Accessory Nerve Schwannoma with Medulla Oblongata Compression: Microsurgical Resection by Far Lateral Suboccipital Transcondylar Approach: 2-Dimensional Operative Video.

ABSTRACT

Schwannomas overall account for approximately 8% of primary brain tumors, with the majority of them arising from the vestibular nerves.1,2 Non-vestibular schwannomas are considered rare, particularly ones arising from the accessory nerve, constituting only around 4% of craniovertebral junction schwannomas.3,4 The far lateral approach and its variations is an important tool in the armamentarium of skull base neurosurgeons. It allows adequate exposure for accessing ventral and ventrolateral lesions of the craniocervical junction.5-13 A 60-year-old female patient presented with a 3-month history of difficulty walking and progressive right-sided weakness. Magnetic resonance imaging demonstrated an extra-axial solid lesion at the craniocervical junction with significant enhancement on post-contrast imaging. The lesion was ventrolateral to the medulla, causing compression, displacement, and peritumoral edema. The patient consented to the procedure and underwent a far lateral suboccipital craniotomy with C1 hemilaminectomy in a lateral position. Tumor origins were identified at the left accessory nerve rootlet. The patient's postoperative course was uneventful. Follow-up magnetic resonance imaging revealed gross total resection and complete resolution of hemiparesis 3 months after the surgery. Microsurgical resection of tumors at the craniocervical junction is challenging. Preoperative planning and tailoring the approach are essential in the decision-making process to safely perform surgery. This video demonstrates, in detail, the steps, relevant anatomy, and technical nuances for accessory nerve schwannoma ressmoval. To the best of our knowledge, this is the first operative video showing the resection of a pure accessory nerve schwannoma with compression of the medulla. Under our institutional ethical review board regulations, approval was not necessary.