Application of curved needling technique in the treatment of trigeminal neuralgia by radiofrequency ablation through foramen rotundum with inward opening

Abstract

Objective To observe the application effect of radiofrequency puncture needle with individualized and on-demand plastic curved needle technique in the treatment of second-branch trigeminal neuralgia by radiofrequency ablation through foramen rotundum with inward opening. Methods From November 2012 to May 2018, a total of 263 cases of second-branch trigeminal neuralgia were admitted to Department of Anesthesiology, the First Hospital of Jiaxing and underwent foramen rotundum puncture for radiofrequency ablation. All those cases were enrolled into this retrospective analysis. The paranasal sinus model of CT was used to scan the pterygoid fossa with a thickness of 3 mm, and the CT images, including the midpoint of the foramen rotundum tube, the internal and external hole, were selected and the puncture path was designed. The length of the line (puncture depth) and the angle between the straight line and the sagittal plane (the angle of puncture) were measured by using the ruler tool of CT software from the external hole of the foramen rotundum along the lateral wall of the maxillary sinus to the surface of the skin (puncturing point). If the external hole of foramen rotundum demonstrated an inward opening, the angle between the line and the direction of the foramen rotundum tube(the angle of the needle needed to bend) should be measured. The radiofrequency needle was inserted 5 mm into the self-made needle-bender, the corresponding bending angle was pulled out slightly to the side of the needle at the tip of the needle, and the individual radiofrequency needle for the patient was made. Then, puncturing under the guidance of CT followed by designed trajectory. The arc of the needle was turned to the top of the front when the needle reached the external hole of the foramen rotundum. Whereafter, the arc of the needle was turned to the bottom when the needle crossed the external hole. Subsequently, the needle was pushed into the foramen rotundum. Then, electrophysiological test was conducted for radiofrequency treatment. Results Of 263 patients undergoing radiofrequency ablation of the second branch of trigeminal nerve, 71 (27.0%) had an inward opening of the external hole of foramen rotundum, which needed the patient's individually designed radiofrequency puncture needle. The average bending angle was 21.3 °±3.6 °(14°-31 °). When using the individual puncture needle, the needle tip could always reach the puncture target. Using 0.1-0.5 mA current could induce obvious muscle tremor or numbness in the region innervated by the second branch of trigeminal nerve in electrophysiological test. Following radiofrequency ablation, the second-branch trigeminal neuralgia disappeared completely. Ipsilateral palate muscosal numbness and the skin numbness involving the side of the nose, upper lip and zygomatic facial region were reported. None of the patients developed numbness involving the first or third branch of trigeminal nerve. A total of 242 patients were followed up for an average of 3.2±0.6 years. The total recurrence rates at 6 months, 1 year, 2 years, 3 years and 4 years were 2.5% (6/242), 7.9% (19/242), 16.1% (39/242), 24.4% (59/242) and 33.9% (82/242), respectively. Conclusions CT-guided individually made curved needle technology allows the radiofrequency needle tip to bypass the sphenoid bone which obstructs the outer opening of foramen rotundum and enter the middle of foramen rotundum tube with inward opening, so as to improve the radiofrequency effect and reduce the recurrence rate. Key words: Trigeminal neuralgia; Radiofrequency coagulation; Foramen rotundum; Treatment effect