Acute and reversible parkinsonism due to organophosphate pesticide intoxication

Abstract

Objective: To describe five patients who developed acute and reversible parkinsonism following organophosphate (OP) pesticide exposure, and to consider whether this syndrome represents a rare sequela of such exposure in genetically susceptible individuals. Background: Several toxins are known to produce parkinsonism following acute exposure. Although case–control studies have implicated OP pesticides in the etiology of PD, acute parkinsonism following brief pesticide exposure has never been reported. Methods: The authors describe the clinical syndrome affecting five patients who presented with recent OP exposure and symptoms of an acute akinetic–rigid syndrome. Results: All patients developed parkinsonism that resembled PD clinically except for poor response to levodopa. Three genetically related patients were exposed to pesticides in a common environment before onset of parkinsonism; other family members remained unaffected. Other secondary causes of parkinsonism were excluded. Four patients recovered completely without treatment, and one patient was lost to follow-up. One patient experienced repeated episodes of parkinsonism with inadvertent reexposure to a pesticide-contaminated environment. Conclusion: The clinical course of these five patients suggests their syndrome represents a heretofore undescribed toxic effect of OP pesticides. Our observations strengthen epidemiologic studies implicating OP pesticides in the etiology of PD. A genetic susceptibility to OP pesticide-induced parkinsonism may account for three family members developing this syndrome.