Unconventional Facial Entry Points Confirmed Using a 3D CT Reconstruction-Guided Stereotactic Approach to Radiofrequency Thermocoagulation for the Treatment of Trigeminal Neuralgia: A Series of Case Reports.

Abstract

Patients with trigeminal neuralgia who are refractory to medical therapy may choose to undergo Gasserian ganglion percutaneous radiofrequency thermocoagulation. However, in cases where the foramen ovale is difficult to access due to various anatomical anomalies, the typical estimation of the facial entry point is suboptimal. Three-dimensional computed tomography reconstruction imaging performed before surgery revealed anatomical variations in each of the four adult patient cases that made it more difficult to successfully access the foramen ovale (FO) for percutaneous radiofrequency thermocoagulation. Using measurements collected from preoperative imaging that showed each specific anatomical variation in the FO, researchers marked alternate facial entry points that would allow successful probe placement into the FO and recorded the arc angle data in the stereotactic instrument. Patients were evaluated during follow-up visits ranging from seven to 26 months after surgery and asked to rate postoperative pain using a visual analog scale. These scores decreased from 10 to 3 in all four patients by the third day after the procedure. There were no permanent complications or morbidities from the surgery. One patient experienced mild facial numbness; however, this side effect subsided within three months after surgery. During the follow-up period, no patient reported pain recurrence. The expectation for clinicians approaching trigeminal nerve block using a peri-oral approach should be to expect a great degree of potential variability in terms of both distances from the corner of the mouth and needle angle taken to successfully navigate the anatomy and access the foramen ovale.