gms | German Medical Science

Objective: While intraoperative neuronavigation is believed to be highly precise for supratentorial approaches, its accuracy in the posterior fossa, where neuronavigation could be of advantage in special cases, is thought to be less. The aim of the present study was therefore to assess the accuracy of neuronavigation in the posterior fossa.

Method: A navigation plan with 8 supratentorial and 3 infratentorial vascular target points was prepared using CTA data sets of SAH patients. After non-invasive registration of the head, a 2MHz Doppler probe (DWL) was tracked by a Kolibri image-guidance device (Brainlab AG). The probe was directed to the pre-defined target points using the IG device. Then the probe was moved to the point of the optimal Doppler signal where a new trajectory was acquired. This new trajectory was used as reference in all subsequent examinations. The distance between reference point and point of optimal Doppler signal was calculated to quantify the accuracy of IG.

Results: 50 examinations were performed in 10 patients yielding 315 supratentorial and 120 infratentorial trajectories. The mean deviation of the supratentorial trajectories was significantly lower compared to the posterior fossa (3.3 ± 1.7 mm vs. 5.4 ± 2.8 mm). For the vertebral arteries the deviation was significantly lower compared to the basilar artery (4.6 ± 1.9 mm vs. 6.9 ± 3.5 mm).

Conclusions: Neuronavigation provides a higher accuracy for supratentorial targets than for infratentorial target points. For deep infratentorial vessels, the inaccuracy of navigation increases.