Giant fusiform aneurysms in the middle cerebral artery presenting with hemorrhages of different origins. Report of three cases and review of the literature.

Three cases of giant fusiform aneurysms in the middle cerebral artery (MCA) presenting with hemorrhages of different origins are reported, and appropriate literature is reviewed to investigate the characteristics of these lesions. Two patients had suffered a subarachnoid hemorrhage and the other had an intramural hemorrhage (dissection). Pathologically, these aneurysms presented with hemorrhages of different origins; classic rupture type (Case 1), dissection type (Case 2), and atherosclerosis-related thrombosis type (Case 3). Based on surgical and pathological investigations in these three cases and a review of the reported literature, the authors propose that giant fusiform aneurysms in the MCA are characterized by weaknesses in the internal elastic lamina with intimal thickening. Therefore, these lesions have the potential to present with hemorrhage in each of the three types. This finding indicates that there is a strong relationship between the pathological features of giant fusiform aneurysms and their clinical course, and that it is necessary to determine appropriate therapy for giant fusiform aneurysms in the MCA by evaluating cerebral blood flow, even if the lesions are found incidentally.