Wrist and hand

Carpal tunnel syndrome

Mechanism: Compression of the median nerve in the carpal tunnel, between the carpal bones and the flexor retinaculum. Swelling of the tendon sheaths, a change in fluid balance or repeated forceful gripping raise the pressure in the tunnel.
Recognition: Tingling in the thumb, index and middle finger that wakes the patient at night and eases on shaking the hand. Longer standing cases show thenar atrophy and loss of grip strength.
Course: The classic nocturnal tingling is diagnostically more valuable than the provocation tests: Phalen and Tinel both have moderate specificity. Thenar atrophy is a late sign and a reason to stop waiting.

Structures