Abstract
BACKGROUND: Cerebral vasospasm (CVS) following aneurysmal subarachnoid hemorrhage (SAH) typically occurs 3-5 days after the onset of SAH, reaching its peak at day 7, and persists for 2-3 weeks. Generally, once the period of CVS is over and radiological improvement has been observed, recurrence is rare. OBSERVATIONS: The authors present the case of a 92-year-old female with a complaint of unconsciousness. CT showed diffuse SAH and CT angiography revealed a 9-mm right internal carotid-ophthalmic artery aneurysm. On day 1, they performed balloon-assisted coil embolization. On day 8, MR angiography (MRA) showed severe CVS in both distal middle cerebral arteries. On day 15, MRA showed complete improvement of CVS. However, on day 21, MRA showed recurrence of diffuse CVSs, particularly in the right middle cerebral artery, right vertebral artery, and basilar artery, and CVS persisted for approximately 1 week. On day 29, an improvement in the CSV was observed on MRA, and subsequent monitoring revealed no further occurrence of CVS. LESSONS: Here, a novel case of recurrence after complete improvement of CVS following aneurysmal SAH is presented. Even after the period of CVS is over and radiological improvement has been observed, regular imaging follow-up remains crucial. https://thejns.org/doi/10.3171/CASE25138.