Reduction of Serum Substance P and Beta Endorphin in Herpes Zoster After Erector Spinae Plane Block

Acute herpes zoster (AHZ) is caused by the reactivation of varicella-zoster virus. This reactivation results in peripheral nerve fiber damage and triggers an immune reaction, which leads to the production of interleukin-6 (IL-6) and tumor necrosis factor alpha (TNF-alpha). In the skin of patients affected with postherpetic neuralgia (PHN), high levels of calcitonin gene-related peptide (CGRP) have been found.

The primary goal of this study was to compare changes in serum inflammatory cytokines (IL-6, IL-8) and pain neurotransmitters (substance P, CGRP) with those of a control group, and before and after fascial plane blocks.

A prospective, nonrandomized, and case-control study.

The diagnosis of AHZ (< 2 months) and PHN (> 6 months) were determined based on the duration of each patient's pain since the onset of skin eruption. Healthy age- and gender-matched volunteers were included as the control group. For the sake of the enzyme-linked immunosorbent assay (ELISA), blood sampling was performed 2 or 3 times before and after the block. An ultrasound-guided erector spinae plane block (ESPB) was performed 2 or 3 times at an affected dermatome.

The levels of IL-6 and pain neurotransmitters (substance P, CGRP) in HZ patients did not show any significant differences from those in the control group. However, the serum substance P (median, 24.0; IQR, 7.2-49.5) and beta-endorphin levels following the ESPBs (median, 237.8; IQR, 177.4-414.5) were significantly lower than they were prior to the ESPBs (median, 30.6; IQR, 13.3-71.6; P = 0.009).

The AHZ patients in this study did not experience a very acute phase. Since the matter of whether or not the levels of serum inflammatory cytokines in AHZ patients can demonstrate a significant reduction or increase is uncertain, further study is required.

Between the HZ patients and the control group, the levels of inflammatory cytokines (IL-6) and pain neurotransmitters (substance P, CGRP) did not show any significant differences. However, a significant reduction of substance P and beta-endorphin following the ESPBs was observed.