Comparison of sensory nerve conduction in the palmar cutaneous branch and first digital branch of the median nerve: a new diagnostic method for carpal tunnel syndrome.

Comparison of sensory nerve conductions in palmar cutaneous branch (PCB) and digit I nerves was applied in 50 patients suspected of having carpal tunnel syndrome (CTS) and 40 healthy persons. The abnormalities were defined as the differences in latencies and sensory nerve conduction velocities (SNCVs) of more than mean plus 2.5 SD of controls. Comparing these 2 sensory nerves, statistical differences were seen in 83.7% (36 of 43 patients) of their sensory latencies and 76.7% (33 of 43 patients) of their SNCVs. This excluded 7 patients who had unobtainable sensory nerve action potentials in digit I nerves. This method may serve as an adjunctive technique in the diagnosis of CTS. Its diagnostic sensitivity was high in comparison with other testing methods.