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Single fibre EMG in 6 cases of botulism
Abstract:
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.
Insights
Single-fiber EMG (SFEMG) detects neuromuscular transmission defects in mild botulism, showing abnormal jitter and blocking. Findings improve over time but may persist for months, indicating SFEMG
Area of Science:
- Neurology
- Electromyography
- Toxicology
Background:
- Botulinum intoxication affects neuromuscular transmission.
- Conventional EMG and SFEMG are diagnostic tools.
Purpose of the Study:
- To evaluate the utility of SFEMG in mild botulism.
- To assess the temporal evolution of neuromuscular defects in botulism.
Main Methods:
- Six patients with mild botulism underwent conventional EMG and SFEMG.
- Electrophysiological assessments were performed at multiple time points post-admission.
Main Results:
- SFEMG revealed abnormal jitter in nearly all patients initially.
- Jitter and blocking improved over 14 weeks but abnormalities persisted in some cases.
- SFEMG findings correlated with clinical status and conventional EMG.
Conclusions:
- SFEMG is highly sensitive for detecting neuromuscular transmission defects in botulism.
- SFEMG provides valuable insights into the course and recovery from botulism.
- Persistent subtle abnormalities suggest long-term effects of botulinum toxin.