Subarachnoid Hemorrhage Due to Flow-Related Dissection of the Posterior-Inferior Cerebellar Artery Associated with a Distal Arteriovenous Malformation.

Abstract

Cerebral arteriovenous malformations (CAVMs) are characterized by altered hemodynamics and associated with angioanatomic changes, such as aneurysms. We encountered a patient with a CAVM-associated dissection of the medial trunk of the posterior inferior cerebellar artery (PICA) instead of an aneurysm. We report the case of a 56-year-old male patient with spontaneous subarachnoid hemorrhage within the cisterna magna and fourth ventricle. Digital subtraction angiography revealed a cerebellar arteriovenous malformation located within the inferior semilunar lobule that did not anatomically match the bleeding pattern. The left PICA, serving as a primary feeding artery, showed a dissection of the proximal portion of the medial trunk with a precise anatomic association with the blood in the telovelotonsillar space. CAVM-induced hyperdynamic flow through the feeding vessel is the most plausible pathophysiologic explanation for the dissection. Complete microsurgical resection of the CAVM was performed, and 3-month follow-up digital subtraction angiography showed complete regression of the dissection, disappearance of irregularities, and significant caliber reduction of the medial PICA trunk. This is the first report of a hyperdynamic flow-related dissection of a CAVM-associated feeding vessel. Microsurgical resection of the CAVM allowed for spontaneous resolution of the dissected area by restoration of normal rheodynamics.