Surgical Anatomy of Endoscope-Assisted Approaches to Common Aneurysm Sites

BACKGROUND: The endoscope is being introduced as an adjuvant to improve visualization of certain areas in open cranial surgery. OBJECTIVE: To describe the endoscopic anatomy of common aneurysm sites and to compare it with the microsurgical anatomy. METHODS: Pterional, anterior interhemispheric, and subtemporal approaches to the most common aneurysm sites were examined in cadaveric heads under the surgical microscope and with the endoscope. RESULTS: The endoscopic view, particularly with the angled endoscopes, provides a significant improvement compared with the microscopic view, especially for poorly visualized sites such as the medial aspect of the supraclinoid carotid artery and its branches, the area below the anterior perforated substance and optic tract, and the carotid and basilar bifurcations. The endoscope aided in the early visualization of perforating branches at each aneurysm site except the middle cerebral artery. Small-diameter optics (2.7 mm) provided greater space for dissection and less potential for tissue damage in narrow places, whereas the larger 4-mm diameter optics provided better visualization and less panoramic distortion. The positioning of the endoscope for each aneurysm site is reviewed. CONCLUSION: The endoscope provides views that complement or improve the microscopic view at each aneurysm site except the middle cerebral artery. Endoscopy training and a thorough knowledge of endoscopic vascular anatomy are essential to safely introduce endoscopic assistance in vascular surgery.