title: Midline filum of the sellar dura: a useful landmark during endoscopic transsphenoidal pituitary surgery.
abstract: BACKGROUND
  During endoscopic transsphenoidal pituitary surgery, identification and constant awareness of the midline is imperative to prevent injury to critical lateral structures, such as the internal carotid arteries.
  
  
  OBJECTIVE
  To describe the relevance of a midline filum of the sellar dura which, when present, can serve as a useful intraoperative anatomic marker.
  
  
  METHODS
  Intraoperative video recordings of twenty patients undergoing endoscopic transsphenoidal surgery were retrospectively reviewed to assess for the presence and location of a midline dural filum or apparent central dural vascular structure. Prospective intraoperative data were gathered on an additional 16 patients.
  
  
  RESULTS
  A midline dural filum was identified in 18 of 36 patients (50%) undergoing endoscopic transsphenoidal surgery. This structure was identified on the midline in all cases, as confirmed by intraoperative neuronavigation and comparison with the vomer. The midline dural filum was identified as a strand-like dural extension (13 patients) or as a small vascular dural structure usually exhibiting low pressure venous bleeding (5 patients). Samples of the midline dural filum were obtained from 2 patients for histopathological analysis, which demonstrated dense collagenous connective tissue without evidence of vessel wall or ductal epithelium.
  
  
  CONCLUSIONS
  In addition to anatomic structures such as the vomer and midline sphenoid sinus septations, a midline dural filum serves as a useful marker during the sellar phase of endoscopic transsphenoidal surgery. Along with intraoperative neuronavigation and Doppler ultrasonography of the cavernous carotid arteries, identification of this structure may further aid in safeguarding against injury to critical paramedian structures.
authors.affiliation: Department of Neurosurgery, Brigham and Women's Hospital, Harvard Medical School, Boston, Massachusetts, USA. gzada@usc.edu
authors.forename: Gabriel
authors.initials: G
authors.lastname: Zada
authors.forename: Albert H
authors.initials: AH
authors.lastname: Kim
authors.forename: Lance S
authors.initials: LS
authors.lastname: Governale
authors.forename: Edward R
authors.initials: ER
authors.lastname: Laws
mesh_terms: D004210:Dissection / Q000379:methods; D004388:Dura Mater / Q000033:anatomy & histology / Q000601:surgery*; D004724:Endoscopy / Q000379:methods*; D006801:Humans; D007431:Intraoperative Complications / Q000517:prevention & control; D008866:Microsurgery / Q000379:methods; D009296:Nasal Cavity / Q000033:anatomy & histology / Q000601:surgery; D019635:Neurosurgical Procedures / Q000379:methods*; D010911:Pituitary Neoplasms / Q000601:surgery*; D012189:Retrospective Studies; D012658:Sella Turcica / Q000033:anatomy & histology / Q000601:surgery*; D013100:Sphenoid Bone / Q000033:anatomy & histology / Q000601:surgery*