The U.S. Army has commissioned a $2 million study to test a commonly used injection for treating symptoms of post-traumatic stress disorder, in a medical trial that could pave the way for the treatment to get official endorsement. While the neck injections—called stellate ganglion blocks—have already received praise from doctors who say the treatment is effective, the military has been reluctant to endorse the injections without a controlled trial. The injections have previously been used to treat arm pain and shingles, and for PTSD patients they are used to control the fight-or-flight response by interrupting messages sent between nerve fibers. Military doctors who have used the injections say their effect is obvious, with relief for symptoms like anxiety, hypervigilance, and social withdrawal. Col. Jim Lynch, command surgeon at the joint Special Operations Command-Africa, told The Wall Street Journal, “Once people have the shot, they get dramatically better immediately.” Researchers hope to enroll 240 patients in the trial, and they said 45 people had already volunteered to take part.