Orbitozygomatic Transsylvian and Subtemporal Transzygomatic Approaches for Clipping of Basilar Tip Aneurysms: 2-Dimensional Operative Video

Abstract

INDICATIONS: CORRIDOR AND EXPOSURE: The orbitozygomatic transsylvian approach is ideal for basilar tip aneurysms (BTAs) ≤15 mm located at or above the level of posterior clinoid process (PCP), whereas for larger, low-lying BTA's with fetal posterior cerebral artery (PCA), the subtemporal transzygomatic approach is preferred. Both approaches expose the basilar tip area and structures in the interpeduncular fossa from an anterolateral angle and the lateral angle, respectively. ANATOMIC ESSENTIALS: NEED FOR PREOPERATIVE PLANNING AND ASSESSMENT: Aneurysm size and level, brainstem perforators, and PCA size (fetal or not) should be noted preoperatively. ESSENTIAL STEPS OF THE PROCEDURE: A. Orbitozygomatic transsylvian approach 1. Frontotemporal craniotomy with posterolateral orbitotomy. 2. Extradural optic nerve decompression and anterior clinoidectomy. 3. Transsylvian dissection and carotid-optic cistern decompression. 4. Distal dural ring opening. 5. Aneurysm exposure and clipping. Or B. Subtemporal transzygomatic approach 1 1. Frontotemporal incision with zygomatic osteotomy. 2. Temporal lobe retraction, subtemporal dissection, and tentorial division. 3. Cavernous sinus opening and dorsum sellae drilling. 4. Petrous apex resection. 5. Aneurysm exposure and clipping. PITFALLS/AVOIDANCE OF COMPLICATIONS: Complications such as cranial nerve injury, perforator stroke, aneurysm rupture, and hemorrhage can be prevented by neuromonitoring, avoiding temporary basilar occlusion for >10 minutes, use of transient adenosine arrest during clipping, and interposing rubber dam between perforators and aneurysm. 1 VARIANTS AND INDICATIONS OF THEIR USE: Cavernous sinus opening with posterior clinoidectomy and dorsum sellae drilling may be performed if aneurysm neck is at or below the level of PCP. 1-7 The patient consented to the procedure.