Rescue clazosentan for symptomatic cerebral vasospasm following subarachnoid hemorrhage due to anterior cranial fossa dural arteriovenous fistula: A case report with serial angiographic evaluation

Background: Vasospasms associated with dural arteriovenous fistula (dAVF)-related subarachnoid hemorrhage (SAH) are rare, and their management has not been well established. Clazosentan, a selective endothelin A receptor antagonist, is typically administered soon after an SAH to prevent cerebral vasospasms. However, the optimal timing remains controversial because of the risk of fluid retention and related complications. Here, we report the case of dAVF-related SAH in which clazosentan was introduced as rescue therapy to treat cerebral vasospasm. Case Description: A 61-year-old man presented with SAH caused by the rupture of a Borden type III dAVF in the anterior cranial fossa. Following surgical occlusion, intravenous fasudil hydrochloride was administered for vasospasm prophylaxis. However, severe bilateral anterior and middle cerebral artery vasospasms developed on day 10, accompanied by progressive somnolence. Intra-arterial fasudil hydrochloride administration provided limited and transient improvements. Clazosentan was subsequently introduced as rescue therapy and was continuously administered for 4 days. Angiography revealed marked vasodilatation, particularly in the distal vessels, following clazosentan administration. Although fluid retention was observed, the patient was administered diuretics without clinical respiratory deterioration. No cerebral infarction occurred, and the patient was transferred with a favorable outcome (modified Rankin Scale score of 1). Conclusion: This case suggests that rescue administration of clazosentan may have contributed to improvement as part of multimodal vasospasm management following dAVF-related SAH, with vasodilatory effects comparable to those observed in aneurysmal SAH cases. Furthermore, short-term rescue administration of clazosentan may be tolerable in patients at high risk of fluid retention-related complications when careful fluid management and appropriate diuretic use are implemented.