Acute encephalopathy followed by delayed myelopathy a rare presentation of chlorpyriphos (organophosphorus) poisoning

Abstract

Organophosphorus compounds (OPC) are commonly used pesticides and suicidal ingestion is common mode of poisoning. The manifestation of OPC poisoning and its severity depend upon the type, dose and potency of the OPC consumed. Neurological presentations are well defined clinical syndromes consisting of early, intermediate and delayed manifestations (rare), categorized on the basis of time elapsed since OPC exposure. A 21-years-old male presented to us with 100 ml of pesticide consumption (containing chlorpyriphos 50% and cypermethrin 5%) 18 months prior to presentation. Following intake, he developed one episode of seizure followed by altered sensorium for 3 weeks during which he was treated with atropine infusion and supportive management. He was well for the next two months. Subsequently he developed insidious onset and progressive proximal followed by distal weakness leading to pure motor spastic paraparesis without bowel or bladder involvement. He had brisk lower limb reflexes with extensor plantar response. Routine investigations were normal. Electrophysiological studies (nerve conduction studies, electromyography, visual evoked potentials, brainstem auditory evoked potentials and somatosensory evoked potentials[SSEP] in upper limbs) were normal. SSEP of lower limb showed prolonged potentials beyond the popliteal fossa with normal upper limbs. MRI of the spine showed dorsal cord atrophy and MRI brain was normal. This case reports a rare delayed manifestation of organophosphorus poisoning in the form of pure motor spastic paraparesis due to dorsal myelopathy. A possibility of delayed manifestations of toxicity should be considered in individuals presenting with features suggestive of myelopathy and a previous history of organophosphate exposure.