Ome 9000

Following a circumanal skin incision, the anal canal and the sphincter muscles were circumferentially dissected from the surrounding tissue. The posterior wall of the anal segment was separated until identification of the anterior surface of the coccygeal muscle. The levator ani muscle was identified at the lateral and posterior wall, and the anterior wall was then dissected free, behind the prostate. The neurovascular bundles of the pudendal arteries, veins, and nerves run bilaterally inside the ischial tuberosity and reach the external anal sphincter muscle at the 2 o’clock and 10 o’clock positions (Fig. S1A). We then dissected the pudendal nerves to avoid damage (Fig. S1B). In the transection group (N = 3), we transected bilateral pudendal nerves and resected a 1-cm width (Fig. S1C). In the anastomosis group (N = 3), we transected bilateral pudendal nerves and then anastomosed the nerves end-to-end with epineural sutures (10-0 Ethilon; Johnson & Johnson, Tokyo, Japan) using a surgical microscope (OME-9000; Olympus Medical Systems Corp., Tokyo, Japan) (Fig. S1D). The sham operation was performed similarly but without neurotomy. All wounds were closed using skin staples (3 M Precise Vista Skin Staplers; Medema T/A Omega Medical Supplies Ltd., London, UK).

ICG angiography uses intravenously administered ICG as a dye and observes cerebral vessels at high magnification under the operating microscope equipped with near-infrared illumination system. ICG angiography was done at least twice in each case before and after the surgical clips were applied to the aneurysms. ICG was injected intravenously with a dose of 0.2 mg/kg. All operations were performed using an operating microscope equipped with a near-infrared illumination system (OME-9000; Olympus, Tokyo, Japan). During ICG angiography, the operating microscope was not moved. ICG angiography was recorded continuously using a high-definition recording system (AG-MDC10G; Panasonic, Japan).