ObjectiveThe aim of this study was to investigate the severity and the natural course of masticatory muscles weakness that developed after CT-guided percutaneous trigeminal radiofrequency thermocoagulation (PT-RFT) for the treatment of idiopathic trigeminal neuralgia (ITN). MethodsTwenty-seven patients with ITN were treated by CT-guided percutaneous trigeminal radiofrequency thermocoagulation. Each patients' occlusal function and surface electromyographic (sEMG) activity of the ipsilateral anterior temporalis (TA) and masseter muscles (MM) at mandibular postural position (MPP), and during a fast maximum voluntary clenching (MVC) from MPP to intercuspal position (ICP), were simultaneously recorded by the T-Scan III system and Bio-pak sEMG III system before (baseline), 3days, 3months, and 12months after procedure. The incidence, degree, and prognosis of masticatory muscles dysfunction related to trigeminal nerve motor-branch injury were analyzed. ResultsThree days and 3months after procedure, both the occlusal symmetry and the sEMG activity of ipsilateral TA and MM became significantly decreased compared to the baseline (P<0.05). However, they demonstrated a gradual improvement toward preoperative values in follow-up, returning to complete in 23 patients at 12months after procedure. None reported permanent masticatory paralysis. Pain relief was most significant on the third day after procedure. At the final clinical visit, a pain-free status was observed in 25 patients (92.6%). Meanwhile, the intensity of facial dysesthesia was mildest, whereas there were statistic differences compared with baseline. ConclusionCT-guided PT-RFT for ITN remains an effective and safe surgical procedure, but there is a high rate of temporary masticatory dysfunction during a short time after procedure, appearing to be reversible in a period of 12months.