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Stellate ganglion block (SGB) is a procedure involving the injection of a local anesthetic surrounding the stellate ganglion to inhibit sympathetic outflow. The objective of this review was to summarize existing evidence on the use of SGB in adults with psychiatric disorders. A systematic search identified 17 published studies and 4 registered clinical trials. Eighty-eight percent of published studies, including 2 randomized controlled trials (RCTs), used SGB for posttraumatic stress disorder (PTSD), although its use for schizophrenia spectrum disorders was also explored. Administration of 1 to 2 SGBs using right-sided laterality with 0.5% ropivacaine was most common. Preliminary evidence from clinical trials and case studies supports the feasibility of SGB for treating psychiatric disorders involving dysregulation of the sympathetic nervous system, although effectiveness evidence from RCTs is mixed. One RCT concluded that improvement in PTSD symptoms was significant, while the other concluded that it was nonsignificant. Improvements were noted within 5 minutes of SGB and lasted 1 month or longer. Registered clinical trials are exploring the use of SGB in new psychiatric disorders, including major depressive disorder and borderline personality disorder. More studies with larger sample sizes and alternate protocols are needed to further explore therapeutic potential of SGB for psychiatric disorders.

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Conventional monoamine-based pharmacotherapy, considered the first-line treatment for major depressive disorder (MDD), has several challenges, including high rates of non-response. To address these challenges, preclinical and clinical studies have sought to characterize antidepressant response through monoamine-independent mechanisms. One striking example is glutamate, the brain's foremost excitatory neurotransmitter: since the 1990s, studies have consistently reported altered levels of glutamate in MDD, as well as antidepressant effects following molecular targeting of glutamatergic receptors. Therapeutically, this has led to advances in the discovery, testing, and clinical application of a wide array of glutamatergic agents, particularly ketamine. Notably, ketamine has been demonstrated to rapidly improve mood symptoms, unlike monoamine-based interventions, and the neurobiological basis behind this rapid antidepressant response is under active investigation. Advances in brain imaging techniques, including functional magnetic resonance imaging, magnetic resonance spectroscopy, and positron emission tomography, enable the identification of the brain network-based characteristics distinguishing rapid glutamatergic modulation from the effect of slow-acting conventional monoamine-based pharmacology. Here, we review brain imaging studies that examine brain connectivity features associated with rapid antidepressant response in MDD patients treated with glutamatergic pharmacotherapies in contrast with patients treated with slow-acting monoamine-based treatments. Trends in recent brain imaging literature suggest that the activity of brain regions is organized into coherent functionally distinct networks, termed intrinsic connectivity networks (ICNs). We provide an overview of major ICNs implicated in depression and explore how treatment response following glutamatergic modulation alters functional connectivity of limbic, cognitive, and executive nodes within ICNs, with well-characterized anti-anhedonic effects and the enhancement of “top-down” executive control. Alterations within and between the core ICNs could potentially exert downstream effects on the nodes within other brain networks of relevance to MDD that are structurally and functionally interconnected through glutamatergic synapses. Understanding similarities and differences in brain ICNs features underlying treatment response will positively impact the trajectory and outcomes for adults suffering from MDD and will facilitate the development of biomarkers to enable glutamate-based precision therapeutics.