gms | German Medical Science

57th Annual Meeting of the German Society of Neurosurgery
Joint Meeting with the Japanese Neurosurgical Society

German Society of Neurosurgery (DGNC)

11 - 14 May, Essen

Accuracy of a neuronavigated flexible endoscope

Genauigkeit eines neuronavigierten flexiblen Endoskops

Meeting Abstract

  • corresponding author P. Tanner - Neurochirurgische Klinik, Ludwig-Maximilians-Universität, München
  • S. Zausinger - Neurochirurgische Klinik, Ludwig-Maximilians-Universität, München
  • T. Heigl - Neurochirurgische Klinik, Ludwig-Maximilians-Universität, München
  • J. Witte - BrainLAB AG, Heimstetten
  • C. Schichor - Neurochirurgische Klinik, Ludwig-Maximilians-Universität, München
  • E. Uhl - Neurochirurgische Klinik, Ludwig-Maximilians-Universität, München

Deutsche Gesellschaft für Neurochirurgie. Japanische Gesellschaft für Neurochirurgie. 57. Jahrestagung der Deutschen Gesellschaft für Neurochirurgie e.V. (DGNC), Joint Meeting mit der Japanischen Gesellschaft für Neurochirurgie. Essen, 11.-14.05.2006. Düsseldorf, Köln: German Medical Science; 2006. DocFR.12.08

The electronic version of this article is the complete one and can be found online at:

Published: May 8, 2006

© 2006 Tanner et al.
This is an Open Access article distributed under the terms of the Creative Commons Attribution License ( You are free: to Share – to copy, distribute and transmit the work, provided the original author and source are credited.



Objective: Neuroendoscopy is an important tool in a variety of neurosurgical procedures. The combination of an endoscope and an image guidance system (IGS) is being used frequently, especially in pathologies with an altered anatomy. Flexible in contrast to rigid endoscopes allow the surgeon to look at different angles without the necessity to move the shaft of the endoscope itself. The goal of our preclinical study was to evaluate the accuracy of the combination of an image guidance system with a flexible endoscope.

Methods: A flexible endoscope (Storz, Neuro Fiberscope) was equipped with a guide wire used by a magnetic field based image guidance system (Kolibri, BrainLAB). The guide wire was introduced into the instrument channel of the endoscope. A plastic skull model was used as test phantom, 12 screws were distributed inside of the skull. The phantom was registered using a pair-point algorithm. The tip of the endoscope was placed on each screw. The distance between the virtual endoscope tip and the screw, which in reality amount to 0 mm, was measured using the IGS system. This accuracy test was performed twice with 0, 45 and 90 degree angle of the endoscope and the mean deviation at each angle was calculated.

Results: At 0 degree angle the mean accuracy was 2.13 (SD 1.06) mm, ranging from 1.00-4.47 mm. After setting the angle to 45 degrees the accuracy did not decrease and remained stable at 1.45 (SD 1.02) mm, with a range of 1.00-3.16mm. The angle of 90 degrees showed an equal accuracy with 1.76 (SD 0.72)mm, range 1.00-3.16 mm.

Conclusions: Our preclinical study shows that the combination of an IGS system with a flexible endoscope is possible with an accuracy comparable to other IGS procedures. Additionally changing the angle of the flexible endoscope does not alter the accuracy thus making it possible to use this device safely in neurosurgical procedures. Our first clinical experiences support the preclinical data. Even with the bent tip of the endoscope the IGS system achieved satisfactory accuracy and the surgeon could benefit from the additional orientational information during these procedures.