Multivariate Analysis of Factors Influencing Facial Nerve Outcome following Microsurgical Resection of Vestibular Schwannoma

Abstract

Objective To assess through multivariate analysis the clinical pre- and intraoperative factors of facial nerve outcomes at day 8 and 1-year recovery of facial palsy, as compared with day 8 status among patients who underwent total resection of unilateral vestibular schwannoma. Study Design Case series with chart review. Setting Tertiary referral center. Subjects and Methods This study included 229 patients with preoperative normal facial function and anatomic preservation of the facial nerve. Clinical, radiologic, and intraoperative factors were assessed according to facial nerve function at day 8 and 1 year. Results We observed that 74% and 84% of patients had good facial function (House-Brackmann [HB] I-II) at day 8 and 1 year, respectively. Of 60 patients, 26 (43%) who had impaired facial function (HB III-VI) at day 8 recovered good facial function (HB I-II) 1 year after surgery. A structured equation model showed that advanced tumor stage and strong facial nerve adhesion were independently associated with facial nerve conduction block at day 8. No predictive factor of impaired facial function recovery was seen at 1 year. In terms of the extracanalicular diameter of the tumor, the cutoff point to minimize the risk of impaired facial function was 16 mm. Conclusion At day 8 after vestibular schwannoma resection, facial function was impaired in the case of large tumors or strong facial nerve adhesion to the tumor. After 1 year, less than half of the patients recovered good facial function, and no predictive factor was found to be associated with this possible recovery.

Current Management of Large Vestibular Schwannomas for NF2 Patients in a National Reference Center

“…It was demonstrated that large VS and severe adherence of the facial nerve to the tumor capsule were independent predictive factors of a postoperative facial palsy. 35 We are performing less GTR than in published series, 8 our tumor resection being guided by intraoperative facial nerve monitoring, and a small tongue of tumor being left adherent to the nerve if the supramaximal responses decreased by more than 30% to 50% of the baseline value at the proximal segment of the facial nerve. 28,31,36 Accordingly, 57% of VS resections were GTR or NTR, with no gadolinium enhancement on postoperative MRI, although STR and partial planned resections were more frequently performed than for sporadic VS to preserve as much facial and hearing function as possible.…”

How to radiologically identify a spontaneous regression of sporadic vestibular schwannoma?

“…For each scan, MRI data included location of the tumor (intrameatal and/or extrameatal), tumor size, homolateral and contralateral internal meatus size on the anteroposterior axis, inner ear signal on HRT2-weighted imaging compared to the contralateral side, and tumor characteristics (tumor outline, spontaneous signal in T1-weighted imaging, cystic component). Tumors were classified according to a functional classification described in previous studies [8–10]: stage I for intrameatal tumors, stage II for tumors up to 15 mm in extrameatal size, stage III for tumors from 16 to 30 mm, and stage IV if the tumor was more than 30 mm in extrameatal largest diameter. Tumors were also divided into three groups depending on intrameatal extent: (A) if the entire internal auditory meatus (IAM) was invaded up to the fundus, (B) if the IAM was partially invaded, and (C) if IAM invasion was minimal [9].…”

Therapy of Sporadic and NF2-Related Vestibular Schwannoma

“…Function preservation of surrounding structures and mainly the 7 th nerve is an important part of VS surgery. The surgical outcome in sporadic VS is associated with the following factors: tumor size, adhesion to the brainstem and CNs, the use of CN monitoring technology and surgeon's experience [64][65][66][67][68][69]. Surgical treatments include subtotal resection (STR), near-total resection (NTR) and total resection [70].…”