title: Staged 'intentional' bridging vein ligation: a safe strategy in gaining wide access to skull base tumors.
abstract: BACKGROUND
  The venous drainage of the temporal lobe, through bridging veins to the middle cranial fossa, is pivotal in determining the surgical corridor for skull base lesions. In dealing with select cases, where venous drainage was an obstacle in the surgical approach, we hypothesized that staged 'intentional' ligation of the dominant pathway of venous drainage would provide a safer and wider access to skull base tumors. We study the indications and safety of this surgical strategy in the management of skull base lesions.
  
  
  METHODS
  From 1995 to 2012, 318 patients with skull base tumors were treated at our institute by the fronto-orbito-zygomatic (FOZ) or transpetrosal approaches, eight of whom we planned for staged 'intentional' bridging vein ligation. Seven patients underwent planned ligation of the bridging veins from the temporal lobe to the middle cranial fossa floor in the first stage, followed by definitive surgery through the desired skull base approach, in the second stage, while in one patient the strategy was abandoned. These patients were evaluated with respect to their clinical presentation, pre- and post-operative radiology including venogram, intra-operative findings and post-operative course.
  
  
  RESULTS
  Seven patients, four males and three females, with ages ranging from 16 to 63 years, underwent staged 'intentional' bridging vein ligation. The diagnoses were recurrent craniopharyngioma in four, and petroclival meningioma, sphenopetroclival meningioma and spheno-orbital meningioma in one each. Six of these lesions were approached from the dominant (left) side, while one lesion was on the right side. Venograms done after the first-stage procedure showed obliteration of the dominant venous drainage with opening up of anastomotic venous channels in all patients. All patients tolerated the first-stage procedure well; only one patient showed asymptomatic mild temporal lobe edema on MRI, which resolved in 3 weeks. None of the patients had venous complications after definitive surgery. One patient with recurrent chordoma, who was planned for staged ligation, did not undergo ligation as, intra-operatively, the draining channel turned out to be a cortical vein, which could be mobilized without ligation.
  
  
  CONCLUSIONS
  In an attempt to detether the temporal lobe, the disconnection of the bridging veins from the temporal lobe to the middle cranial fossa floor in the first stage may lead to re-direction of the venous outflow over time. This may allow skull base surgeons a better surgical corridor and ensure safety of venous structures during the definitive surgery.
authors.affiliation: Department of Neurosurgery, Post-graduate Institute of Medical Education and Research, Chandigarh, India.
authors.forename: Amey R
authors.initials: AR
authors.lastname: Savardekar
authors.forename: Takeo
authors.initials: T
authors.lastname: Goto
authors.forename: Takashi
authors.initials: T
authors.lastname: Nagata
authors.forename: Kenichi
authors.initials: K
authors.lastname: Ishibashi
authors.forename: Yuzo
authors.initials: Y
authors.lastname: Terakawa
authors.forename: Hiroki
authors.initials: H
authors.lastname: Morisako
authors.forename: Kenji
authors.initials: K
authors.lastname: Ohata
mesh_terms: D000293:Adolescent; D000328:Adult; D002550:Cerebral Veins / Q000601:surgery*; D035301:Cranial Fossa, Middle / Q000098:blood supply / Q000601:surgery; D003397:Craniopharyngioma / Q000098:blood supply / Q000601:surgery*; D004322:Drainage / Q000379:methods; D005260:Female; D006801:Humans; D008026:Ligation / Q000379:methods; D008297:Male; D008579:Meningioma / Q000098:blood supply / Q000601:surgery*; D008875:Middle Aged; D019635:Neurosurgical Procedures / Q000379:methods*; D012189:Retrospective Studies; D019291:Skull Base / Q000098:blood supply / Q000601:surgery; D019292:Skull Base Neoplasms / Q000098:blood supply / Q000601:surgery*; D013702:Temporal Lobe / Q000098:blood supply / Q000601:surgery; D016896:Treatment Outcome; D055815:Young Adult