Sympathetic nerve blocks for the management of postherpetic neuralgia - 19 years of pain clinic experience.

Background: Sympathetic system involvement in postherpetic neuralgia (PHN) has been targeted using peripheral sympathetic nerve blocks for a number of years with variable efficacy. The aim of this report is to present the outcomes of PHN management with concomitant use of pharmacological treatment and sympathetic nerve blocks. Methods: We retrospectively evaluated clinical data on 563 patients with PHN symptoms treated in the pain clinic and identified cases in which sympathetic nerve blocks were implemented in the years 1992−2010. A Numeric Rating Scale was used as a pain severity assessment, with a reduction to values under 3 considered a positive therapy result. Three time intervals were considered: years 1992−1997 (I), 1998−2002 (II) and 2003−2010 (III). Results: In group I, 27% of patients had poor treatment results, while in group II, the failure rate dropped to 18%. The same 18% failure rate was observed in group III as well. Treatment introduced early yielded the best results, but there was no difference among groups with a similar duration from herpes zoster onset to treatment commencement in the time periods assessed; however, from 1998 onward, the same rate of poor outcomes was also noted in the groups who started the sympathetic blockade, which aided pain clinic treatment up to 3 months and between 3 and 6 months from the onset of herpes zoster. Conclusion: Major progress in the pharmacological treatment of PHN appears to be an obvious factor contributing to the overall improvement in PHN management (introduction of gabapentin). Nevertheless, safely administered regional anaesthesia techniques, although performed in a very similar manner for many years, appear to provide some support as part of a multimodal approach to PHN management.