The report is a product of the VA/HSR Evidence Synthesis Program.

Effectiveness of Stellate Ganglion Block for Treatment of PTSD

Post-traumatic stress disorder (PTSD) is the third most common psychiatric diagnosis among Veterans treated within the VA healthcare system. Experts estimate that up to 20% of Operation Enduring Freedom and Operation Iraqi Freedom (OEF/OIF) Veterans, up to 12% of Gulf War Veterans, and up to 30% of Vietnam War Veterans have experienced PTSD. Consequently, the need for PTSD treatment may increase within the Veteran population in the coming years. Conventional treatments for PTSD include psychotherapy, pharmacotherapy, or their combination; however, several challenges have been identified in their effectiveness and reach. Stellate ganglion block (SGB) has been promoted as an add-on therapy for individuals with PTSD who have not fully responded to conventional treatments.

The stellate ganglion is a cluster of nerve cell bodies located between the C6 and C7 vertebrae. Injection of local anesthetic to the stellate ganglion, a procedure known as stellate ganglion block (SGB), inhibits sympathetic nerve impulses to the head, neck, and upper extremities, and has been used to treat various disorders (i.e., migraines, facial pain, hot flashes). The specific mechanisms of action by which SGB may mitigate PTSD symptoms remains incompletely understood, but some suggest that SGB may suppress amygdala over-activity and nerve growth factor – and consequent perivascular norepinephrine increases and induces a sedative effect. Some of the proposed benefits of SGB for PTSD may include:

• Destigmatizing treatment by offering a biologic approach;
• Offering a fast-acting treatment alternative with improvements reported within minutes to days of the procedure; and
• Increasing compliance as it does not require continuous daily or weekly administration.

This Evidence Brief discusses to what extent SGB provides clinically relevant benefits, any potential harms, and identifies those Veterans who might be most likely to benefit from this treatment. Investigators with VA's Evidence-based Synthesis Program Coordinating Center located in Portland, OR searched multiple data sources (i.e., MEDLINE^®, CINAHL, Cochrane Register of Controlled Trials, etc.) for relevant articles through February 7, 2017. After reviewing 174 records, including some identified via reference lists and hand-searching, they identified only 1 comparative study. An overview of initial findings from uncontrolled case series also was provided.

Summary of Findings
Stellate ganglion block for PTSD is currently supported only by evidence from uncontrolled, unblinded case series which were neither confirmed nor refuted by a single randomized controlled trial (RCT) with imprecise findings, moderate methodological limitations, and which did not directly focus on clinically relevant outcomes. In currently used evidence grading systems, such evidence is considered "insufficient" for estimating an effect. In the aforementioned case series, SGB for PTSD had high rates of rapid clinical improvement in PTSD symptoms (70% to 75%). However, findings from the first RCT of stellate ganglion block for PTSD were inconclusive, neither confirming nor refuting findings from case series. In the RCT, the range of mean percent PTSD improvement after one round of SGB was 5% to 15%, and was 12% to 21% after the second round, which was no better than an injection of saline. In addition, certain population characteristics and intervention and comparator techniques used in the RCT were suboptimal for determining efficacy, and it was too small to estimate rates of serious complications. The majority of study participants were active-duty military personnel with unknown psychological and medical comorbidities, and previous conventional therapy trials.

Due to the high risk of bias of case series, the pattern of their finding very encouraging results, followed by a negative RCT, is quite common. It suggests that while it is possible that some patients benefit, the response rates seen in case series will not hold up in actual practice. Substantial uncertainty remains about the potential harms of SGB as well. The randomized controlled trial, as well as RCTs of SGB for complex regional pain syndrome, were inadequately powered to support or refute findings from the frequently cited, but methodologically weak, 1992 German questionnaire survey of 45,000 SGBs that found 1.7 instances of severe complications per every 1,000 individuals.

Evidence also was insufficient to determine which Veterans are most likely to benefit from SGB for PTSD. Clinical factors that could be used to select patients include failure to respond to – or high risk of non-compliance with conventional therapies, low risk of bleeding and other complications, patient preference, and availability of SGB.

Future Research
Investigators recommend that more rigorous studies are needed to more precisely determine the balance of benefits and harms of SGB for the treatment of PTSD. Both randomized trials and controlled observational studies can contribute to our knowledge of SGB for PTSD. A randomized trial – conducted by the Research Triangle Institute with Department of Defense funding – is underway. This study will compare SGB to placebo in a planned enrollment of 240 active-duty military personnel with PTSD. Controlled observational studies also could further contribute to our knowledge by incorporating the following additional features:

• Use of rigorous standards for registry studies.
• Assessment of long-term sustainability.
• Helping determine who may be more likely to benefit from SGB by better documentation of and comparing outcomes between subgroups of patients with different demographics, prior conventional PTSD treatment trials, predominant PTSD symptom clusters, or comorbidities. For example, it should be explored whether weak findings that hyperarousal and avoidance are the symptom types most impacted by SGB translate into SGB being more useful overall in patients with those predominant symptoms.
• Use of active rather then opportunistic assessment of harms.

Moreover, outcome assessment and data analysis should be conducted by research or quality improvement personnel who do not have strong prior views of the effectiveness of SGB.

For additional related evidence review work, investigators further recommend that a review of the state-of-the-science of PTSD outcome assessment methods, such as has been done in the field of chronic pain outcome assessment, could be useful in informing the direction of future research for PTSD as a whole.

Reference
Peterson K, Bourne D, Anderson J, Mackey K, Helfand M. Evidence Brief: Effectiveness of Stellate Ganglion Block for Treatment of Posttraumatic Stress Disorder. VA ESP Project #09-199; 2017.

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