Comparative therapeutic evaluation of intrathecal versus epidural methylprednisolone for long-term analgesia in patients with intractable postherpetic neuralgia

Background and Objectives. The goal of this study was to evaluate the analg esic effects of intrathecal versus epidural methylprednisolone acetate (MPA ) in patients with intractable postherpetic neuralgia (PHN). Methods. We st udied 25 patients with a duration of PHN of more than 1 year. The patients were randomly allocated to one of two groups: an intrathecal group (n = 13) and an epidural group (n = 12). Sixty milligrams of MPA was administered e ither into the intrathecal or the epidural space four times at 1-week inter vals depending on the treatment group. Continuous and lancinating pain and allodynia were evaluated by a physician unaware of group assignment with a 10-cm visual analogue scale before treatment, at the end of treatment, and 1 and 24 weeks after treatment. In addition, cerebrospinal fluid (CSF) ;was obtained for measurement of interleukin (IL)-1 beta, -6, and -8 and tumor necrosis factor-alpha before and 1 week: after treatment. Results. We found marked alleviation of continuous and lancinating pain and allodynia in the intrathecal group (P < .001). The improvements were much greater in the in trathecal group than in the epidural group at all time points after the end of treatment (P < .005). IL-8 in the CSF decreased significantly in the in trathecal group as compared to the epidural group at the 1-week time point (P < .01), whereas the other cytokines were undetectable. Conclusions. Our results suggest the effectiveness of intrathecal as compared to epi dural M PA for relieving the pain and allodynia associated with Pi-IN. Also, our fi ndings, together with the decrease in IL-8, may indicate that intrathecal M PA improves analgesia by decreasing an ongoing inflammatory reaction in the CSF.