve does not branch off the radial nerve until distal to the elbow; it would not be able to reach proximal enough to coapt to the nerve to the brachialis or biceps. The pronator teres does not flex the elbow; the median nerve is not injured. The flexor carpi radialis does not flex the elbow; the median nerve is not injured.
A 26-year-old man is referred for evaluation 9 months after sustaining a lower trunk brachial plexus traction injury after being hit by a motor vehicle. At the time of injury, he had paresthesia in the ring and small fingers and weakness of grip. Today, physical examination shows intrinsic atrophy and mild ulnar claw hand. A photograph is shown. He demonstrates increased sensation in the ring and small fingers since the time of the accident, but he has no clinical or electrodiagnostic improvement in motor function. Which of the following is most likely to improve the claw hand posture?
A) Anterior interosseous nerve branch of median nerve to ulnar nerve transfer in forearm
B) Brachialis branch of musculocutaneous nerve to ulnar nerve transfer in upper arm
C) Exploration and neurolysis of the lower trunk of the brachial plexus
D) Posterior interosseous nerve branch of radial nerve to ulnar nerve transfer in forearm
The correct response is Option A.
Lower trunk brachial plexus injuries can lead to deficits in hand function. Some can cause global hand dysfunction (median and ulnar nerve), while others can present as isolated ulnar nerve dysfunction. The signs and symptoms of isolated ulnar nerve dysfunction include numbness and tingling in the ring and small fingers, as well as weakness of the intrinsics. Ulnar nerve dysfunction may or may not present with clawing of the ulnar two digits, depending upon whether the flexor digitorum profundus (FDP) tendon to the ring and small fingers is involved. This patient has signs and symptoms consistent with low ulnar nerve palsy, and would benefit from an anterior interosseous nerve (AIN) to ulnar motor nerve transfer in the forearm.
The brachialis branch of the musculocutaneous nerve is classically used to reinnervate the AIN in the upper arm. This transfer is employed in cases of AIN palsy. The extensor carpi radialis brevis branch of the posterior interosseous nerve is most commonly used to reinnervate the AIN (median nerve), but can also be transferred to the ulnar nerve. This transfer occurs more proximally in the forearm and, therefore, would require a greater distance to travel to reach its endpoint (intrinsics of hand). The better and more appropriate transfer is the AIN to ulnar motor in this case.
Internal neurolysis can be used for neuromas in situ or neuropraxic nerves, but it would not be indicated for deficit in the hand. The length needed to recover function is too great, and motor end plate death is likely to occur before meaningful recovery can be seen.
A 65-year-old woman presents with recurrent carpal tunnel syndrome after carpal tunnel release on her dominant right hand. She complains of weakness gripping doors and jars and constant pain and she has a positive grind test on her right. The following measure would most likely provide her long term relief…
A) Steroid injection
B) Splint
C) Repeat carpal tunnel release
D) Basilar joint arthroplasty and carpal tunnel release
E) Splint basilar joint and carpal tunnel release
Correct answer is option D.
Basilar joint arthritis can be associated with carpal tunnel syndrome. Basilar joint arthritis presents as pain with loading during such activities as opening doors, gripping keys, and opening jars. Patients will have worsened pain with axial load grinding of the thumb metacarpal base against the trapezium. Persistent basilar joint arthritis can be a contributor to the development of recurrent carpal tunnel syndrome. In this circumstance it may be necessary to repeat the carpal tunnel release in conjunction with basilar joint arthroplasty. The proximity of the basilar joint to the carpal tunnel explains why these conditions can be seen together. Other causes for recurrent carpal tunnel include inadequate release, pronator syndrome, or concurrent cervical radiculopathy.
Question:
A 60-year-old right-handed civil construction educator presents with a 6-year history of bilateral focal pain and tenderness just distal to the lateral epicondyle. His symptoms interfere with daily activities, including physical labor, chopping firewood, and playing golf. Clinical examination reveals tenderness over the radial tunnel without tenderness over the lateral epicondyle. Resisted middle finger extension and resisted active supination in elbow extension do not aggravate the pain. There is no weakness or atrophy of posterior interosseous nerve (PIN)-innervated muscles. Previous electrophysiological studies and imaging have been inconclusive. Ultrasound-guided corticosteroid and anesthetic injection around the PIN produced dramatic but temporary improvement. What is the most likely diagnosis?
A) Lateral epicondylitis (tennis elbow)
B) Radial tunnel syndrome
C) Carpal tunnel syndrome
D) Cervical radiculopathy
E) Posterior interosseous nerve syndrome
Correct Answer: B) Radial tunnel syndrome
• Radial Tunnel Syndrome: Characterized by lateral forearm pain without motor symptoms. Tenderness is localized over the posterior interosseous nerve route, 4–5 cm distal to the lateral epicondyle at the supinator muscle, as seen in this case. Other described examination findings include pain with resisted extension of the middle finger and pain with resisted supination of the extended elbow. Electrodiagnostic studies are usually not helpful in making the diagnosis. MRI has been shown to be of benefit, however, and can help diagnose other syndromes which may produce similar complaints, including tendinopathy at the elbow. Temporary relief following corticosteroid injection supports the diagnosis. The radial tunnel is anatomically defined by the following structures: • Medial wall: The brachialis muscle and the biceps tendon. • Anterolateral wall: The mobile wad of muscles, including the brachioradialis, extensor carpi radialis longus (ECRL), and extensor carpi radialis brevis (ECRB). • Posterior wall (floor): The capitellum of the humerus and the radiocapitellar joint capsule, which continues distally as the deep head of the supinator. • Anterior wall (roof): Formed by the radial recurrent vessels, the superficial head of the supinator, and the brachialis muscle.
There are five described levels of posterior interosseous nerve (PIN) entrapment within the radial tunnel:
1. Anterior to the radiocapitellar joint: Between the brachialis and the brachioradialis.
2. At the level of the recurrent radial vessels (Leash of Henry) and the radial neck.
3. At the leading tendinous edge of the ECRB: Medial proximal border.
4. At the fibrous proximal edge of the superficial head of the supinator: Known as the arcade of Frohse.
5. At the distal edge of the superficial supinator head.
• Lateral Epicondylitis (A): Typically presents with pain over the lateral epicondyle itself, often exacerbated by resisted middle finger extension or wrist extension, which were not observed here.
• Carpal Tunnel Syndrome (C): Involves median nerve compression at the wrist, presenting with sensory changes in the hand and sparing the forearm, unlike this case.
• Cervical Radiculopathy (D): Would likely present with neck pain, radiating symptoms, and possibly weakness in a nerve root distribution, all of which were absent.
• Posterior Interosseous Nerve Syndrome (E): Causes motor deficits without pain, unlike this patient’s primary complaint of pain
