title: Image-guided endoscopic ventriculostomy with a new frameless armless neuronavigation system.
abstract: OBJECTIVE
  Complications resulting from imprecise placement of the ventriculoscope and reduced visibility through the endoscopic lens under certain conditions during third ventriculostomy have been reported in the literature. The following is a report of our first experience with image-guided endoscopic ventriculostomy.
  
  
  METHODS
  Between September 1996 and October 1997, 11 patients diagnosed with aqueduct stenosis were found to be eligible for image-guided neuroendoscopy. The image-guided system (BrainLab, Heimstetten, Germany) links a freehand probe, tracked by a passive-marker sensor system, to a virtual computer image space. A 4-mm rigid ventriculoscope (Storz Instruments GMBH, Tuttlingen, Germany) was used.
  
  
  RESULTS
  Eight patients improved clinically directly after surgery, two patients stabilized, and one patient improved only after insertion of an additional ventriculo-peritoneal shunt. The computer- calculated registration accuracy ranged from 1. 1 to 3.1 mm (median 1.4 mm) using 3-mm computed tomographic slices. The accuracy of the tool tip calibration for the endoscope was in the range of 0.35-0.9 mm (mean = 0.47 +/- 0.21). The described technique provided maximal flexibility for the surgeon and helped in performing a safe and accurate endoscopical procedure.
  
  
  CONCLUSIONS
  Although not all cases of ventriculostomy require additional image guidance, we found the technique to be helpful in patients with atypical or large ventricles, in cases where orientation became difficult owing to bloody or blurry cerebrospinal fluid, and in patients with small foramina of Monroe, where the entrance angle of the endoscope needs precise definition for an atraumatic procedure to be performed.
authors.affiliation: Department of Neurosurgery, Klinikum Grosshadern, Ludwig-Maximilians-University, Munich, Germany. alexander.muacevic@nc.med.uni-muenchen.de
authors.forename: A
authors.initials: A
authors.lastname: Muacevic
authors.forename: A
authors.initials: A
authors.lastname: Müller
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D002138:Calibration; D002535:Cerebral Aqueduct / Q000000981:diagnostic imaging / Q000473:pathology; D002648:Child; D003251:Constriction, Pathologic / Q000000981:diagnostic imaging / Q000601:surgery; D019723:Endoscopes; D004724:Endoscopy / Q000379:methods*; D004867:Equipment Design; D005260:Female; D006801:Humans; D006849:Hydrocephalus / Q000601:surgery; D007091:Image Processing, Computer-Assisted; D008297:Male; D008875:Middle Aged; D012449:Safety; D013238:Stereotaxic Techniques / Q000295:instrumentation; D013813:Therapy, Computer-Assisted; D014057:Tomography, X-Ray Computed; D014584:User-Computer Interface; D017287:Ventriculoperitoneal Shunt; D014696:Ventriculostomy / Q000295:instrumentation / Q000379:methods*