Background Moyamoya disease (MMD) is a rare cerebrovascular disease usually characterized by progressive bilateral distal internal carotid artery stenosis or occlusion and its consequences. Direct (ie, extracranial–intracranial bypass) or indirect cerebral revascularization procedures are the most established and effective treatment strategies for MMD. The case history is presented of a patient with MMD with delayed severe intracranial and subarachnoid hemorrhage following intracranial carotid artery stent placement.

Clinical presentation An 18-year-old women presented with a history of seizures, recurrent episodes of transient right hemiparesis and aphasia. Cerebral catheter angiography and perfusion CT scan with azetozaolamide challenge confirmed impaired left hemispheric perfusion due to severe bilateral carotid artery stenosis combined with pathological collaterals, consistent with moyamoya disease. Endovascular stenting of the left supraclinoidal internal cerebral artery was performed uneventfully. Five hours after treatment the patient presented with sudden headache, nausea and speech disorders and a CT scan revealed intracerebral and subarachnoid hemorrhage. Due to further rapid clinical deterioration, surgical removal of the hematoma and decompression were required. The patient’s poor neurological outcome did not improve during the 2-year follow-up period.

Conclusion This case report illustrates a severe intracerebral and subarachnoid hemorrhage following intracranial stenting of the internal carotid artery in a young patient with MMD. Potentially this complication could be attributed to high perfusion pressure breakthrough phenomenon, a known complication after cerebral high-flow bypass surgery. The role of intracranial stenting, despite established revascularization procedures in patients with MMD, therefore remains highly questionable.