The Carpal Tunnel Syndrome - what is it ?


This condition previously occurred most commonly in women, 30 to 60 years of age. With the increased use of computers, men as well as women are affected. The age of onset has also become lower.

Carpal Tunnel Syndrome is due to compression of the median nerve as it passes through the carpal tunnel leads to signs and symptoms in the distribution of the median nerve such as numbness in the thumb, index and long fingers, awakening at night with numbness, pain, and/or burning.

Compression of the nerve occurs in the area under the transverse carpal ligament.

Occupations that require chronic repetitive wrist
motion in flexion, extension, and gripping are prone to develop carpal tunnel syndrome. Common occupations include typists, computer operators, grocery checkers, dental hygienists, and packing house workers.

Carpal tunnel syndrome may also be result of a motor vehical accident.

Another factor in the development of carpal tunnel syndrome is any activity that results in chronic trauma to the volar side of the wrist.

Carpal tunnel syndrome that develops as a result of repetitive vibrational injury may have a worse prognosis as the nerve may be injured both by compression as well as recurrent mechanical trauma. Assembly line, construction workers involved in repetitive hammering, carpenters, and
electrical workers are prone to develop carpal tunnel syndrome.

Many times it is helpful if patients can perform different types of activities during an 8-hour shift (part of time assembly line, part of time another job within same factory).

Not all cases of carpal tunnel syndrome are due to repetitve trauma. Premenstrual fluid retention, early rheumatoid arthritis with synovial tendon sheath thickening, distal radius or carpal fractures may be responsible as they restrict the space left for the nerve in the carpal tunnel.

The condition is sometimes seen in association with thyroid disease, acromegaly, and pregnancy.

Diabetic patients are also at increased risk.

Often, however, no obvious cause can be found.

Patients complain of paresthesias in the hand and weakness in handling objects. Often they claim that all the fingers are involved and, although theoretically the little finger should be spared, approximately 30% of patients also have paresthesias in the ulnar nerve distribution.

Pain may radiate proximally to the elbow or shoulder. Weakness of grip is also common. The symptoms often become most marked at night, often awakening the patient (called nocturnal paresthesias).

Typically the patient will shake the hand or hang it over the side of the bed. In some cases the history and clinical examination are unequivocal.

In others it may be difficult to differentiate the patient's symptoms from those produced by radiculitis of the sixth cervical root, pronator syndrome, or diabetic
peripheral neuropathy; indeed both conditions may
be present at the same time as carpal tunnel syndrome.

Two-point discrimination testing
useful when screening for any of the compression
neuropathies such as carpal tunnel syndrome. The test is performed by either bending the prongs of a small paper clip so that there is a 6 mm distance between the tips or by using a commercially available two-point discrimination caliper. The tips are placed against the volar pulp of the fingers until there is a slight blanching of the skin under the prongs.
The patient is then asked if he/she is able to discriminate between one or two points. Both hands should always be tested as bilateral carpal tunnel syndrome is common.
Normal two-point discrimination is 4-6 mm. On physical examination two-point discrimination may be abnormal (greater than 6 mm), grip strength diminished, and thenar
atrophy present.

Tinel Test

This test is performed by having the examiner
gently tap the area over the median nerve at the
wrist. While this can be done with a reflex hammer it is better done using the examiner's long finger bent 90 degrees at the PIP joint as this joint is more sensitive. The test result is considered positive if this produces
tingling in the fingers.

Phalen's (Wrist-Flexion) Test

The patient actively places the wrist in complete but
unforced flexion. If numbness and tingling are produced or exaggerated in the median nerve distribution of the hand (thumb, index and long fingers) within 60 seconds, the
test result is considered positive (abnormal).
In patients with limited wrist motion gentle compression over the median nerve may produce the same result.



For patients seen early, before the development of abnormal two-point discrimination or thenar atrophy, splinting of the wrist with or without injection of steroids into the carpal canal may prove successful.
If conservative treatment does not relieve the symptoms - 
electrodiagnostic testing (EMG, NCV) is useful when contemplating surgery or trying to rule out another etiology.

If, there is either thenar atrophy (muscle wasting) or abnormal two-point discrimination in the distribution of the median nerve then surgical release of the transverse carpal ligament is the best treatment .. 

This can be done either using the traditional open approach or using the newer endoscopic technique. The endoscopic technique gives a quicker return to work and activity and has less post-operative pain in most patients.

Postoperatively, patients are protected in a removable volar resting wrist splint for 2 to 3 weeks.
During this time finger motion is encouraged. After the splint is removed wrist range of motion exercises and grip
strengthening are started.

Most patients will return to their preoperative level of grip strength and wrist motion by 3 months.

Not all patients will require therapy after surgery but if progress appears slow, referral to an Occupational or hand therapist should be made.

Patients are usually ready to return to work between 3 and 6 weeks postoperatively.

carpal tunnel anatomy

Phalen's Test

Tinel's Test