Double origin of the posterior inferior cerebellar artery dissection causing subarachnoid hemorrhage with pathological confirmation: illustrative case.

backgroundDouble origin of the posterior inferior cerebellar artery (DOPICA) is a rare anatomical variation, and subarachnoid hemorrhage (SAH) due to DOPICA dissection has been reported. Although previous cases of SAH from DOPICA have been diagnosed as dissection based on imaging, reports of pathological confirmation of dissection as the source of hemorrhage are lacking. OBSERVATIONS: Herein, the authors report the case of a 52-year-old man with an SAH caused by an intracranial DOPICA dissection. Surgical trapping of the dissected vessels was performed after direct visualization was obtained. Histopathological examination confirmed disruption of the internal elastic lamina and a hematoma within the media, which are typical findings of cerebral vascular dissection. Dissection occurred at the intersection of the vessel with the dentate ligament, suggesting that supporting structures may contribute to dissection in DOPICA. LESSONS: To the authors' knowledge, this is the first report of a case in which cerebral vascular dissection was pathologically confirmed as the source of hemorrhage in an SAH associated with DOPICA. This case suggests that surrounding anatomical supporting structures may be involved in the etiology of dissection. In cases of SAH associated with DOPICA with uncertain vascular anatomy or bleeding source, surgical trapping via direct visualization should be considered as a treatment option. https://thejns.org/doi/10.3171/CASE25919.