title: Usefulness of facial nerve monitoring for confirmation of greater superficial petrosal nerve in anterior transpetrosal approach.
abstract: BACKGROUND
  The greater superficial petrosal nerve (GSPN) is especially important in anterior transpetrosal approach (ATPA) as the most reliable superficial landmark of Kawase's triangle. The GSPN can be considered as the superficial lateral border of anterior petrosectomy on the middle fossa to avoid internal carotid artery (ICA) injury. Although experienced operators can find the GSPN, its confirmation is not always easy to achieve.
  
  
  METHODS
  We introduce our recent GSPN confirmation methods using facial nerve monitoring. In 10 recent cases, antidromic GSPN stimulation and free-running facial muscle electromyography (EMG) monitoring were performed.
  
  
  RESULTS
  Facial nerve evoked-EMG by antidromic GSPN stimulation confirmed the location of the GSPN course with precision in all cases. Free-running facial muscle EMG informed the mechanical stress of facial nerves through the GSPN. There was no postoperative facial palsy or dry eye in these cases.
  
  
  CONCLUSIONS
  GSPN confirmation and preservation are not always easy to achieve. These monitoring methods are useful for the confirmation of the GSPN, which is a landmark for safe extradural anterior petrosectomy, and for the preservation of the GSPN itself.
authors: Department of Neurosurgery, Keio University School of Medicine, 35 Shinanomachi, Shinjuku, Tokyo, 160-8582, Japan, tomy0807@hotmail.com.
authors: Ryosuke
authors: R
authors: Tomio
authors: Takenori
authors: T
authors: Akiyama
authors: Takayuki
authors: T
authors: Ohira
authors: Tomo
authors: T
authors: Horikoshi
authors: Kazunari
authors: K
authors: Yoshida
mesh_terms: D000768:Anesthesia, General; D020295:Brain Stem Neoplasms / Q000601:surgery; D035301:Cranial Fossa, Middle / Q000033:anatomy & histology; D003399:Craniotomy / Q000379:methods* / Q000592:standards; D004558:Electric Stimulation / Q000295:instrumentation / Q000379:methods; D004576:Electromyography / Q000295:instrumentation / Q000379:methods; D005152:Facial Muscles / Q000502:physiology*; D005154:Facial Nerve / Q000502:physiology*; D006801:Humans; D016343:Monitoring, Intraoperative / Q000295:instrumentation / Q000379:methods*; D019635:Neurosurgical Procedures / Q000295:instrumentation / Q000379:methods*; D010579:Petrous Bone / Q000601:surgery; D019292:Skull Base Neoplasms / Q000601:surgery