Objective To evaluate the effectiveness of three-dimensional computed tomography （3D-CT） guided radiofrequency trige- minal rhizotomy （RF-TR） in treatment of idiopathic trigeminal neuralgia （ITN）. Methods From 1999 to 2001

18 patients with ITN were treated with percutaneous controlled RF-TR. Intraoperative 3D-CT scanning was performed to guide the trajectory of the puncture. After correction of the needle tip according to the CT scans and stimulation effects

2 to 5 lesions were made for a duration of 60-90 seconds at a temperature of 60℃ to 75℃ depend- ing on the pain distribution and the age of patient. Results The needles located in foramen ovale. Pain alleviated immediately with no serious complication in all patients. The patients were followed up for an average of 31.5 months （range 24-41 months）. Acute pain relief was experienced by 17 patients after the procedure

reaching an initial success rate of 94.4%. Early （< 6 months） pain recurrence was observed in 2 patients （11.1%）

whereas late （> 6 months） recurrence was reported in 3 patients （16.7%）. Thirteen patients had complete pain control

with no need for medication thereafter. Five cases experienced partial pain relief

but required medication at a lower dose than in the preoperative period. Conclusion 3D-CT foramen ovale locations can raise the successful rate of puncture

enhance the safety

and reduce the incidence rate of complication. H