gms | German Medical Science

Objective: According to ISUIA cerebral aneurysms smaller than 7mm are believed to be associated with a low bleeding risk. Previous bleedings, size and location of aneurysms have been well addressed in previous studies to increase the likelihood of SAH. However, little is known about the morphological aspects and ist impact on rupture.

Method: 231 SAH-patients with 289 aneurysms were scanned for aneurysm size smaller than 7mm. Angiography of 106 SAH-patients were reviewed by two independent investigators classifying the morphological features (true saccular, lobulated/fusiform, broad neck, associated abnormality of cerebral vessels) location and multiplicity of aneurysms. Aneurysms were divided into two groups (<7mm/ ≥7mm) and analyzed for age, gender, Glasgow Coma Scale (GCS), Hunt&Hess grade (H&H), Fisher scale, implantation of an external ventricular catheter (EVD), treatment by coil/clip and outcome at discharge using Glasgow Outcome scale (GOS). Data were statistically examined using t-test and Chi-square test.

Results: There were 106 SAH-patients (mean age 52yrs., male/female ratio 1/2) with aneurysms located in the basilar/vertebral circulation (n=23), at the posterior communicating artery (n=19) and in the anterior circulation (n=64). In 38 patients, the aneurysms were smaller than 3mm, in 40 aneurysms the size ranged from 3 to 5mm and in 28 its size was between 5 and 7mm. True saccular aneurysms without any other abnormalities were seen in 13 (12%) patients, while 48 (70%) aneurysms were irregularly lobulated or even fusiform in their shape. Broad neck aneurysms (n=23), associated malformations of cerebral vessels (n=27), and multiple manifestations were seen in 30 patients. H&H grade was higher in aneurysms ≥7mm (p=0.024), no difference was found in GCS (p=0.062). The rate of coiling vs. clipping demonstrated a significant difference between the two groups (p=0.002). All other parameters had no statistically significant influence.

Conclusions: Strikingly shaped aneurysms, smaller than 7mm in diameter, are more dangerous than ISUIA data may suggest. Our results confirm previous findings of UCAS and others that a conspicuous appearance of cerebral aneurysms is a strong argument for treating incidental findings, even if less than 7mm in diameter. Further efforts should focus on imaging modalities examining structural differences of aneurysmal walls and its texture thereby giving us more substantial facts for advising our patients.