Nerve potentials and afferent conduction velocities in the differential diagnosis of amyotrophy of the hand.

Nerve action potentials recorded over the elbow after stimulation of the wrist were studied in patients with hand amyotrophy of different origin. In amyotrophic lateral sclerosis the amplitude of nerve action potentials does not change significantly even with extreme muscle wasting and loss of motor units.Studies of multisegmental afferent conduction velocities may demonstrate a strictly localized lesion with normal values above the compression.