The association of intracranial aneurysms and arteriovenous malformation of the brain. Case report

Multiple intracranial aneurysms: determining the site of rupture

A retrospective hospital chart and radiograph review was performed of all patients with multiple intracranial aneurysms seen over a 52-month period. Sixty-nine patients with a total of 205 aneurysms were studied. Among the patients with aneurysms, the incidence of multiple aneurysms was 33.5%. Multiple aneurysms were much more common in women, with a female to male ratio of 5:1 for all patients and 11:1 for patients with three or more aneurysms. Common locations for multiple aneurysms were the posterior communicating artery (22%), middle cerebral artery (21.5%), anterior communicating artery (12%), and ophthalmic artery (11%). However, locations with the highest probability of rupture were the anterior communicating artery (62%), posterior inferior cerebellar artery (50%), and basilar artery summit (50%). The middle cerebral artery was the least likely site for rupture. In contrast to previous studies, in this series irregularity of contour was more important than size in identifying the site of rupture. Using a simple algorithm outlined in the text, it was possible to identify the site of aneurysm rupture in 97.5% of cases.

Posterior inferior cerebellar artery aneurysm associated with arteriovenous malformation fed by the same artery

A 37-year-old man presented with a peripheral aneurysm of the left posterior inferior cerebellar artery associated with a more peripheral arteriovenous malformation fed by the same artery. Recurrent subarachnoid hemorrhage occurred from rupture of the aneurysm. Review of the pertinent literature indicates that the aneurysm of the posterior inferior cerebellar artery originates from the peripheral portion of the artery, when associated with arteriovenous malformation.

Risk factors for the development and rupture of intracranial berry aneurysms

Risk factors for the development and rupture of intracranial saccular (berry) aneurysms were identified in a case-control study of autopsy subjects. The development of berry aneurysms was positively correlated with increased frequencies of systemic arterial hypertension (p less than 0.001), cerebral artery atherosclerosis (p less than 0.05), and marked asymmetry of the cerebral vessels comprising the circle of Willis (p less than 0.005). In addition, patients with berry aneurysms more frequently had histories of persistent headache (p less than 0.001), pregnancy-induced hypertension (p less than 0.01), long-term use of analgesics (p less than 0.001), especially aspirin (p less than 0.05), and a family history of stroke (p less than 0.05). Factors associated with a decreased risk of berry aneurysms included treatment with insulin to control diabetes mellitus (p less than 0.005), leanness (p less than 0.05), chronic pancreatitis (p less than 0.001), malignant tumors (p less than 0.001), and moderate or severe coronary or renal atherosclerosis (p less than 0.05). Rupture of berry aneurysms was positively correlated with size (p less than 0.05) and the presence of multiple aneurysms (p less than 0.005), but also with long-term analgesic usage (p less than 0.05), excessive ethanol consumption (p less than 0.01), and fatty metamorphosis of the liver (p less than 0.01). The factors that predispose to rupture of berry aneurysms are interrelated in the sense that several of them are known to cause a decrease in the synthesis of prostaglandin E, whereas one of the factors that appears to be protective has the opposite effect. Marked and abrupt lowering of serum prostaglandin levels would cause dilatation of cerebral vasculature and increased cerebral blood flow; in the setting of hypertension, focal defects in cerebral arteries could develop, leading to the formation and subsequent rupture of berry aneurysms.

[Spontaneous thrombosis of a giant aneurysm after excision of an associated vascular malformation. Report of a case]

A case of a patient with a giant aneurysm of the left middle cerebral artery and a huge arteriovenous malformation hemodynamically related is reported. Complete thrombosis of the aneurysm was observed after extirpation of the arteriovenous malformation as shown by angiography one week, six months and a year post-operatively. Reduction of the regional cerebral blood flow after extirpation of the arteriovenous malformation and the natural tendency of these giant aneurysms to partially thrombose were to be the explanation for our results.

Aneurysm growth and hemodynamic stress

Two cases of intracranial saccular aneurysm related to an arteriovenous malformation (AVM) are illustrated, in which a remarkable growth of the sac over the years was demonstrated angiographically. According to the relevant literature, aneurysm enlargement is correlated to the flow toward the AVM, increasing the intrasaccular turbulence and stress on the wall to which "solitary" aneurysms are usually subjected. The presence of bilateral infundibular widening at the origin of the posterior communicating artery is noted in one of the cases. This finding possibly confirms further the effects of hemodynamic stress.