The Glass Half Empty or Half Full-How Effective Are Long-Term Intrathecal Opioids in Post-herpetic Neuralgia? A Case Series and Review of the Literature.

Objectives. Post-herpetic neuralgia (PHN) is a painful complication of herpes zoster infection and a common cause of chronic severe pain in elderly and/or debilitated patients. Although a wide range of treatments have been tried, a substantial number of patients continue to experience pain which remains refractory to all therapies. Increasingly, studies have demonstrated that oral opioids can have a beneficial effect on neuropathic pain. However, to date, few studies have examined the potential benefit(s) of chronic intrathecal opioids in the treatment of PHN. Methods. Long-term outcome results of four PHN patients who had a successful intrathecal opioid trial and underwent implantation of an intrathecal opioid pump were examined. Data were analyzed using univariate analysis of variance. Results. Duration of continuous intrathecal opioid therapy ranged from five to 50 months and mean pain reduction was 41% (range 27-50%) as measured by a verbal pain score (0-100), with the greatest benefit noticed earlier in therapy. Mean 24-hour intrathecal morphine dose was 2.29 mg (range 0.78-3.94 mg). Intrathecal therapy was discontinued in two patients because of opioid side-effects, depression, and loss of efficacy. Revision surgery was required in two cases. Patients most commonly reported improvement in the deep component of their pain, next allodynia, and less so superficial lancinating pain. Conclusions. In conclusion, while a complex therapy, long-term use of intrathecal opioids is well tolerated, doses are titratable, administration is safe, and may help relieve severe short- and long-term neuropathic pain in selected PHN patients. Whether the addition of newer investigational intrathecal agents could improve these results is yet to be determined.