Histological change in permanently clipped or ligated cerebral arterial wall. Part II: Autopsy cases of aneurysmal neck clipping.

An investigation was carried out on clinical autopsy cases into histological changes in the vessel wall and into the surrounding tissue reaction after permanent clipping. 1. There were 17 autopsy cases of cerebral aneurysm, which included seven cases treated with the Yaşargil clip, five with the Heifetz clip, and five control cases. 2. Clipping period ranged from 6 days to 11 months. Both the Yaşargil and the Heifetz clips, even with long duration of clipping, caused no changes, and inflammatory reaction was slight. 3. As for the necrosis of the vessel wall beneath the blade, the Yaşargil clip produced marked necrosis at the blade edge in 4 of 7 cases (57%), while the Heifetz clip caused necrosis under the midconvexity of the blades in all 5 cases (100%). 4. The granulation tissue reaction round the clip began to occur after one month, and was enough to embed the blade of the clip after three months. We considered it very unlikely for a slip-out accident to occur after this stage. 5. Formation of mural red thrombus and deposition of fibrin with irregular intimal thickening were noted in the aneurysmal lumen in cases clipped for less than 13 days. After one month the intimal thickening was diffuse, and organized thrombus was noted. After three months or more, the aneurysmal lumen was found to have been filled almost completely by intimal thickening. Based on the above finding, the optimum condition for temporary and permanent clips was also considered.