Abstract: To investigate the efficacy and safety of radiofrequency temperature-controlled thermocoagulation of the semilunar ganglion under quadruple localization in the treatment of primary trigeminal neuralgia. Methods: 29 patients were accurately localized by symptoms and signs, anatomy, X-ray and electrical stimulation, and then under general anesthesia with isoproterenol, radiofrequency temperature-controlled thermocoagulation was performed, with the temperature set to 70oC, 80oC and 85oC three times, and the duration of each time was 60 s. Results: 29 patients had a 100% success rate of puncture, 100% disappearance rate of pain immediately after surgery, and no 1 case of recurrence from 1 to 5 months of follow-up. No recurrence; 1 case of complication of keratitis, complication rate of 3.4%. Conclusion: The treatment of primary trigeminal neuralgia by radiofrequency temperature-controlled thermocoagulation of the semilunar ganglion under general anesthesia with isoproterenol is safe, accurate, effective, and easy to be popularized. I. Data and methods (I) General data: There were 29 patients in this group, including 17 males and 12 females. The age ranged from 32 to 71 years old, with an average of 57.1 years old. There were 22 cases on the right side and 7 cases on the left side. There were 5 cases of branch II pain, 3 cases of branch III pain, 19 cases of branch II+III pain, and 2 cases of branch I+II+III pain, with the duration of disease ranging from 6 months to 23 years, with an average of 5 years and 2 months. One of the patients had undergone radiofrequency of the semilunar ganglion twice, and the other patient had undergone trigeminal sensory posterior rhizotomy. (B) Methods: All patients were first treated with medication, nerve branch block or radiofrequency, and then radiofrequency temperature-controlled thermocoagulation of the semilunar ganglion was performed when the pain could not be effectively controlled by the above treatments. A 9600 C-arm X-ray machine from GE, USA, was used to localize the foramen ovale, and a LNG30-1 radiofrequency instrument from ELEKA, Sweden, was used for treatment. The operation steps of radiofrequency temperature-controlled thermocoagulation of the semilunar ganglion by quadruple localization method: (1) Quadruple localization: ①Symptoms and signs localization: pain and trigger point located above the eye fissure is trigeminal nerve branch Ⅰ pain, located between the eye fissure and the mouth fissure is branch Ⅱ pain, located below the mouth fissure is branch Ⅲ pain. ②Anatomical localization: the puncture point and the puncture direction were both localized by Song’s modified anterior approach [1] (see Figure 1). ③X-ray localization: a. Oval foramen localization with a C-arm X-ray machine (generally, the affected oval foramen can be clearly revealed by rotating the X-ray generator about 30o toward the cephalic end and about 20o toward the healthy side) (see Figure 2); b. Puncture: sterilization, sheeting, and puncture under orthogonal X-ray fluoroscopy; if the localization and orientation are accurate and the operation is skilled, the hole can often be directly entered, and there is a sense of falling and the tip of the needle being sucked when puncturing the oval foramen, At the same time, the patient has severe electric shock-like pain in the corresponding area of the face (see Figure 3). c. The depth of the puncture needle is adjusted by lateral X-ray fluoroscopy, and the front end of the needle tip does not pass through the skull base plate in patients with branch III trigeminal neuralgia, that is, the needle tip does not enter the skull; the front end of the needle tip passes through the skull base plate and enters the skull 0.5-1 cm in patients with branches I and II trigeminal neuralgia (see Figure 4). If the needle tip is correctly positioned, pain should appear at the lesion site; then the motor nerve should be stimulated with low-frequency current, and if the needle tip is correctly positioned, soreness, numbness and swelling should appear at the lesion site for trigeminal neuralgia of branches Ⅰ and Ⅱ, and occlusal muscle spasm should appear for trigeminal neuralgia of branch Ⅲ. (2) Anesthesia: intravenous push of isoproterenol (1.5-2mg/kg) to make the patient lose consciousness and then start RF destruction. (3) Temperature-controlled thermocoagulation: radiofrequency destruction, the temperature was set to 70oC, 80oC and 85oC for three times, and the duration was 60s. After the patient’s consciousness was restored, the facial skin and tongue tip were needled to test the nociceptive and tactile changes in the innervated area of the lesion until the nociceptive sensation disappeared and the tactile sensation was dulled; if the nociceptive sensation still existed, the puncture needle position was adjusted and then radiofrequency thermocoagulation was performed as appropriate. II. Results (1) Efficacy: In this group of 29 patients, radiofrequency temperature-controlled thermocoagulation of the semilunar ganglion was performed after quadruple localization, and all of them were successfully punctured, with a 100% puncture success rate, and the puncture time ranged from 5 to 23 min, with an average of 1 min; the pain disappeared completely after the operation, with an immediate postoperative pain disappearance rate of 100%, and no recurrence from 1 to 5 months of follow-up. (2) Complications: 1 case of keratitis, for patients with trigeminal neuralgia combined with branch I. The incidence rate was 3.4%, which returned to normal after 6 days of symptomatic treatment. III. Discussion Radiofrequency temperature-controlled thermocoagulation of the semilunar ganglion as the main method for the treatment of primary trigeminal neuralgia can be divided into blind exploration method, X-ray localization method, CT localization method and open magnetic resonance localization method. We believe that the blind exploration method is more blind and easy to damage the structures around the foramen ovale; the simple X-ray localization method has better safety and efficacy than the blind exploration method; and the CT and open MRI localization methods are costly and difficult to be widely used. The success rate of puncture, immediate postoperative pain disappearance rate and recurrence rate were all better than those of blind exploration, X-ray localization, CT localization and open MRI localization; the complication rate was lower than those of blind exploration, X-ray localization and CT localization, and higher than those of open MRI localization. There are two traditional anesthesia methods for radiofrequency temperature-controlled thermocoagulation of the semilunar ganglion: one is to inject local anesthetic after the puncture is in place; the other is to take the method of gradually increasing the radiofrequency temperature from low to high without injecting local anesthetic after the puncture is in place. The disadvantages of the former are: (1) the possibility of local anesthetic accidentally entering the cerebrospinal fluid and blood; (2) the inaccuracy of locating the branch of trigeminal neuralgia by local anesthetic test; (3) when it is necessary to adjust the position of the puncture needle, it is necessary to wait until the effect of the first local anesthetic wears off, making the operation time longer. The disadvantage of the latter is that patients suffer a lot of pain, especially for patients with combined hypertension and coronary artery disease, who are more prone to cardiovascular accidents. Keratitis is a common complication of radiofrequency temperature-controlled thermocoagulation of the semilunar ganglion and is caused by damage to the Ⅰ branch of the trigeminal nerve, resulting in decreased or absent corneal reflexes and decreased resistance. Prevention is the key, and for the treatment of branch II and/or III trigeminal neuralgia, the key is to carefully perform various localization checks before radiofrequency, and the location of the puncture needle should not be too deep; while for branch I trigeminal neuralgia, medication and supraorbital nerve block or radiofrequency are feasible, and deep radiofrequency of the semilunar ganglion should be performed carefully. In case of keratitis, symptomatic treatment is available. In conclusion, we believe that the treatment of primary trigeminal neuralgia by radiofrequency temperature-controlled thermocoagulation of the semilunar ganglion under general anesthesia with isoproterenol is safe, accurate, effective, and easy to be popularized.