Methomyl–alphamethrin poisoning presented with cholinergic crisis, cortical blindness, and delayed peripheral neuropathy

Abstract

Objective. Methomyl–alphamethrin is a mixture of carbamate and pyrethroid insecticides. Carbamate insecticides function as reversible cholinesterase inhibitors, which may produce life-threatening cholinergic syndrome. Cortical blindness and delayed neuropathy were rarely reported complications of carbamate insecticide exposures. Here we reported a case of intentional methomyl–alphamethrin ingestion. Case report. A 41-year-old woman attempted suicide by drinking 200 mL of methomyl–alphamethrin insecticide and soon presented with unconsciousness, hypothermia, and shock. She developed pulseless electrical activity and regained spontaneous circulation after resuscitation. Diagnosis of carbamate poisoning was made by her clinical features, decreased levels of cholinesterases and the presence of methomyl in her urine. She complained of blurred vision and blindness 4 days post-exposure. Visual evoked potential and brain magnetic resonance imaging study confirmed the diagnosis of cortical blindness. On day 21, she had low limbs numbness, progressive weakness, and right foot drop. Electophysiological tests performed on day 27 revealed neuropathy of bilateral peroneal nerves. Conclusion. We reported a patient who manifested severe carbamate insecticide poisoning and developed cortical blindness and delayed neuropathy. Physicians should be aware of these rare toxicities among patients with severe carbamate insecticide poisoning.

• Cortical blindness
• Delayed neuropathy
• Methomyl–alphamethrin poisoning

Acknowledgments

This work had been presented at the XXX International Congress of European Association of Poisons Centers and Clinical Toxicologists (EAPCCT), Bordeaux, France, May 11–14, 2010.

Declaration of interest

Financial support was provided from the Department of Health for Taiwan Poison Control Center in Taipei Veterans General Hospital, 2009. The authors report no conflicts of interest. The authors alone are responsible for the content and writing of this article.