Clinical Review of Organophosphate Poisoning & Sequelae ; Organophosphate Induced Delayed Polyneuropathy

ABSTRACT

BACKGROUND: Organophosphate induced delayed polyneuropathy(OIDP) by ingestion is not common, and the mechanism is not well known. In this study, we present clinical characteristics, electrophysiological findings and pathology of sural nerve in our four cases with OIDP. METHODS: Retrospectively, we reviewed 38 patients diagnosed as organophosphate intoxication at Asan Medical Center from January, 1990 to July, 1998. Among these patients we present four patients with OIDP, who received electrophysiological and pathological studies and discuss similar cases from the literature. RESULTS: OIDP occurred usually 2-4 weeks after exposure. They complained quadriplegia, paresthesia and pain mainly in distal extremities. Two patients had facial diplegia. No definite pyramidal sign was found in all patients. Elelctrophysiological study showed sensorimotor(predominantly motor) axonal polyneuropathy with marked denervation potentials in all tested muscles. Follow-up electrophysiological study after two years showed slightly increased amplitude of sensory nerve or compound motor action potentials with persistent denervation potentials in the distal muscles. Sural nerve biopsy confirmed severe axonal neuropathy with marked decrease of large and small myelinated fibers with myelin ovoids. CONCLUSIONS: OIDP was a cause of severe generalized weakness and paresthesia, decreased sensation in distal extremities after high dose organophosphate ingestion and usually occurred two to four weeks later. The prognosis was poor in patients who had severe weakness of four extremities with facial diplegia at the initial examination.