Sphenoid Ridge Keyhole for Clipping of Middle Cerebral Artery Aneurysms in the Era of Endovascular Treatment: Anatomy (Sphenoid Depression), Surgical Technique, and Surgical Results

Abstract

Less-invasive clipping techniques for middle cerebral artery (MCA) aneurysms are required during the era of endovascular treatment. The sphenoid-ridge keyhole approach is an option. For cosmetic reasons, a skin incision is made within the temporal hair (sideburn skin incision), and the temporal muscle dissected without cutting the muscle belly to expose the skull. Visually identifying the location of a sphenoid ridge over the skull is difficult. Based on anatomical studies, the sphenoid depression is located anterior to the bony prominence caused by the sphenosquamous suture (SSS), and we recommend palpation to locate this bony depression. Using this technique, pinpoint sphenoid ridge keyhole craniotomy can be performed. After opening the dura mater, the operative field includes the centrally located Sylvian fissure. We treated 34 cases of unruptured MCA aneurysms using this technique and accomplished neck clipping in all cases, with a mean postoperative hospital stay of 3 ds. The mean maximum craniotomy diameter was 29 mm. None of the patients showed a decreased neurological status, including cognitive function. The mental state (depression scores) significantly improved 3 months following the operation. In conclusion, sphenoid ridge keyhole clipping focused on the sphenoid depression is considered an effective and less invasive surgical approach in the era of endovascular treatments.