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The Silent Loss of Neuronavigation Accuracy: A Systematic Retrospective Analysis of Factors Influencing the Mismatch of Frameless Stereotactic Systems in Cranial Neurosurgery

Stieglitz, Lennart Henning MD; Fichtner, Jens MD; Andres, Robert MD; Schucht, Philippe MD; Krähenbühl, Ann-Kathrin MD; Raabe, Andreas MD; Beck, Jürgen MD

doi: 10.1227/NEU.0b013e318287072d
Research-Human-Clinical Studies

BACKGROUND: Neuronavigation has become an intrinsic part of preoperative surgical planning and surgical procedures. However, many surgeons have the impression that accuracy decreases during surgery.

OBJECTIVE: To quantify the decrease of neuronavigation accuracy and identify possible origins, we performed a retrospective quality-control study.

METHODS: Between April and July 2011, a neuronavigation system was used in conjunction with a specially prepared head holder in 55 consecutive patients. Two different neuronavigation systems were investigated separately. Coregistration was performed with laser-surface matching, paired-point matching using skin fiducials, anatomic landmarks, or bone screws. The initial target registration error (TRE1) was measured using the nasion as the anatomic landmark. Then, after draping and during surgery, the accuracy was checked at predefined procedural landmark steps (Mayfield measurement point and bone measurement point), and deviations were recorded.

RESULTS: After initial coregistration, the mean (SD) TRE1 was 2.9 (3.3) mm. The TRE1 was significantly dependent on patient positioning, lesion localization, type of neuroimaging, and coregistration method. The following procedures decreased neuronavigation accuracy: attachment of surgical drapes (DTRE2 = 2.7 [1.7] mm), skin retractor attachment (DTRE3 = 1.2 [1.0] mm), craniotomy (DTRE3 = 1.0 [1.4] mm), and Halo ring installation (DTRE3 = 0.5 [0.5] mm). Surgery duration was a significant factor also; the overall DTRE was 1.3 [1.5] mm after 30 minutes and increased to 4.4 [1.8] mm after 5.5 hours of surgery.

CONCLUSION: After registration, there is an ongoing loss of neuronavigation accuracy. The major factors were draping, attachment of skin retractors, and duration of surgery. Surgeons should be aware of this silent loss of accuracy when using neuronavigation.

ABBREVIATIONS: BMP, bone measurement point


MMP, Mayfield measuring point

TRE, target registration error

TRE1, initial target registration error

TRE2, target registration error at the Mayfield measurement point

TRE3, target registration error at bone measurement point

Department of Neurosurgery, Bern University Hospital, Bern, Switzerland

Correspondence: Lennart Henning Stieglitz, MD, Department of Neurosurgery, Bern University Hospital, 10 Freiburgstrasse, 3010 Bern, Switzerland. E-mail:

Received October 16, 2012

Accepted December 25, 2012

Copyright © by the Congress of Neurological Surgeons