Nerve Block Efficacy and Safety for Acute Thoracic Herpes Zoster: A Systematic Review and Meta-analysis.

Background: Acute zoster-related pain affects more than 90% of patients with acute herpes zoster. While nerve blocks with local anesthetics and steroids are commonly used to manage acute postoperative and chronic pain, their efficacy and safety in treating acute herpes zoster remain underexplored.

Objectives: Our systematic review and meta-analysis aimed to evaluate the efficacy and safety of various nerve blocks for managing acute herpes zoster.

Study design: We conducted a systematic review and meta-analysis of randomized controlled trials (RCTs) and observational studies adhering to the Preferred Reporting Items for Systematic Reviews and Meta-analyses (PRISMA) checklist.

Methods: A comprehensive search of MEDLINE, Embase, and the Cochrane Central Register of Controlled Trials was conducted to identify studies of patients with acute herpes zoster who received nerve blocks. Study quality was assessed using risk-of-bias tools for randomized and nonrandomized studies. The primary outcome was analgesic efficacy; secondary outcomes included postherpetic neuralgia (PHN) incidences, analgesic consumption, and adverse events.

Results: Thirteen studies (9 RCTs, n = 815; 4 observational studies, n = 253) were included. Nerve blocks administered were  paravertebral blocks (PVB), erector spinae plane (ESP) blocks, epidural blocks, and intercostal nerve blocks. The meta-analysis, which included 6 RCTs, indicated that at 4 weeks postprocedure, nerve blocks significantly reduced Visual Analog Scale pain scores. The blocks also reduced the need for acetaminophen and pregabalin compared with the control group. However, no differences in Visual Analog Scale pain scores were observed at 12 weeks. Both PVB and ESP blocks significantly decreased the PHN incidences at 3 and 6 months postprocedure. Five studies demonstrated that ultrasound-guided ESP blocks significantly reduced pain severity, duration, and the incidence of PHN without notable adverse events. Eight studies found PVBs to be effective in reducing pain scores and PHN incidences, though adverse events such as dizziness, drowsiness, and pain at the injection site were reported. Four observational studies comparing epidural or intercostal nerve blocks with other techniques provided weak evidence for their use.

Limitations: Our study's limitations include its small sample size with only 6 RCTs, significant heterogeneity in study designs, and variations in the interventions. Subjectivity in measuring pain and the lack of blinding introduces potential bias. Additionally, limited evidence on intercostal and epidural blocks for acute herpes zoster highlights the need for more high-quality RCTs.

Conclusion: In conclusion, nerve blocks with local anesthetics and steroids provide effective analgesia, reduce analgesic consumption, and lower PHN incidences in patients with acute thoracic herpes zoster. We recommend an ESP block due to its safety profile, while a PVB may offer similar analgesic benefits but with a higher risk. Further high-quality studies are necessary to confirm these findings.