title: Single burr hole rigid endoscopic third ventriculostomy and endoscopic tumor biopsy: what is the safe displacement range for the foramen of Monro?
abstract: OBJECTIVE
  To investigate the safe displacement range of the foramen of Monro (FM) during single burr hole rigid endoscopic third ventriculostomy (ETV) and endoscopic tumor biopsy (ETB).
  
  
  METHODS
  Eleven patients who received ETV/ETB for third ventricular and pineal region tumor were reviewed. The burr-hole location, the size, and the virtual displacement of FM were measured using neuronavigation software.
  
  
  RESULTS
  Hydrocephalus was resolved, and no subsequent cerebrospinal fluid (CSF) shunting was required in all cases. Histological diagnosis was established in 11 patients. Ten cases received instrumental cognitive and memory assessment postoperatively. The results were within the normal range for eight cases. The mean burr-hole location was 1.7 cm anterior to coronal suture and 3 cm from the midline. The mean diameters of FM measured on the axial, coronal, sagittal, and views were 5.7, 7.8, and 5.6 mm, respectively. The mean virtual displacements of the FM were 1.9±2.0 mm (range=0-4.8) for ETV and 2.4±2.1 mm (range=0-5.5) for ETB. The maximum displacements were 4.8 mm anteriorly for ETV and 5.5 mm posteriorly for ETB.
  
  
  CONCLUSIONS
  Single burr hole rigid ETV/ETB is likely to be safe within maximum FM displacements of 4.8 mm anterior for ETV and 5.5 mm posterior for ETB. Preoperative trajectory planning using neuronavigation software is recommended.
authors.affiliation: Division of Neurosurgery, Department of Surgery, Prince of Wales Hospital, The Chinese University of Hong Kong, HKSAR, China.
authors.forename: Xian Lun
authors.initials: XL
authors.lastname: Zhu
authors.forename: Rong
authors.initials: R
authors.lastname: Gao
authors.forename: George Kwok Chu
authors.initials: GK
authors.lastname: Wong
authors.forename: Hoi Tung
authors.initials: HT
authors.lastname: Wong
authors.forename: Rebecca Yuen Ting
authors.initials: RY
authors.lastname: Ng
authors.forename: Yong
authors.initials: Y
authors.lastname: Yu
authors.forename: Rosanna Kit Man
authors.initials: RK
authors.lastname: Wong
authors.forename: Wai Sang
authors.initials: WS
authors.lastname: Poon
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D002552:Cerebral Ventricles; D002648:Child; D005260:Female; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D044583:Neuroendoscopy / Q000379:methods*; D038361:Neuronavigation; D012189:Retrospective Studies; D014057:Tomography, X-Ray Computed; D014696:Ventriculostomy / Q000379:methods*; D055815:Young Adult