title: CT-based, fiducial-free frameless stereotaxy for difficult ventriculoperitoneal shunt insertion: experience in 26 consecutive patients.
abstract: BACKGROUND
  Patients with small or dysmorphic ventricles requiring ventriculoperitoneal shunt (VPS) insertion for hydrocephalus can be challenging. The 'freehand' technique does not always provide for accurate catheter insertion, particularly in patients with slit ventricles, complex hydrocephalus or displaced ventricles. Consequently, many surgeons use stereotaxy for assistance. We have employed a frameless stereotactic technique, obviating the need for fiducials or preoperative MRI, for difficult ventricular catheter placement over the past 1.5 years with excellent results. We describe our experience with frameless stereotactic VPS insertion.
  
  
  METHODS
  We retrospectively reviewed the charts of 26 patients who underwent frameless stereotactic VPS insertion. All patients had preoperative CT scans using a navigation protocol and were registered into the Stealth Station via the face tracer program. Catheters were inserted using the Medtronic frameless trajectory guide kit. We recorded demographic data, operative time, complications and follow-up.
  
  
  RESULTS
  The mean patient age was 31 years. The average operative time was 46 min. There were 3 complications. The average follow-up was 5 months. Twenty-one patients had postoperative imaging, with 20 having excellent catheter positioning.
  
  
  CONCLUSIONS
  Our results confirm that frameless stereotactic VPS without fiducial marker placement is a feasible technique for catheter insertion in patients who have small/dysmorphic ventricles. In experienced hands, there is negligible added operative time and a low complication rate.
authors.affiliation: Department of Neurological Surgery, Vanderbilt University Medical Center, Nashville, TN 37232-9557, USA.
authors.forename: Adam S
authors.initials: AS
authors.lastname: Reig
authors.forename: Charles B
authors.initials: CB
authors.lastname: Stevenson
authors.forename: Noel B
authors.initials: NB
authors.lastname: Tulipan
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D002552:Cerebral Ventricles / Q000601:surgery; D002675:Child, Preschool; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D006849:Hydrocephalus / Q000000981:diagnostic imaging / Q000601:surgery; D007223:Infant; D008297:Male; D008875:Middle Aged; D038361:Neuronavigation / Q000379:methods*; D012189:Retrospective Studies; D014057:Tomography, X-Ray Computed / Q000379:methods*; D017287:Ventriculoperitoneal Shunt / Q000379:methods*; D055815:Young Adult