The role of the Sylvian fissure configuration and the vascular anatomy on different bleeding patterns in ruptured middle cerebral artery aneurysms

Ruptured middle cerebral artery (MCA) aneurysms are one of the causes of subarachnoid (SAH) or intracerebral hemorrhage (ICH) but the factors associated with the bleeding type are unknown. The aim of the study was to analyze the association of the morphological variations of the Sylvian fissure (SF) and vascular parameters on occurrence of different bleeding patterns in patients with ruptured MCA aneurysms. The data of consecutive 202 patients with ruptured MCA aneurysm of two centers were included for analysis. Patients were divided into three groups: Group 1 with SAH, Group 2 with accompanying ICH and Group 3 with intrasylvian hemorrhage (ISH). The SF was divided into five types according to the previously described classification. Analyzed vascular parameters were aneurysm size, localization, presence of a daughter aneurysm, shape, and angulation of the aneurysm sac. A total of 202 patients (141 female, 61 male, mean age 52.4 yr) were included in this study. 67 patients (33.2%) had a SAH, 122 (60.4%) an ICH and 13 (6.4%) presented with ISH. Statistical analysis showed a significant association of narrow and twisted SF types 4 and 5 (p < 0.001) and temporal angulation of the aneurysm (p = 0.030) for occurrence of ICH. All other vascular parameters showed no significant association for any kind of hemorrhage. Our results allow the conclusion that the complex SF types 4 and 5, as well as the temporal angulation of the aneurysm sac are associated with the occurrence of ICH in ruptured MCA aneurysms.