Carpal Tunnel Syndrome Flashcards
Background
Carpal tunnel syndrome (CTS) is a collection of characteristic symptoms and signs that occurs following compression of the median nerve within the carpal tunnel. Usual symptoms include numbness, paresthesias, and pain in the median nerve distribution. These symptoms may or may not be accompanied by objective changes in sensation and strength of median-innervated structures in the hand
Pathophysiology
Until the advent of electrophysiologic testing in the 1940s, carpal tunnel syndrome (CTS) commonly was thought to be the result of compression of the brachial plexus by cervical ribs and other structures in the anterior neck region.
It is now known that the median nerve is damaged within the rigid confines of the carpal tunnel, initially undergoing demyelination followed by axonal degeneration. Sensory fibers often are affected first, followed by motor fibers. Autonomic nerve fibers carried in the median nerve also may be affected.
The cause of the damage is subject to some debate; however, it seems likely that abnormally high carpal tunnel pressures exist in patients with CTS. This pressure causes obstruction to venous outflow, back pressure, edema formation, and ultimately, ischemia in the nerve.
The risk of development of CTS appears to be associated, at least in part, with a number of different epidemiologic factors, including genetic, medical, social, vocational, avocational, and demographic. A complex interaction probably exists between some or all these factors, eventually leading to the development of CTS. Definite causative factors, however, are far from clear.
Carpal Tunnel Syndrome Epidemiology
Mortality/Morbidity
Carpal tunnel syndrome is not fatal, but it can lead to complete, irreversible median nerve damage, with consequent severe loss of hand function, if left untreated.
Race
Whites are probably at highest risk of developing carpal tunnel syndrome (CTS). The syndrome appears to be very rare in some racial groups (eg, nonwhite South Africans). In North America, white US Navy personnel have CTS at a rate 2-3 times that of black personnel.
Sex
The female-to-male ratio for carpal tunnel syndrome is 3-10:1.
WOMEN get it more
Age
The peak age range for development of carpal tunnel syndrome (CTS) is 45-60 years. Only 10% of patients with CTS are younger than 31 years.
Pathophysiology to know for Carpal Tunnel syndrome
It is now known that the median nerve is damaged within the rigid confines of the carpal tunnel, initially undergoing demyelination followed by axonal degeneration. Sensory fibers often are affected first, followed by motor fibers. Autonomic nerve fibers carried in the median nerve also may be affected.
The cause of the damage is subject to some debate; however, it seems likely that abnormally high carpal tunnel pressures exist in patients with CTS. This pressure causes obstruction to venous outflow, back pressure, edema formation, and ultimately, ischemia in the nerve.
The risk of development of CTS appears to be associated, at least in part, with a number of different epidemiologic factors, including genetic, medical, social, vocational, avocational, and demographic.
History
The patient’s history often is more important than the physical examination in making the diagnosis of carpal tunnel syndrome (CTS).
- Numbness and tingling
i. Among the most common complaints, patients will reveal that their hands fall asleep or that things slip from their fingers without their noticing (loss of grip, dropping things); numbness and tingling also are commonly described.
ii. Symptoms are usually intermittent and are associated with certain activities (eg, driving, reading the newspaper, crocheting, painting).
iii. Nighttime symptoms that wake the individual are more specific to CTS, especially if the patient relieves symptoms by shaking the hand/wrist. Bilateral CTS is common, although the dominant hand is usually affected first and more severely than the other hand.
iv. Complaints should be localized to the palmar aspect of the first to the fourth fingers and the distal palm (ie, the sensory distribution of the median nerve at the wrist). Numbness existing predominantly in the fifth finger or extending to the thenar eminence or dorsum of the hand should suggest other diagnoses. A surprising number of CTS patients are unable to localize their symptoms further (eg, whole hand/arm feeling dead). This generalized numbness may indicate autonomic fiber involvement and does not exclude CTS from the diagnosis.
- Pain
i. The sensory symptoms above commonly are accompanied by an aching sensation over the ventral aspect of the wrist. This pain can radiate distally to the palm and fingers or, more commonly, extend proximally along the ventral forearm.
ii. Pain in the epicondylar region of the elbow, upper arm, shoulder, or neck is more likely to be due to other musculoskeletal diagnoses (eg, epicondylitis) with which CTS commonly is associated. This more proximal pain also should prompt a careful search for other neurologic diagnoses (eg, cervical radiculopathy).
- Autonomic symptoms
Not infrequently, patients report symptoms in the whole hand. Many patients with CTS also complain of a tight or swollen feeling in the hands and/or temperature changes (eg, hands being cold/hot all the time).
Many patients also report sensitivity to changes in temperature (particularly cold) and a difference in skin color. In rare cases, there are complaints of changes in sweating. In all likelihood, these symptoms are due to autonomic nerve fiber involvement (the median nerve carries most of the autonomic fibers to the hand). - Weakness/clumsiness - Loss of power in the hand (particularly for precision grips involving the thumb) does occur; in practice, however, loss of sensory feedback and pain is often a more important cause of weakness and clumsiness than is loss of motor power per se.
Numbness and tingling
Carpal Tunnel syndrome
i. Among the most common complaints, patients will reveal that their hands fall asleep or that things slip from their fingers without their noticing (loss of grip, dropping things); numbness and tingling also are commonly described.
ii. Symptoms are usually intermittent and are associated with certain activities (eg, driving, reading the newspaper, crocheting, painting).
iii. Nighttime symptoms that wake the individual are more specific to CTS, especially if the patient relieves symptoms by shaking the hand/wrist. Bilateral CTS is common, although the dominant hand is usually affected first and more severely than the other hand.
iv. Complaints should be localized to the palmar aspect of the first to the fourth fingers and the distal palm (ie, the sensory distribution of the median nerve at the wrist).
v. Numbness existing predominantly in the fifth finger or extending to the thenar eminence or dorsum of the hand should suggest other diagnoses. A surprising number of CTS patients are unable to localize their symptoms further (eg, whole hand/arm feeling dead).
This generalized numbness may indicate autonomic fiber involvement and does not exclude CTS from the diagnosis.
Pain in Carpal Tunnel Syndrome
i. The sensory symptoms above commonly are accompanied by an aching sensation over the ventral aspect of the wrist. This pain can radiate distally to the palm and fingers or, more commonly, extend proximally along the ventral forearm.
ii. Pain in the epicondylar region of the elbow, upper arm, shoulder, or neck is more likely to be due to other musculoskeletal diagnoses (eg, epicondylitis) with which CTS commonly is associated. This more proximal pain also should prompt a careful search for other neurologic diagnoses (eg, cervical radiculopathy).
Carpal Tunnel Syndrome
Autonomic Symptoms and Weakness
Autonomic symptoms
i. Not infrequently, patients report symptoms in the whole hand. Many patients with CTS also complain of a tight or swollen feeling in the hands and/or temperature changes (eg, hands being cold/hot all the time).
ii. Many patients also report sensitivity to changes in temperature (particularly cold) and a difference in skin color. In rare cases, there are complaints of changes in sweating.
iii. In all likelihood, these symptoms are due to autonomic nerve fiber involvement (the median nerve carries most of the autonomic fibers to the hand).
Weakness/clumsiness - Loss of power in the hand (particularly for precision grips involving the thumb) does occur; in practice, however, loss of sensory feedback and pain is often a more important cause of weakness and clumsiness than is loss of motor power per se.
Carpal Tunnel Syndrome Differential Diagnoses
Diagnostic Considerations:
Focal CNS pathology ( multiple sclerosis, tumor, stroke)
Proximal median nerve mononeuropathy (eg, pronator teres syndrome)
Polyneuropathies
Raynaud syndrome
Degenerative arthritis in the hand and wrist
Workup
Laboratory Studies
No blood tests exist for the diagnosis of carpal tunnel syndrome; however, laboratory testing for associated conditions (eg, diabetes) may be performed when clinically indicated.
Imaging Studies
No imaging studies are considered routine in the diagnosis of carpal tunnel syndrome (CTS).
Magnetic resonance imaging (MRI) of the carpal tunnel is particularly useful preoperatively if a space-occupying lesion in the carpal tunnel is suggested. Signal abnormality can be detected in the median nerve in some cases of CTS, but how these abnormalities correlate to diagnosis and physiologic severity is not clear. MRI does not rule out the multitude of other differential diagnoses and is time consuming and resource intensive. [
Many clinical neurophysiology laboratories are now using ultrasonography as an adjunct to electrodiagnostic studies. Ultrasound potentially can identify space-occupying lesions in and around the median nerve, confirm abnormalities in the median nerve (eg increased cross sectional area) that can be diagnostic of CTS, and help guide steroid injections into the carpal tunnel.
Other Tests
Electrophysiologic studies, [17, 18, 19] including electromyography (EMG) and nerve conductions studies (NCS), are the first-line investigations in suggested carpal tunnel syndrome (CTS). [20] Abnormalities on electrophysiologic testing, in association with specific symptoms and signs, are considered the criterion standard for CTS diagnosis. In addition, other neurologic diagnoses can be excluded with these test results.
Medical Treatment
Most individuals with mild to moderate carpal tunnel syndrome (CTS; according to electrophysiologic data) respond to conservative management, usually consisting of splinting the wrist at nighttime for a minimum of 3 weeks. Many off-the-shelf wrist splints seem to work well, although theoretically, a custom-made splint in neutral is probably the best choice.
Steroid injection into the carpal tunnel has been shown to be of long-term benefit and can be tried if more conservative treatments have failed
- Injections may also be worthwhile prior to surgical management or in cases in which surgery is relatively contraindicated (eg, because of pregnancy).
- Ultrasound measurements of the median nerve can help predict response to steroid injection.
A randomized clinical trial by Raeissadat et al indicated that in patients with mild to moderate CTS, a local progesterone injection produces improvement comparable to that from a corticosteroid injection, with functional outcome actually being superior to that from corticosteroid treatment
Nonsteroidal anti-inflammatory drugs (NSAIDs) and/or diuretics may be of benefit against CTS in certain populations (eg patients with fluid retention or with wrist flexor tendinitis). The efficacy of gabapentin, diuretics, and NSAIDs is controversial, however, with guidelines from the American Academy of Orthopaedic Surgeons stating that oral agents are no better than placebo in the treatment of CTS
Surgical Intervention
Patients whose condition does not improve following conservative treatment and patients who initially are in the severe carpal tunnel syndrome (CTS) category (as defined by electrophysiologic testing) should be considered for surgery. [36] Surgical release of the transverse ligament provides high initial success rates (greater than 90%), with low rates of complication; however, it has been suggested that the long-term success rate may be much lower than previously thought (approximately 60% at 5 y). Success rates also are considerably lower for individuals with normal electrophysiologic studies.
