Objectives: We present the results of a prospective study of post-operative angiographic data in a consecutive series of 267 intracranial aneurysms (in 217 patients) operated on by the same surgeon (M.S.).
Material and methods: All patients underwent a preoperative as well as a postoperative angiographic control. Besides, an analysis of the operative reports was done in order to correlate the surgical and angiographic data.
Results: Out of 267 operated aneurysms, 257 (96%) were located in the anterior circulation, and 10 (4%) in the posterior circulation. The surgical clipping was considered incomplete in 17 aneurysms (6.3%). Aneurysmal remnants were classified in 5 grades; grade I: remnant less than 50% of the neck size; grade II: remnant more than 50% of the neck size; grade III: remnant of a multilobed aneurysmal sac; grade IV: residual sac less than 75% of the aneurysmal size; and grade V: residual sac more than 75% of the aneurysmal size. The analysis of the operative reports helped in understanding the favoring factors of incomplete clipping: large neck and/or huge sized sac, insufficient exposure and dissection of the neck. The presence of a collateral artery with a large infundibulum in the vicinity of the neck-implantation zone on the parent artery.
Conclusions: In most cases the surgeon can easily control peroperatively under the microscope, after puncture-evacuation of the sac, the watertightness of clipping and the absence of any residual neck or sac of the aneurysm. Therefore the remaining place for a postoperative arteriography can be limited to those cases when the surgeon has some doubt concerning the perfection of clipping, as well as for giant and/or "difficult" aneurysms. A re-operation or a complementary endovascular treatment can be discussed for remnants in graded III, IV or V. Knowledge concerning the percentages of aneurysm with neck remnant only and of aneurysms with sac remnant obtained by surgery is interesting at the present time when endovascular treatment is becoming popular. In our series they amounted at 4.1% and 2.2%, respectively. These percentages are those of a series comprising all types of aneurysms. Needless to say, that the percentage of incomplete occlusion will be less if only the aneurysms with small-sized neck were taken into account.