The No-Drill Technique of Anterior Clinoidectomy—A Skull Base Approach Tailored to Pathology

Introduction: Published articles describe a power drilling technique for anterior clinoidectomy. The entire “shaft” of the power drill is exposed in the operative field; thus all neurovascular structures in proximity to the full length of the rotating drill bit are at risk of direct mechanical and thermal injury. Ultrasonic bone removal has been recently developed to mitigate these risks. However, ultrasound-related cranial neuropathies are recognized complications of its use, in addition to its increased cost for the ultrasonic bone curettage device.

Methods: A retrospective review of the author's 40 consecutive cases of anterior clinoidectomy utilizing the “no-drill” technique is presented. Clinical indications include: ophthalmic segment aneurysms, tuberculum sellae meningiomas, clinoidal meningiomas, selected ICA-Pcomm and ICA bifurcation aneurysms, other large/giant/complex anterior circulation aneurysms, basilar bifurcation aneurysms, cavernous sinus lesions, pituitary macroadenomas, other perichiasmal lesions (sarcoid), and fibrous dysplasia.

Results: A bony opening is made in the mid to posterior orbital roof during the process of the initial craniotomy. Periorbita is dissected from the orbital roof from inside the orbital compartment. Subsequent piecemeal resection of the medial sphenoid wing, anterior clinoid process, and optic canal roof is performed with various bone-biting instruments. No power drilling was employed in this series. Optimal microsurgical exposure was obtained in all cases. There were no cases of direct injury to surrounding neurovascular structures. Illustrative cases and operative videos/photos are presented, demonstrating the surgical technique.

Conclusions: Power drilling is generally not necessary for anterior clinoidectomy. Rigorous study of preoperative CT, MRI, and angiogram is essential to identify important anatomic relationships between the anterior clinoid and neighboring neurovascular structures. The “no-drill” technique eliminates the risks of direct power drilling mechanical/thermal injury and the risk of ultrasound-associated cranial neuropathies. This technique achieves efficient and directly effective microsurgical exposure of the parasellar and paraclinoid regions for a variety of clinical scenarios in neurosurgery.