Central motor conduction in a family with hereditary motor and sensory neuropathy with pyramidal signs (HMSN V).

Two generations of a family affected by hereditary motor and sensory neuropathy with pyramidal signs (HMSN V) were clinically and electrophysiologically examined. Apart from electroneurographic studies, the central motor conduction (CMC) to arm and leg muscles was assessed using magnetic transcranial motor cortex stimulation. Abnormal CMC was confined to the clinically affected members, with the exception of an unaffected subject who had a diminished but normal latency response in a leg. The typical pattern was a significant diminution of the compound muscle action potential from the tibialis anterior and a moderately prolonged cortico-muscular conduction time (CoMCT) to this muscle.