Cranioorbital Pretemporal Skull Base Approach with Anterior Clinoidectomy for Removal of Large Left Clinoid Meningioma: "Unwrapping" Encircled Internal Carotid Artery and Decompressing Optic Nerve: 2-Dimensional Operative Video.

Clinoidal meningiomas are meningiomas arising from or in the vicinity of the anterior clinoid process. Despite advanced microsurgical techniques, clinoidal meningiomas remain challenging. Extradural anterior clinoidectomy with optical unroofing remains an important tool in skull base surgery, which provides a safe operative corridor, facilitating greater extent of resection and enhancing overall outcome, particularly visual function. A 66-year-old woman presented with history of visual disturbances. Magnetic resonance imaging revealed a dural-based tumor consistent with a large left clinoidal meningioma, with tumor wrapping (encircling) around the left trunk and internal carotid artery (ICA) bifurcation, elevating the left middle cerebral artery M1 segment, and invading the left optic canal. Left cranio-orbital craniotomy with pretemporal exposure was used (Video 1). A high-speed diamond drill with irrigation completed the extradural anterior clinoidectomy and optical canal unroofing. Use of a 1-mm Kerrison rongeur should be done with utmost care. The tumor was unwrapped via meticulous piecemeal removal. Final dissection and ICA unwrapping was done when the tumor was debulked enough that dissecting it off the artery was safe and under less tension. Due to its obscurity, final decompression of the left optic nerve with incision and opening of the falciform ligament was performed at the end of the procedure. Postoperative neuro-ophthalmologic examination showed a grossly unchanged left visual field with some visual acuity improvement. Resection of tumor encircling the ICA has been described previously; however, to the best of our knowledge, this is the first video describing removal of a tumor surrounding the ICA (perfomed by senior author K.I.A.), essentially "unwrapping" the left ICA trunk and its bifurcation. The patient consented to publication.