title: Surgical exposure of the internal auditory canal through the retrosigmoid approach with semicircular canals anatomical preservation.
abstract: OBJECTIVE
  Evaluate the feasibility of an adequate exposure with anatomical preservation of labyrinth structures through retrosigmoid transmeatal approach (RSA) in surgeries for resection of acoustic neuromas/vestibular schwannomas (VS).
  
  
  METHODS
  Thirty patients underwent surgical resection and were preoperatively evaluated with fine slice high definition CT scans and 3D-MRI volumetric reconstructions. Extension of internal auditory canal (IAC) opening during surgery was measured using 3 mm right-angle calibrated hook and neuronavigation parameters. Postoperatively, the extension of IAC opening and integrity of the labyrinth were confirmed through preoperatively images procedures.
  
  
  RESULTS
  The preoperative length of IACs varied between 7.8 and 12.0 mm (mean 9.3 mm, SD 0.98, 95%CI 8.9 to 9.6, and median 9.0 mm). Postoperative images demonstrated adequate opening of the IAC and semicircular channels integrity.
  
  
  CONCLUSIONS
  A complete drilling of the posterior wall of IAC through the RSA is feasible and allows direct visualization of the IAC-fundus without damaging the semicircular canals.
authors.affiliation: Instituto de Neurologia de Curitiba, Curitiba, PR, Brazil.
authors.forename: Andre Giacomelli
authors.initials: AG
authors.lastname: Leal
authors.affiliation: Instituto de Neurologia de Curitiba, Curitiba, PR, Brazil.
authors.forename: Erasmo Barros da
authors.initials: EB
authors.lastname: Silva
authors.forename: Ricardo
authors.initials: R
authors.lastname: Ramina
mesh_terms: D007758:Ear, Inner / Q000601:surgery*; D005240:Feasibility Studies; D005260:Female; D006801:Humans; D008279:Magnetic Resonance Imaging / Q000379:methods; D008297:Male; D008866:Microsurgery / Q000379:methods; D008875:Middle Aged; D009464:Neuroma, Acoustic / Q000473:pathology / Q000601:surgery*; D038361:Neuronavigation / Q000379:methods; D059351:Organ Sparing Treatments / Q000379:methods*; D013506:Otologic Surgical Procedures / Q000379:methods; D011184:Postoperative Period; D011446:Prospective Studies; D015203:Reproducibility of Results; D012665:Semicircular Canals / Q000033:anatomy & histology* / Q000601:surgery; D014057:Tomography, X-Ray Computed / Q000379:methods; D016896:Treatment Outcome; D047368:Tumor Burden