The electromyographic silent period in Huntington's chorea--a comparison between childhood and adult values.

The electromyographic silent period produced by electrical stimulation of the median nerve was recorded in the abductor pollicis brevis muscle in a group of 7 patients with Huntington's chorea (5 adults and 2 children). The adults had short values of 60.0--75 ms, while the values in the children were within normal limits (90--140 ms). These results suggest: (i) that the short silent period in Huntington's chorea is due to reduced excitation (or increased inhibition) of spinal interneurons; and (ii) that Huntington's chorea in childhood differs from that in adults not only with regard to the clinical picture but with regard to silent period values elicited by stimulation of the median nerve.