Central motor conduction in cerebrovascular disease and motor neuron disease

Conduction in the central motor pathways was studied in 9 patients with cerebrovascular disease (CVD), 13 with amyotrophic lateral sclerosis (ALS) and 3 with spinal progressive muscular atrophy (SPMA). Motor responses evoked in the limb by cortical, cervical and lumbar stimulations were recorded. The central conduction time (CCT) was calculated for each muscle. In patients with CVD, responses to cortical stimulation were unobtainable or delayed in the paretic limb muscles. In patients with ALS the abnormality of central motor conduction had significant correlation with the extensor plantar response. The CCTs were normal in patients with SPMA. This technique demonstrated a subclinical lesion in some patients. We conclude that the new technique of examining motor conduction along the corticospinal tract may be useful to detect a subclinical lesion in the corticospinal tract.