title: Endoscopic endonasal approach for resection of cranial base chordomas:  outcomes and learning curve.
abstract: BACKGROUND
  Gross total resection (GTR) of cranial base chordomas represents a surgical challenge because of the location, invasiveness, and tumor extension. In the past decade, the endoscopic endonasal approach (EEA) has been used with notable outcomes.
  
  
  OBJECTIVE
  To present the endoscopic endonasal experience in the treatment of cranial base chordomas at our institution.
  
  
  METHODS
  From April 2003 to March 2011, 60 patients underwent an EEA for primary (n = 35) or previously treated (n = 25) cranial base chordomas. We evaluated the degree of GTR and complications. We studied the factors that influenced outcomes and compared our surgical results in the early and late years of our experience.
  
  
  RESULTS
  The overall rate of GTR of cranial base chordomas was 66.7% (82.9% in primary and 44% in previously treated patients). The most important limitations for GTR were tumor volume greater than 20 cm (P = .042), tumor location in the lower clivus with lateral extension (P = .022), and previously treated disease (P = .002). The learning curve had a significant impact on GTR, increasing the success rate to 88.9% (92.6% in primary patients and 63.6% in previously treated patients) during recent years (P < .0001). The most frequent complication was cerebrospinal fluid leak (20%) resulting in meningitis in 3.3%. Carotid injuries occurred in 2 patients without any resulting deficit. Neurological complications included new cranial neuropathies (6.7%) and long tract deficits (1.7%). There was no operative mortality in our series.
  
  
  CONCLUSIONS
  For the treatment of cranial base chordomas, the EEA is a competitive alternative to transcranial approaches with minimal morbidity and high success rates of GTR when performed by experienced cranial base surgeons.
authors.affiliation: Department of Neurological Surgery, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania 15213, USA.
authors.forename: Maria
authors.initials: M
authors.lastname: Koutourousiou
authors.forename: Paul A
authors.initials: PA
authors.lastname: Gardner
authors.forename: Matthew J
authors.initials: MJ
authors.lastname: Tormenti
authors.forename: Stephanie L
authors.initials: SL
authors.lastname: Henry
authors.forename: Susan T
authors.initials: ST
authors.lastname: Stefko
authors.forename: Amin B
authors.initials: AB
authors.lastname: Kassam
authors.forename: Juan C
authors.initials: JC
authors.lastname: Fernandez-Miranda
authors.forename: Carl H
authors.initials: CH
authors.lastname: Snyderman
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D002648:Child; D002675:Child, Preschool; D002817:Chordoma / Q000601:surgery*; D005260:Female; D006801:Humans; D059032:Learning Curve; D008297:Male; D008875:Middle Aged; D044583:Neuroendoscopy / Q000009:adverse effects / Q000379:methods*; D011183:Postoperative Complications / Q000209:etiology; D012189:Retrospective Studies; D019291:Skull Base / Q000601:surgery; D019292:Skull Base Neoplasms / Q000601:surgery*; D016896:Treatment Outcome; D055815:Young Adult