Delayed evacuation of bilateral chronic subdural hematoma with herniation-induced bilateral posterior cerebral artery infarction: illustrative case.

backgroundChronic subdural hematoma (cSDH) is a frequent neurosurgical condition, yet its preoperative natural history, particularly in patients receiving antiplatelet therapy, remains poorly defined. Although delaying surgery to allow aspirin washout is a common practice, the evidence supporting fixed discontinuation intervals is limited. Bilateral cSDH is associated with a higher risk of rapid deterioration, highlighting the need to consider emergency evacuation even in clinically stable patients. OBSERVATIONS: A 71-year-old man with a history of ischemic stroke on aspirin presented with bilateral cSDH causing moderate mass effect but preserved consciousness with mild right-sided hemiparesis. Aspirin was withdrawn and surgery scheduled after a standard 5-day washout. On day 3 of interruption, he developed abrupt neurological deterioration. Emergency CT showed acute rebleeding within both hematomas and marked mass effect consistent with impending transtentorial herniation. Urgent bilateral burr hole evacuation achieved complete decompression. However, postoperative imaging revealed bilateral posterior cerebral artery (PCA) territory infarctions with thalamic involvement, consistent with herniation-related compromise of the basilar apex and proximal PCA segments. The patient never regained consciousness. LESSONS: This case highlights the hazards of delaying surgery for aspirin washout in bilateral cSDH. Individualized risk assessment and early evacuation may help prevent catastrophic herniation-related posterior circulation infarction. https://thejns.org/doi/10.3171/CASE25934.