Acute reversible Parkinsonism following accidental exposure to organophosphate insecticide

Organophosphate insecticide (OPI) poisoning is one of the most common poisonings seen in rural south India. OPIs act by inhibiting acetylcholine esterase enzyme activity and thereby increasing acetylcholine at synapses. The usual neurological complications of OPI compounds are acute cholinergic crisis, intermediate syndrome, and delayed sensorimotor polyneuropathy. Extrapyramidal symptoms, though very rare, can also occur following OPI exposure. Parkinsonism is a movement disorder that develops as a consequence of reduced function of the dopaminergic neurons within the basal ganglia. The etiology of parkinsonism is multifactorial, with both genetic and environmental determinants. The development of typical parkinsonism following brief inhalational OPI exposure is very rare and there are only a few reports in the literature. We report a 50-year-old male who presented with cholinergic crisis following acute accidental inhalational exposure to chlorpyriphos, an OPI compound; he developed features of parkinsonism on day 6 of hospital admission, but recovered completely without treatment in 7 days.