Difficulties in assessing brain death in a case of benzodiazepine poisoning with persistent cerebral blood flow

Abstract

Assessing brain death may sometimes be difficult, with isoelectric EEG following psychotrope overdoses or normal cerebral blood flow (CBF) persisting despite brain death in the case of ventricular drainage or craniotomy. A 42-year-old man, resuscitated after cardiac arrest following a suicidal ingestion of ethanol, bromazepam and zopiclone, was admitted in deep coma. On day 4, his brainstem reflexes and EEG activity disappeared. On day 5, his serum bromazepam concentration was 817 ng/ml (therapeutic: 80-150). The patient was unresponsive to 1 mg of flumazenil. MRI showed diffuse cerebral swelling. CBF assessed by angiography and Doppler remained normal and EEG isoelectric until he died on day 8 with multiorgan failure. There was a discrepancy between the clinically and EEG-assessed brain death, and CBF persistence. We hypothesized that brain death, resulting from diffuse anoxic injury, may lead, in the absence of major intracranial hypertension, to angiographic misdiagnoses. Therefore, EEG remains useful to assess diagnosis in such unusual cases.