Comparison of Extended Duration Pulsed Radiofrequency Plus Low Temperature Thermal Radiofrequency With Thermal Radiofrequency Alone in Treatment of Recurrent Trigeminal Neuralgia

All interventions were done in a specialized well-equipped unit at Assiut University hospital and continuous hemodynamic monitoring with pulse oximetry, blood pressure and ECG applied for each patient. Light sedation by using midazolam 5mg bolus. In a supine position with slightly extended head and under fluoroscopic control, C arm rotated caudo-cranially and ipsilateraly to produce an oblique submental view and visualize foramen ovale beside the ramus of the mandible. The point of entry varied according to the affected branch, but it ranged from 0.5-1.5 cm from the corner of the mouth. The point of entry cleaned by aseptic solution and anaesthetized with 1% of Lidocaine. C arm has been rotated laterally to confirm the depth of penetration once the needle entered into Meckel's cavity. RF electrode (22-G, 10 cm needle, with a curved 5 mm active tip, Neurotherm 1100) was used and the exact position of the needle confirmed by sensory stimulation, motor stimulation and negative aspiration as the following criteria:-

1. Sensory stimulation (50 Hz) threshold between 0.1-0.3 V which made paresthesia and/ or tingling in the affected painful area. Patient was awake to respond to the sensory stimulation
2. Motor stimulation at 2Hz with 0.1-1.5V caused muscle contraction of the lower mandible.

After confirming the position of the RF electrode, each patient received 0.5 ml of 1% of Lidocaine to avoid discomfort during treatment. Then the type of intervention determined by the person who was responsible for randomisation process and who did not involve in assessing eligibility or interventional technique and divided into:-

• Group A: pulsed radiofrequency was applied for 4 cycles of 120 seconds ( 8 minutes in total) at 45 V and temperature was set at 42 C. then conventional radiofrequency thermal lesion was applied for 3 cycles of 90 seconds at 60 c.
• Group B: thermal energy was applied gradually for 3 cycles of 90 seconds at 70 C.