title: Operative planning aid for optimal endoscopic third ventriculostomy entry points in pediatric cases.
abstract: OBJECTIVE
  Endoscopic third ventriculostomy (ETV) uses anatomical spaces of the ventricular system to reach the third ventricle floor and create an alternative pathway for cerebrospinal fluid flow. Optimal ETV trajectories have been previously proposed in the literature, designed to grant access to the third ventricle floor without a displacement of eloquent periventricular structures. However, in hydrocephalus, there is a significant variability to the configuration of the ventricular system, implying that the optimal ETV trajectory and cranial entry point needs to be planned on a case-by-case basis. In the current study, we created a mathematical model, which tailors the optimal ETV entry point to the individual case by incorporating the ventricle dimensions.
  
  
  METHODS
  We retrospectively reviewed the imaging of 30 consecutive pediatric patients with varying degrees of ventriculomegaly. Three dimensional radioanatomical models were created using preoperative MRI scans to simulate the optimal ETV trajectory and entry point for each case. The surface location of cranial entry points for individual ETV trajectories was recorded as Cartesian coordinates centered at Bregma. The distance from the Bregma in the coronal plane represented as "x", and the distance from the coronal suture in the sagittal plane represented as "y". The correlation between the ventricle dimensions and the x, y coordinates were tested using linear regression models.
  
  
  RESULTS
  The distance of the optimal ETV entry point from the Bregma in the coronal plane ("x") and from the coronal suture in the sagittal plane ("y") correlated well with the frontal horn ratio (FHR). The coordinates for x and y were fitted along the following linear equations: x = 85.8 FHR-13.3 (r2= 0.84, p < 0.001) and y = -69.6 FHR + 16.7 (r2= 0.83, p < 0.001).
  
  
  CONCLUSIONS
  The surface location of the optimal cranial ETV entry point correlates well with the ventricle size. We provide the first model that can be used as a surgical planning aid for a case specific ETV entry site with the incorporation of the ventricle size.
authors.affiliation: Department of Pediatric Neurosurgery, Royal Manchester Children's Hospital, Manchester, M13 9WL, UK. zadzso@gmail.com.|Department of Neurosurgery, Greater Manchester Neuroscience Centre, Salford Royal NHS Foundation Trust, Salford, UK. zadzso@gmail.com.|Institute of Cardiovascular Sciences, Centre for Vascular and Stroke Research, University of Manchester, Manchester, UK. zadzso@gmail.com.
authors.forename: Zsolt
authors.identifier: http://orcid.org/0000-0003-4297-616X
authors.initials: Z
authors.lastname: Zador
authors.affiliation: Department of Pediatric Neurosurgery, Royal Manchester Children's Hospital, Manchester, M13 9WL, UK.|Department of Neurosurgery, Greater Manchester Neuroscience Centre, Salford Royal NHS Foundation Trust, Salford, UK.|Wolfson Molecular Imaging Centre, The University of Manchester, Manchester, UK.
authors.forename: David J
authors.initials: DJ
authors.lastname: Coope
authors.affiliation: Department of Neurosurgery, Greater Manchester Neuroscience Centre, Salford Royal NHS Foundation Trust, Salford, UK.
authors.forename: Abteen
authors.initials: A
authors.lastname: Mostofi
authors.affiliation: Department of Pediatric Neurosurgery, Royal Manchester Children's Hospital, Manchester, M13 9WL, UK.
authors.forename: Ian D
authors.initials: ID
authors.lastname: Kamaly-Asl
mesh_terms: D000293:Adolescent; D002648:Child; D002675:Child, Preschool; D005260:Female; D006801:Humans; D006849:Hydrocephalus / Q000000981:diagnostic imaging / Q000601:surgery*; D007091:Image Processing, Computer-Assisted; D007223:Infant; D016014:Linear Models; D008279:Magnetic Resonance Imaging; D008297:Male; D044583:Neuroendoscopy / Q000379:methods*; D012189:Retrospective Studies; D020542:Third Ventricle / Q000601:surgery*; D016896:Treatment Outcome; D014696:Ventriculostomy / Q000379:methods*
keywords: Endoscopic third ventriculostomy; Optimal ETV trajectory; Pediatric hydrocephalus