Stellate Ganglion Block May Promote Placebo Effect in PTSD

A novel treatment for post-traumatic stress disorder turned out to be no better than sham treatment in a randomized controlled trial, disappointed researchers reported in a poster presentation at the 31^st Annual Meeting of the American Academy of Pain Medicine.

Although stellate ganglion block had reportedly induced rapid, dramatic, and long-lasting improvements in PTSD symptoms in case series and uncontrolled trials, researchers from the University of California, San Diego, the Naval Medical Center in San Diego, and the Naval Hospital of Okinawa, Japan were unable to replicate the results under more controlled conditions.

The stellate ganglion nerves in the back of the neck are thought to influence fight or flight response and mediate pain signals. The response can be blocked by injecting a local anesthetic, after which some physicians have noted an improvement in depression, nightmares, flashbacks, and anxiety in patients.

The researchers set out to prove the impressive claims by injecting 42 military service members with PTSD with either stellate ganglion block or a sham injection. PTSD severity was measured one week and one month after injection. Patients who continued to meet PTSD criteria were able to get a second injection or switch from sham to the stellate ganglion block. Pain, depression, anxiety, cognitive function, and disability were also measured.

Although PTSD symptoms significantly improved for both groups after treatment, there was no statistical difference between stellate ganglion block and the sham injection. However, researchers did note that even greater improvements were recorded in patients who received a second stellate ganglion block.

“The most obvious explanation would be that the previously-reported benefits for PTSD were attributable to placebo effect,” said study author Robert McLay, MD, PhD. “Alternatively, it is possible that only particular people with PTSD respond well to the SGB treatment, or that small variations in how the technique is performed result in different outcomes for PTSD.”

McLay and colleagues expressed interest in working more closely with researchers and physicians who observed positive results in order to better understand the mechanism behind the possible therapeutic effect. If positive results could be replicated in clinical studies, stellate ganglion block would potentially be favored over other treatments for PTSD since it may curb dependence on psychotherapy and psychiatric drugs. 

Reference

1. McLay R et al. “A Randomized, Double-Blind, Placebo-Controlled Trial of Stellate Ganglion Block in the Treatment of Post-Traumatic Stress Disorder.” Poster 126. Presented at: AAPM Annual Meeting. March 19-22, 2015; National Harbor, Maryland.