Comparison of efficacy of continuous epidural block and pulsed radiofrequency to the dorsal root ganglion for management of pain persisting beyond the acute phase of herpes zoster

<div><p>Background</p><p>There is little evidence regarding the effectiveness of intervention methods in the treatment of zoster-related pain (ZAP) after the acute phase of zoster. Generally, if ZAP remains after more than 180 days from its onset, the likelihood of pain reduction is very low; this condition is considered as a “well established” post-herpetic neuralgia (PHN). Although the clinical efficacy of intrathecal steroid injection and spinal cord stimulation (SCS) for ZAP management has been reported, these interventions are not widely used due to inherent disadvantages. Continuous epidural block is widely used in clinical practice, and the effectiveness of pulsed radiofrequency (PRF) to the dorsal root ganglion (DRG) in the treatment of ZAP already has been reported.</p><p>Objectives</p><p>The purpose of this study was to compare the clinical efficacy of continuous epidural block and DRG PRF beyond acute phase of zoster, bur before PHN was well established (from 30 days to180 days after zoster onset).</p><p>Study design</p><p>Retrospective comparative study.</p><p>Methods</p><p>A total of 42 medical records were analyzed. Patients were divided into two groups according to the type of procedure utilized: continuous epidural block (continuous epidural group) and DRG PRF (PRF group). The clinical efficacy of the procedure was evaluated using a numeric rating scale (NRS) and the medication dose before and 1 to 6 months after the procedure.</p><p>Results</p><p>There was a significant decrease in the NRS value with time in both groups. However, this decrease was more significant in the PRF group than in the continuous epidural group. The medication doses decreased significantly in the PRF group over time, but not in the continuous epidural group. The rate of clinically meaningful PHN (NRS≥3) was also lower in the PRF group than in the continuous epidural group.</p><p>Conclusions</p><p>This study revealed that DRG PRF was more effective than a continuous epidural block in treating ZAP after the acute phase of zoster. A neuromodulation method such as DRG PRF may be a useful option for reducing the progression of neuropathic changes caused by the persistent transmission of a pain signal after the acute phase of zoster.</p></div

Rate of clinically meaningful PHN (NRS ≥3).

<p>NRS: numerical rating scale. PRF: pulsed radiofrequency. *: p<0.05.</p

Changes in NRS after continuous epidural block and DRG PRF.

<p>Although significant NRS changes throughout the time course were shown in both groups compared to the pre-procedure time point, the reduction in NRS was more profound in the PRF group (p = 0.029). NRS was significantly lower in the PRF group one to three months and six months after the procedure than in the continuous epidural group. Blue line with circle box and red line with circle box indicate NRS changes in continuous epidural group andPRF group respectively. NRS: numerical rating scale. DRG: dorsal root ganglion. PRF: pulsed radiofrequency. *: p<0.05 compared to pre-procedure NRS. #: p<0.05 compared to the continuous epidural group.</p

Patient demographic data.

<p>Patient demographic data.</p

Changes in doses of analgesics with time.

<p>In the PRF group, doses of analgesics one to six months after DRG PRF were significantly decreased compared to pre-procedure. There were no significant changes in analgesic doses with time in the continuous epidural group. Blue line with circle box and red line with circle box indicate analgesics dose changes in continuous epidural group and PRF group respectively. DRG: dorsal root ganglion. PRF: pulsed radiofrequency. *: p<0.05 compared to pre-procedure.</p

Fluoroscopic images of DRG PRF.

<p>Fluoroscopic anteroposterior view (A) and lateral view (B) of the DRG PRF.</p

Fluoroscopic images of continuous epidural block.

<p>Insertion of an epidural catheter via Tuohy needle (A) and confirmation of catheter tip position using contrast media (B). White arrowheads indicate the catheter inserted through a Tuohy needle.</p