Endoscopic endonasal transmaxillary-pterygoid approach for skull-base non-vestibular schwannomas in 10 consecutive patients

Purpose Non-vestibular schwannomas (NVSs) of the skull base occur in several sites, and few previous studies have evaluated the usefulness of the endoscopic endonasal transmaxillary-pterygoid approach (EETMPA) to resect these lesions. We aimed to evaluate the characteristics and clinical outcomes of patients who underwent EETMPA for skull-base NVSs and to investigate the efficacy, safety, and indications for the procedure. Methods We retrospectively reviewed the clinical data of 10 consecutive patients (mean age, 45 +/- 17) who underwent EETMPA for skull-base NVSs at the University of Tsukuba hospital between 2013 and 2020. We also calculated the total tumor volume and the size of the corridor to the tumor for EEA (SCEEA) in nine patients who underwent EEA for NVSs adjacent to the Meckel's cave or cavernous sinus. Results Nine patients (9/10), including five women (5/10), underwent primary surgery. Gross total resection and subtotal resection were achieved in five patients each (5/10). Postoperatively, one patient showed a new and mild cranial nerve V sensory deficit and one patient showed slight worsening of abducens nerve palsy. The greater palatine nerve was amputated in two patients; however, permanent perception loss in the soft palate was observed in one patient. The Vidian nerve was sacrificed in four patients, and new dry eye occurred in one patient. None of the patients experienced postoperative tumor recurrence or regrowth during the follow-up period of 40 +/- 28 months. Conclusion EETMPA is safe and effective for excising skull-base NVSs which are not eligible for radiosurgery leading to a high rate of successful resection and a high rate of but mild neurological sequela. The EEA is appropriate when the tumor extends to the paranasal sinus with sufficient SCEEA.