Extensive Skull Base Epidermoid Cyst Surgery: Cranial Nerve Tractography and Surgical Nuances Through a 2-Dimensional...

The surgery of skull base epidermoid cysts can be challenging because of intracerebral extensions and the encasement of cranial nerves and internal carotid artery branches.^1-3 Advances in magnetic resonance imaging, particularly tractography, may help to visualize the trajectory of displaced cranial nerves,^4,5 and thus reduce the surgical risks. We report here the case of a 59-year-old woman who presented with diplopia, left ataxia, and cognitive impairment, which revealed a large right skull base epidermoid cyst with infra-, supra-, and latero-sellar extensions (Video 1). The optic chiasma was pushed superiorly, and the oculomotor nerves were unidentifiable within the tumor. The internal carotid artery termination was stretched by the tumor and the first segment of the middle cerebral artery. Tractography was used to identify the position of the optic, oculomotor, and trigeminal nerves, which were encased within the tumor. A transsylvian approach allowed us to reach the tumor components using interoptic, opticocarotid, and laterocarotid triangles. This multiple window method gave access to most of the tumor's supratentorial component, which was removed using various size suction. Mirrors were useful to enhance the resection. Finally, a near-total removal of the tumor was achieved including the decompression of the brainstem, cranial nerves, and vessels. The capsule was kept in place to preserve critical anatomic structures; however, it should be removed when possible depending on tumor configuration. The patient, who consented to the procedure and to the publication of her images, recovered within a few days.