Introduction: Methods to achieve highly accurate placement of intracranial devices using frameless methods are needed. In the present study, we evaluate the accuracy of a CT-guided frameless stereotactic drilling and catheter system.

Methods: A prospective, single-arm study was conducted using human cadaver heads to evaluate the placement accuracy of a novel, flexible intracranial catheter using frameless stereotaxy and a stabilizing bone-anchor system and drill kit. A total of 20 catheter placements were included for analysis. The primary endpoint of this study was the accuracy of catheter tip location as assessed by the deviation (mm) of the planned compared to the actual tip position on intra-operative computed tomography (CT). Secondary endpoints included: target registration error (TRE), entry and target point error, both pre-and post-drilling. Measurements are reported as mean SD (median, range).

Results: Based on 20 trajectories, the TRE was 0.46 0.26 (0.50, -1.00-1.00) mm. Two (10%) target point trajectories were negatively impacted by drilling, with variances of 0.6 mm and 0.7 mm, respectively. Intracranial catheter depth was 59.8 9.4 (60.5, 38.0-80.0) mm. Deviation between the planned and the actual entry point on CT was 1.04 0.38 (1.00, 0.40-2.00) mm. Deviation between the planned and actual target point on CT was 1.60 0.98 (1.40, 0.40-4.00) mm. No correlation was observed between the intracranial catheter depth and the target point deviation (accuracy) (Pearson’s coefficient: 0.018), technician experience and accuracy (Pearson’s coefficient: 0.020), or trajectories performed for different cadaver heads (p=0.362).

Conclusions: Highly accurate catheter placement is achievable using this novel system of a flexible catheter and bone-anchor system, placed via frameless stereotaxy, with an average deviation between the planned and actual target point of 1.60 0.98 (1.40, 0.40-4.00) mm. Large, prospective studies, in live human tissue, are needed to confirm the accuracy exhibited in this study.

Patient Care: Our results demonstrate that highly accurate intracranial catheter placement is achievable using the frameless stereotactic neuronavigation and bone-anchor based drilling system described in this study, with an average deviation between the planned and actual target point of 1.60 0.98 (1.40, 0.40-4.00) mm. This CED catheter placement technique and system can allow neurosurgeons to reach their desired target without causing injury to nearby anatomic structures, minimizes operative time spent on repeated attempts, and avoids intraoperative complications.

Learning Objectives: To evaluate the accuracy of intracranial catheter placement using a novel frameless stereotactic drilling and catheter system in human cadaver heads.

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