Clinician expectation and anatomical studies suggest that the distribution of sensory dysfunction in carpal tunnel syndrome (CTS) should be confined to the thumb, index, middle and half of the ring fingers. We mapped the distribution of disturbance to evaluate the accuracy of these assumptions.

We evaluated 64 wrists in 64 patients with nerve conduction study confirmed CTS. Each patient filled out a Katz hand diagram and we collated the distribution of pain and non-painful (tingling, numbness & decreased sensation) sensory disturbance. Frequency of reporting was analysed; dividing symptoms into thenar and hypo-thenar eminence, distal palm, each digit, posterior hand and forearm.

Non-painful sensory disturbance occurred in all patients. The index finger was the most common location (94%) followed by the middle finger (91%), the distal palm (84%), the ring finger (72%), the thumb (69%), the thenar eminence (63%), the little finger (39%), the dorsal hand (31%), the hypothenar eminence (25%) and the forearm (13%).

Pain was less common, reported in 59% of cases. Pain occurred most frequently over the wrist crease (33%) followed by thenar eminence (27%), the forearm (20%), the middle finger (23%), the index finger (22%), the ring finger (19%), the distal palm (16%), the thumb (14%), the dorsal hand (11%), the little finger (11%) and least frequently the hypothenar eminence (6%)

In CTS sensory disturbance occurs most frequently in the median nerve distribution; however it occurs almost as often elsewhere. An atypical distribution of symptoms should not discourage diagnosis of CTS.