The Effects of Stellate Ganglion Block on Sleep in U.S. Active Duty Service Members and Veterans Receiving Prolonged Exposure Therapy for Posttraumatic Stress Disorder (PTSD)

Sleep disorders are the number one complaint of service members following a combat deployment. They also are a hallmark symptom of posttraumatic stress disorder, with STRONG STAR studies showing that insomnia affects 92% and nightmares affect 69% of military and veterans with PTSD. Moreover, they are associated with PTSD treatment resistance and, in the majority of cases, tend to persist even after PTSD treatment has been successfully completed.

First-line recommended treatments for insomnia and nightmares are behavioral interventions that involve long treatment sessions over the course of two to four months, and they are not widely available. Medications are available, but they have limited efficacy, cause side effects that can interfere with military duty, and can result in long-term usage or dependence.

This necessitates the search for a faster, safe, effective, and accessible way to treat these sleep disorders on their own or alongside PTSD therapy, where it potentially could lead to improvements in both conditions.

A STRONG STAR study led by Kristi Pruiksma, PhD, DBSM, at The University of Texas at San Antonio Long School of Medicine is investigating whether a stellate ganglion block (SGB) might be such a treatment. Her team’s observational study is an optional add-on to a large STRONG STAR randomized clinical trial (RCT) led by Alan Peterson, PhD, ABPP, also of UT San Antonio Long School of Medicine, testing the addition of SGB to evidence-based psychotherapy for PTSD in military members from San Antonio and Fort Hood in Killeen, Texas.

What is a stellate ganglion block?

SGB is an injection of a local anesthetic into the sympathetic nerve tissue located on either side of the neck, temporarily blocking nerve signals that go to the arms and face. It is primarily used to treat pain but has emerged as a promising approach to PTSD treatment, since it helps block, or turns down, physiological stress response symptoms that are overactive in PTSD. The procedure is widely used in military treatment facilities across the U.S. and appears to be well received, particularly by Special Forces.

In the STRONG STAR RCT led by Dr. Peterson, researchers are evaluating whether an SGB given at the beginning of treatment with Prolonged Exposure improves the therapy’s efficacy and patients’ recovery. They theorize that the temporary reduction in stress response will make it easier for patients to discuss and mentally process traumatic memories and emotions, which should lead to more significant and long-lasting symptom improvement.

Why examine SGB for sleep?

Preliminary research indicates that SGB also may improve sleep and sleep quality. Dr. Pruiksma believes her add-on observational study provides the perfect opportunity to test that objectively and to better understand the physiology behind it, particularly as it relates to the interplay of sleep problems and PTSD.

There is indication that SGB can improve sleep by reducing stimulation of key brain regions involved in stress and arousal and the release of stress-related neurotransmitters and hormones. Another intriguing finding from meta-analyses is that PTSD is associated with significant disturbances in sleep architecture—the structural, cyclical pattern of sleep that impacts sleep quality and, in turn, sleep’s physical and mental health benefits.

A first of its kind

This has not previously been tested since, to date, preliminary human studies have relied solely on patients’ self-report about sleep improvement with SGB. Dr. Pruiksma’s STRONG STAR study is the first to utilize both self-report and objective measures of sleep parameters to examine the impact of SGB on sleep in individuals with PTSD.

The study team particularly wants to examine SGB’s potential impact on sleep architecture on two levels. Does it change sleep macroarchitecture, or how the brain cycles through sleep in stages, along with total sleep time sleep efficiency (amount of time in bed vs. amount of sleep)? Does it change sleep microarchitecture, those detailed, moment-to-moment neurophysiological events within sleep stages, such as brain waves, rapid eye movement, and transient events like arousal from sleep?

In addition to influencing a person’s amount and quality of sleep, these architectural changes also are associated with the cognitive and emotional processing of memories and the extinction of cued fear conditioning—the hypothesized mechanisms of action of exposure-based PTSD treatments.

How the study works

For the parent study on PTSD, participants will be randomly placed into one of two groups: one will receive an active SGB using the sedative ropivacaine; the other will receive a “sham SGB,” a harmless placebo injection. Then all participants will receive PE therapy for PTSD.

For the add-on sleep study, 40 study participants will be invited to undergo sleep assessments before and after their SGB injection. In addition to completing questionnaires about their sleep problems, they will take home and wear EEG headbands for three nights each pre- and post-injection to gauge brain activity during sleep.

Researchers will use the data obtained to determine whether the real SGB leads to more sleep, better REM sleep, fewer awakenings, fewer nightmares, and better overall sleep quality.

Expected benefits

If SGB with ropivacaine is shown to improve sleep macro- and microarchitecture, insomnia, and nightmares, it could be a novel and efficient adjunctive treatment to target sleep disturbances which are resistant to PTSD treatments.

Study findings also are expected to inform the field about the role of sleep in PTSD and potentially identify characteristics that could serve as biomarkers that are predictive of PTSD symptom change.