Evaluating the Sensory Index for Success of Trigeminal RF
Condition: Radiotherapy; Complications
Study type: Interventional

Summary: 
      Trigeminal neuralgia (TN) is defined by the International Headache Society (IHS) as
      "unilateral disorder characterized by brief electric shock-like pains, abrupt in onset and
      termination, and limited to the distribution of one or more divisions of the trigeminal
      nerve". It is considered the worst type of facial pain and described as intense, sharp,
      stabbing, and shooting like electric shock pain. It can be triggered by touch, chewing,
      laughing, shaving or face wash. Interventional therapies for TN are of variable efficacy and
      safety, and have different results for different periods of time before the recurrence of
      symptoms. Interventional therapy for TN is either destructive with trigeminal nerve sensory
      function destroyed intentionally or non-destructive with decompression of the trigeminal
      nerve and preservation of its regular function. The most common procedures in treating TN
      pain are the use of radiofrequency (RF).Combined conventional and pulsed radiofrequency
      (CCPRF) achieved comparable pain relief to PRF treatment alone in patients with chronic pain,
      the combination of PRF and CRF would increase the effect of CRF and reduce the need for
      long-duration CRF (LCRF) and its attendant side effects .
    

Detailed description: 
      Trigeminal neuralgia (TN) is defined by the International Headache Society (IHS) as
      "unilateral disorder characterized by brief electric shock-like pains, abrupt in onset and
      termination, and limited to the distribution of one or more divisions of the trigeminal
      nerve" . It is considered the worst type of facial pain and described as intense, sharp,
      stabbing, and shooting like electric shock pain. It can be triggered by touch, chewing,
      laughing, shaving or face wash.

      The IHS suggests a classification of TN as either classic (essential or idiopathic) TN (CTN)
      or symptomatic TN (STN; pain indistinguishable from that of CTN, but caused by a demonstrable
      structural lesion other than vascular compression).

      Treatment of TN is conservative, surgical or interventional. Pharmacotherapy with
      carbamazepine is tried early in cases of TN but has many side effects .Other medications can
      be used in the treatment of TN, include oxycarbazepine, gabapentin, pregabalin, baclofen,
      valproate, clonazepam, phenytoin, and lamotrigime .

      The most clinically appropriate treatment includes surgical microvascular decompression
      (MVD), stereotactic radiation therapy, gamma knife (SGK), percutaneous balloon decompression,
      percutaneous glycerol rhizolysis, percutaneous radiofrequency (RF) of the Gasserian ganglion
      (GG), and GG stimulation and neuromodulation .

      Interventional therapies for TN are of variable efficacy and safety, and have different
      results for different periods of time before the recurrence of symptoms. Interventional
      therapy for TN is either destructive with trigeminal nerve sensory function destroyed
      intentionally or non-destructive with decompression of the trigeminalnerve and preservation
      of its regular function. The most common procedures in treating TN pain are the use of
      radiofrequency (RF) .

      Radiofrequency thermos-coagulation of the GG is thought to selectively destroy the pain
      fibers by thermos-coagulation at > 65°C , that helps reduce pain and prevent triggering, but
      can cause bothersome dysesthesia .

      Another method, pulsed radiofrequency (PRF) which defined as the delivery of short pulses of
      RF via a needle tip, thereby a short exposure at the same temperature will result in less
      thermal tissue destruction .

      Combined conventional and pulsed radiofrequency (CCPRF) achieved comparable pain relief to
      PRF treatment alone in patients with chronic pain, the combination of PRF and CRF would
      increase the effect of CRF and reduce the need for long-duration CRF (LCRF) and its attendant
      side effects .
    

Intervention name(s): combined conventional and pulsed RF
Intervention type(s): Procedure
Intervention description(s): the classic Hartle technique is used to reach the Gasserian ganglion
Sensory stimulation with the RF equipment is conducted and parathesia of the affected branch is achieved at 0.1-0.2 V (50 Hz), keeping in mind that the mandibular part of the Gasserian ganglion is ventrolateral and the ophthalmic rootlets are postrolateral. Motor pre-stimulation (2 Hz) is achieved with masseter contraction at 0.1-0.3 V .
After sensory and motor stimulation, RF therapy is conducted by use of the RF generator , in the sequence:
Conventional RF 1st lesion at 60 °C for 60 s then 2nd lesion at 65°C for 60 seconds then 3rd lesion at 70°C for 60 seconds
Finally, PRF is applied for 360 second repeated at 45 V, with a pulse width of 10 ms and a pulse frequency of 4 Hz. The cut-off needle tip temperature is set at 42 °C.
Before withdrawal of needle 1 cc xylocaine 1% + 0.5 cc dexamethasone 4mg to be given
Intervention model: Single Group Assignment
Masking: None (Open Label)
Primary purpose: Treatment