Morphological Differences Between Ruptured and Unruptured Cases in Middle Cerebral Artery Aneurysms

Abstract

Type C and equality of the diameters of two daughter arteries, together with high AP ratios, seem to be morphological factors that associate with aneurysmal rupture.

Unruptured intracranial aneurysms and the assessment of rupture risk based on anatomical and morphological factors: sifting through the sands of data

“…Furthermore, there is a considerable variability in the ratios of patients with ruptured and unruptured lesions. However, Beck 4 and Sadatomo 34 had nearly equal numbers of ruptured and unruptured aneurysms in their reports and the studies by Weir 40,41 had a majority of ruptured aneurysms.…”

“…3,4,13,16,17,22,26,34,38,40 More specifically, neck width, dome width, aneurysm shape, aspect ratio (height/neck width), and bottleneck factor (dome width/neck width) have been examined. Among these, aspect ratio has shown the greatest promise as a parameter to associate with rupture risk (Fig.…”

“…With few exceptions, 4,5 a higher aspect ratio has been associated with ruptured lesions (Table 2). 5,16,26,34,40 Hoh et al 16 published aneurysm characteristics of 30 patients with multiple aneurysms (30 ruptured and 37 unruptured); namely, 7 1D geometric indices and 5 2D indices were evaluated. Aneurysm height, diameter, aspect ratio, bottleneck factor, and aneurysm/parent artery ratio were all statistically significantly different between unruptured and ruptured aneurysms.…”

“…Aneurysm wall irregularity and daughter sacs have long been associated with higher rupture risk. 5,13,22,34 Hademenos et al 13 published their account of 74 patients with aneurysms (40 ruptured and 34 unruptured) and evaluated the location and morphological factors, for example, lobulations, and reported that 16 (84%) of 19 multilobulated aneurysms had ruptured, compared with only 24 (44%) of 55 unilobular aneurysms, a statistically significant difference. Posterior circulation aneurysms were also noted to be of higher risk with multilobular posterior circulation aneurysms at the highest risk of all.…”

“…With respect to the surrounding vasculature, Sadatomo et al 34 reported on the relationship among aneurysm neck, parent artery, and daughter branches in 22 consecutive MCA bifurcation aneurysms, which were divided into a classic-type (aneurysm at midline relative to parent artery) and a deviating-type (aneurysm deviates to the side of 1 daughter artery). They found that in all cases, the deviating-type aneurysms were located on the side of the daughter artery with a narrower angle to the parent artery.…”