Effects of stellate ganglion block on vasomotor symptoms: findings from a randomized controlled clinical trial in postmenopausal women.

OBJECTIVE Uncontrolled intervention studies, including studies involving breast cancer survivors, have demonstrated improvements in vasomotor symptoms (VMS) after stellate ganglion blockade (SGB) with a local anesthetic. This study presents the first randomized sham-controlled trial of SGB for the treatment of VMS. METHODS Participants included 40 postmenopausal women, aged 30 to 70 years, with moderate to severe VMS. The study was a randomized sham-controlled trial comparing the effects of SGB versus sham injection on the frequencies of total and moderate to severe VMS, as measured by daily diaries. Image-guided SGB was performed with 5 mL of 0.5% bupivacaine. Sham injection of saline was performed in subcutaneous tissues in the neck. VMS were recorded at baseline and for 6 months thereafter. Objective VMS were recorded using ambulatory sternal skin conductance monitoring during a 24-hour period at baseline and on 3-month follow-up. RESULTS There were no significant group differences in overall VMS frequency, but the frequency of moderate to very severe VMS was reduced more in the active group compared with the sham treatment group (event rate ratio, 0.50; 95% CI, 0.35-0.71; P < 0.001). The frequency of objective VMS was also reduced to a greater degree in the SGB group than in the sham group (event rate ratio, 0.71; 95% CI, 0.64-0.99; P < 0.05). There were no study-related serious adverse events. CONCLUSIONS SGB may provide effective treatment of VMS in women who seek nonhormonal treatments because of safety concerns and personal preference. The finding that SGB significantly reduces objectively measured VMS provides further evidence of efficacy. A larger trial is warranted to confirm these findings.