Among the patients with intracranial 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.
It occurs especially in postmenopausal women.
This phenomenon may be related to the loss of estrogen protection. MIA patients are associated with IgE syndrome 1).
MIA accounts for about a third of the patients with subarachnoid hemorrhage 2).
The Beijing Tiantan Hospital reported that MIA cases account for 8.1% (123/1511) of all treated cases of aneurysms in the same period 3).
To date, the genesis and pathogenesis of MIA are not clearly elucidated.
MIA coexists with various vascular malformations 6).
Hypertension and bad habits, such as drinking and, smoking, can induce multiple aneurysms. MIA detection has gradually become widespread because of the popularity of cerebral angiography.
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 the series of Neels et al. irregularity of contour was more important than size in identifying the site of rupture. Using a simple algorithm, it was possible to identify the site of aneurysm rupture in 97.5% of cases 7).
MR-VWI may be useful for identifying the rupture site in patients with spontaneous SAH and multiple cerebral aneurysms 8).
Determination of the offending aneurysm and initially undergoing occlusion are necessary. Different indices have been established by imaging observation to distinguish ruptured aneurysms from unruptured aneurysms. Baumann 9) observed that larger aneurysms and anterior communicating aneurysms often rupture. The size ratio (SR) value of the ruptured aneurysms is significantly larger than unruptured aneurysms. This result is based on the ratio of aneurysms and aneurysmal arteries by Rahman 10).
The increased bottleneck factor and the height–width ratio are considered inherent characteristics of the ruptured aneurysms in the control of ruptured and unruptured aneurysms by Hoh 11).
Aneurysm was also identified according to its 12) morphology and near vascular response
Correct localization of the rupture aneurysm based on a comprehensive diagnosis is key to MIA treatment.
The decision regarding the type of surgery to be used (either one-stage or multiple-stage surgery) as an operation strategy for multiple aneurysms and the location of bilateral multiple aneurysms (either along the bilateral approach or the unilateral approach) are still not clearly elucidated.
All the aneurysms should be treated in one session whenever possible to protect the patient from rebleeding 15).
Single-stage coil embolization of multiple unruptured intracranial aneurysms is technically feasible. The time required for such procedures and the rate of complications observed seem acceptable 16) 17).
Although a number of reports are available on occlusion of bilateral aneurysms in the middle cerebral artery bifurcation along the unilateral approach 18) 19) , according to Oshiro’s study 20) , contralateral middle cerebral artery bifurcation is difficult to observe along the unilateral pterional approach when the contralateral M1 segment is >14 mm.