Preoperative Rehearsal Sketch for Cerebral Aneurysm Clipping Improves the Accuracy and the Safety of the Surgical Procedure

-OBJECTIVE: With advances in endovascular therapy, the -umber of cerebral aneurysm clippings has been decreasing. However, some patients are indicated for clipping surgeries. In such circumstances, preoperative simulation is important for the safety and educational as-pects of the operation. Herein, we introduce a simulation method using the preoperative rehearsal sketch and report its applicability. -METHODS: We compared the preoperative rehearsal sketch with the surgical view for all patients who under-went cerebral aneurysm clipping by neurosurgeons below the seventh grade between April 2019 and September 2022 in our facility. The aneurysm, running of parent and branched arteries, perforators, veins, and clip working were evaluated by senior doctors and scored as follows: correct, 2; partially correct, 1; incorrect, 0; and total score, 12. We retrospectively evaluated the relationship between these scores and postoperative perforator infarctions and, in addition, compared that between simulated and not simulated cases. -RESULTS: In the simulated cases, the total scores did not correlate with perforator infarctions, but assessments of the aneurysm, perforators, and clip working affected the total score (P = 0.039, 0.014, and 0.049, respectively). Moreover, perforator infarctions were significantly less in the simulated cases (6.3% vs. 38.5%; P = 0.03). -CONCLUSIONS: Precise interpretations of preoperative images and considerations of three-dimensional images are imperative to perform safe and accurate surgeries us-ing preoperative simulation. Although perforators are not always detected preoperatively, it is possible to presume in the surgical view using anatomic knowledge. Therefore, drawing the preoperative rehearsal sketch improves the safety of surgical procedure.