Resection of Large Petrotentorial Tumor via a Retrosigmoid Approach: 3-Dimensional Operative Video

A 22-yr-old female college athlete had noted ataxia during competitive gymnastic events. Magnetic resonance imaging revealed a large tumor compatible with preoperative diagnosis of meningioma arising from the petrotentorial region with marked brainstem compression. The technical challenges associated with this removal include safe dissection of cranial nerves IV to VIII and dissection from the brainstem and cerebellum, taking care to not interfere with blood supply to these structures. The vascular tumor was removed via standard suboccipital approach, with the trajectory above the seventh/eighth nerve complex. The attachment was at the petrotentorial junction, and the fourth nerve was intimately involved with the tumor as the tumor was emanating from the tentorial edge where the fourth nerve entered. In most instances, the nerves are displaced by the tumor but in this case injury to the fourth nerve ensued with dissection at the tumor attachment. After tumor resection, the interrupted fourth nerve was repaired microsurgically. A hemangiopericytoma was identified on pathological analysis, and the patient received postoperative radiation therapy, which has been given postoperatively or at recurrence in the literature. Technical nuances of removal are discussed. Patient consent was granted for publication of this video.