The relationship between resilience and neurophysiological stress in Special Operations Forces combat service members.

Military resilience research is increasing due to the growing literature associating resilience with stress adaptation. This study aimed to investigate which physiological stress adaptation components were associated with resilience in Special Operations Forces combat service members. Special Operations Forces combat service members (n = 117) self-reported resilience (ER89) and lifetime clinician-confirmed mild traumatic brain injury history. Participants also underwent transcranial Doppler ultrasonography to measure middle cerebral artery velocity during rest and a breath-holding task. Neither resilience nor mild traumatic brain injury history was significantly associated with middle cerebral artery velocity percent increase following breath-holding; younger Special Operations Forces combat service members had a higher percent increase in middle cerebral artery velocity following a breath-holding task. Resilience was negatively associated with time to return to baseline middle cerebral artery velocity following peak velocity; whereas, mild traumatic brain injury history did not have a significant association. The Special Operations Forces combat service members that scored higher in resilience tended to return to baseline middle cerebral artery velocity following peak velocity faster than their less resilient counterparts. More resilient Special Operations Forces combat service members recovered faster from physiological stress (breath-holding) than less resilient counterparts. This is the first study to investigate resilience and cerebrovascular stress response and recovery in this population. Our initial findings indicated that the Ego Resiliency Scale may be an optimal resilience psychometric and should be used to evaluate effective military resilience trainings, which aim to improve performance and mental health.

Posttraumatic Stress Disorder in Elite Athletes.

ABSTRACT: Posttraumatic stress disorder (PTSD), which may develop following exposure to severe trauma, can occur in all people at any age. PTSD affects approximately 10 million Americans, with an incidence of approximately 3.5% diagnosed every year. Elite athletes are not immune to posttraumatic stress. While difficult to precisely quantify, an estimated 1 in 8 elite athletes suffers from PTSD. Because of its complex presentation, PTSD can be challenging to diagnose and effectively treat in athletes. Several barriers unique to elite athletes exist which may inadvertently delay or prevent access to the appropriate clinical experts. Several best practice models for mental health screening in elite athletes have been developed in the past decade. Treatment of PTSD in the athlete population is similar to trauma-informed treatment in the general population, but should involve the athlete's multidisciplinary team of clinical experts to account for unique demands and preferences in the context of sport.

Neuroinflammatory Biomarkers Associated With Mild Traumatic Brain Injury History in Special Operations Forces Combat Soldiers.

BACKGROUND: Special Operations Forces (SOF) combat soldiers are frequently exposed to blast and blunt neurotrauma, most often classified as mild traumatic brain injury (mTBI). Repetitive mTBI may increase the risk of developing long-term neurological sequelae. Identifying changes in neuroinflammatory biomarkers before chronic conditions emerge could serve as preliminary evidence of developing neuropathology. OBJECTIVE: To determine the effects of mTBI history, lifetime mTBI incidence, and recency on blood biomarker concentrations of axonal protein neurofilament light (NfL), glycolytic enzyme neuron-specific enolase (NSE), astrocyte-expressed S100 calcium-binding protein B (S100B), and neurotrophic cytokine interleukin-6 (IL-6) in healthy, active duty SOF combat soldiers. METHODS: Self-reported mTBI history/recency and fasted blood samples were collected in this cross-sectional study of 104 asymptomatic SOF combat soldiers. Biomarker concentrations were quantified using commercial enzyme-linked immunosorbent assays. Mann-Whitney U and Kruskal-Wallis tests were used to compare groups. Post hoc tests with appropriate corrections were conducted as warranted. RESULTS: Soldiers with mTBI history had higher NSE concentrations than those without (z = -2.60, P = .01). We also observed significant main effects of lifetime mTBI incidence on NSE (χ(3) = 9.52, P = .02) and S100B (χ(3) = 8.21, P = .04) concentrations and a significant main effect of mTBI recency on NfL concentration (χ(2) = 6.02, P = .049). CONCLUSION: The SOF combat soldiers with mTBI history had increased NSE. Longitudinal studies in this population are needed due to between-subject heterogeneity in biomarker concentrations. The NfL concentrations in our SOF combat soldiers-regardless of mTBI history or recency-were similar to values previously reported in civilian acute TBI patients.

Evaluation of elbow pain in adults.

The elbow is a complex joint designed to withstand a wide range of dynamic exertional forces. The location and quality of elbow pain can generally localize the injury to one of the four anatomic regions: anterior, medial, lateral, or posterior. The history should include questions about the onset of pain, what the patient was doing when the pain started, and the type and frequency of athletic and occupational activities. Lateral and medial epicondylitis are two of the more common diagnoses and often occur as a result of occupational activities. Patients have pain and tenderness over the affected tendinous insertion that are accentuated with specific movements. If lateral and medial epicondylitis treatments are unsuccessful, ulnar neuropathy and radial tunnel syndrome should be considered. Ulnar collateral ligament injuries occur in athletes participating in sports that involve overhead throwing. Biceps tendinopathy is a relatively common source of pain in the anterior elbow; history often includes repeated elbow flexion with forearm supination and pronation. Olecranon bursitis is a common cause of posterior elbow pain and swelling. It can be septic or aseptic, and is diagnosed based on history, physical examination, and bursal fluid analysis if necessary. Plain radiography is the initial choice for the evaluation of acute injuries and is best for showing bony injuries, soft tissue swelling, and joint effusions. Magnetic resonance imaging is the preferred imaging modality for chronic elbow pain. Musculoskeletal ultrasonography allows for an inexpensive dynamic evaluation of commonly injured structures.

Barotrauma with extreme pressures in sport: from scuba to skydiving.

The human body is well adapted to dealing with small variations in atmospheric pressure. However when our pursuit of sport and recreation takes us to extreme altitudes or ocean depths, the change in surrounding pressure has the potential to cause significant morbidity. Sports with more extreme changes in atmospheric pressure such as skydiving and scuba diving commonly place the athlete at risk for barotrauma injuries, especially in the middle ear and sinuses. Middle ear barotrauma occurs when a pressure differential develops between the middle ear and the pressure outside of the tympanic membrane. Early symptoms include ear pain, dizziness, and muffled hearing. When extreme pressure gradients are not relieved, middle ear effusions and rupture of the tympanic membrane can occur. A similar mechanism and injury pattern occurs in the sinuses as well. With proper training and prevention strategies, athletes in these sports can protect themselves from most barotrauma injuries.

Reversible Increased Anxiety Following Left-Sided Stellate Ganglion Block to Treat Posttraumatic Stress Disorder: A Case Report.

Describe a 2-patient case report of a rare occurrence of significantly increased anxiety after a left-sided stellate ganglion block (SGB) and the subsequent improvement of that anxiety through a right-sided SGB. Right-sided SGB to treat post-traumatic stress disorder (PTSD) has over 23 supporting publications in the peer-reviewed medical literature, including level 1 evidence. A published case series of 285 patients showed that two-level SGB may improve anxiety-related symptoms in patients. However, a recently published study indicates that some patients only respond to a left-sided SGB. The patients had an ultrasound-guided right-sided SGB for the treatment of PTSD and experienced a reduction in anxiety symptoms based on Posttraumatic Stress Disorder Checklist for DSM-5 (PCL-5) scores. Later, a left-sided SGB was performed. Clinically, the addition of a left-sided SGB is typically associated with further anxiety reduction, but in these 2 cases, the patients had a significant reversal of the improvements experienced after a right-sided SGB. Following this unusual response to a left-sided SGB, these patients were offered another right-sided SGB, after which, they experienced a significant and durable improvement in anxiety symptoms beyond the original baseline PCL-score. In rare cases and for unknown reasons, a left-sided SGB may result in acute worsening of anxiety symptoms, which can be addressed and significantly improved with the application of a subsequent right-sided SGB.

The Successful Use of Bilateral 2-Level Ultrasound-Guided Stellate Ganglion Block to Improve Traumatic Brain Injury Symptoms: A Retrospective Analysis of 23 Patients.

PURPOSE: The purpose of the study was to determine whether performing ultrasound-guided, bilateral stellate ganglion blocks (SGBs; performed on subsequent days) improved traumatic brain injury (TBI) symptoms. METHODS: A retrospective chart review was conducted for the time period between August 2022 and February 2023 to identify patients who received bilateral, 2-level (C6 and C4) SGBs for PTSD symptoms but who also had a history of TBI. Neurobehavioral Symptoms Inventory (NSI) scores were collected at baseline, 1 week, and 1 month post-treatment in 14 males and 9 females. RESULTS: Out of 23 patients, 22 showed improvement in their NSI scores. NSI baseline average score was 42.7; the average score at 1 week post-treatment was 18.8; 1 month post-treatment was 20.1. This represents a 53% improvement in the NSI score between baseline and 1 month. CONCLUSION: The use of bilateral, 2-level SGBs may be indicated in treating patients with PTSD symptoms with concomitant diagnoses of mild-to-moderate TBI.

Acute mountain sickness prophylaxis: a high-altitude perspective.

Acute mountain sickness (AMS) is the most common form of altitude illness affecting athletes and adventurists who work or play at elevations greater than 10,000 ft above mean sea level. Considerable research has been conducted to mitigate risk for those who work or play in environmental extremes. This article describes the experiences of a group of U.S. Army Special Operations soldiers who tested recommended doses of acetazolamide prophylaxis for AMS during six expeditions to elevations between 19,000 and 23,000 ft. In addition, we briefly review the literature as it pertains to prophylaxis of AMS. In our experience, prophylaxis with the recommended doses of acetazolamide resulted in fewer AMS symptoms and seemed to confer a higher likelihood of successfully summiting each peak. We conclude that acetazolamide is an acceptable choice for AMS prevention along with a slow, controlled ascent and proper fitness, nutrition, clothing, and gear.

Stellate Ganglion Block Reduces Anxiety Symptoms by Half: A Case Series of 285 Patients.

The stellate ganglion block (SGB) procedure has been used successfully for over twelve years to treat thousands of patients suffering from posttraumatic stress disorder (PTSD). Level 1b evidence supports this use of SGB, but no studies to date have reported specifically on anxiety symptom improvements following SGB. We collected Generalized Anxiety Disorder questionnaire (GAD-7) scores pre-procedure and at 1-week and 1-month post-procedure from 285 patients. The mean baseline GAD-7 score of 15.9 (indicating severe anxiety) declined significantly following SGB treatment. Changes in GAD-7 scores ≥ 4 were considered clinically meaningful. From baseline to 1 week, the GAD-7 scores dropped by 9.0 points (95% CI = 8.3-9.7, p < 0.001, d = 1.8), with 211 (79.6%) patients demonstrating clinically meaningful improvement. Furthermore, from baseline to 1 month, the GAD-7 scores dropped by 8.3 points (95% CI = 7.6-9.0, p < 0.001, d = 1.7), with 200 (75.5%) patients demonstrating clinically meaningful improvement. The stellate ganglion block treatment resulted in a decrease of GAD-7 scores of over twice the minimal clinically important difference in treating anxiety for at least 1 month following SGB. Given the results from this retrospective observational study, larger prospective studies should be conducted to determine the effects of SGB treatment as a novel therapeutic treatment for generalized anxiety disorder and other anxiety disorders.

The Successful Use of Left-sided Stellate Ganglion Block in Patients That Fail to Respond to Right-sided Stellate Ganglion Block for the Treatment of Post-traumatic Stress Disorder Symptoms: A Retrospective Analysis of 205 Patients.

INTRODUCTION: Ultrasound-guided stellate ganglion block (SGB) is an injection of local anesthetic (8mL of 0.5% ropivacaine) in the neck to temporarily block the cervical sympathetic trunk which controls the body's fight-or-flight response. This outpatient procedure takes less than thirty minutes and is immediately effective. Our goal was to determine if a left-sided stellate ganglion block is effective for treating posttraumatic stress disorder (PTSD) symptoms. While right-sided SGB has been extensively studied, left-sided SGB has not been formally evaluated for this indication. MATERIALS AND METHODS: Our hypothesis was that patients who fail to improve following a right-sided SGB will report significant improvement following a left-sided SGB. A retrospective chart review was conducted for patients who received SGB for PTSD symptoms between August 2019 and March 2020. All procedures were performed at an established musculoskeletal practice by the same anesthesia/pain fellowship-trained physician. Subjects included those who underwent a left-sided SGB (LSGB) only after non-response to a right-sided SGB (RSGB). Non-response was defined as less than 10 points of improvement on a PTSD Checklist (PCL-5). RESULTS: Out of 205 patients, 20 did not respond to an RSGB and were included in our analysis. Ten of these patients subsequently received an LSGB, and 90% responded favorably (PCL-5 mean improvement = 28.3 points). CONCLUSIONS: Based on our sample of 205 patients receiving SGB for PTSD, we concluded that at least 4.4% did not respond to a right-sided SGB but did have a significant response to a left-sided SGB.

Warfighter Resilience.

PURPOSE: Our aim in this study was to psychometrically test resilience assessments (Ego Resiliency Scale [ER89], Connor-Davidson Resilience Scale [CD-RISC 25], Responses to Stressful Experiences Scale [RSES short-form]) and describe resilience levels in a Special Operations Forces (SOF) combat sample. METHODS: Fifty-eight SOF combat Servicemembers either entering SOF (career start; n = 38) or having served multiple years with their SOF organization (mid-career; n = 20) self-reported resilience, mild traumatic brain injury (mTBI) history, and total military service. RESULTS: All resilience metrics demonstrated acceptable internal consistency, but ceiling effects were found for CD-RISC and RSES scores. ER89 scores were moderate on average. ER89 scores were higher in SOF career start than mid-career Servicemembers (ηρ2 = 0.07) when accounting for the interaction between SOF career stage and total military service (ηρ2 = 0.07). DISCUSSION: SOF mid-career Servicemembers had similar ER89 resilience scores with more total military service. The SOF career start combat Servicemembers had higher ER89 measured resilience with less total military service only, potentially showing a protective effect of greater service before entering SOF. CONCLUSION: The ER89 may be a more optimal military resilience metric than the other metrics studied; longitudinal research on SOF combat Servicemember resilience is warranted.

Active Warfighter Mental Health Lower in Mid-Career.

PURPOSE: The present study investigated Special Operations Forces (SOF) combat Servicemember mental health at different SOF career stages in association with resilience. METHODS: Fifty-eight SOF combat Service Members either entering SOF (career start; n=38) or multiple years with their SOF organization (mid-career; n=20) self-reported mild traumatic brain injury (TBI) history, resilience, subjective well-being, depression, anxiety, and posttraumatic stress. Poisson regression analyses were employed to test SOF career stage differences in each mental health symptom using resilience, while accounting for other pertinent military factors. RESULTS: There were significant interaction effects of SOF career stage and resilience on mental health symptoms. SOF career start combat Servicemembers endorsed lower depression and posttraumatic stress and higher subjective well-being with higher resilience, but these associations between resilience and mental health symptoms were not seen in SOF mid-career Servicemembers. CONCLUSIONS: Although preliminary, the adaptive association between resilience and mental health seemed to be blunted in combat Servicemembers having served multiple years in SOF. This information informs research to provide evaluation tools to support prophylactic performance and long-term health preservation in military populations.

Behavioral health clinicians endorse stellate ganglion block as a valuable intervention in the treatment of trauma-related disorders.

The stellate ganglion block (SGB) procedure has been used successfully for over 10 years to treat post-traumatic stress symptoms in thousands of US military service members, civilians, and veterans in select hospitals in Europe and North America. Primarily through targeting the autonomic nervous system, the SGB procedure serves as an invaluable adjunct to trauma-focused psychotherapy. Without published best practices for emerging therapies, clinicians are left on their own to determine how best to apply new treatments to their patient populations. The aim of this qualitative research was to compile attitudes and recommendations from therapists with expertise in using SGB for treating symptoms of post-traumatic stress disorder, so that their experiences could be disseminated widely to clinicians without SGB expertise. An 18-item survey was developed and distributed electronically to a group of behavioral health professionals of various specialties between May and June 2020. Of surveyed behavioral health clinicians with personal experience incorporating SGB into their trauma-focused psychotherapy, 95% of respondents would recommend SGB to a colleague as a useful tool for the treatment of trauma-related disorders. SGB was rated at least as useful as the most valuable interventions listed in the American Psychological Association Clinical Practice Guideline for the Treatment of Post-traumatic Stress Disorder with 100% of respondents characterizing SGB as 'Very Beneficial' or 'Somewhat Beneficial', and 0 respondents characterizing SGB as 'Not Helpful' or 'Harmful'. Given the feedback from this study, behavioral health providers should consider using SGB in conjunction with standard trauma-focused care.

Neurovascular Coupling in Special Operations Forces Combat Soldiers.

The purpose of this study was to investigate how concussion history affects neurovascular coupling in Special Operations Forces (SOF) combat Soldiers. We studied 100 SOF combat Soldiers [age = 33.5 ± 4.3 years; height = 180.4 ± 6.0 cm; 55 (55.0%) with self-reported concussion history]. We employed transcranial Doppler (TCD) ultrasound to assess neurovascular coupling (NVC) via changes in posterior cerebral artery (PCA) velocity in response to a reading and a visual search task. Baseline TCD data were collected for 2 min. NVC was quantified by the percent change in overall PCA response curves. We employed linear mixed effect models using a linear spline with one knot to assess group differences in percent change observed in the PCA velocity response curves between SOF combat Soldiers with and without a concussion history. Baseline PCA velocity did not significantly differ (t98 = 1.28, p = 0.20) between those with and without concussion history. Relative PCA velocity response curves did not differ between those with and without a concussion history during the reading task (F1,98 = 0.80, p = 0.37) or the visual search task (F1,98 = 0.52, p = 0.47). When assessing only SOF combat Soldiers with a concussion history, differential response to task was significantly greater in those with 3 or more concussions (F1,4341 = 27.24, p < 0.0001) relative to those with 1-2 concussions. Despite no main effect of concussion history on neurovascular coupling response in SOF combat Soldiers, we observed a dose-response based on lifetime concussion incidence. While long-term neurophysiological effects associated with head impact and blast-related injury are currently unknown, assessing NVC response may provide further insight into cerebrovascular function and overall physiological health.

Mental Health Symptoms Are Associated With Mild Traumatic Brain Injury History in Active Special Operations Forces (SOF) Combat and Combat Support Soldiers.

INTRODUCTION: Special Operations Forces (SOF) combat arms and combat support Soldiers are at risk for impaired mental health, such as mood- and stress-related disorders, due to operational and training demands. Additionally, these individuals experience high risk for sustaining mild traumatic brain injury (mTBI). These mTBIs have also been linked to negative psychological outcomes, such as anxiety and depressive symptoms. Studying mental illnesses and their related symptoms alone does not fully address mental health, which may be better understood by 2 separate but overlapping continua measuring both mental illness and subjective well-being (ie, emotional, psychological, and social well-being). Due to the lack of research in this area, current mental health symptoms in active SOF combat Soldiers in relation to mTBI warrants investigation. MATERIALS AND METHODS: In this study, 113 SOF combat and combat support Soldiers completed self-report psychological and mTBI history measures during an in-person laboratory setting. These psychometric measures included (1) psychological distress (Brief Symptom Inventory 18), (2) anxiety (Generalized Anxiety Disorder 7-item), (3) posttraumatic stress (PTSD Checklist for DSM-5), (4) somatization (Patient Health Questionnaire-15), and (5) subjective well-being (Mental Health Continuum Short Form). RESULTS: On average, SOF combat Soldiers endorsed moderate well-being and low psychological distress, somatization, posttraumatic stress, and anxiety. Most SOF combat Soldiers had sustained 1 or more mTBI. We observed mTBI history had significant effects on each dependent variable in the expected directions. History of more mTBIs, controlling for age, was associated with lower subjective well-being as well as higher psychological distress, somatization, posttraumatic stress, and anxiety symptoms. CONCLUSION: Although SOF combat Soldiers reported relatively adaptive mental health symptoms across participants, there was considerable variance in the measures reported. Some of the variance in mental health symptoms was accounted for by mTBI history while controlling for age, with reporting higher numbers of lifetime mTBIs and older age being associated with worse mental health symptoms. Longitudinal investigations into these associations and their impact on Soldier performance is warranted.

Cerebrovascular Reactivity in Special Operations Forces Combat Soldiers.

The purpose of this study was to investigate how concussion history affects cerebrovascular reactivity (CVR) in Special Operations Forces (SOF) combat soldiers. We studied 104 SOF soldiers [age = 33.5 ± 4.3 years; height = 179.7 ± 6.3 cm; 59 (56.7%) with self-reported concussion history]. We employed transcranial Doppler (TCD) ultrasound to measure middle cerebral artery (MCA) velocity. Baseline TCD data were collected for 2 min. Changes in MCA velocity were measured in response to five breath-holding trials and five hyperventilation trials. Cerebrovascular reactivity was quantified by the breath-holding index (BHI), vasomotor reactivity reserve (VMRr), and percent change in overall response curves. Independent t tests were employed to assess group differences in BHI, and VMRr values. We employed mixed effects models with quadratic mean structures to assess group differences in percent change MCA velocity response curves. There were no significant group differences in BHI (t102 = 0.04, p = 0.97) or VMRr (t102 = -0.33, p = 0.75). There were no group differences in relative MCA velocity response curves during the breath-holding task (F1,5092 = 0.19, p = 0.66) or during the hyperventilation task (F1,5092 = 0.41, p = 0.52) between SOF soldiers with and without a self-reported concussion history. If CVR deficits exist immediately post-concussion, our study suggests that these deficits recover over time in this population. While long-term neurophysiological effects of blast-related injury are currently unknown, assessing CVR response may provide further insight into cerebrovascular function and overall physiological health following blast exposure.

The relationship between neurovascular coupling, vision and sensory performance, and concussion history in Special Operations Forces combat soldiers.

OBJECTIVE: To determine the relationship between neurovascular coupling (NVC), vision and sensory performance in Special Operations Forces (SOF) combat soldiers with and without concussion history. METHODS: We studied 61 SOF combat soldiers (male, age = 33.8 ± 3.7 years, n = 40 with concussion history [Median = 3; range = 1-10+]). We instrumented our participants with transcranial Doppler to quantify NVC response during reading and visual search tasks. All participants completed vision and sensory performance testing (Senaptec Sensory Station). We performed separate multiple regressions to determine if relationships between NVC and vision and sensory performance testing existed while controlling for concussion history, and to investigate the interaction between NVC and concussion history. RESULTS: Those with higher visual search NVC response magnitudes demonstrated significantly worse contrast sensitivity when controlling for concussion history (F1,60=4.57, ß = 0.03, p = .04, R2 = 12.6%). We did not observe any other significant relationships between NVC and visual and sensory performance tests nor did we observe any significant interactions between NVC and concussion history (p > .05). CONCLUSIONS: Heightened NVC response magnitudes are related to reduced contrast sensitivity in SOF combat soldiers. Because concussion history does not impact the relationships between outcomes, these measures may be utilized for performance evaluation at any point in a soldier's career. The lack of relationships between NVC response magnitude and some of the other vision and sensory performance outcomes suggests that implementing NVC assessment may add unique information and enable clinicians to detect physiological deficits that may otherwise go undetected.

Effect of Stellate Ganglion Block Treatment on Posttraumatic Stress Disorder Symptoms: A Randomized Clinical Trial.

Importance: This is the first multisite, randomized clinical trial of stellate ganglion block (SGB) outcomes on posttraumatic stress disorder (PTSD) symptoms. Objective: To determine whether paired SGB treatments at 0 and 2 weeks would result in improvement in mean Clinician-Administered PTSD Scale for DSM-5 (CAPS-5) total symptom severity scores from baseline to 8 weeks. Design, Setting, and Participants: This multisite, blinded, sham-procedure, randomized clinical trial used a 2:1 SGB:sham ratio and was conducted from May 2016 through March 2018 in 3 US Army Interdisciplinary Pain Management Centers. Only physicians performing the procedures and the procedure nurses were aware of the intervention (but not the participants or assessors); their interactions with the participants were scripted and limited to the 2 interventions. Active-duty service members on stable psychotropic medication dosages who had a PTSD Checklist-Civilian Version (PCL-C) score of 32 or more at screening were included. Key exclusion criteria included a prior SGB treatment, selected psychiatric disorders or substance use disorders, moderate or severe traumatic brain injury, or suicidal ideation in the prior 2 months. Interventions: Paired right-sided SGB or sham procedures at weeks 0 and 2. Main Outcomes and Measures: Improvement of 10 or more points on mean CAPS-5 total symptom severity scores from baseline to 8 weeks, adjusted for site and baseline total symptom severity scores (planned a priori). Results: Of 190 screened individuals, 113 (59.5%; 100 male and 13 female participants; mean [SD] age, 37.3 [6.7] years) were eligible and randomized (74 to SGB and 39 to sham treatment), and 108 (95.6% of 113) completed the study. Baseline characteristics were similar in the SGB and sham treatment groups, with mean (SD) CAPS-5 scores of 37.6 (11.2) and 39.8 (14.4), respectively (on a scale of 0-80); 91 (80.0%) met CAPS-5 PTSD criteria. In an intent-to-treat analysis, adjusted mean total symptom severity score change was -12.6 points (95% CI, -15.5 to -9.7 points) for the group receiving SGB treatments, compared with -6.1 points (95% CI, -9.8 to -2.3 points) for those receiving sham treatment (P = .01). Conclusions and Relevance: In this trial of active-duty service members with PTSD symptoms (at a clinical threshold and subthreshold), 2 SGB treatments 2 weeks apart were effective in reducing CAPS-5 total symptom severity scores over 8 weeks. The mild-moderate baseline level of PTSD symptom severity and short follow-up time limit the generalizability of these findings, but the study suggests that SGB merits further trials as a PTSD treatment adjunct. Trial Registration: ClinicalTrials.gov identifier: NCT03077919.