title: Frameless neuronavigation applied to endoscopic neurosurgery.
abstract: OBJECTIVE
  We retrospectively analyzed the indications, surgical techniques, and applicability of frameless neuronavigation to endoscopic procedures in a heterogeneous group of 15 patients.
  
  
  METHODS
  In 8 patients indications for surgery were cystic lesions, in 3 patients intraventricular tumors, and in 4 patients occlusive hydrocephalus. The mean age was 39 years (range 9-76 years). The follow-up period ranged from 5-24 months (mean 10 months). Frameless neuronavigation was accomplished with the "operating arm system" in 10 cases and with the "optical tracking system" in 5 cases (RADIONICS, Burlington, USA).
  
  
  RESULTS
  In all 15 cases, neuronavigation sufficiently provided anatomical orientation, preoperative planning, and intraoperative realization of the approach. The calculated mean calibration error was 2.1 mm. There have been no permanent morbidities and no mortalities related to the use of endoscopes and neuronavigation.
  
  
  CONCLUSIONS
  In endoscopic neurosurgery, frameless neuronavigation is a useful tool in planning and realizing the approach and improving intraoperative orientation in selected cases. Indications are small or hidden lesions, impaired visual conditions, abnormal anatomy, and narrow ventricles. Endoscopic procedures include fenestration and resection of intraventricular or intraparenchymal cysts, biopsy of intraventricular tumors, and third ventriculostomy in selected cases.
authors.affiliation: Department of Neurosurgery, Johannes Gutenberg-University, Mainz, Germany. hopf@nc.klinik.uni-mainz.de
authors.forename: N J
authors.initials: NJ
authors.lastname: Hopf
authors.forename: P
authors.initials: P
authors.lastname: Grunert
authors.forename: K
authors.initials: K
authors.lastname: Darabi
authors.forename: C
authors.initials: C
authors.lastname: Busert
authors.forename: M
authors.initials: M
authors.lastname: Bettag
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D001927:Brain Diseases / Q000601:surgery*; D002648:Child; D019723:Endoscopes; D004724:Endoscopy / Q000379:methods*; D004867:Equipment Design; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D019635:Neurosurgical Procedures / Q000295:instrumentation / Q000379:methods*; D012189:Retrospective Studies