Carpal tunnel syndrome

From Ganfyd

Carpal tunnel syndrome (CTS) is a very frequent condition. This is associated with the narrow space the median nerve passes through at the wrist, in proximity to the flexor tendons and limited by the flexor retinaculum.

History

Carpal tunnel syndrome is generally strongly suspected from the history alone, but may co-exist or be confused with other problems in the nerve's course. Symptoms of tingling and numbness in a distribution consistent with the anatomy and with some relationship to activity and also particularly pain in the fingers and up the arm wakening the patient are highly suggestive.

Clinical signs

• Objective testing for loss of sensation in the fingers may be done, more commonly the halves of fingers which the patient reports disturbance in are taken note of.
• The loss of thenar muscles is an uncommonly seen sign suggesting severe compression and demanding rapid action. In the UK it may develop between referral and an out-patient appointment, and it may therefore be worth remarking in the initial note on its absence.
• Tingling in the (relevant) fingers on percussion of the nerve at the wrist. A moment's experiment will demonstrate that it is possible to produce this with forceful percussion of a normal wrist, but the sign is elicited with gentle percussion. Tinel sign.
• Reproduction of symptoms by flexing the wrist to 90 degrees. Again, this requires minimal force to elicit the sign in an abnormal wrist. Phalen sign.

Special examinations

In cases of real doubt electrical studies of conduction in the nerve may be useful. While waiting, in the UK, for these to happen re-examination of the patient may give the diagnosis more clearly as the condition evolves over a year or two. Electrical testing is recommended before surgical decompression, but should not delay injection.

Imaging is not normally used.

Canterbury Score

A score (0-5 with zero being normal) for severity of CTS). From Kent and Canterbury Hospital. It is reported to correlate with surgical findings.

Treatment

Advice on keeping the wrist in a neutral position while typing or doing other repetitive tasks is presumed to do no harm, and this along with moderation of the activity and splinting (with a Futuro splint) at night may be tried before injecting the carpal tunnel. If the thenar muscles are wasted, or there is no improvement after an injection an Orthopaedic opinion should be sought, likewise if three injections at monthly intervals are followed by prompt recurrence.

Genetics

There is the possibility of genetic predisposition. Heterozygotes for a mutation of ST3TC2 manifest through recessive inheritence with peroneal muscular atrophy develop carpal tunnel syndrome in late life ^[1] and it will occur in hereditary neuropathy with liability to pressure palsies caused by mutations in PMP22

References

See also

Clinical review, BMJ 2007 Bland, J.