Monocrotophos-Induced Intermediate Syndrome Complicated by Hyperammonemic Encephalopathy: A Case Report

Organophosphorus (OP) poisoning is the most common type of poisoning in India. Amongst the OP, monocrotophos poisoning has the highest lethality and need for mechanical ventilation. Monocrotophos is also implicated in causing OP-induced intermediate syndrome, the prevalence of which is 10-40% of all OP poisoning. The other neurological manifestations are delayed neuropathy and neuropsychiatric syndrome. We herein discuss a case of a 58-year-old male who presented with monocrotophos poisoning and intermediate syndrome. During the hospitalisation course, the patient developed hyperammonemic encephalopathy, resulting in difficulty in weaning from mechanical ventilation. After ruling out all possible causes of hyperammonemia, it was attributed to monocrotophos poisoning. The patient improved significantly after initiating lactulose and was successfully weaned off from the ventilator. This report highlights the high index of suspicion of hyperammonemic encephalopathy in monocrotophos toxicity, which can be easily missed due to other commoner neurological manifestations of organophosphorus poisoning.