Microsurgical Removal of an Anterior Clinoid Meningioma With Extensive Vascular Encasement: 2-Dimensional Operative Video.

Anterior clinoid meningiomas are challenging skull base lesions especially when they encase the internal carotid artery and its branches. According to the Al-Mefty classification, type I can originate in the subclinoid dura, type II on the superolateral aspect of the anterior clinoid process, and type III at the optic foramen, with type I being the most often associated with vascular encasement.1,2 We present the case of a 70-year-old patient who presented with visual disturbances revealing a large type I anterior clinoid meningioma encasing the internal carotid artery and its branches. The extended pterional approach with removal of the posterior part of the superior and lateral walls of the orbit3 was offered to the patient given the size of the tumor and the visual impairment. We present the main steps of the surgery: extended pterional approach with postero-lateral orbitotomy, extradural removal of the anterior clinoid process, and hyperosthosis. The meningioma is removed in a stepwise fashion starting in the less dangerous frontal sector of the tumor and ending in the supra cavernous and supra diaphragmatic sectors of the meningioma. The postoperative course was favorable, and at 3-month follow-up, the patient showed a significant visual improvement. Brain MRI showed a subtotal resection of the meningioma and no postoperative complications. We present the nuances and the surgical technique for anterior clinoid meningiomas with extensive vascular encasement. We discuss the factors predicting the preservation of the arachnoid planes reported in the literature.4 The patient consented to the procedure and to the publication of the images. Our Institutional Review Board ethics committee does not require an approval for this type of publication.