Central Auditory Processing Dysfunction in Service Members and Veterans: Treatment Considerations and Strategies.

PURPOSE: Military risk factors such as blast exposure, noise exposure, head trauma, and neurotoxin exposure place Service members and Veterans at risk for deficits associated with auditory processing dysfunction. However, there is no clinical guidance specific to the treatment of auditory processing deficits in this unique population. We provide an overview of available treatments and their limited supporting evidence for use in adults, emphasizing the need for multidisciplinary case management and interdisciplinary research to support evidence-based solutions. METHOD: We explored relevant literature to inform the treatment of auditory processing dysfunction in adults, with emphasis on findings involving active or former military personnel. We were able to identify a limited number of studies, pertaining primarily to the treatment of auditory processing deficits through the use of assistive technologies and training strategies. We assessed the current state of the science for knowledge gaps that warrant additional study. CONCLUSIONS: Auditory processing deficits often co-occur with other military injuries and may pose significant risk in military operational and occupational settings. Research is needed to advance clinical diagnostic and rehabilitative capabilities, guide treatment planning, support effective multidisciplinary management, and inform fitness-for-duty standards. We emphasize the need for an inclusive approach to the assessment and treatment of auditory processing concerns in Service members and Veterans and for evidence-based solutions to address complex military risk factors and injuries.

Battlefield Acupuncture as a Treatment Option for Chronic Tinnitus: A Pilot Study.

INTRODUCTION: There is no cure for tinnitus, which is a highly prevalent condition in service members and veterans. Battlefield acupuncture (BFA) can be used to manage pain and stress-related symptoms. We investigated BFA as a safe, low-cost treatment for tinnitus perception and coping in eight chronic tinnitus patients who were followed for 6 months after two BFA treatments to identify changes in tinnitus severity or impact. MATERIALS AND METHODS: Patients completed case history, Tinnitus Screener, Tinnitus Functional Index (TFI), Tinnitus Reaction Questionnaire (TRQ), and Hospital Anxiety and Depression Scale (HADS) questionnaires at baseline, at two BFA treatment sessions (2 weeks apart), and at four follow-up sessions (at 1, 2, 4 and 6 months after treatment). Questionnaire score changes were evaluated over time by using restricted maximum likelihood hierarchical regression modeling from baseline to 1-, 2-, 4-, and 6-month post-treatment follow-ups. RESULTS: TFI and TRQ group means were both significantly reduced at 1 month after treatment, and these reductions persisted through the 2- and 4-month follow-ups. The TRQ group mean remained significantly reduced after 6 months. CONCLUSIONS: Findings from eight chronic tinnitus sufferers who received two BFA treatment sessions are reported here, suggesting at least short-term treatment benefits observed as reductions in tinnitus-related psychological distress and impact. Although these findings are constrained by the study's small sample size and limited treatment period, its findings underscore the need for further research to determine the potential benefits of BFA for individuals who suffer from chronic tinnitus. Future research should consider the possibility of more lasting benefits through extended BFA treatment, with a comparison of BFA treatment against other treatment methods.

Acquired Central Auditory Processing Disorder in Service Members and Veterans.

Purpose A growing body of evidence suggests that military service members and military veterans are at risk for deficits in central auditory processing. Risk factors include exposure to blast, neurotrauma, hazardous noise, and ototoxicants. We overview these risk factors and comorbidities, address implications for clinical assessment and care of central auditory processing deficits in service members and veterans, and specify knowledge gaps that warrant research. Method We reviewed the literature to identify studies of risk factors, assessment, and care of central auditory processing deficits in service members and veterans. We also assessed the current state of the science for knowledge gaps that warrant additional study. This literature review describes key findings relating to military risk factors and clinical considerations for the assessment and care of those exposed. Conclusions Central auditory processing deficits are associated with exposure to known military risk factors. Research is needed to characterize mechanisms, sources of variance, and differential diagnosis in this population. Existing best practices do not explicitly consider confounds faced by military personnel. Assessment and rehabilitation strategies that account for these challenges are needed. Finally, investment is critical to ensure that Veterans Affairs and Department of Defense clinical staff are informed, trained, and equipped to implement effective patient care.

Hidden Hearing Injury: The Emerging Science and Military Relevance of Cochlear Synaptopathy.

INTRODUCTION: The phenomenon recently described as "hidden hearing loss" was the subject of a meeting co-hosted by the Department of Defense Hearing Center of Excellence and MIT Lincoln Laboratory to consider the potential relevance of noise-related synaptopathic injury to military settings and performance, service-related injury scenarios, and military medical priorities. Participants included approximately 50 researchers and subject matter experts from academic, federal, and military laboratories. Here we present a synthesis of discussion topics and concerns, as well as specific research objectives identified to develop militarily relevant knowledge. MATERIALS AND METHODS: We consider findings from studies to date that have demonstrated cochlear synaptopathy and neurodegenerative processes apparently linked to noise exposure in animal models. We explore the potential relevance of these findings to the prediction and prevention of military hearing injuries, and to comorbid injuries in the neurological domain. RESULTS: Noise-induced cochlear synaptopathic injury is not detected by conventional audiometric assessment of threshold sensitivity. Animal studies suggest there may be a generous window of opportunity for intervention to mitigate or prevent cochlear neurodegenerative processes, e.g., by administration of neurotrophins or antioxidants. However, it is not yet known if the mechanisms that underlie "hidden hearing loss" also occur in human beings or, if so, how to identify them early, and how and when to intervene. CONCLUSION: Neurological injuries resulting from noise exposures via the auditory system have potentially significant implications for military Service Member performance, long-term Veteran health, and noise exposure standards. Mediated via auditory pathways, such injuries have possible relationship to clinical impairments including speech perception, and may be a largely overlooked contributor to cognitive symptoms associated with other military service-related injuries such as blast exposure and brain trauma. The potential health and performance consequences of noise-induced cochlear synaptopathic injury are easily overlooked, especially if it is assumed that hearing threshold sensitivity loss is the major concern. There should be a renewed impetus to further characterize and model synaptopathic mechanisms of auditory injury; study its potential impact on human auditory function, cognition, and performance metrics of military relevance; and develop solutions for auditory protection (including noise dosimetry) and treatment if appropriate following noise or blast exposure in military scenarios. We identify specific problems, solution objectives, and research objectives. Recommended research calls for a multidisciplinary approach to address cochlear nerve synaptopathy, central (brain) dysfunction, noise exposure measurement and metrics, and clinical assessment.

The Biological Basis of Chronic Traumatic Encephalopathy following Blast Injury: A Literature Review.

The United States Department of Defense Blast Injury Research Program Coordinating Office organized the 2015 International State-of-the-Science meeting to explore links between blast-related head injury and the development of chronic traumatic encephalopathy (CTE). Before the meeting, the planning committee examined articles published between 2005 and October 2015 and prepared this literature review, which summarized broadly CTE research and addressed questions about the pathophysiological basis of CTE and its relationship to blast- and nonblast-related head injury. It served to inform participants objectively and help focus meeting discussion on identifying knowledge gaps and priority research areas. CTE is described generally as a progressive neurodegenerative disorder affecting persons exposed to head injury. Affected individuals have been participants primarily in contact sports and military personnel, some of whom were exposed to blast. The symptomatology of CTE overlaps with Alzheimer's disease and includes neurological and cognitive deficits, psychiatric and behavioral problems, and dementia. There are no validated diagnostic criteria, and neuropathological evidence of CTE has come exclusively from autopsy examination of subjects with histories of exposure to head injury. The perivascular accumulation of hyperphosphorylated tau (p-tau) at the depths of cortical sulci is thought to be unique to CTE and has been proposed as a diagnostic requirement, although the contribution of p-tau and other reported pathologies to the development of clinical symptoms of CTE are unknown. The literature on CTE is limited and is focused predominantly on head injuries unrelated to blast exposure (e.g., football players and boxers). In addition, comparative analyses of clinical case reports has been challenging because of small case numbers, selection biases, methodological differences, and lack of matched controls, particularly for blast-exposed individuals. Consequently, the existing literature is not sufficient to determine whether the development of CTE is associated with head injury frequency (e.g., single vs. multiple exposures) or head injury type (e.g., impact, nonimpact, blast-related). Moreover, the incidence and prevalence of CTE in at-risk populations is unknown. Future research priorities should include identifying additional risk factors, pursuing population-based longitudinal studies, and developing the ability to detect and diagnose CTE in living persons using validated criteria.

Characterization and Comparison of Combat-Related Injuries in Women During OIF and OEF.

Although historically restricted from combat roles, women suffer from combat-related injuries, especially in recent conflicts where asymmetrical warfare erases distinctions between forward and rear operating areas. U.S. servicewomen who sustained combat-related injury in Operation Iraqi Freedom (OIF) or Operation Enduring Freedom (OEF) between January 2003 and May 2014 were identified from the Expeditionary Medical Encounter Database. Injuries were characterized using Abbreviated Injury Scale and International Classification of Diseases, 9th Revision codes. Of the 844 combat-related injury episodes in women, 51% (n = 433) were OIF injuries and 49% (n = 411) were OEF injuries. Blast events were responsible for 90% of injuries. The average Injury Severity Score was 3, with no statistical difference in means between OIF and OEF. Of significance were increased head injuries in OEF compared with OIF (80% vs. 48%; p < 0.001). Although the majority of combat-related injuries suffered by women were mild, some women suffered life-threatening injuries, and nearly 65% of the injury episodes resulted in more than one injury. More research is needed as the roles of women in the military continue to expand. Future studies will investigate quality of life outcomes and gender differences in combat-related injuries.

Women in Combat: Summary of Findings and a Way Ahead.

The Women in Combat Symposium was held at the Defense Health Headquarters April 29 to May 1, 2014, cohosted by the Office of the Assistant Secretary of Defense for Health Affairs and the Consortium for Health and Military Performance. The conference was a call to renew and extend research investment and policy commitment to recognize operational scenarios, requirements, health priorities, and combat-related injury exposures uniquely relevant to the performance and well-being of female Service members. Symposium participants worked in groups to identify knowledge and capability gaps critical to the successful integration, health, and performance of female Service members in combat roles and to develop recommendations for researchers and policy makers to address gaps in three specific areas of concern: Leadership and Peer Behavior, Operational Performance, and Health and Well-Being. Consensus findings are summarized as 20 research gaps and accompanying recommendations. Each represents an opportunity to advance health and performance outcomes and to leverage female Service members' strengths and capacities to the general benefit of all Service members and their families.

Neuromodulation research and application in the U.S. Department of Defense.

BACKGROUND: Modern neuromodulatory techniques for military applications have been explored for the past decade, with an intent to optimize operator performance and, ultimately, to improve overall military effectiveness. In light of potential military applications, some researchers have voiced concern about national security agency involvement in this area of research, and possible exploitation of research findings to support military objectives. The aim of this article is to examine the U.S. Department of Defense's interest in and application of neuromodulation. METHODS: We explored articles, cases, and historical context to identify critical considerations of debate concerning dual use (i.e., national security and civilian) technologies, specifically focusing on non-invasive brain stimulation (NIBS). DISCUSSION: We review the background and recent examples of DoD-sponsored neuromodulation research, framed in the more general context of research that aims to optimize and/or rehabilitate human performance. We propose that concerns about military exploitation of neuromodulatory science and technology are not unique, but rather are part of a larger philosophic debate pertaining to military application of human performance science and technology. We consider unique aspects of the Department of Defense research enterprise--which includes programs crucial to the advancement of military medicine--and why it is well-situated to fund and perform such research. We conclude that debate concerning DoD investment in human performance research must recognize the significant potential for dual use (civilian, medical) benefit as well as the need for civilian scientific insight and influence. Military interests in the health and performance of service members provide research funding and impetus to dual use applications that will benefit the civilian community.