Malignant cerebellar edema in three-year-old girl following accidental opioid ingestion and fentanyl administration.

A three-year-old girl was found altered with an unknown timeline. Gas chromatography mass spectrometry was positive for hydromorphone, dihydrocodeine, and hydrocodone. Initial computed tomography and magnetic resonance imaging suggested a malignant cerebellar edema not confined to a vascular distribution. She received fentanyl boluses on hospital days 0 and 1 before receiving a continuous infusion on day 1. On day 3, she had an episode of acute hypertension and bradycardia. Emergent computed tomography showed an evolving hydrocephalus and similar diffuse edema throughout both cerebellar hemispheres. External ventricular drain was placed to relieve the increased intracranial pressure. Following drain placement and fentanyl discontinuation, the patient recovered, though not without fine- and gross-motor deficits at the four-month follow-up. Our case adds to a handful of case reports of opioid toxicity in pediatric patients that present as toxic leukoencephalopathy. Though the mechanism is poorly understood, it has been suggested to be a consequence of the neurotoxic effects of the drug, which has particular affinity for µ opioid receptors-the primary opioid receptor found in the cerebellum. Clinicians would do well to recognize that this syndrome is primarily caused by direct toxicity rather than ischemia. This case adds insight by suggesting that lipophilic opioid analgesics may worsen this neurotoxicity. When intervening with mechanical ventilation, clinicians should consider avoiding lipophilic opioid drugs for analgesia until the pathogenesis of cerebellar edema is better understood.