Resection of the Clinoidal Meningioma Encasing the Carotid Artery: A Complex and Delicate Surgical Procedure.

Abstract

Surgery for anterior clinoidal meningioma (CMs) can be daunting, especially when encased in the internal carotid artery (ICA).¹ In particular, the growth and infiltration of the tumor at the skull base with the involvement of optic nerves and the ICA are major impediments to radical tumor resection.² For 2 patients, we took the following measures to ensure a smooth operation (Video). First, preoperative MRI showed that there was obvious peritumoral brain edema in both cases. Peritumoral edema can arise from venous compression or from vascular permeability and inflammation. We administered steroids to both patients preoperatively to reduce the edema caused by vascular permeability, so as to obtain more operative space during the operation. Second, we carefully drilled and flattened the sphenoid ridge using a high-speed drill, thereby creating a larger operative space. After flattening the sphenoid ridge, we cut the meningo-orbital band and detached the temporal fossa dura from the lateral wall of the cavernous sinus. We then drilled the lesser wing of the sphenoid bone and the roof of the orbital apex to a thin eggshell layer. Finally, we removed the remaining bone piece. Complete extradural drilling of the anterior clinoid process was performed, which allowed us to process the tumor base at the start of dissection rather than after partial resection. Third, we conducted CTA and CTV before surgery and did not observe abundant blood supply to the tumor. In addition, studies have shown that CMs are predominantly fed by feeders from the supraclinoid ICA.³ Embolization is deemed not feasible due to the ICA-dominant supply.⁴ Therefore, in order to reduce injury to the patients, we did not perform DSA and preoperative embolization. In order to reduce intraoperative bleeding and a clear surgical view, we prioritized dissecting the tumor base to reduce blood supply from the dura. However, when preoperative CTA and CTV suggest that the tumor blood supply is abundant and there is ECA blood supply, we recommend preoperative DSA and embolization. Finally, the optic nerve, ICA, and oculomotor nerve are relatively fixed in the skull base. Early exposure of these structures helps protect them from injury.