Facial Nerve Outcome after Vestibular Schwannoma Surgery: Neurophysiological and Clinical Assessment

Anna Podgorska; Przemyslaw Kunert; Bartosz Sieradzki; Andrzej Marchel

doi:10.1055/s-0036-1592486

Journal of Neurological Surgery Part B: Skull Base, Inhaltsverzeichnis

Facial Nerve Outcome after Vestibular Schwannoma Surgery: Neurophysiological and Clinical Assessment

Anna Podgorska ¹, Przemyslaw Kunert ¹, Bartosz Sieradzki ², Andrzej Marchel ¹

¹Department of Neurosurgery, Medical University of Warsaw, Warsaw, Poland
²Students Scientific Group, Medical University of Warsaw, Warsaw, Poland

Abstract

Objective: The aim of study is to evaluate neurophysiological and clinical facial nerve (CNVII) function after total vestibular schwannoma surgery.

Methods: We investigated data of 48 patients who underwent vestibular schwannoma surgical removal with direct CNVII stimulation at the brain stem (proximal) and deep in the internal acoustic meatus (distal) after total tumor removal to assess CNVII function. The ratio of CNVII evoked response amplitude obtained with proximal and distal stimulation was estimated. Early and late CNVII outcome and postoperative electrophysiological results were correlated with results of final intraoperative stimulation. At postoperative electrophysiological examination (at 7th day after surgery) the ratio of evoked CNVII response amplitude on the side of surgery to the amplitude on the contralateral side was estimated. CNVII function was assessed in House-Brackman scale at discharge from hospital (early outcome) and 6 or more months after surgery (late outcome).

Results: There was a good correlation between final intraoperative CNVII amplitude ratio and early and late outcome. However patients with pronounced reduction of final amplitude ratio (up to 90%) had good late outcome. There was no clear correlation between results of electrophysiological CNVII function assessment and early and late outcome, however patients with unresponsive CNVII had bad late outcome.

Conclusion: (1) Patients with responsive CNVII on final intraoperative stimulation and at postoperative electrophysiological examination (amplitude ratio >10%) have good long-term prognosis. (2) The unresponsive CNVII on the final intraoperative stimulation and at electrophysiological examination (or amplitude ratio—not more than 10%) is bad long-term prognostic factor.