Scanning electron microscopy analysis of incidence and growth pattern of experimentally induced intracranial aneurysms in rat model

Experimental animal models are most valuable to study the initiation and growth of cerebral aneurysms. The aim of our study is to analyze the time course, incidence, location and growth pattern of intracranial aneurysms in an experimental rat model. Vascular corrosion casts were produced at time points 1, 3 and 4 months after aneurysm induction. Arterial changes were visualized and analyzed by scanning electron microscopy (SEM). A total of 32 treated animals were analyzed. In 4 out of 5 treated animals (80 %) at one month after surgery vessel wall protrusions could be detected, at 3 months in 10 animals out of 13 (76.9 %) and at 4 months after induction all 14 animals demonstrated aneurysms (100 %). The dome size of aneurysms was 31.45 µm (±17.78) at 3 months and significantly increased (53.26 ± 47.77 µm; p < 0.02) at 4 months. The dome/neck ratio of aneurysms differed significantly between 3 (0.45 ± 0.25) and 4 months (0.85 ± 0.48; p < 0.0001). Our study demonstrates that the Hashimoto animal model is reliable and produces aneurysms in 80–100 % of animals over time and that significant morphological changes occur between 3 and 4 months follow-up time points.