Sensory conduction in the syndrome of Guyon's tunnel.

The conduction velocity and potentials of the sensory part of the ulnar nerve were studied in the syndrome of Guyon's tunnel. If the superficial branch of the ulnar nerve was injured by entrapment, the sensory conduction velocity was decreased and changes in the sensory potential occurred. The conduction velocity at the forearm remained normal. This aid to diagnosis is recommended in addition to the measurement of conduction velocities in the motor branches to M. abductor digiti minimi and M. interossei dorsales.