SLOW MOTOR CONDUCTION MAINLY LIMITED TO MOTOR ROOT IN AMYOTROPHIC-LATERAL-SCLEROSIS

Motor conduction velocity is expected to be normal or nearly normal in amyotrophic lateral sclerosis (ALS), Some studies have suggested that pathology may be present in the proximal axons. Indeed, some investig ators have shown a decrease in the proximal conduction velocity in ALS by using motor conduction velocity measurements and H-reflex and F-re sponse recordings, but they could not delineate the precise region of the conduction pathology. In this study, unlike the ones carried out p reviously, the most proximal segment has been studied in 11 patients w ith ALS, 13 normal controls, and 5 patients with sequel of poliomyelit is (SPM) by recording sensory and motor spinal root potentials. While no conduction pathology, H-reflex, or F-response abnormalities were fo und in ALS patients compared to normal subjects, it was shown that con duction velocity decreased in the proximal segment of the lower motor neuron of the ventral root. Despite motor neuron pathology in SPM, the re was no proximal motor conduction slowing compared with that in norm al subjects. (C) 1996 John Wiley & Sons, Inc.