title: Position and Course of Facial Nerve and Postoperative Facial Nerve Results in Vestibular Schwannoma Microsurgery.
abstract: OBJECTIVE
  To investigate the variation in the position and course of the facial nerve (FN) in patients undergoing vestibular schwannoma (VS) microsurgery by the keyhole retrosigmoid approach and the relationship between FN position and postoperative facial results.
  
  
  METHODS
  The series consists of 100 patients who underwent VS microsurgery during a 5-year period in whom the position and course of the FN could be confirmed by direct stimulation. The course of the FN was classified into 4 patterns according to its position: anterior (ventral) surface of the tumor (A), anterior-superior (AS), anterior-inferior (AI), and dorsal (D).
  
  
  RESULTS
  The distribution of patterns was as follows: AS in 48 cases, A in 31, AI in 21, and D in zero. For tumors <1.5 cm, the AS pattern was most common (68.4%). For tumors ≥1.5 cm, the proportion of A and AI positions increased (31.4% and 25.5%). Significant differences were observed between position and course patterns of the FN and postoperative nerve results. Patients with AS and AI patterns had better House-Brackmann FN function compared with patients with the A pattern (P < 0.05). Moreover, in tumors >3.0 cm, the FN tended to adhere strongly to the tumor capsule, and postoperative facial deficits were more frequent (P < 0.05).
  
  
  CONCLUSIONS
  The AS pattern was most common for smaller VSs. The A position and course and adhesion of the FN to the tumor capsule were the 2 factors most strongly associated with worse postoperative FN result.
authors.affiliation: Department of Neurosurgery, San Filippo Neri Hospital-ASL Roma 1, Rome, Italy. Electronic address: mastro@tin.it.
authors.forename: Luciano
authors.initials: L
authors.lastname: Mastronardi
authors.affiliation: Department of Neurosurgery, San Filippo Neri Hospital-ASL Roma 1, Rome, Italy.
authors.forename: Guglielmo
authors.initials: G
authors.lastname: Cacciotti
authors.affiliation: Department of Neurophysiology, San Filippo Neri Hospital-ASL Roma 1, Rome, Italy.
authors.forename: Raffaelino
authors.initials: R
authors.lastname: Roperto
authors.affiliation: Department of Neurosurgery, San Filippo Neri Hospital-ASL Roma 1, Rome, Italy.
authors.forename: Ettore
authors.initials: E
authors.lastname: Di Scipio
authors.affiliation: Department of Neurosurgery, San Filippo Neri Hospital-ASL Roma 1, Rome, Italy.
authors.forename: Maria Pia
authors.initials: MP
authors.lastname: Tonelli
authors.affiliation: Department of Neurosurgery, San Filippo Neri Hospital-ASL Roma 1, Rome, Italy.
authors.forename: Ettore
authors.initials: E
authors.lastname: Carpineta
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D005154:Facial Nerve / Q000473:pathology*; D020220:Facial Nerve Injuries / Q000175:diagnosis* / Q000209:etiology*; D005260:Female; D006801:Humans; D008297:Male; D008866:Microsurgery / Q000009:adverse effects* / Q000379:methods*; D008875:Middle Aged; D009361:Neoplasm Invasiveness; D009464:Neuroma, Acoustic / Q000150:complications / Q000473:pathology* / Q000601:surgery*; D016896:Treatment Outcome; D047368:Tumor Burden; D055815:Young Adult
keywords: Facial nerve; Facial nerve adhesion; Facial nerve position; Facial nerve preservation; Retrosigmoid approach; Vestibular schwannoma