Broad-band ultraviolet B phototherapy in zoster patients may reduce the incidence and severity of postherpetic neuralgia.

BACKGROUND

Postherpetic neuralgia (PHN) is one of the common complications of herpes zoster infection, particularly in the elderly. Current therapeutic measures are only partially effective in the affected patients. As inflammatory mediators released by different cells play an important role in the pathogenesis of this neuropathic pain and with regard to the immunomodulatory effects of ultraviolet B (UVB) spectrum, we presumed that UVB phototherapy might be effective in the prevention of PHN.

METHOD: This study was performed in two phases. Phase I was a prospective open controlled trial. Twenty-five patients with severe pain in the first 7 days of zoster rash were divided into two groups: the prevention group (n=12) received oral acyclovir (800 mg five times a day for 10 days) plus broad-band UVB to the affected dermatomes, starting with 20 mJ/cm(2) and gradually increasing the dose by 10 mJ/cm(2) each session to a maximum dose of 100 mJ/cm(2). Treatment sessions were repeated three times a week until pain relief or to a maximum of 15 sessions. The control group (n=13), who had disease characteristics similar to the prevention group, received only oral acyclovir with the same dose. All patients reported their severity of pain on a verbal rating scale (VRS, score 0-4) before treatment and at 1 and 3 months' follow-up. In phase II of the study, five patients with established PHN (more than 3 months after rash onset) received UVB with the above-mentioned protocol.

RESULTS

A total of 17 patients older than 40 (10 females, seven males; mean age, 65.5 years; range: 47-82 years) who had intractable pain due to zoster infection received UVB in two phases of the study. In patients who received phototherapy in the first 7 days of rash, 58.33% and 83.33% were completely pain free at 1-and 3-month follow-up, respectively. The corresponding figure in the control group was significantly lower (38.46% at 1 month and 53.85% at 3 months). The severity of pain was also lower in the phototherapy group than the control group (mean VRS 2.50 vs. 3.28 at 3 months). None of the patients who were treated more than 3 months after rash onset (established PHN) experienced significant (more than 50%) pain relief.

CONCLUSION

UVB phototherapy in the acute stage of zoster rash might reduce the incidence and severity of PHN. Treatment after 3 months does not seem to have a significant beneficial effect.