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J Neurol Surg B Skull Base 2017; 78(04): 283-287
DOI: 10.1055/s-0037-1598636
Original Article
Georg Thieme Verlag KG Stuttgart · New York

Facial Nerve Schwannomas Mimicking as Vestibular Schwannomas

Beth N. McNulty
1   Michigan Ear Institute, Farmington Hills, Michigan, United States
,
Sean Wise
2   Department of Otology, Neurotology and Skull Base Surgery, Naval Medical Center, San Diego, California, United States
,
David S. Cohen
3   Department of Otolaryngology, Wayne State University, Detroit, Michigan, United States
,
Jason Bell
4   Department of Otolaryngology, Loyola University, Maywood, Illinois, United States
,
Dennis Bojrab
5   Department of Otology, Neurotology and Skull Base Surgery, Michigan Ear Institute, Farmington Hills, Michigan, United States
,
Michael LaRouere
5   Department of Otology, Neurotology and Skull Base Surgery, Michigan Ear Institute, Farmington Hills, Michigan, United States
,
Matthew Kircher
4   Department of Otolaryngology, Loyola University, Maywood, Illinois, United States
,
Seilesh Babu
5   Department of Otology, Neurotology and Skull Base Surgery, Michigan Ear Institute, Farmington Hills, Michigan, United States
› Author Affiliations
Further Information

Publication History

13 June 2016

01 December 2016

Publication Date:
30 January 2017 (online)

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Abstract

Objective The objective of this study was to identify preoperative and intraoperative findings that may aid in distinguishing facial nerve schwannomas (FNS) from vestibular schwannomas (VSs), particularly in cases limited to the internal auditory canal (IAC) and cerebellopontine angle (CPA).

Study Design This was a retrospective study.

Setting This study was set at a Tertiary Referral Center.

Patients Seventeen cases from October 2002 to July 2015 with an IAC/CPA mass presumed to be a VS who were found to have a FNS intraoperatively.

Main Outcome Measures The main outcome measures included preoperative presentation, intraoperative findings, and subsequent intervention.

Results Preoperative hearing loss and imbalance were seen in 70.5 and 64.7%, respectively. Suspicious intraoperative findings included: facial nerve incorporated intimately with the tumor capsule in 12 cases; spontaneous action potentials noted while drilling the bony IAC in 3 cases; and action potentials noted on stimulation of the entire tumor capsule in 10 cases. The mean long-term facial function was House–Brackmann grade II and the mean length of follow-up was 4.86 years.

Conclusion FNSs are rare and may be difficult to distinguish from VS preoperatively. Surgical findings that should raise concern include spontaneous action potentials during drilling the bony IAC, absence of a plane of dissection between the facial nerve and tumor, or stimulation of the tumor capsule.

Keywords

facial nerve schwannoma - electroneuronography - facial nerve monitoring

Letter to this article:

In Response to “Facial Nerve Schwannomas Mimicking as Vestibular Schwannomas” by Beth N. McNulty et alJ Neurol Surg B Skull Base 2019; 80(03): 327-328
DOI: 10.1055/s-0037-1609032

 

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