[Significance of hemodynamic stress on the development of intracranial aneurysms. - Analysis of the cases of coexisting intracranial aneurysm and arteriovenous malformation of the brain (author's transl)].

The effect of hemodynamic stress on the development of cerebral aneurysms was evaluated in cases of intracranial aneurysm coexistent with arteriovenous malformation (AVM) of the brain. Three such cases were presented, in which 5 aneurysms were noted on the feeding arteries to the AVM. The findings strongly indicated the importance of hemodynamic stress on aneurysm formation. The first patient, a 39-year-old male, had 3 aneurysms on the anterior cerebral artery feeding the left frontal AVM. Although two of these aneurysms received no surgical treatment, they almost disappeared several months after excision of the AVM. The second patient, a 54-year-old female, had a huge left fronto-parietal AVM and an aneurysm of the cavernous portion of the dilated internal carotid artery. No surgical treatment was performed. The third patient, a 25-year-old male, had a deep-seated AVM fed by the right anterior choroidal artery, the lenticulostriate artery, and the insular branches of the middle cerebral artery. Although no aneurysm was noted in the first angiogram taken immediately after an attack of subarachnoid hemorrhage, a small aneurysm appeared on the lenticulostriate artery in the second angiogram taken 8 days after the attack. The aneurysm gradually reduced in size during the following several weeks, and he was discharged with no neurological deficit. Twenty-one months after the first attack, he suffered a second apoplectic attack of intracerebral hematoma and received surgical evacuation of the hematoma. The aneurysm was histologically found to be a false one. These facts further explain the association of these two different kinds of lesions. Seventy-five previously reported cases of intracranial aneurysm with AVM were reviewed and the effect of hemodynamic stress on aneurysm formation was evaluated. These findings also strongly indicated that the hemodynamic stress due to the presence of the AVM seems to have played an important role in the development of aneurysms in these cases.