Carpal tunnel syndrome is the commonest mononeuropathy. Mononeuropathy means the lesion only affect one nerve. Carpal tunnel syndrome occurs at wrist region. At this region median nerve has to compete with other 9 tendons for space. Compression will occur especially on women that have small wrists and similar sized tendons to men.
The patients will complaint of pain at hand and arm especially at night. There is also paraesthesia (numbness) in the thumb. It means reduce sensation of the thumb, index and middle fingers (because median nerve supplies the sensation to this area). Pain usually improves after dangling the hand over the edge of the bed. Some patients do claim that pain reduce after shaking he hand. There may also some weakness and sensory loss over the abductor pollicis brevis. In some patients, wasting of thenar eminence can be observed. Due to this problem, light touch, 2 point discrimination and sweating may be impaired.
Carpal tunnel syndrome may be found in pregnant ladies, patient with rheumatoid arthritis, diabetes mellitus, hypothyroidism and acromegaly. Some other risk factors are trauma and dialysis.
There are 2 tests that have been used widely use. The first one is phalen’s test. During this test, maximal flexion of the wrist for 1 minute will produce the symptoms. However, the test are not reliable, some patients will have false negative test. The other test is tinnel’s test. During this test, tapping over the nerve at the wrist will induce tingling sensation especially over the thumb, index and middle finger. However this test is rather non specific. The diagnosis is mainly done by clinical history.
Treatment includes splinting and local steroid injection. Some patients require decompression surgery. In some patients, symptoms will improve spontaneously after the cause is removed or controlled, for example after the delivery of the baby in pregnant ladies.
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Reference:
1. Oxford Handbook of Clinical Medicine. 7th edition. Oxford. 2008.
