title: A magnetic resonance imaging-directed method for transventricular targeting of midline structures for deep brain stimulation using implantable guide tubes.
abstract: OBJECTIVE
  The periventricular gray/periaqueductal gray (PVG/PAG) is a target site for deep brain stimulation for chronic pain. The pedunculopontine nucleus (PPN) is a target for the treatment of axial disturbance in Parkinson's disease. Conventionally, a trajectory lateral to the ventricle is used in targeting deep subcortical structures; however, this limits the number of active contacts that can be placed in these midline targets. To maximize the number of contacts within these targets, a trajectory traversing the ventricles may be used; however, this is avoided because lead placement remains unpredictable with problems including ventricular lead migration and hemorrhage. We describe a novel method for accurate and safe transventricular targeting.
  
  
  METHODS
  Magnetic resonance imaging is used for visualizing the target structure. A trajectory traversing the lateral ventricle is planned, avoiding blood vessels. The guide tube is inserted through the ventricle to a position short of the target site and its proximal end is fixed. A stylet is inserted in the guide tube with its distal end at the target site. After intraoperative radiological confirmation of placement, the indwelling stylet is removed and the guide tube acts as a port for delivering the stimulating electrode.
  
  
  RESULTS
  The PVG/PAG matter and the PPN were targeted, taking a transventricular trajectory. We implanted unilateral PVG/PAG matter electrodes in 10 patients and bilateral PPN electrodes in 3 patients. All electrodes were implanted accurately within the desired target with no complications.
  
  
  CONCLUSIONS
  The use of an implanted guide tube enables the safe and accurate transventricular targeting of the PVG/PAG matter and the PPN.
authors.affiliation: Institute of Neurosciences, Frenchay Hospital, Bristol, United Kingdom.
authors.forename: Sadaquate
authors.initials: S
authors.lastname: Khan
authors.forename: Shazia
authors.initials: S
authors.lastname: Javed
authors.forename: Nicholas
authors.initials: N
authors.lastname: Park
authors.forename: Steven S
authors.initials: SS
authors.lastname: Gill
authors.forename: Nikunj K
authors.initials: NK
authors.lastname: Patel
mesh_terms: D001933:Brain Stem / Q000033:anatomy & histology / Q000601:surgery*; D046690:Deep Brain Stimulation / Q000295:instrumentation / Q000379:methods*; D004567:Electrodes, Implanted / Q000592:standards; D006801:Humans; D020547:Lateral Ventricles / Q000033:anatomy & histology / Q000601:surgery*; D008279:Magnetic Resonance Imaging / Q000295:instrumentation / Q000379:methods*; D009434:Neural Pathways / Q000033:anatomy & histology / Q000502:physiology; D038361:Neuronavigation / Q000295:instrumentation / Q000379:methods*; D010148:Intractable Pain / Q000601:surgery; D045042:Pedunculopontine Tegmental Nucleus / Q000033:anatomy & histology / Q000601:surgery; D010487:Periaqueductal Gray / Q000033:anatomy & histology / Q000601:surgery; D019919:Prosthesis Implantation / Q000295:instrumentation / Q000379:methods; D013238:Stereotaxic Techniques