CONTRIBUTION OF ELECTROMYOGRAPHY TO THE D IAGNOSIS OF BOTULISM

Botulism is a cause of neuromuscular transmission impairment. We repor t here an electrophysiological study of the neuromuscular junction in a patient presenting with botulism. Repetitive stimulation of a motor nerve showed a characteristic triad, indicating presynaptic block of n euromuscular transmission: the muscle action potential amplitude was l ow; repetitive high frequency stimulation (20 Hz) induced a more than 100% increment in the amplitude; low frequency repetitive stimulation (3Hz) induced a more than 10% decrement in the amplitude. Progressive clinical improvement spontaneously occurred and the electrophysiologic al control recording that was done I month later was normal. Botulism toxin reduces acetylcholine quanta released in the autonomic and neuro muscular junction, causing presynaptic block. Electrophysiological rec ordings associated with clinical data contributed more to the diagnosi s of botulism than serological analysis, which remained negative in th is patients.