Extradural Anterior Clinoidectomy and Optic Canal Unroofing for Paraclinoid and Basilar Aneurysms: Usefulness of a No-Drill Instrumental Method

The authors describe extradural anterior clinoidectomy without the use of a high-speed drill or ultrasonic device to clip paraclinoid and basilar aneurysms, which can eliminate potential complications related to traditional power drilling or ultrasonic device use. This method involves four steps: (1) partial osteotomy of the sphenoid wing at the superior orbital fissure (SOF); (2) peeling of the dura propria of the temporal lobe from the inner cavernous membrane of the SOF; (3) isolation and resection of the exposed meningo-orbital band to expose the superolateral aspect of the anterior clinoid process (ACP); and (4) piecemeal rongeuring of ACP and the roof of the optic canal. The entire procedure was performed using surgical instruments, including micro-rongeurs, a fine Kerrison punch, and micro-dissectors. Subsequently, intradural neck clipping was performed. Twenty consecutive patients with paraclinoid and basilar aneurysms successfully underwent clipping after this non-drill extradural clinoidectomy. Minor morbidity was noted in two patients (cerebrospinal fluid leakage in one and transient oculomotor palsy in the other). The non-drill method is a simple, easy, safe, and quick alternative to traditional power drilling in extradural clinoidectomy, and this method can avoid morbidity related to direct mechanical/ thermal injury of important neurovascular structures.