Forty patients with history of recurrent TN were recruited in Assiut University Hospitals, Pain Unit from 2012 to 2017. Before the study, all patients were given adequate and informative data about the nature of the study, interventional procedure and its possible complications, and a well-informed written consent was obtained from each patients.

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.

Inclusion Criteria:

• • Patient with severe, recurrent TN for more than 6 months, non-satisfactory pain relief with medical treatment or/and intolerable to medical drugs

  • Age more than 18 years old
  • Pain score ≥ 7
  • Patient consent to participate

Exclusion Criteria:

• • Known concurrent neurological or neurodegenerative diseases such as multiple sclerosis, and myasthenia gravis

  • Breast feeding or pregnant women
  • Advanced malignancy or brain stem tumors
  • Coagulopathy or patients on anticoagulant medications
  • Allergy/ sensitivity to Lidocaine anesthetic or/and non- ionic contrast media
  • Presence of Progressive Motor or sensory deficit in the distribution of trigeminal nerve
  • Active psychological or mental diseases
  • Uncontrolled medical or respiratory conditions
  • Patients who are unwilling to participate