PATTERNS OF HEMORRHAGE WITH RUPTURED POSTERIOR INFERIOR CEREBELLAR ARTERY ANEURYSMS - CT FINDINGS IN 44 CASES

OBJECTIVE. We intended to characterize the CT patterns of hemorrhage a ssociated with ruptured posterior inferior cerebellar artery (PICA) an eurysms. MATERIALS AND METHODS. CT scans of 44 cases of angiographical ly confirmed ruptured saccular PICA aneurysms (31 aneurysms at the jun ction of the vertebral artery and the PICA and three distal PICA aneur ysms) were retrospectively reviewed. All scans had been obtained withi n 2 days of the subarachnoid hemorrhage (SAH) (day 0 [less than 24 hr] , 35 patients; day 1, eight patients; day 2, one patient). Presence or absence of hemorrhage in specific subarachnoid, intraventricular, and intraparenchymal locations was noted, as were the presence and degree of hydrocephalus. RESULTS, Posterior fossa SAH was present in 95% of cases. Isolated posterior fossa SAH was present in 30% of cases, but i n no case was isolated supratentorial SAH present. Supratentorial SAH was present in 70% of cases. SAH involving the sylvian fissure or the interhemispheric region was present in 25% and 23% of cases, respectiv ely. SAH along the convexity was present in 2% of cases. Intraventricu lar hemorrhage (NH) with or without associated SAH was seen in 95% of cases, whereas isolated IVH was seen in 5% of cases. Hydrocephalus was present in 95% of cases and was moderate to marked in 70%. Both IVH a nd hydrocephalus were present in 93% of cases. CONCLUSION, Ruptured PI CA aneurysms almost always coexist with hydrocephalus and IVH, as seen in 93% of cases, and almost never coexist with SAH along the convexit y. The most common pattern of hemorrhage associated with such aneurysm s includes IVH and posterior fossa hemorrhage. Extensive supratentoria l SAH, in conjunction with posterior fossa SAH, is a common finding in patients with ruptured PICA aneurysms. SAH isolated to the posterior fossa is present in a sizeable minority of cases.