Acyclovir and postherpetic neuralgia

Efficacy of continuous epidural infusion with epidural electric stimulation compared to that of conventional continuous epidural infusion for acute herpes zoster management: a retrospective study

Background

Continuous epidural infusions are commonly used in clinical settings to reduce the likelihood of transition to postherpetic neuralgia via pain control. The purpose of this study was to compare the efficacy of conventional continuous epidural infusion to that of continuous epidural infusion in which the catheter is guided by electric stimulation to areas with neurological damage for the treatment of zoster-related pain and prevention of postherpetic neuralgia.

Methods

We analyzed the medical records of 114 patients in this study. The patients were divided into two groups: contrast (conventional continuous epidural infusion) and stimulation (continuous epidural infusion with epidural electric stimulation). In the contrast group, the position of the epidural catheter was confirmed using contrast medium alone, whereas in the stimulation group, the site of herpes zoster infection was identified through electric stimulation using a guidewire in the catheter. Clinical efficacy was assessed using a numerical rating scale (pain score) up to 6 months after the procedures. We compared the percentage of patients who showed complete remission (pain score less than 2 and no further medication) in each group. We also investigated whether the patients required additional interventional treatment due to insufficient pain control during the 6-month follow-up period after each procedure.

Results

After adjusting for confounding variables, the pain score was significantly lower in the stimulation group than in the contrast group for 6 months after the procedure. After adjustment, the odds of complete remission were 1.9-times higher in the stimulation group than in the contrast group (95% confidence interval [CI]: 0.81–4.44, P = 0.14). Patients in the contrast group were significantly more likely to require other interventions within 6 months of the procedure than patients in the stimulation group (odds ratio: 3.62, 95% CI: 1.17–11.19, P = 0.03).

Conclusion

Epidural drug administration to specific spinal segments using electric stimulation catheters may be more helpful than conventional continuous epidural infusion for improving pain and preventing postherpetic neuralgia in the acute phase of herpes zoster.

Effects of applying nerve blocks to prevent postherpetic neuralgia in patients with acute herpes zoster: a systematic review and meta-analysis

BACKGROUND

Postherpetic neuralgia (PHN) is a common and painful complication of acute herpes zoster. In some cases, it is refractory to medical treatment. Preventing its occurrence is an important issue. We hypothesized that applying nerve blocks during the acute phase of herpes zoster could reduce PHN incidence by attenuating central sensitization and minimizing nerve damage and the anti-inflammatory effects of local anesthetics and steroids.

METHODS

This systematic review and meta-analysis evaluates the efficacy of using nerve blocks to prevent PHN. We searched the MEDLINE, EMBASE, Cochrane Library, ClinicalTrials.gov and KoreaMed databases without language restrictions on April, 30 2014. We included all randomized controlled trials performed within 3 weeks after the onset of herpes zoster in order to compare nerve blocks vs active placebo and standard therapy.

RESULTS

Nine trials were included in this systematic review and meta-analysis. Nerve blocks reduced the duration of herpes zoster-related pain and PHN incidence of at 3, 6, and 12 months after final intervention. Stellate ganglion block and single epidural injection did not achieve positive outcomes, but administering paravertebral blockage and continuous/repeated epidural blocks reduced PHN incidence at 3 months. None of the included trials reported clinically meaningful serious adverse events.

CONCLUSIONS

Applying nerve blocks during the acute phase of the herpes zoster shortens the duration of zoster-related pain, and somatic blocks (including paravertebral and repeated/continuous epidural blocks) are recommended to prevent PHN. In future studies, consensus-based PHN definitions, clinical cutoff points that define successful treatment outcomes and standardized outcome-assessment tools will be needed.