Clazosentan-induced reversible focal brain edema in basal ganglia following aneurysmal subarachnoid hemorrhage treatment: illustrative case.

backgroundClazosentan, a selective endothelin A receptor antagonist, effectively prevents cerebral vasospasm following aneurysmal subarachnoid hemorrhage. Although various adverse effects have been reported, there have been no specific case reports of clazosentan-associated focal brain edema. This report highlights a rare complication associated with clazosentan treatment. OBSERVATIONS: A female in her 70s with a subarachnoid hemorrhage underwent surgical clipping of a ruptured middle cerebral artery aneurysm and received clazosentan postoperatively. Six days after surgery, magnetic resonance imaging revealed high-intensity signals in the left basal ganglia on fluid-attenuated inversion recovery and apparent diffusion coefficient sequences without changes on diffusion-weighted imaging. The patient's right-sided hemiparesis and disturbance of consciousness gradually progressed. On day 9, clazosentan was discontinued because of suspected adverse effects. Within approximately 2 weeks of discontinuation, both imaging findings and neurological symptoms improved. The temporal relationship between clazosentan administration, symptom onset, and improvement after discontinuation strongly suggested clazosentan-induced vasogenic edema. LESSONS: Clazosentan can cause reversible localized vasogenic brain edema in the basal ganglia following subarachnoid hemorrhage treatment. This rare but significant complication underscores the importance of careful neurological monitoring and timely imaging in patients receiving clazosentan. Further research is required to understand the risk factors and mechanisms underlying this phenomenon. https://thejns.org/doi/10.3171/CASE24567.