Neuromuscular transmission failure due to common krait (Bungarus caeruleus) envenomation

Neurophysiological studies were performed in 12 patients with neuromuscular paralysis due to envenomation by the common krait (Bungarus caeruleus). Al l patients presented with an acute, reversible, oculofaciobulbar paresis. I n addition, 7 patients had weakness of the limb muscles and 4 required assi sted mechanical ventilation. Neurophysiological abnormalities included: (1) a reduction in the amplitude of the median-elicited compound muscle action potential (CMAP) in 4 patients; and (2) a decremental response (>10%) to 3 -Hz repetitive nerve stimulation (RNS) in 4 patients. With 1 exception, the se abnormalities were noted only in clinically weak muscles. The administra tion of edrophonium to 6 patients produced an insignificant increase in CMA P amplitudes as well as partial (not significant) improvement in the decrem ental response to 3-Hz RNS. Neurophysiological studies were performed in 2 patients before and after the administration of 20 mt of polyvalent antiven om. A decrease in amplitude of the median-elicited CMAP amplitude occurred after the administration of antivenom. In I patient, administered 100 mt of antivenom, the median-elicited CMAP amplitude increased and the decrement to 3-Hz RNS decreased. Neurophysiological studies can provide useful inform ation regarding the nature, severity, and therapy of the neuroparalytic syn drome of krait envenomation. (C) 1999 John Wiley & Sons, Inc. Muscle Nerve 22: 1637-1643, 1999.