Carpal Tunnel Syndrome

CARPAL TUNNEL SYNDROME

Carpal tunnel  syndrome was first described by *Sir James Paget in 1854, but the term was coined by Moerisch.

Anatomy

The carpal tunnel is bounded by bones on three sides and a ligament on one side. The floor is an osseous arch formed by the carpal bones and the roof is formed by the transverse carpal ligament.

Contents

Tendons of flexor digitorum superficialis and profundus in a common sheath, tendon of flexor pollicis longus in an independent sheath and the median nerve.

Synovitis of the above tendons can generate pressure on the nerve.

Causes

General

Inflammatory-e.g. rheumatoid arthritis.

Endocrine-hypothyroidism, diabetes mellitus, meno pause, pregnancy, etc. are some of the important endocrine causes.

Metabolic cause-gout.

Local These cause crowding of the space. Malunited Colles' fracture, ganglion in the carpal region, osteoarthritis of the carpal bones, and wrist contusions, haematoma, etc. are some of the important local causes.

Mnemonic PRAGMTIC for causes of Carpal Tunnel syndrome [(P-Pregnancy, R-Rheumatoid arthritis, A Arthritis degenerative, G-Growth hormone abnormalities (acromegaly), M-Metabolic (gout, diabetes myxoedema, etc.), T-Tumors, I-Idiopathic, C-Connective tissue disorders (e.g. amyloidosis)].

Clinical Features

Stage I In this stage, pain is usually the presenting complaint and the patient complains of characteristic discomfort in the hand but there is no precise localization to the median nerve. There may be history of morning stiffness in the hand.

Stage II In this stage, symptoms of tingling and numbness, pain, paraesthesia, etc. are localized to areas supplied by the median nerve.

Stage III Here the patient complains of clumsiness in the hand and impairment of digital function, etc.

Stage IV In this stage sensory loss in the median nerve distribution area can be elicited and there is obvious wasting of the thenar eminence.

Clinical Tests

These are provocative tests and act as important screening methods and as an adjunct to the electrophysiologic testing.

Wrist flexion (Phalen's test) The patient is asked to actively place the wrist in complete but unforced flexion. If tingling and numbness are produced in the median nerve distribution of the hand within 60 secs, the test is positive. It is the most sensitive provocative test (Fig. 19.55). It has a specificity of 80 percent.

Tourniquet test A pneumatic blood pressure cuff is applied proximal to the elbow and inflated higher than the patient's systolic blood pressure. The test is positive if there is paraesthesia or numbness in the region of median nerve distribution of the hand. It is less reliable and is specific in 65 percent of cases only.

Median nerve percussion test (Fig. 19.56) The examiner gently taps the median nerve at the wrist. The test is positive if there is tingling sensation. Seen only in 45 percent of cases.

Median nerve compression test (Fig. 19.57) Direct pressure is exerted equally over both wrists by the examiner. The first phase of the test is the time taken for symptoms to appear (15 sec to 2 min). The second phase is the time taken for the symptoms to disappear after release of pressure.

Other Tests

Two-point discrimination test This test is positive one-third cases.

Electrodiagnostic tests are not totally infallible with 10 percent individuals having normal values.

Treatment

Non-operative methods In the initial stages non-steroidal anti inflammatory drugs (NSAIDs) are given. If it is unsuccessful steroids like prednisolone for 8 days starting with 40 mg for 2 days and tapering by 10 mg every 2 days are tried. Use of carpal tunnel splint is also advocated (Fig. 19.58).

Physiotherapy measures

Thermotherapy Using ultrasound, SWD helps to relieve pain.

Exercises Gentle relaxed passive movements, active assisted and active movements of the wrist and fingers area indicated. Treatment of the underlying disease is of utmost importance.

Splints Carpal tunnel splint helps.

Injection treatment This is indicated in patients with intermittent symptoms, duration of complaints less than one year and if there is no sensory deficits, no marked thenar wasting, etc.

In the injection therapy, a single infusion of cortisone with splinting for 3 weeks is tried.

Surgery This consists of division of flexor retinaculum and transverse carpal ligament and is indicated in failed nono perative treatment, thenar atrophy, sensory loss, etc.