Abstract Background In this randomized controlled, double-blind study, we aimed to investigate the involvement of sympathetic nerve fibers in erector spinae plane block (ESPB) and to compare it with thoracic epidural analgesia (TEA) in patients scheduled for unilateral mastectomy. Additionally, we compared sympathetic blockade-related hemodynamic effects, sensory blockade distribution, and analgesic effects. Methods Thirty-eight female patients aged 18–70 years, American Society of Anesthesiologists (ASA) classification I–III, were included in the study. The patients were divided into Group E (those who received general anesthesia after the ESPB) and Group T (those who received general anesthesia after TEA). The extent of sympathetic blockade (via the hot-cold test) and skin conductance (GSR) were recorded as the co-primary outcome measures. Secondary outcomes included skin temperature, perioperative hemodynamic data, sensory block extent, postoperative pain scores, and analgesic consumption. Results Regarding the co-primary outcomes, there was no statistically significant difference between the groups in the hot-cold test or GSR values. In terms of secondary outcomes, although the rate of skin temperature change differed ( p = 0.028), both groups showed significant warming. Hemodynamic data were comparable. However, ESPB produced a wider ipsilateral sensory block than TEA. The postoperative pain scores, patient-controlled analgesia (PCA) demand, and rescue analgesic consumption were not statistically significantly different between the two groups. Conclusion ESPB demonstrated similar sympathetic blockade efficacy to TEA. Additionally, it produced similar hemodynamic effects and postoperative analgesia in patients undergoing unilateral mastectomy due to malignancy. Trial registration ClinicalTrials.gov, NCT04702061, Date of registration: 24/12/2020, https://clinicaltrials.gov/study/NCT04702061 .
KURADA et al. (Sat,) studied this question.