title: Quantification of Working Volumes, Exposure, and Target-Specific Maneuverability of the Pterional Craniotomy and Its Minimally Invasive Variants.
abstract: OBJECTIVE
  Quantitative comparison of minimally invasive and standard cranial approaches remains a methodologic challenge. The aim of this study was to apply a new digital, navigation-based method to quantify multiple parameters of the pterional, supraorbital, lateral supraorbital and mini-pterional approaches and to describe a target-specific maneuverability score.
  
  
  METHODS
  Supraorbital, lateral supraorbital, mini-pterional, and standard pterional craniotomies were performed on 8 sides in 4 cadaver heads. The limits of superficial and deep exposure and surgical target points were registered with image-guidance (Medtronic Stealth). A custom software (Guided Therapeutics Eyes II Software [GTxEyesII]) calculated superficial and deep surface areas, working volumes, and target distances. Volumes were reconstructed digitally and visualized with GTxEyesII. Finally, we defined for each approach a target-specific maneuverability score based on surface exposure, target distance, target position, and anatomical obstacles.
  
  
  RESULTS
  Surface exposure and volumes were significantly smaller for keyhole approaches compared with standard pterional craniotomy (P < 0.01). Maneuverability index scores showed the greatest values for standard pterional craniotomies, but nearly equally high scores could be achieved by one or several of the less-invasive approaches for most of the targets.
  
  
  CONCLUSIONS
  The combination of a navigation-based measurement method with custom software (GTxEyesII) provides a powerful tool for visualization and quantification of surgical approaches. Compared with standard pterional craniotomy, alternative keyhole craniotomies offer comparable deep exposure with smaller working volumes and relatively high maneuverability for specific targets.
authors.affiliation: Division of Neurosurgery, Geneva University Hospitals and University of Geneva, Geneva, Switzerland. Electronic address: max.jaegersberg@hcuge.ch.
authors.forename: Max
authors.initials: M
authors.lastname: Jägersberg
authors.affiliation: Division of Neurosurgery, Geneva University Hospitals and University of Geneva, Geneva, Switzerland.
authors.forename: Jerermy
authors.initials: J
authors.lastname: Brodard
authors.affiliation: Department of Medical Imaging, Toronto General Hospital, University Health Network and University of Toronto, Toronto, Ontario, Canada.
authors.forename: Jimmy
authors.initials: J
authors.lastname: Qiu
authors.affiliation: Division of Neurosurgery, Toronto Western Hospital, University Health Network and Department of Surgery, University of Toronto, Toronto, Ontario, Canada.
authors.forename: Alireza
authors.initials: A
authors.lastname: Mansouri
authors.affiliation: Division of Neurosurgery, University of Brescia, Brescia, Italy.
authors.forename: Francesco
authors.initials: F
authors.lastname: Doglietto
authors.affiliation: Division of Neurosurgery, Toronto Western Hospital, University Health Network and Department of Surgery, University of Toronto, Toronto, Ontario, Canada.
authors.forename: Fred
authors.initials: F
authors.lastname: Gentili
authors.affiliation: Department of Medical Imaging, Toronto General Hospital, University Health Network and University of Toronto, Toronto, Ontario, Canada.
authors.forename: Walter
authors.initials: W
authors.lastname: Kucharczyk
authors.affiliation: Clinical Anatomy Research Group, Department of Cellular Physiology and Metabolism, University Medical Center, Geneva, Switzerland.
authors.forename: Jean
authors.initials: J
authors.lastname: Fasel
authors.affiliation: Division of Neurosurgery, Geneva University Hospitals and University of Geneva, Geneva, Switzerland.
authors.forename: Karl
authors.initials: K
authors.lastname: Schaller
authors.affiliation: Division of Neurosurgery, Toronto Western Hospital, University Health Network and Department of Surgery, University of Toronto, Toronto, Ontario, Canada.
authors.forename: Ivan
authors.initials: I
authors.lastname: Radovanovic
mesh_terms: D002102:Cadaver; D003399:Craniotomy / Q000379:methods*; D006257:Head / Q000000981:diagnostic imaging* / Q000601:surgery*; D006801:Humans; D007091:Image Processing, Computer-Assisted / Q000379:methods; D019060:Minimally Invasive Surgical Procedures / Q000379:methods*; D038361:Neuronavigation / Q000379:methods*
keywords: Anterior fossa; GTxEyes; Keyhole approach; Maneuverability; Mini-pterional; Pterional; Score; Supraorbital