title: Intraoperative Conversion from Endoscopic to Open Transcortical-Transventricular Removal of Colloid Cysts as a Salvage Procedure.
abstract: OBJECTIVE
  To describe the transcortical-transventricular as an intraoperative salvage procedure and its effect of operative time and outcome.
  
  
  METHODS
  Thirty-three patients were included in the study. Twenty patients had an endoscopic operation, five had a transcortical-transventricular approach, and eight underwent an interhemispheric approach for resection. Based on common cyst location in the roof of the third ventricle, we propose a simple classification of surgical operative zones based on relationships defined by the anterior column of the fornix, the septal vein, and the medial atrial vein.
  
  
  RESULTS
  Complete capsule removal was achieved in 35% of endoscopic operations, 100% of transcortical-transventricular operations, and 63% of the interhemispheric operations. Operative time was 176 minutes for endoscopic operations, whereas the operative time for cases that converted to the transcortical-transventricular approach was 190 minutes (p=0.39).
  
  
  CONCLUSIONS
  A surgical-based classification of zones within the roof of the third ventricle that can be accessed with microsurgical techniques is proposed. Both endoscopic and microsurgical cyst aspiration and excision remain options. We believe that younger patients, patients with large cysts that fill the third ventricle, or those with recurrence after prior treatment would benefit from open transcortical excision as a safe and effective operative approach using modern image-guided systems. Consent was formally obtained or waived for all subjects present within this study.
authors.affiliation: Department of Neurological Surgery, University of California, San Francisco.
authors.forename: Joseph A
authors.initials: JA
authors.lastname: Osorio
authors.affiliation: Department of Neurological Surgery, University of California, San Francisco.
authors.forename: Aaron J
authors.initials: AJ
authors.lastname: Clark
authors.affiliation: Department of Neurological Surgery, University of California, San Francisco.
authors.forename: Michael
authors.initials: M
authors.lastname: Safaee
authors.affiliation: Neurological Surgery, Northwestern University Feinberg School of Medicine.
authors.forename: Matthew C
authors.initials: MC
authors.lastname: Tate
authors.affiliation: Department of Neurological Surgery, University of California, San Francisco.
authors.forename: Manish K
authors.initials: MK
authors.lastname: Aghi
authors.affiliation: Department of Neurological Surgery, University of California, San Francisco.
authors.forename: Andrew
authors.initials: A
authors.lastname: Parsa
authors.affiliation: Department of Neurosurgery, University of California, San Francisco.
authors.forename: Michael W
authors.initials: MW
authors.lastname: McDermott
keywords: colloid cyst; endoscopic; interhemispheric; surgical approach; transcortical