Analysis of Nonvestibular Cranial Nerve Schwannomas

Cranial nerve (CN) schwannomas other than the eighth nerve schwannoma are called nonvestibular cranial nerve schwannomas (NVCNS). This study aims to analyze the clinical profile, distribution, and surgical outcome of the NVCNS.

Methods and Materials/Patients:

 This is a retrospective study analyzing the NVCNS conducted between January 2007 and December 2021. VIIIth cranial nerve schwannomas and conservatively managed NVCNS were excluded from the study.

This study included 25 patients with NVCNS. Ten patients (40%) had trigeminal schwannomas, 3(12%) facial nerve schwannomas, 9 (36%) lower cranial nerve (LCN) schwannomas, 1 (4%) vagal schwannoma in neck and 2(8%) hypoglossal schwannomas.Eight patients (32%) were male and 17(68%) were female. The age of the patients ranges from 13 to 62 years (mean 39 years +/- 14 SD). Findings of cerebellar involvement, VIIIth CN involvement, and headache are the most common clinical features. The posterior cranial fossa is the most common location of the tumors. Thirteen patients (52%) underwent gross total resection (GTR), 7(28%) underwent neartotal resection (NTR) and 5(20%) underwent subtotal resection (STR). All the patients improved in the postoperative period. Facial nerve palsy is the most common cranial nerve palsy occurring in the postoperative period.

Trigeminal and lower cranial nerve (LCN) schwannomas are the most common NVCNS. The retrosigmoid suboccipital approach is the most commonly used surgical approach for tumors located in the posterior cranial fossa. Since NVCNS are benign lesions, postoperative clinical improvement along with decreased complications should be the goal of the surgery. Hence, gross total resection is the most commonly achieved extent of resection, near-total or subtotal resection can be done wherever gross total resection (GTR) is not possible in NVCNS.