Successful Clazosentan Therapy for Subarachnoid Hemorrhage after Coil Embolization of Ruptured Posterior Cerebral Artery Aneurysm in a Patient with Moyamoya Disease: A Case Report

Moyamoya disease is a progressive steno-occlusive cerebrovascular disorder that may be complicated by intracranial aneurysms, particularly, in the posterior circulation, which are at higher risk of rupture than those in the general population. Clazosentan, a selective endothelin A receptor antagonist, has been approved in Japan for the prevention of cerebral vasospasm after aneurysmal subarachnoid hemorrhage. However, cerebral hemodynamics after subarachnoid hemorrhage and safety of clazosentan in patients with moyamoya disease remain unknown. We report the case of a 46-year-old man with bilateral moyamoya disease who presented with severe subarachnoid hemorrhage caused by a ruptured saccular aneurysm in the right P2 segment of the posterior cerebral artery. Coil embolization was successfully performed, and clazosentan (10 mg/hr), along with cilostazol, was administered to prevent vasospasm. Fluid balance was carefully managed, and no clazosentan-related adverse events were observed. Follow-up radiological examinations showed no evidence of cerebral vasospasm or ischemic lesions. The patient made a favorable recovery and was discharged with a modified Rankin scale score of 1. Four months later, revascularization surgery was performed to reduce hemodynamic stress and the risk of hemorrhage from choroidal collaterals. The aneurysm remained occluded, the choroidal channels regressed, and no recurrent strokes occurred during 1 year of follow-up. To the best of our knowledge, this is the first report of successful clazosentan therapy for aneurysmal subarachnoid hemorrhage in a patient with moyamoya disease. Careful perioperative management allowed the safe use of clazosentan without complications. Further studies are needed to evaluate its broader safety and efficacy in this population.