Stellate Ganglion Blockade in Post-Menopausal Women

Scope: Post-menopausal women with moderate to severe VMS will be enrolled as participants in this study. Specific Goals and Objectives: Primary Objective 1. To determine the effect of SGB for reducing frequency and intensity of menopausal VMS. Hypothesis 1a. Seven-day mean frequency of VMS will be lower in women randomized to active SGB compared to sham control. Hypothesis 1b. Seven-day mean intensity of VMS will be lower in women randomized to active SGB compared to sham control. Hypothesis 1c. The VMS Intensity (Frequency\*Severity), will be lower in women randomized to active SGB compared to sham control. Secondary Objectives 2. To evaluate the effect of SGB on VMS Intensity, objective VMS, mood, memory, and sleep quality. Hypothesis 2a The frequency of objectively measured VMS will be lower in women randomized to active SGB compared to sham control. Hypothesis 2b. Depressive symptoms and memory, but not sleep quality, will improve more in women randomized to active SGB compared to sham control. Hypothesis 2c. The magnitude of improvements in memory will relate to the magnitude of reduction in VMS, even after controlling for sleep. 3. To probe the mechanisms by which SGB improves VMS. Hypothesis 3a. In a nested sub study, neuroimaging assessments will reveal that compared to sham control, active SGB is associated with a) decreased functional connectivity in the default mode network during the resting state, particularly for networks supporting the insula and hippocampus; b) reduced activation in the hippocampus, dorsolateral prefrontal cortex, and anterior cingulate during a verbal memory task; and c) reduced activation in the amygdala during an emotion processing task. Hypothesis 3b. Compared to sham control, SGB will immediately diminish ipsilateral stellate ganglion nerve activity and sympathetic tone as measured by skin sympathetic nerve monitoring (SKNA) and these effects will be reassessed at 2 and 4 weeks after the intervention to assess if effects of SGB on stellate ganglion activity are long lasting.