Clin Exp Otorhinolaryngol.  2014 Sep;7(3):157-159. 10.3342/ceo.2014.7.3.157.

Surgical Findings to Differentiate Between Facial Nerve Schwannoma and Vestibular Schwannoma

• Lee JD
• Lee WS

• KMID: 1973462
• DOI: http://doi.org/10.3342/ceo.2014.7.3.157

Abstract

OBJECTIVES
Facial nerve schwannomas may be misdiagnosed as vestibular schwannomas (VSs) if the tumor is confined to the internal auditory canal (IAC) without involvement the geniculated ganglion or labyrinthine segment of facial nerve. Because facial nerve schwannomas may be misdiagnosed as VSs, we investigated the differences between the two.
METHODS
The study included 187 patients with a preoperative diagnosis of VS. Of these, six were diagnosed with facial nerve schwannomas during surgery. We reviewed the preoperative evaluations and surgical findings of facial nerve schwannomas mimicking VSs.
RESULTS
No useful preoperative predictors are available for facial nerve schwannomas mimicking VSs. Facial nerve schwannomas are usually confined to the IAC. After opening the dura of the IAC, a facial nerve schwannoma can be diagnosed after identifying a normal-appearing nerve located lateral to the tumor. When this was the case, we performed facial nerve preservation surgery or decompression.
CONCLUSION
Facial nerve schwannomas can be differentiated from VSs by identifying specific findings during surgery.

Keyword

Facial nerve; Neurilemmoma; Acoustic neuroma

MeSH Terms

Decompression
Diagnosis
Facial Nerve*
Ganglion Cysts
Humans
Neurilemmoma*
Neuroma, Acoustic*

Figure

• 

  Fig. 1 Surgical finding of vestibular schwannoma (VS). (A) The VS is seen only as a tumor mass after opening the dura of the internal auditory canal (IAC). (B) Schematic drawing of a VS after opening the dura of the IAC. T, tumor; FN, facial nerve.

• 

  Fig. 2 Surgical finding of facial nerve schwannoma mimicking a vestibular schwannoma (VS). (A, B) Facial nerve schwannoma has a normal-appearing nerve lateral to the tumor mass in each case. (C) Schematic drawing of a facial nerve schwannoma mimicking a VS after opening the dura of the internal auditory canal. T, tumor; SV, superior vestibular nerve.

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