Fatal intracerebral hemorrhage following endovascular Onyx embolization of an arteriovenous malformation: A case report

Introduction: Patients with cerebral arteriovenous malformation (AVM) have a lifetime risk of hemorrhagic stroke. Although identified asymptomatic cases can be monitored with imaging follow-up, treatment is considered in cases of AVM rupture or hemodynamic instability. Patient concerns: A 43-year-old man who had been taking antihypertensive drugs for the past 5 years visited our hospital 3 days after the abrupt onset of headache. The patient also complained of progressive ptosis in the left eye. Diagnoses: Brain computed tomography (CT) showed a small intraventricular hemorrhage with obstructive hydrocephalus. Subsequent brain CT angiography and magnetic resonance imaging confirmed the presence of an AVM in the cerebellar vermis. Interventions: Endovascular embolization was performed directly through the right femoral artery. Near-Total obliteration of the AVM nidus was achieved by using multiple Onyx castings. Outcomes: The patient developed an altered mental status and right hemiparesis after the procedure. CT performed after the procedure revealed intraventricular hemorrhage in all ventricles, with a left thalamic intracerebral hemorrhage. Despite emergency external ventricular drainage and aggressive treatment for intracranial pressure control, the patient expired on the 14th day after the embolization procedure. Lessons: When treating AVMs, especially those with a large nidus of high flow, it is necessary to consider possible hemorrhagic complications and preventive measures.