Grund1 and later Shelden and Woltman2 found that the intrathecal injection of procaine in an amount sufficient to produce complete motor paralysis of the legs did not abolish the muscular fibrillations in patients with amyotrophic lateral sclerosis. These experiments were interpreted as showing that the impulses causing these fibrillations did not arise from the cell bodies of the motor neurons of the ventral horn. Each of these investigations consisted of but 1 experiment; the nature of the muscular twitchings was not controlled by electrical recordings, and no further attempt was made to locate the source of the impulses causing the fibrillations. For these reasons the present study was undertaken.
Three patients with typical and advanced amyotrophic lateral sclerosis and 2 others with progressive muscular atrophy with muscular fibrillation3 were utilized in this study. Three of the patients exhibited many and 2 relatively infrequent muscular fibrillations at