title: Surgical findings to differentiate between facial nerve schwannoma and vestibular schwannoma.
abstract: OBJECTIVE
  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.
  
  
  CONCLUSIONS
  Facial nerve schwannomas can be differentiated from VSs by identifying specific findings during surgery.
authors.affiliation: Department of Otorhinolaryngology, Soonchunhyang University College of Medicine, Bucheon, Korea.
authors.forename: Jong Dae
authors.initials: JD
authors.lastname: Lee
authors.affiliation: Department of Otorhinolaryngology, Yonsei University College of Medicine, Seoul, Korea.
authors.forename: Won-Sang
authors.initials: WS
authors.lastname: Lee
keywords: Acoustic neuroma; Facial nerve; Neurilemmoma