Reversible posterior encephalopathy syndrome and metamizole: A new pharmacological precipitant?

Introduction

The link between reversible posterior encephalopathy syndrome (PRES) and certain drugs is well documented, especially for immunosuppressive and/or cytotoxic drugs. Metamizole is a non-opioid analgesic whose exact mechanism of action is still not fully understood, but it seems to involve the inhibition of prostaglandin synthesis. Prostaglandins are important vasoactive molecules involved in either arterial vasoconstriction and vasodilation, thus may promote loss of autoregulation of vascular circulation.

Methods

Description of a case of PRES after metamizole intake.

Results

An 18-year-old female with no significant medical history presented to the emergency department with new-onset generalized tonic-clonic seizures and visual disturbances. After reviewing the patient's medical records and brain MRI findings, the diagnosis of PRES was suspected, and classical precipitants were ruled out. However, the ingestion of metamizole was found to be the only plausible precipitating factor. The patient was treated with nimodipine 60 mg every 4 h and started on levetiracetam 500 mg twice daily. She was discharged asymptomatic and normotensive. The follow-up brain MRI performed three months after discharge was unremarkable.

Conclusions

This case-report may suggest a new pharmacological precipitant associated with PRES. Our hypothesis is that endothelial dysfunction resulting from the inhibition of the prostaglandin pathway may lead to the disruption of blood-brain barrier permeability, resulting in the loss of autoregulation of vascular circulation.