Combined Application of Pulsed RF and Steroids to the DRG for PHN
Condition: Postherpetic Neuralgia; Chronic Pain
MeSH terms: Neuralgia; Neuralgia, Postherpetic; Chronic Pain
Study type: Interventional

Summary: 
      Recently, the use of pulsed radiofrequency has increased in many chronic pain conditions,
      including trigeminal neuralgia, chronic spinal pain, musculoskeletal pain, and it was
      recently used effectively for postherpetic neuralgia. Transforaminal epidural steroid
      injection has been proven in previous studies to provide effective analgesia for cases of
      herpes zoster-related pain. We hypothesize that the combined use of pulsed RF and steroid
      injection applied to the DRG may achieve better outcomes than the use of epidural steroid
      injection alone.
    

Detailed description: 
      Varicella-zoster virus reactivates in sensory ganglia as the dorsal root ganglion (DRG). The
      DRG contains many receptor channels and is an important region for pain signal transduction.
      Sustained abnormal electrical activity to the spinal cord via the DRG in acute herpes zoster
      can result in neuropathic conditions such as postherpetic neuralgia (PHN). Postherpetic
      neuralgia (PHN) is the final stage of varicella-zoster infection and is manifested as severe
      refractory neuropathic pain. Preventing the transition of herpes zoster-related pain to PHN
      is a very important therapeutic principle for patients at an early stage, especially for
      older patients. The exact discriminative time point for PHN has not yet been standardized.
      Various criteria have been used, from 30 days to 180 days after zoster onset. If pain
      persists for more than 180 days after zoster onset, the likelihood of pain reduction is very
      low and such a condition is considered "well established" PHN. Therefore, it is advisable to
      actively attempt various treatment modalities for pain control before the condition
      progresses to a recalcitrant state. Pulsed radiofrequency (PRF) is a variant of thermal
      radiofrequency that applies pulsed current to limit heat generation to less than 42˚C,
      creating a little risk of thermal or nerve injury. Recently, the use of PRF has increased in
      many chronic pain conditions, including trigeminal neuralgia, chronic spinal pain,
      musculoskeletal pain, and it was recently used effectively for postherpetic neuralgia.
      Transforaminal epidural steroid injection has been proven in previous studies to provide
      effective analgesia for cases of herpes zoster-related pain. We hypothesize that combined use
      of pulsed RF and steroid injection applied to the DRG may achieve a better outcome than use
      of epidural steroid injection alone.
    

Intervention name(s): Epidural steroid; PRF plus steroids injection
Intervention type(s): Procedure; Procedure
Intervention description(s): Injection of Depo-Medrol of affected dermatomes; Pulsed radiofrequency with temperature 42 degrees for 6 minutes to be applied to the dorsal root ganglion plus injection of Depo-Medrol of affected dermatomes
Allocation: Randomized
Intervention model: Parallel Assignment
Masking: Double (Participant, Outcomes Assessor)
Primary purpose: Treatment