Background: Latent varicella zoster virus reactivates mainly in sensory ganglia such as the dorsal
root ganglion (DRG) or trigeminal ganglion. 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). Although the efficacy of pulsed radiofrequency (PRF) application to the DRG in
various pain conditions has been previously reported, the application of PRF to the DRG in patients
with herpes zoster has not yet been studied.
Objectives: The aim of the present study was to compare the clinical effects of PRF to the DRG in
patients with herpes zoster to those of PRF to the DRG in patients with PHN.
Study Design: Retrospective comparative study.
Setting: University hospital pain center in Korea.
Methods: The medical records of 58 patients who underwent PRF to the DRG due to zoster
related pain (herpes zoster or PHN) were retrospectively analyzed. Patients were divided into 2
groups according to the timing of PRF after zoster onset: an early PRF group (within 90 days) and
a PHN PRF group (more than 90 days). The efficacy of PRF was assessed by a numeric rating scale
(NRS) and by recording patient medication doses before PRF and at one week, 4 weeks, 8 weeks,
and 12 weeks after PRF.
Results: Pain intensity was decreased after PRF in all participants. However, the degree of pain
reduction was significantly higher in the early PRF group. Moreover, more patients discontinued
their medication in the early PRF group, and the PRF success rate was also higher in the early PRF
group.
Limitations: The relatively small sample size from a single center, short duration of review of
medical records, and the retrospective nature of the study.
Conclusions: PRF to the DRG is a useful treatment for treatment-resistant cases of herpes zoster
and PHN. Particularly in herpes zoster patients with intractable pain, application of PRF to the DRG
should be considered for pain control and prevention of PHN.
Key words: Pulsed radiofrequency, dorsal root ganglion, herpes zoster, postherpetic neuralgia