Single fibre EMG in 6 cases of botulism.

In 6 cases of mild botulinum intoxication, conventional EMG and single fibre EMG (SFEMG) were performed on admission to our ward (about 15 days after ingestion of the toxin) and 4, 8 and 14 weeks after admission. In 4 cases, conventional EMG resulted in abnormal findings; and they normalized 4 weeks later. On the first examination, SFEMG revealed in all cases but one the occurrence of potential pairs with abnormal jitter (above 50 mus). The % of the potential pairs with abnormal jitter ranged in different cases from 17% to 44%. Some of the potential pairs with abnormal jitter showed blockings; the occurrence of blockings was not strictly related to jitter value. Mean jitter value and % of potential pairs with abnormal jitter became progressively reduced with increasing time after intoxication. Nevertheless, in 4 cases slightly abnormal findings were still present after 4 months. The data obtained in the basal condition are in agreement with those reported by others. SFEMG findings relate fairly well to conventional EMG data and clinical status. SFEMG has proved to be a very sensitive method for studying the neuromuscular transmission defect in botulism and in obtaining further information on the course of the syndrome.