A prospective randomized comparison of the efficacy of standard antiviral therapy versus ultrasound-guided thoracic paravertebral block for acute herpes zoster

OBJECTIVES: To evaluate the effectiveness of repetitive thoracic paravertebral block (TPVB) under ultrasound (US) guidance for acute pain associated to herpes zoster (HZ) and its prophylactic effects on post-herpetic neuralgia (PHN). METHODS: Patients who suffered from acute pain associated to HZ within 1 week of rash onset were randomized in a ratio of 1:1 to receive a seven-day course antiviral therapy, antiviral therapy with additional US-guided repetitive TPVB using transverse short axial (TSA) approach every 48 h for a week after antiviral therapy. All patients were allowed to receive rescue analgesics. The primary endpoint was HZ burden of illness (HZ-BOI) measured by a severity-by-duration composite pain assessment conducted 1-month post inclusion. Adverse events were also recorded. RESULTS: A total of 96 patients completed the entire 6-month follow-up. The BOI-30(AUC) was 112.5 (95%CI: 105.2, 119.9) in control group, and 82.7 (95%CI: 75.4, 90.1) in TPVB group (F = 32.252, p<.001) at D30 after inclusion. Compared with control group, significant reductions of BOI-30–90(AUC), and BOI-90–180(AUC) were observed in TPVB group (F = 11.392, p=.001 at D90; F = 7.467, p=.007 at D180, respectively). At 3 and 6 months after inclusion, the incidence of PHN in TPVB group was significantly lower than control group. Quality of life (QoL) in TPVB group also showed greater improvements at all the time points in all domains of EQ-5D-3L (p<.05). No serious adverse events were observed. CONCLUSIONS: US-guided repetitive TPVB significantly reduced the HZ-BOI and the PHN incidence compared to antiviral therapy alone. It might be considered as an early intervention and preventive strategy to the development of PHN after acute HZ. KEY MESSAGE: This is a prospective randomized comparative study. We made a hypothesis that US-guided repetitive thoracic paravertebral block (TPVB) using a transverse short axial (TSA) approach to treat thoracic herpes zoster (HZ) in acute phase could reduce the burden of illness associated to acute pain. Moreover, this therapy might be a feasible preventive strategy to reduce the incidence of post-herpetic neuralgia.