Optimizing Percutaneous Rhizotomy for Trigeminal Neuralgia Through Reverse Cannulation of Donor Bodies

Introduction: Percutaneous rhizotomy with balloon compression, chemodenervation, or radiofrequency ablation is an efficacious treatment for medically refractory trigeminal neuralgia in patients with significant medical comorbidities. While generally associated with low mortality rates, the proximity of the foramen ovale to critical neurovascular structures causes percutaneous approaches to carry substantial risks. The aim of this study was to utilize “reverse” cannulation on donor bodies to identify best-trajectories for needle insertion.

Methods: 114 donor bodies (228 sides) were included in this study. A cannula was guided through trajectories from the foramen ovale (FO) and porus trigeminus (PT) to the skin to determine best entry points for percutaneous rhizotomy. These trajectories included central FO and central PT, lateral FO and medial PT, and medial FO and lateral PT. The skin entry points were described by utilizing digital calipers to measure the distance from the angle of the mouth, as well as depth to the target of interest. Geometric morphometric analysis, including principal component analysis, was subsequently applied to analyze the data.

Results: Approach through the medial FO to lateral PT was most successful (79.4%), followed by central FO to central PT (61.0%), and lateral FO to medial PT (11.4%). Mean lateral distance from the angle of the mouth, independent of target, was 19.9 mm in females and 20.9 mm in males, with a mean superior-inferior distance of 0 mm in both sexes. Mean depth to FO was 76.7 mm in females and 79.9 mm in males (p = 0.0284). Mean depth was 79.6 mm to the left FO and 77.2 mm to the right FO (p = 0.0024).

Conclusion : These findings can be utilized to guide surgical decision-making during percutaneous rhizotomy to reduce the risk of miscannulation and adverse outcomes.