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Plastic Surgery - HAND > Chapter 34 - Nerve Compression Syndromes > Flashcards

Chapter 34 - Nerve Compression Syndromes Flashcards

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1
Q

How is nerve conduction in the carpal tunnel reported?

A

Latency is reported in milliseconds (ms)

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2
Q

What is latency?

A

Latency is the time it takes for an electrical stimulus to travel along a nerve from the site of stimulation to a recording electrode in a target muscle

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3
Q

What is the normal value for motor latency in the carpal tunnel?

A

Less than 0.4ms

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4
Q

How is nerve conduction at the elbow reported?

A

Nerve conduction is reported as velocity in meters/sec

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5
Q

What is a clinically significant decrease in velocity at the elbow?

A

A decrease in velocity of 10m/s or more is considered clinically significant

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6
Q

What is the difference between the compressive neuropathies and peripheral neuropathies?

A

In peripheral (systemic) neuropathies the nerve conduction is decreased diffusely both proximally and distally in multiple nerves. In compressive neuropathies nerve conduction is decreased distal to the compression only

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7
Q

What are typical EMG findings for long-standing nerve compression and axonal damage?

A

EMG will demonstrate wide biphasic fibrillation potentials in the presence of long-standing nerve compression

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8
Q

What is double crush syndrome?

A

The double crush syndrome hypothesizes that a site of proximal nerve compression in a series with a site of distal compression results in the same clinical neuropathy, whereas independently, neither site of compression is severe enough to cause clinical neuropathy

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9
Q

What is the treatment of choice for a ulnar neuroma in continuity with intact motor function?

A

The current optimal therapy involves micro-dissection of the neuroma using electrostimulation to identify and preserve motor fascicles. En bloc resection of the neuroma is inappropriate, as this would sacrifice nerve fascicles.

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10
Q

What are some of the non surgical modalities that can be used to desensitize an amputation stump neuroma?

A

Vibration, massage, and transcutaneous nerve stimulation

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11
Q

What is complex regional pain syndrome?

A

CRPS is a constellation of symptoms including pain at rest, vasomotor instability and swelling that results in functional impairment of the affected hand or limb. It usually is the result after trauma

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12
Q

What diagnostic study can help establish the diagnosis of complex regional pain syndrome?

A

Three phase bone scintigraphy has been shown to be highly specific for the diagnosis of CRPS in the upper extremity

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13
Q

What nerve is affected with Thoracic outlet syndrome?

A

Lower trunk of the brachial plexus with symptoms mimicking cubital tunnel syndrome

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14
Q

What are the contents of the thoracic outlet?

A

Subclavian vein, subclavian arterty, brachial plexus

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15
Q

In what gender is Thoracic outlet syndrome more prevalent?

A

Females 3.5:1

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16
Q

Among the population of patients with cervical ribs, how many are bilateral?

A

50%

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17
Q

When do patients with Thoracic outlet syndrome typically get their symptoms?

A

Symptoms worsen when hands are elevated above their head

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18
Q

What is the Adson maneuver?

A

Dampening of the radial pulse with inhalation, neck extension, and head rotation towards the affected side in patients with thoracic outlet syndrome.; False positives are common

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19
Q

What is Wright maneuver?

A

Reproduction of thoracic outlet syndrome symptoms or dampening of the radial pulse with arm hyperabduction with patient’s head neutral or turned contralateral; can be positive in 7% of normal patients

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20
Q

What is Roos maneuver?

A

Placing both arms in 90 degrees of abduction and external rotation and patient opens and closes hands for 3 minutes. Thoracic outlet syndrome patients will have reproduction of symptoms, normal patients have forearm fatigue; The most accurate of the maneuvers

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21
Q

What are the electrodiagnostic testing results seen with thoracic outlet syndrome?

A

Negative EMG for ulnar nerve, positive somatosensory -evoked potentials with arm in offending position

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22
Q

What is the first line therapy for thoracic outlet syndrome?

A

Conservative treatment with exercises to strengthen the shoulder girdle, weight loss, occasionally breast reduction in women

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23
Q

Name two approaches to the thoracic outlet?

A

Supraclavicular and transaxillary

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24
Q

What is similar and what is different about the presentation of thoracic outlet syndrome and cubital tunnel syndrome?

A

Both TOS and cubital tunnel syndrome can present with ulnar distributions of numbness, although TOS also presents with medial forearm numbness

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25
How do you tell the difference between ulnar nerve compression at the cubital tunnel from compression at the wrist (Guyon canal)?
Diminished sensation of the dorsoulnar hand is present with cubital tunnel syndrome. This is due to the dorsal sensory branch of the ulnar nerve exits 7cm proximal to pisiform
26
What is the distribution of motor weakness seen with cubital tunnel syndrome?
Motor weakness in FDP of ring and small fingers, as well as ulnar intrinsic muscles
27
Describe Froment sign?
With ulnar nerve palsy, patients compensate for lack of adductor pollicis (ulnar innervated) function by flexing the thumb IP joint (pinch power is provided entirely by median-innervated FPL)
28
Where are potential sites of ulnar nerve compression?
Arcade of struthers, Intermuscular septum, Medial head of the triceps, Osbourne ligament (MC - between heads of FCU), Flexor-pronator apparatus, Guyon's canal (second MC)
29
Where/what is the arcade of struthers?
Located 8cm proximal to the medial epicondyle of the elbow, it is an upper arm fascicle arcade through which the ulnar nerve passes, Present in 70% of population
30
What are the boundaries of the cubital tunnel?
Floor- medial collateral ligament (spans from medial epicondyle to the olecranon) Roof - Osborne ligament Sides - medial epicondyle and olecranon
31
Explain why elbow hyperflexion test elicits symptoms of cubital tunnel syndrome?
Elbow flexion increases the distance the ulnar nerve has to travel to traverse the elbow
32
How sensitive is electrodiagnostic testing at the elbow?
Electrodiagnostic testing has 50% false negative rate for nerve compression at the elbow
33
What is a Martin-Gruber anastomosis? What is the significance with Cubital tunnel syndrome?
Naturally occurring anatomic variant involving an interconnection between the median nerve and the ulnar nerves in the forearm. If it is present, it can result in spared intrinsic muscle function with cubital tunnel syndrome (because then median nerve innervates intrinsics)
34
What is Riche-Cannieu anastomosis?
Naturally occurring anatomic variant involving an interconnection between the median and ulnar nerve in the hand, typically the deep or motor branch of the ulnar nerve. Muscles usually innervated by the ulnar nerve continue to function on exam
35
What are the key steps involved in anterior submuscular ulnar transposition?
Release of the FCU origin, transposition of the ulnar nerve anterior to the medial epicondyle, resuturing the FCU to the condyle. The nerve may also be transposed subcutaneously.
36
What is a common post operative complication of ulnar nerve surgery at the cubital tunnel that generally results in a painful incision.
Injury to the medial antebrachial cutaneous nerve can result in painful neuroma formation.
37
What are the boundaries of Guyon's canal?
Roof: Volar carpal ligament Floor: transverse carpal ligament Ulnar wall: pisiform Radial wall: hamate hook (although ulnar NV bundle may lie palmar or radial to hook)
38
What are the usual causes of ulnar tunnel syndrome?
Ganglions, trauma (hamate fractures), tumors, vascular anomalies, arthritis
39
What is the distribution of numbness with ulnar tunnel syndrome?
Small and ring fingers but not dorsum of hand (because of dorsal sensory branch originates proximal to Guyon's canal)
40
How does motor exam differ between ulnar nerve compression at the wrist vs elbow?
Wrist: affects pinch strength Elbow: affects pinch and grip strength
41
What is the treatment for ulnar tunnel syndrome?
Exploration of the Guyon canal, decompression of the nerve, removal of the space-occupying lesion(s), ulnar artery reconstruction (if necessary). Masses are responsible 30-45% of the time, always palpate.
42
What ligaments must be released when surgically treating ulnar tunnel syndrome?
Pisohamate ligament and volar carpal ligament
43
In what position of the ulnar nerve cross section is the motor fascicle at the level of the wrist?
Ulnar and dorsal
44
What are the three syndromes associated with median nerve compression?
1. Pronator syndrome 2. Anterior interosseous syndrome 3. Carpal tunnel syndrome
45
What conditions are associated with an increased incidence of Carpal Tunnel Syndrome?
Most are idiopathic. Can be a/w diabetes, alcoholism, arthritis, amyloidosis, or thyroid disorders.
46
How often is carpal tunnel syndrome bilateral?
60%
47
What are the borders of the carpal tunnel?
Roof: transverse carpal ligament Floor: carpal bones and their ligaments Radial wall: trapezium and scaphoid tubercle Ulnar wall: hook of hamate
48
Describe classic symptoms of carpal tunnel syndrome
Numbness in median nerve distribution (index, middle and radial ring), weakness, nocturnal pain, relief of symptoms when wearing wrist brace
49
What are the structures thought to cause effort-associated carpal tunnel syndrome (ie repetitive gripping)?
Lumbrical muscles. Originate from the FDP tendons and reside within the carpal tunnel during gripping activities.
50
What is Phalen's test?
Wrist is passively dropped into flexion. If symptoms seen in 30 seconds, the test is positive.
51
What is the most sensitive physical exam test for carpal tunnel syndrome? And how is it performed/reported?
Carpal compression test. Number of seconds from initiation of thumb pressure over carpal tunnel (enough to make examiners thumb blanch)
52
What electrodiagnostic study results signify median nerve conduction changes?
Median nerve latency increase of 10% of more above the ulnar nerve
53
What electrodiagnostic study result signifies muscle denervation with carpal tunnel syndrome?
Fibrillation potentials in the APB
54
What is the earliest one might expect to see electromyographic changes after suspected nerve damage?
2-3 weeks after injury
55
What is the success rate of steroid injections for carpal tunnel syndrome?
20-22% of patients get long term relief (>18 mo)
56
Where is the median nerve located in the proximal forearm?
between the superficial (humeral) and deep (ulnar) heads of the pronator teres muscle
57
Where is the motor fascicle of the median nerve cross-section of the wrist?
Radial and volar
58
Where is the motor fascicle of the ulnar nerve cross-section of the wrist?
Ulnar and dorsal
59
What is Kaplan's line and how is it used to determine the position of the motor branch of the median nerve?
Extension along the ulnar border of the abducted thumb. The intersection of Kaplan's line and one drawn longitudinally from index-middle finger webspace is a rough approximation of the entrance of the recurrent motor branch of the median nerve into the thenar musculature.
60
What are the patterns of the route of the motor branch to the thenar musculature in relation to the transverse carpal ligament?
Extraligamentous (approximately 50%), subligamentous (30%) , transligamentous (20-25%)
61
What are the 4 muscles innervated by the motor branch of the median nerve in the hand?
1. Opponens pollicis 2. Flexor pollicis brevis 3. Abductor pollicis brevis 4. Two radial lumbricals
62
What are the advantages of endoscopic carpal tunnel release when compared with the open technique?
Slightly higher incidence of reversible nerve injury (neuropraxia and numbness)
63
Which outcomes between endoscopic and open carpal tunnel release have been found to be equivocal?
Pain and return to work
64
Is internal neurolysis indicated during routine carpal tunnel decompression?
no
65
During secondary surgery for recurrent carpal tunnel syndrome where should the incision be made?
More ulnar to the previous scar because the median nerve is adherent to or within the transverse carpal ligament
66
What are the 4 sites of median nerve compression in the elbow/forearm?
1. Ligament of Struthers - located between humeral supracondylar process and medial epicondyle 2. Lacertus fibrosis (aka bicipital aponeurosis) a fascial band between biceps tendon and fascia of the pronator mass 3. Two heads of the pronator teres 4. FDS fibrous arch
67
How can one specifically test for median nerve compression at the ligament of Struthers?
Flex elbow against resistance, symptoms will be exacerbated
68
How can one specifically test for median nerve compression at the pronator teres?
Patient fully extends elbow and pronates forearm while examiner provides resistance to pronation. Elbow must be fully extended to avoid confusion with compression at bicipital aponeurosis
69
How can one specifically test for median nerve compression at the FDS arch?
Long finger flexion test: with resisted flexion of the long finger, the FDS arch compresses the median nerve, and symptoms are exacerbated
70
What is a Ganzer muscle?
An accessory head of the FPL originating from the medial humeral epicondyle and possibly the coronoid process of the ulna. Present in 45%, can cause median nerve compression.
71
What is the difference between pronator syndrome and AIN syndrome?
Deficits in pronator syndrome are sensory, AIN syndrome deficits are motor
72
What are the symptoms of pronator syndrome?
Pain in the forearm, numbness in the median nerve sensory distribution (thumb, index, middle)
73
What 4 muscles are innervated by the AIN?
1. FPL 2. Pronator quadratus 3. FDP to index finger 4. FDP to middle finger
74
What are the symptoms of AIN syndrome?
Loss of precision pinch (cannot flex thumb IP or index DIP). and pain in the forearm relieved by rest
75
What can patients with AIN syndrome NOT do?
Make an "ok" sign. They cannot flex their thumb IP or index DIP joints
76
Is there a difference between the surgical treatment of AIN and pronator syndromes?
No. Both cases nerve is explored completely and released from all compressing structures from the elbow to the distal forearm.
77
What are the possible sites (6) of radial nerve compression?
1. Lateral humeral intermuscular septum 2. Radial head 3. Supinator fascia (arcade of Froehse) - Most Common 4. Vascular leash of Henry 5. ECRB origin 6. Between brachioradialis and ECRL (Warenberg syndrome)
78
What is Wartenberg syndrome?
Compression of the radial sensory nerve between brachioradialis and ECRL. Involves the superficial sensory branch of the radial nerve only. AKA superficial radial neuritis or "cheiralgia paresthetica". Can also be caused by external compression (handcuffs, tight watch), surgical scarring or repetitive activities.
79
Where is the radial tunnel, what are the borders?
Runs from the radial head to the distal edge of the supinator. The biceps tendon is the medial wall and the ERCL and the ERCB origins form the lateral wall.
80
How is the radial nerve approached in the distal forearm?
Between the ERCB and the extensor digitorum communis
81
What are the symptoms of radial tunnel syndrome?
Lateral elbow pain, especially with repeated elbow extension. Motor findings are usually absent.
82
What physical exam finding differentiates radial tunnel syndrome from lateral epicondylitis?
Tenderness 4cm distal to the lateral epicondyle (Between brachioradialis and ECRL) is seen with radial tunnel syndrome
83
Is there typically a sensory component to PIN syndrome?
No. PIN innervated the extensors, resulting in weakness and pain.
84
What is the difference between radial tunnel syndrome and PIN compression?
In radial tunnel syndrome symptoms involve pain over the dorsoradial forearm near the elbow (rarely weakness). In PIN compression syndrome symptoms include weakness of the thumb and finger extensors AS WELL AS PAIN
85
Is it common to see electrodiagnostic changes with radial nerve compression?
Often EMG/NCS is normal. Diagnosis usually based on physical exam/history.
86
What is the role for surgery in PIN syndrome and radial tunnel syndrome?
Radial tunnel syndrome should be initially managed non-operatively (muscle palsy is not seen). PIN syndrome should be treated operatively to prevent permanent muscle palsy.
87
What is the vascular leash of Henry?
Network of radial recurrent vessels at the elbow that can compress the PIN, radial sensory nerve, or both.
88
What is Wartenberg sign?
Indicates ulnar neuropathy and is seen when the small finger is unable to adduct against the ring finger.
89
How does one differentiate radial sensory nerve compression from DeQuervain extensor tenosynovitis in the presence of a positive Finkelstein test?
Resisted thumb extension with the wrist held in neutral causes pain in tendinitis but not in nerve entrapment.
90
What is Volkmann contracture?
Sequelae of forearm compartment syndrome generally following supracondylar humerus fracture that results in severely contracted forearm and hand. Forearm is pronated, wrist flexed, MCP joints hyperextended and IP joints flexed (non-functional claw hand)
91
How high must forearm compartments pressures be to develop Volkmann's contracture?
>30mmHg for 6-12 hours
92
What muscles are most at risk of ischemic sequelae from forearm compartment syndrome?
FDP muscle within the deep compartment
93
What is the treatment for Volkmann's contracture?
Moderate Volkmann's contractures are treated with operative exploration of the forearm with neurolysis of the median and ulnar nerves as well as a muscle slide tendon-lengthening procedure.

Plastic Surgery - HAND (16 decks)

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