Percutaneous Radiofrequency Thermocogulation Via Foramen Ovale For Recurrent Trigeminal Neuralgia Under Digital Subtraction Angiography

[Background]Trigeminal neuralgia(TN) is a refractory facial pain,it happens frequently, mostly occurs in the the elderly.The clinical features of the disease are described as paroxysmal"sharp","electrical-like,""stabbing","lancinating","bolts"pain confined to the somatosensory distribution of the trigeminal nerve,which last from seconds to minutes.The patients suffer from this disease,and severe pain usually affects the patient's physical and mental health.Drug treatment for trigeminal neuralgia is mostly used for mild pain and the early stage.There should be other methods to manage pain when the patients developed poor response to oral drugs or experienced untoward side effects.For those patients,radiofrequency thermocogulation,microvascular decompression,percutaneous balloon microcompression,glycerol rhizolysis,gamma knife radiosurgery are commonly used.They are effective recently((＜6 mon),the effective power is from 91- 99 percent,and the long-term recurrent rate is 10-25 percent.The recurrent cases appear mostly in 2-3y after the treatment.Histopathological studies showed that not only A Delta and C fibers were affected by radiofrequency thermocoagulation,but other fibers as well.A Delta and C fibers are more sensitive to heat inflicted lesions.The thermocontrolled radiofrequency trigeminal rhizotomy can be successfully on the treatment for idiopathic trigeminal neuralgia according to the international publishes,whereas there is no research about recurrent trigeminal neuralgia in our country.Moreover,according to recent study,the shapes of Chinese foramen ovale are different individually,and there are significantly difference in long diameter between male and female.So DSA-guided percutaneous radiofrequency thermocoagulation for recurrent trigeminal neuralgia was performed to evaluate the effect and safety.[Objective]In this study,we have performed percutaneous radiofrequency thermocoagulation for recurrent trigeminal neuralgia under digital subtraction angiography,and evaluate its therapeutic effect and safety in patients with recurrent trigeminal neuralgia,give the patients an effective and safe treatment option.[Materials and Methods]Thirty eight patients who suffered from uncontrolled,incapacitating recurrent trigeminal neuralgia were enrolled in this study.In this study,carbamazepine was the principal medication used for medical therapy before percutaneous radiofrequency thermocoagulation treatment.The medication was not tolerated or did not suppress the pain.All patients were checked in order to evacuate them with contraindication and were given information on the procedures and its possible complications,and written informed consent was obtained.Then they did not get the analgesic on the treatment day and were sent to interventional therapy center.The patient was placed in the supine position and keep head normotopia.Blood pressure recordings of patients were made at 5-minute intervals;we routinely and continuously assessed blood oxygen saturation and cardiac function.The venous channel was kept unblocked,and the oxygen was given through their noses.The operator and assistants put on the clothes of radiation protection.At the beginning of the procedure,x-rays of the patient in the submentovertical position provided information that allowed us to place the needle around the foramen ovale;the needle was then inserted through the foramen.Lateral x-rays were obtained to ensure that the tip of the needle did not reach beyond the petroclival junction.We deployed a combined method to locate the foramen ovale, which was Hartel's anterior approach and dynamic radioactive ray.The line between picking point and foramen ovale could direct the puncture.The radiofrequency equipment(Elekta Leksell LNG30-1) and the matched puncture needle with 5 mm exposed tip were used.At the beginning of the procedure,x-rays of the patient in the submentovertical position provided information that allowed us to place the needle around the foramen ovale;the needle was then inserted through the foramen when patients felt intractable pain or we had a feeling of coming nothing.Lateral x-rays were obtained to ensure that the tip of the needle did not reach beyond the petroclival junction.The desired target area was assured by precise localization via stimulation process.We confirmed localization within the nerve by electrical stimulation at 0.5 to 1mA(100 Hz),if the patient felt the same area painful as before,the needlepoint should be right position.Then another electrical stimulation at 1 to 2mA(3-10Hz) were performed to identify the nerve type.When the needle was inserted over 7.5 cm,it should be withdraw and we would repeat for the precise localization of destructive target.After correction of the needle tip according to the stimulation effect,three lesion units were made for a duration of 270 seconds at a temperature 60-75℃.One unit last 90 seconds.Intravenous slow injection of fentanyl and midazolam usually brought about the desired level of analgesia and sedation throughout the procedure.The ciliary reflex (masseter function) and sensory distribution affected facial areas after stimulation were cautiously monitored after radiofrequency thermocogulation.The procedure was completed if adequate hypalgesia was achieved in the targeted branch and if pain could not be triggered as it had been preoperatively.VAS and side effects were evaluated at four time points as the moment of postoperative,1 mon,2 mon,3 mon after the procedure. Any complications could be treated carefully.[Results]1.The treatment of pain was significantly satisfied in 31 patients,moderate in 6,while no effect in 1.2.After the procedure,the average VAS score was significantly lower(P＜0.01).The median of VAS score was 9.00,inter-quartile range was 1.05 before treatment;The median of VAS score was 0,and the inter-quartile range was 0,0,1.30,2.80 at the moment of postoperative,1 mon,2mon,3 mon after the procedure.3.After undergoing the procedure,face haematoma was observed in 4 patients(10.5%), and relieved by corresponding treatment in 7 days.Hypesthesia was observed in 28 patients(73.9%).Keratitis as a result of corneal anesthesia were the most important complications,and was observed in 1 patient(2.6%),ophthalmological treatment could manage the symptom.Masseter dysfunction was observed in 5 patients (13.2%),and they felt better after one months.[Conclusion]Percutaneous radiofrequency thermocogulation via foramen ovale for recurrent trigeminal neuralgia under digital subtraction angiography is an effective,safe and minimally invasive procedure that can be performed according to the objective localization of foramen ovale.This procedure was easier to be performed than conventional neurosurgical operation.However,there was no effect in one patient with this procedure,which needs make more effort to explore the pathogenesis and optimal treatment for recurrent trigeminal neuralgia.