Slowed nerve conduction with wrist flexion in carpal tunnel syndrome.

Phalen's wrist flexion test may reproduce the sensory symptoms of carpal tunnel syndrome (CTS). We have used this test in conjunction with motor and sensory latency studies in 20 patients with symptomatic CTS in one or both hands. The test caused an increase in the motor or sensory latency in half the patients. In 2 patients the latencies were abnormal only after wrist flexion. The test may thus be useful in diagnosis of borderline cases.