Impact of TBI, PTSD, and Hearing Loss on Tinnitus Progression in a US Marine Cohort

[Chronic tinnitus from a psychological perspective]

Chronic tinnitus is a common and often highly distressing phenomenon that, in its chronic phase, is primarily maintained by psychological factors. Individuals affected by tinnitus frequently attribute fluctuations in their emotional well-being causally to the tinnitus symptom. However, from a psychotherapeutic perspective, both the perception of symptoms and the resulting emotional distress are shaped by complex, dynamic interactions involving (a) personal life experiences, (b) personality traits, (c) the subjective interpretation of intrapsychic and interpersonal stimuli, (d) emotional states, and (e) coping strategies at both intrapsychic and interpersonal levels. This review begins with a brief introduction and then connects a well-established psychological theory of chronic tinnitus development and maintenance with a broader vulnerability-stress-coping model. Within this framework, we present key research findings from both somatic and psychological perspectives, ultimately offering insights for psychotherapeutic prevention and treatment approaches.

Resilience after combat: A prospective, longitudinal study of Marines and Navy Corpsmen

Resilience is common, yet our understanding of key biopsychosocial and environmental correlates is limited. Additionally, perceived resilience is often conflated with absence of psychiatric symptoms. Here we leverage prospective, longitudinal data from 1835 Marines and Navy Corpsmen to examine predictors of perceived resilience 3 months after a combat deployment, while controlling for pre-deployment and concurrent psychiatric symptoms. Marines and Corpsmen did not differ significantly on psychosocial or clinical factors, and 50.4% reported high perceived resilience after deployment. Across groups, the strongest predictors of post-deployment perceived resilience were pre-deployment perceived resilience, positive emotions, and social support. Concurrent depression was the only clinical symptom negatively associated with perceived resilience. Our findings suggest that perceived resilience is a multi-dimensional construct that involves both psychosocial and personality factors, including but not limited to low psychopathology. Notably, establishing strong social support networks and encouraging positive emotions may help promote resilience following deployment.

Incidence and Risk Factors for Tinnitus Among Military Service Members in the Millennium Cohort Study

PURPOSE

Military personnel may be repeatedly exposed to high-noise environments that may increase tinnitus risk. Previous military research on tinnitus has often utilized small samples of personnel with specific experiences and exposures (e.g., combat deployment), with few examinations leveraging longitudinal data. The purpose of this study was to determine the incidence and associated risk factors for new-onset tinnitus in a large prospective and representative military cohort.

METHOD

This study utilized data from the Millennium Cohort Study, the largest and longest running longitudinal health study of service members and veterans, to ascertain self-reported and medical diagnoses of tinnitus. Multivariable logistic regression was employed to identify factors associated with new-onset tinnitus.

RESULTS

New-onset tinnitus was self-reported by 10.7% (n = 2,527) of participants while 3.5% (n = 511) had a medical record tinnitus diagnosis. Tinnitus risk was associated with multiple characteristics, including active duty service, being a member of the Army or Marine Corps, combat deployment experience, combat specialist occupation, prior history of mild traumatic brain injury, panic/anxiety, posttraumatic stress disorder (PTSD) alone, and PTSD comorbid with depression.

CONCLUSIONS

This may be the first study to determine new-onset tinnitus utilizing both self-reported and medical record data in a large prospective cohort of service members and veterans. Additional prospective studies are needed to corroborate our findings and further describe the temporal relationships of military occupational and mental health characteristics with service-related new-onset tinnitus.

Access to Hearing Healthcare and Barriers Among United States Veterans: A Survey-Based Study

Objective

We investigated use of hearing care among US veterans and explore motivations, barriers, and adherence to hearing healthcare.

Study Design

Cross-sectional online survey.

Setting

US Veterans.

Methods

This cross-sectional, online survey-based study included 287 respondents who identified themselves as veterans on ResearchMatch (NIH-sponsored national registry of research volunteers). Questions regarding hearing loss, tinnitus, use of hearing care, and facilitators/barriers to hearing care were asked. Descriptive statistics were utilized for data analysis.

Results

In this cohort, the rate of self-reported hearing loss and tinnitus were 61.0% and 74.2%, respectively. Among these, 66.9% of those with hearing loss and 36.2% of those with tinnitus reported seeking hearing care. Most important motivators of seeking hearing care (average on 1-5 Likert scale) included personal importance of hearing (4.0; SD = 1.1), difficulty hearing others (3.6; SD = 1.1), and degree of hearing loss (3.3; SD = 1.1). Most common barriers included uncertainty regarding who to reach out to for hearing care (42.9%), inability to get time off work (34.3%), and nervousness about seeing a provider (28.6%). Common reasons to decline hearing aids reporting that hearing was not bad enough for hearing aids (72.2%) and included inability to afford hearing aid (55.6%).

Conclusion

In this cohort, many US veterans sought care for hearing loss, though barriers still exist, including uncertainty regarding how to access appropriate care, being too far from a provider, and challenges with cost. Future studies should investigate methods to alleviate these internal and external barriers to hearing care and emphasize the importance of motivators for seeking care.

Associations of Traumatic Brain Injury and Hearing: Results From the Atherosclerosis Risk in Communities Neurocognitive Study (ARIC-NCS)

OBJECTIVE

To examine associations of traumatic brain injury (TBI) with self-reported and clinical measures of hearing function.

SETTING

Four US communities.

PARTICIPANTS

A total of 3176 Atherosclerosis Risk in Communities Study participants who attended the sixth study visit in 2016-2017, when hearing was assessed.

DESIGN

Prospective cohort study. TBI occurring prior to the hearing assessment was defined using self-reported questions and "International Classification of Diseases-9th/10th Edition" (ICD-9/10) codes.

MAIN MEASURES

Hearing function was assessed by self-reported questionnaires and clinically measured indices (audiometry [4-frequency pure tone average for each ear] and speech-in-noise testing). Linear, logistic, and multinomial logistic models adjusted for sociodemographics, vascular risk factors, and occupational noise exposure were used to examine associations.

RESULTS

Participants were a mean age of 79 years, 59% were female, 21% were of self-reported Black race, and 33% had a history of TBI (median time from first TBI to hearing assessment: 39 years (25th-75th percentile = 19-63 years). Compared to participants without TBI, participants with prior TBI had higher age-adjusted prevalence of self-reported hearing loss (42.3% vs 35.3%), tinnitus (28.0% vs 23.8%), hearing aid use (23.4% vs 17.8%), pure tone average > 40 dB (30.6% vs 24.8%), and presence in the lowest quartile of speech-in-noise performance (27.6% vs 22.8%). With further adjustment, and particularly with adjustment for occupational noise exposure, associations with hearing measures were largely no longer statistically significant. In secondary analyses of associations of TBI frequency and severity with hearing function, results were similar to our main analyses, without evidence of dose-dependent associations.

CONCLUSIONS AND RELEVANCE

In this community-based cohort, prior TBI was associated with impaired hearing on both self-reported and clinically measured assessments, but these associations were attenuated after adjustment for occupational noise exposure. These results underscore the importance of the consideration of loud noise exposures, which may confound associations of TBI with hearing, in future studies.

Mild Traumatic Brain Injury and the Auditory System: An Overview of the Mechanisms, Clinical Presentations, and Current Diagnostic Modalities

The acute and long-term consequences of mild traumatic brain injury (mTBI) are far reaching. Though it may often be overlooked due to the now expansive field of research dedicated to understanding the consequences of mTBI on the brain, recent work has revealed that substantial changes in the vestibulo-auditory system can also occur due to mTBI. These changes, termed "labyrinthine" or "cochlear concussion," include hearing loss, vertigo, and tinnitus that develop after mTBI in the setting of an intact bony labyrinthine capsule (as detected on imaging). In the review that follows, we focus our discussion on the effects of mTBI on the peripheral structures and pathways of the auditory and vestibular systems. Although the effects of indirect trauma (e.g., noise and blast trauma) have been well-investigated, there exists a profound need to improve our understanding of the effects of direct head injury (such as mTBI) on the auditory and vestibular systems. Our aim is to summarize the current evidentiary foundation upon which labyrinthine and/or cochlear concussion are based to shed light on the ways in which clinicians can refine the existing modalities used to diagnose and treat patients experiencing mTBI as it relates to hearing and balance.

Pilot Study on Classification of Sensory Symptoms in PTSD

PTSD treatment that focused on a sensory symptoms is increasing. The study aimed to explore symptoms and abnormalities in the five senses exhibited by persons with PTSD and to examine whether there are any differences depending on type of traumatic experience. Questionnaire was followed by interviews to clinical psychologists involved in the treatment of PTSD. 249 PTSD symptoms exhibited in the sensory organs were collected. Sensory symptoms were classified into three categories according to the type of symptoms and the type of traumatic events. Cluster 1 is a group formed by child abuse and violence together with audition, tactile, and hyperarousal. Cluster 2 is made up of natural disaster, accident, and sexual assault together with vision, olfaction and intrusion. Cluster 3 is made up of multiple traumas together with gustation and dissociation. It is speculated that the survivors of Child abuse and violence are hypersensitive to sounds, the presence of others, and physical contact because they try to quickly sense when a perpetrator is approaching. Natural disasters, accidents, and sexual assault are events with strong smell and severe visual impact, it is possible that they may easily cause reliving of the event in the form of shocking visual images and smells in flashbacks. Dissociation symptoms were related with complex trauma and taste. The mouth is the site of first contact between mother and child, and it is possible that gustatory dissociation may occur mainly in cases of severe and repeated trauma since early childhood.

Associations Between Traumatic Brain Injury and Severity of Tinnitus-Related Functional Impairment Among US Military Veterans: A National, Population-Based Study

OBJECTIVE

To describe associations between a history of traumatic brain injury (TBI) and the severity of tinnitus-related functional impairment among a national, stratified random sample of veterans diagnosed with tinnitus by the Department of Veterans Affairs (VA) healthcare system.

SETTING

A multimodal (mailed and internet) survey administered in 2018. Participants: VA healthcare-using veterans diagnosed with tinnitus; veterans with comorbid TBI diagnosis were oversampled.

DESIGN

A population-based survey.

MAIN MEASURES

TBI history was assessed using International Classification of Diseases (ICD) diagnosis codes in veterans' VA electronic health records. The severity of participants' overall tinnitus-related functional impairment was measured using the Tinnitus Functional Index. Population prevalence and 95% confidence intervals (CIs) were estimated using inverse probability weights accounting for sample stratification and survey nonresponse. Veterans' relative risk ratios of very severe or moderate/severe tinnitus-related functional impairment, versus none/mild impairment, were estimated by TBI history using bivariable and multivariable multinomial logistic regression.

RESULTS

The population prevalence of TBI was 5.6% (95% CI: 4.8-6.4) among veterans diagnosed with tinnitus. Veterans with a TBI diagnosis, compared with those without a TBI diagnosis, had 3.6 times greater likelihood of rating their tinnitus-related impairment as very severe (95% CI: 2.1-6.3), and 1.5 times greater likelihood of rating their impairment as moderate/severe (95% CI: 1.0-2.4), versus none/mild.

CONCLUSIONS

These findings suggest an important role of TBI in the severity of tinnitus-related functional impairment among veterans. This knowledge can help inform the integration of tinnitus management services into the care received by veterans with TBI.

The Impact of Tinnitus Severity on Work Functioning among U.S. Military Veterans with Tinnitus

Tinnitus is highly prevalent among military Veterans. Severe tinnitus can be associated with negative impacts on daily life. Veterans with severe tinnitus may also have greater difficulties in functional roles, including work. However, few studies have explicitly explored this relationship. Traumatic brain injury (TBI), also prevalent among Veterans, is associated with tinnitus and can additionally impair work functioning. This quantitative investigation used a population-based survey to assess the relationship between tinnitus severity, measured using the Tinnitus Functional Index (TFI), and the impact of tinnitus on work, measured using a composite score from the Tinnitus History Questionnaire, among a stratified random sample of VA healthcare-using Veterans diagnosed with tinnitus, with and without comorbid TBI. Analyses were weighted to account for sampling design and Veteran non-response; multiple imputation was used to account for missing data. Results indicated that for every 1-point increase in TFI score, there was an average 8% increase in the odds of reporting a high level of impact on work functioning (OR: 1.08; 95% CI: 1.06, 1.11). Veterans with a comorbid TBI diagnosis, compared with those without, were more likely to have high tinnitus-related impact on work functioning (OR: 2.69, 95% CI: 1.85, 3.91), but the relationship between tinnitus severity and the impact of tinnitus on work functioning did not differ by TBI status. These data can help researchers and clinicians understand complex symptoms experienced by Veterans with tinnitus, with and without TBI, supporting the improved provision of clinical services to these patients.

Self-Reported Hearing Aid Requirements among U.S. Military Personnel and the Association with Probable Posttraumatic Stress Disorder

BACKGROUND

 Auditory problems are ubiquitous among U.S. military personnel. Hearing aids are an effective treatment for both hearing loss and tinnitus, two of the most common diagnoses among veterans awarded disability compensation, but the prevalence of hearing aid requirements in the U.S. military is unknown. Another military health problem is posttraumatic stress disorder (PTSD), an anxiety disorder characterized by exposure to a traumatic event. While some studies have found an association between auditory problems and PTSD, no research has examined the relationship between hearing aid requirements and PTSD.

PURPOSE

 To identify the prevalence of self-reported hearing aid requirements in U.S. military personnel and examine the association with PTSD.

RESEARCH DESIGN

 Cross-sectional study.

STUDY SAMPLE

 The study population included 104,728 U.S. Navy and Marine Corps service members who completed a Periodic Health Assessment between August and December 2021.

DATA ANALYSIS

 Prevalence of self-reported hearing aid requirements was calculated. A multivariable logistic regression model was used to determine the association between hearing aid requirements and PTSD, while adjusting for covariates.

RESULTS

 Overall, 1.0% (1,088/104,728) of the study population self-reported requiring hearing aids. Hearing aid requirements were positively associated with age, and the highest prevalence was among those aged 40 years and older (3.8%). There was also a statistically higher prevalence among men compared with women (1.2 vs. 0.5%), Marines compared with Navy personnel (1.2 vs. 0.9%), and active duty compared with National Guard/Reserve components (1.1 vs. 0.6%). A significantly higher proportion of service members who required hearing aids screened positive for PTSD than those without hearing aids (30.4 vs. 7.5%). In multivariable regression, those who required a hearing aid, compared with those who did not, had more than three times higher odds of screening positive for PTSD (odds ratio: 3.45; 95% confidence interval: 3.00-3.96).

CONCLUSION

 To our knowledge, this is the first study to report the prevalence of self-reported hearing aid requirements in the U.S. military as well as an association between requiring hearing aids and screening positive for PTSD. Our findings reaffirm the need for interprofessional collaboration between audiologists and psychological health professionals when providing care for these patients.

Relationship Between Tinnitus and Hearing Outcomes Among US Military Personnel After Blast Injury

OBJECTIVES

To examine the association between tinnitus and hearing outcomes among US military personnel after blast injury, including any hearing loss, low-frequency hearing loss, high-frequency hearing loss, early warning shift, and significant threshold shift.

DESIGN

In this retrospective study, the Blast-Related Auditory Injury Database was queried for male military service members who had audiometric data 2 years before and after blast injury between 2004 and 2012 with no history of hearing loss or tinnitus before injury (n = 1693). Tinnitus was defined by diagnostic codes in electronic health records. Multivariable logistic regression examined the association between tinnitus and hearing outcomes, while adjusting for covariates.

RESULTS

Overall, 14.2% (n = 241) of the study sample was diagnosed with tinnitus within 2 years after blast injury. The proportions of all examined hearing outcomes were higher among service members with tinnitus than those without ( p < 0.001). In multivariable analysis, service members with tinnitus had higher adjusted odds of any hearing loss (odds ratio [OR] = 1.72, 95% confidence interval [CI] = 1.20-2.47), low-frequency hearing loss (OR = 2.77, 95% CI = 1.80-4.26), high-frequency hearing loss (OR = 2.15, 95% CI = 1.47-3.16), early warning shift (OR = 1.83, 95% CI = 1.36-2.45), and significant threshold shift (OR = 2.15, 95% CI = 1.60-2.89) compared with service members without tinnitus.

CONCLUSIONS

The findings of this study demonstrate that tinnitus diagnosed within 2 years after blast injury is associated with the examined hearing outcomes in US military personnel. Service members with blast injury who subsequently experience tinnitus should receive routine audiometric hearing conservation testing and be carefully examined for poor hearing outcomes by an audiologist.

Evaluation and Management of Tinnitus: Are There Opportunities for Improvement?

OBJECTIVE

To review current information about diagnosis and management of tinnitus aiming to identify opportunities for achieving a cost-effective, efficient, evidence-based approach that meets the needs of tinnitus sufferers.

DATA SOURCES

PubMed/MEDLINE.

REVIEW METHODS

In total, 249 relevant published reports were reviewed. Pertinent keywords and MeSH terms identified reports via PubMed and EMBASE. Acknowledged experts were consulted on ways to improve tinnitus management.

CONCLUSIONS

There may be opportunities to improve evaluation and management of patients with tinnitus using modern modes of communication and a multidisciplinary therapeutic approach.

IMPLICATIONS FOR PRACTICE

Tinnitus can adversely affect quality of life while being time-consuming and costly to evaluate and manage. Based on both personal experience and the reports of others, patients with tinnitus who choose to see a physician primarily want to know two things: (1) that the tinnitus that is so distressing will not remain at the same level of severity forever and (2) that something can be done to help cope with the tinnitus that is so annoying. Recent advancements in internet communications, social media, information technology, artificial intelligence, machine learning, holistic medical care, mind-body integrative health care, and multidisciplinary approaches in medical therapeutics may be possibly making new ways of meeting the needs of patients with tinnitus.

Clusters of conditions among US service members diagnosed with mild TBI from 2017 through 2019

Background

Many US Military Service Members (SMs) newly diagnosed with mild Traumatic Brain Injury (mTBI) may exhibit a range of symptoms and comorbidities, making for a complex patient profile that challenges clinicians and healthcare administrators. This study used clustering techniques to determine if conditions co-occurred as clusters among those newly injured with mTBI and up to one year post-injury.

Methods

We measured the co-occurrence of 41 conditions among SMs diagnosed with mTBI within the acute phase, one or three months post-mTBI diagnosis, and chronic phase, one year post-mTBI diagnosis. Conditions were identified from the literature, clinical subject matter experts, and mTBI care guidelines. The presence of conditions were based on medical encounters recorded within the military health care data system. Through a two-step approach, we identified clusters. Principal component analysis (PCA) determined the optimal number of clusters, and hierarchical cluster analyses (HCA) identified the composition of clusters. Further, we explored how the composition of these clusters changed over time.

Results

Of the 42,018 SMs with mTBI, 23,478 (55.9%) had at least one condition of interest one-month post-injury, 26,831 (63.9%) three months post-injury, and 29,860 (71.1%) one year post injury. Across these three periods, six clusters were identified. One cluster included vision, cognitive, ear, and sleep disorders that occurred one month, three months, and one year post-injury. Another subgroup included psychological conditions such as anxiety, depression, PTSD, and other emotional symptoms that co-occurred in the acute and chronic phases post-injury. Nausea and vomiting symptoms clustered with cervicogenic symptoms one month post-injury, but later shifted to other clusters. Vestibular disorders clustered with sleep disorders and headache disorders one-month post-injury and included numbness and neuropathic pain one year post-injury. Substance abuse symptoms, alcohol disorders, and suicidal attempt clustered one year post-injury in a fifth cluster. Speech disorders co-occurred with headache disorders one month and one year post-injury to form a sixth cluster.

Conclusion

PCA and HCA identified six distinct subgroups among newly diagnosed mTBI patients during the acute and chronic phases post-injury. These subgroups may help clinicians better understand the complex profile of SMs newly diagnosed with mTBI.

The Interrelationship of Tinnitus and Hearing Loss Secondary to Age, Noise Exposure, and Traumatic Brain Injury

OBJECTIVE

Tinnitus has been the No. 1 disability at the Veteran Administration for the last 15 years, yet its interaction with hearing loss secondary to etiologies such as age, noise trauma, and traumatic brain injuries remains poorly characterized. Our objective was to analyze hearing loss and tinnitus, including audiogram data, of the Million Veteran Program within the context of military exposures in an aging population.

DESIGN

Health records, questionnaires, audiograms, and military data were aggregated for 758,005 Veteran participants in the Million Veteran Program 2011 to 2020, with relative risks (RR) calculated for ancestries, sex, hearing loss and military exposures such as combat, blast, and military era served. A multivariate model with significant demographic measures and exposures was then analyzed. Next, audiogram data stratified by sex were compared for those with and without tinnitus by two methods: first, mean thresholds at standard frequencies were compared to thresholds adjusted per ISO 7029:2000E age and sex formulae. Second, levels for those ≤40 years of age were compared with those 41 and older. Finally, a proportional hazards model was examined to ascertain the timing between the onset of tinnitus and hearing loss, calculated separately for electronic health record diagnoses (ICD) and self-report.

RESULTS

Tinnitus was either self-reported, diagnosed, or both in 37.5% (95% CI, 37.4 to 37.6), mean age 61.5 (95% CI, 61.4 to 61.5), range 18 to 112 years. Those with hearing loss were 4.15 times (95% CI, 4.12 to 4.15) as likely to have tinnitus. Americans of African descent were less likely to manifest tinnitus (RR 0.61, 95% CI, 0.60 to 0.61), as were women (RR 0.65, 95% CI, 0.64 to 0.65). A multivariate model indicated a higher RR of 1.73 for traumatic brain injury (95% CI, 1.71 to 1.73) and daily combat noise exposure (1.17, 95% CI, 1.14 to 1.17) than age (0.998, 95% CI, 0.997 to 0.998). Subjects ≤40 years of age had small but significantly elevated hearing thresholds through all standard frequencies compared to Veterans without tinnitus, and the effect of tinnitus on hearing thresholds diminished with age. In the hazard model, those >40 with new onset of tinnitus were at risk for hearing loss sooner and with greater incidence than those who were younger. The rate of hearing loss following tinnitus approached 100%. In contrast, only approximately 50% of those who self-reported hearing loss initially were at risk for later hearing loss, in contrast to ICD comparison, where those with ICD of hearing loss were more likely to sustain an ICD of tinnitus subsequently.

CONCLUSIONS

Evidence suggests that the occurrence of tinnitus in the military is more closely related to environmental exposures than to aging. The finding that tinnitus affects hearing frequencies across the audiogram spectrum suggests an acoustic injury independent of tonotopicity. Particularly for males >40, tinnitus may be a harbinger of audiologic damage predictive of later hearing loss.

Loss of central mineralocorticoid or glucocorticoid receptors impacts auditory nerve processing in the cochlea

The key auditory signature that may associate peripheral hearing with central auditory cognitive defects remains elusive. Suggesting the involvement of stress receptors, we here deleted the mineralocorticoid and glucocorticoid receptors (MR and GR) using a CaMKIIα-based tamoxifen-inducible Cre^ERT2/loxP approach to generate mice with single or double deletion of central but not cochlear MR and GR. Hearing thresholds of MRGR^{CaMKIIαCreERT2} conditional knockouts (cKO) were unchanged, whereas auditory nerve fiber (ANF) responses were larger and faster and auditory steady state responses were improved. Subsequent analysis of single MR or GR cKO revealed discrete roles for both, central MR and GR on cochlear functions. Limbic MR deletion reduced inner hair cell (IHC) ribbon numbers and ANF responses. In contrast, GR deletion shortened the latency and improved the synchronization to amplitude-modulated tones without affecting IHC ribbon numbers. These findings imply that stress hormone-dependent functions of central MR/GR contribute to “precognitive” sound processing in the cochlea.

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Top-down MR/GR signaling differentially contributes to cochlear sound processing

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Limbic MR stimulates auditory nerve fiber discharge rates

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Central GR deteriorates auditory nerve fiber synchrony

Hearing Loss Increases Inhibitory Effects of Prefrontal Cortex Stimulation on Sound Evoked Activity in Medial Geniculate Nucleus

Sensory gating is the process whereby irrelevant sensory stimuli are inhibited on their way to higher cortical areas, allowing for focus on salient information. Sensory gating circuitry includes the thalamus as well as several cortical regions including the prefrontal cortex (PFC). Defective sensory gating has been implicated in a range of neurological disorders, including tinnitus, a phantom auditory perception strongly associated with cochlear trauma. Recently, we have shown in rats that functional connectivity between PFC and auditory thalamus, i.e., the medial geniculate nucleus (MGN), changes following cochlear trauma, showing an increased inhibitory effect from PFC activation on the spontaneous firing rate of MGN neurons. In this study, we further investigated this phenomenon using a guinea pig model, in order to demonstrate the validity of our finding beyond a single species and extend data to include data on sound evoked responses. Effects of PFC electrical stimulation on spontaneous and sound-evoked activity of single neurons in MGN were recorded in anaesthetised guinea pigs with normal hearing or hearing loss 2 weeks after acoustic trauma. No effect, inhibition and excitation were observed following PFC stimulation. The proportions of these effects were not different in animals with normal hearing and hearing loss but the magnitude of effect was. Indeed, hearing loss significantly increased the magnitude of inhibition for sound evoked responses, but not for spontaneous activity. The findings support previous observations that PFC can modulate MGN activity and that functional changes occur within this pathway after cochlear trauma. These data suggest hearing loss can alter sensory gating which may be a contributing factor toward tinnitus development.

A Retrospective Study of the Effects of Traumatic Brain Injury on Auditory Function: From a Clinical Perspective

PURPOSE

The main purpose of this retrospective study was to identify auditory dysfunctions related to traumatic brain injury (TBI) in individuals evaluated in an Audiology clinic.

METHOD

Peripheral and central auditory evaluations were performed from March 2014 to June 2018 in 26 patients (14 males) with TBI. The age of the participants ranged from 9 to 59 years old (34.24 ± 15.21). Six participants had blast-related TBI and 20 had blunt force TBI. Sixteen experienced a single TBI event whereas ten experienced several. Correlation analyses were performed to verify the relationship, if any, between the number of auditory tests failed and the number, type, and severity of TBIs.

RESULT

All participants failed at least one auditory test. Nearly 60% had abnormal results on degraded speech tests (compressed and echoed, filtered or in background noise) and 25% had a high frequency hearing loss. There was no statistically significant correlation between the number of auditory tests failed and the number, type, and severity of TBIs.

CONCLUSION

Results indicated negative and heterogenous effects of TBI on peripheral and central auditory function and highlighted the need for a more extensive auditory assessment in individuals with TBI.

Prevalence of Comorbidities in Active and Reserve Service Members Pre and Post Traumatic Brain Injury, 2017-2019

OBJECTIVE

To understand the prevalence of comorbidities associated with traumatic brain injury (TBI) patients among active and reserve service members in the U.S. Military.

METHODS

Active and reserve SMs diagnosed with an incident TBI from January 2017 to October 2019 were selected. Nineteen comorbidities associated with TBI as identified in the literature and by clinical subject matter experts were described in this article. Each patient's medical encounters were evaluated from 6 months before to 2 years following the initial TBI diagnoses date in the Military Data Repository, if data were available. Time-to-event analyses were conducted to assess the cumulative prevalence over time of each comorbidity to the incident TBI diagnosis.

RESULTS

We identified 47,299 TBI patients, of which most were mild (88.8%), followed by moderate (10.5%), severe (0.5%), and of penetrating (0.2%) TBI severity. Two years from the initial TBI diagnoses, the top five comorbidities within our cohort were cognitive disorders (51.9%), sleep disorders (45.0%), post-traumatic stress disorder (PTSD; 36.0%), emotional disorders (22.7%), and anxiety disorders (22.6%) across severity groups. Cognitive, sleep, PTSD, and emotional disorders were the top comorbidities seen within each TBI severity group. Comorbidities increased pre-TBI to post-TBI; the more severe the TBI, the greater the prevalence of associated comorbidities.

CONCLUSION

A large proportion of our TBI patients are afflicted with comorbidities, particularly post-TBI, indicating many have a complex profile. The military health system should continue tracking comorbidities associated with TBI within the U.S. Military and devise clinical practices that acknowledge the complexity of the TBI patient.

Mental Health Symptoms Among Veteran VA Users by Tinnitus Severity:A Population-based Survey

INTRODUCTION

Tinnitus is prevalent among Service members and Veterans and is often comorbid with mental health disorders. Associations between the severity of individuals' tinnitus and mental health symptoms are not well described.

MATERIALS AND METHODS

We conducted a population-based survey of a stratified random sample of 1,800 Veterans diagnosed with tinnitus. We used the Tinnitus Functional Index to measure tinnitus severity and the Primary Care-Posttraumatic Stress Disorder (PTSD) screen and the Hospital Anxiety and Depression Scale to assess PTSD, depression, and anxiety. Descriptive statistics and bivariable and multivariable regression models were used to estimate associations between Veterans' tinnitus severity and mental health symptoms. Inverse probability weights were used to account for sample stratification and survey non-response. Multivariable odds ratios (ORs) and 95% confidence intervals (CIs) controlled for Veterans' demographics, military history, and health diagnoses.

RESULTS

A total of 891 Veterans completed surveys (adjusted response rate = 53%). Large proportions rated their tinnitus as severe (29.4%; 95% CI: 27.2-31.6) or very severe (18.7%; 95% CI: 16.8-20.5). In multivariable regression models, and compared with Veterans with none/mild tinnitus, the likelihood of screening positive for PTSD was increased for those who reported moderate (OR = 4.0; 95% CI: 1.6-10.3), severe (OR = 7.5; 95% CI: 3.1-18.5), or very severe (OR = 17.5; 95% CI: 4.4-70.0) tinnitus. Similarly, Veterans' likelihood of positive depression screens were elevated for those with moderate (OR = 2.6; 95% CI: 1.1-5.9), severe (OR = 3.0; 95% CI: 1.4-6.5), or very severe (OR = 15.5; 95% CI: 4.3-55.5) tinnitus, as was the likelihood of positive anxiety screens for those with severe (OR = 2.6; 95% CI: 1.1-6.3) or very severe (OR = 13.4; 95% CI: 4.0-44.3) tinnitus.

CONCLUSIONS

Mental health symptoms are strongly associated with Veterans' tinnitus severity. A better understanding of the interplay between these conditions may help improve the provision of interdisciplinary (Audiology and Mental Health) care for Service members and Veterans.

Psychosocial Variables That Predict Chronic and Disabling Tinnitus: A Systematic Review

To improve tinnitus management we have to gain more knowledge of factors that explain how a persistent distressing tinnitus develops. The central aim of this systematic review was to identify longitudinal studies that investigated psychosocial variables predicting the transition from an acute to a chronic, disabling tinnitus (i.e. tinnitus decompensation) or tinnitus outcomes in chronic tinnitus sufferers. We conducted a systematic literature search of electronic databases and searched manually reference lists. We identified 16 eligible studies: Four longitudinal studies targeted predictors of the transition from acute to chronic tinnitus and 12 longitudinal studies investigated predictors of tinnitus distress (k = 9 observational, longitudinal studies; k = 3 ecological momentary assessment [EMA] and diary studies). The results of this systematic review showed that tinnitus distress, general psychological distress, tendencies to somatize, tinnitus-related delay of sleep onset, certain health behaviors, general illness coping, and certain personality traits (e.g. neuroticism) predicted the transition from acute to chronic, disabling tinnitus. General psychological, mental disorders, tinnitus distress, tinnitus disability (e.g. in different domains of physical, emotional, and social functioning; sleep disturbances), certain health behaviors (e.g. physical exercise), the level of physical and social functioning, and the report of other somatic problems such as pain were predictors of tinnitus outcomes in chronic tinnitus patients at a later follow-up. Studies that examined psychosocial variables as predictors of tinnitus distress are rare and had substantial methodological shortcomings. Future research should focus on core outcome domains and use standardized outcome measures to improve the comparability of results from different studies. Numerous psychosocial variables that have already been investigated as correlates of tinnitus sufferers' functioning in cross-sectional studies are worth investigating with longitudinal designs in future research. Identified predictors of the transition from acute to chronic, disabling tinnitus have to be addressed by health care practitioners who commonly function as the first contact person of individuals with acute tinnitus in the healthcare system.

Natural history of tinnitus in adults: a cross-sectional and longitudinal analysis

OBJECTIVE

To assess incidence and changes in tinnitus and bothersome tinnitus as well as associated risk factors in a large sample of UK adults.

DESIGN

Prospective cohort study.

SETTING

UK.

PARTICIPANTS

For cross-sectional analysis, a group of 168 348 participants aged between 40 and 69 years with hearing and tinnitus data from the UK Biobank resource. Longitudinal analysis included a subset of 4746 people who attended a 4-year retest assessment.

MAIN OUTCOME MEASURES

Presence and bothersomeness of tinnitus.

RESULTS

17.7% and 5.8% of participants reported tinnitus or bothersome tinnitus, respectively. The 4-year incidence of tinnitus was 8.7%. Multivariate logistic regression models suggested that age, hearing difficulties, work noise exposure, ototoxic medication and neuroticism were all positively associated with both tinnitus and bothersome tinnitus. Reduced odds of tinnitus, but not bothersome tinnitus, was seen in alcohol drinkers versus non-drinkers. Male gender was associated with increased odds of tinnitus, while female gender was associated with increased odds of bothersome tinnitus. At follow-up, of those originally reporting tinnitus, 18.3% reported no tinnitus. Of those still reporting tinnitus, 9% reported improvement and 9% reported tinnitus becoming more bothersome, with the rest unchanged. Male gender and alcohol consumption were associated with tinnitus being reported less bothersome, and hearing difficulties were associated with the odds of tinnitus being reported as more bothersome.

CONCLUSIONS

This study is one of the few to provide data on the natural history of tinnitus in a non-clinical population, suggesting that resolution is relatively uncommon, with improvement and worsening of symptoms equally likely. There was limited evidence for any modifiable lifestyle factors being associated with changes in tinnitus symptoms. In view of the largely persistent nature of tinnitus, public health strategies should focus on: (1) primary prevention and (2) managing symptoms in people that have tinnitus and monitoring changes in bothersomeness.

Deployment and Psychological Correlates of Suicide Ideation: A Prospective, Longitudinal Study of Risk and Resilience Among Combat Veterans

INTRODUCTION

Suicide rates among military personnel have risen in part due to war zone deployments. Yet, the degree to which deployment-related stressors, in combination with preexisting and co-occurring psychiatric symptoms and individual resilience factors, contribute to suicide ideation (SI) remains unclear. The current study leverages prospective, longitudinal data to examine both risk and protective factors associated with SI in deployed service members.

MATERIALS AND METHODS

Participants were 1,805 active duty enlisted Marines and Navy service members assessed before and after a 7-month deployment for SI, preexisting and concurrent symptoms of depression, post-traumatic stress disorder (PTSD), alcohol consumption, as well as prior and deployment-related traumatic brain injury (TBI). Current self-reported psychological resilience and social support were analyzed as potential protective factors.

RESULTS

Rates of SI were 7.3% and 3.9% before and after deployment, respectively. Of those with post-deployment SI, 68.6% were new-onset cases. Multivariate regression revealed that concurrent mild depression was the strongest risk factor (odds ratio [OR] = 10.03, 95% CI 5.28-19.07). Other significant risk factors included prior SI (OR = 3.36, 95% CI 1.60-7.05), prior subthreshold PTSD (OR = 2.10, 95% CI 1.10-3.99), and deployment TBI (OR = 1.84, 95% CI 1.03-3.28). Controlling for clinical symptoms and TBI, the risk of SI was reduced for those with moderate (OR = 0.50, 95% CI 0.27-0.93) and high psychological resilience scores (OR = 0.25, 95% CI 0.08-0.79) after deployment.

CONCLUSIONS

Results indicate that even mild symptoms of depression and PTSD may increase the risk of SI. Screening for subthreshold clinical symptoms and TBI while incorporating psychological resilience training would allow for a more multidimensional approach to suicide risk assessment.

Prevalence of Tinnitus and Association with Self-Rated Health among Military Personnel Injured on Combat Deployment

INTRODUCTION

Tinnitus is an auditory problem frequently reported by military personnel and is currently responsible for 1 billion dollars annually in disability compensation. Recent military conflicts in Iraq and Afghanistan saw high levels of combat exposure coupled with a surge in blast weaponry, both of which can adversely affect hearing. The present study explored the prevalence of tinnitus and the association with self-rated health among military personnel injured during combat deployment.

MATERIALS AND METHODS

A total of 1,026 U.S. military personnel who sustained an injury during operations (592 battle blast, 73 battle nonblast, 361 nonbattle) in Iraq were identified from clinical records. Post-Deployment Health Assessments administered at two separate points in time were used to identify self-reported tinnitus symptoms and self-rated health within 1 year of injury.

RESULTS

Those with a battle blast injury had the highest prevalence of tinnitus with 19.1% and 31.3% on the first and second health assessments, respectively. In a multivariate model adjusting for combat exposure, concussion, posttraumatic stress disorder, and other covariates, tinnitus was associated with lower self-rated health for both the first (odds ratio [OR] = 3.31, 95% confidence interval [CI] = 2.07-5.30, P < 0.001) and second assessments (OR = 2.52, 95% CI = 1.76-3.61, P < 0.001).

CONCLUSIONS

Tinnitus is a common source of impairment among military personnel injured during combat deployment and is associated with poorer self-rated health. Future research should determine whether timing of assessment is linked to symptom recognition or reporting, and what interventions are best suited for ameliorating the negative impact of tinnitus.

Behavioral Deficits in Animal Models of Blast Traumatic Brain Injury

Blast exposure has been identified to be the most common cause for traumatic brain injury (TBI) in soldiers. Over the years, rodent models to mimic blast exposures and the behavioral outcomes observed in veterans have been developed extensively. However, blast tube design and varying experimental parameters lead to inconsistencies in the behavioral outcomes reported across research laboratories. This review aims to curate the behavioral outcomes reported in rodent models of blast TBI using shockwave tubes or open field detonations between the years 2008–2019 and highlight the important experimental parameters that affect behavioral outcome. Further, we discuss the role of various design parameters of the blast tube that can affect the nature of blast exposure experienced by the rodents. Finally, we assess the most common behavioral tests done to measure cognitive, motor, anxiety, auditory, and fear conditioning deficits in blast TBI (bTBI) and discuss the advantages and disadvantages of these tests.

Co-occurrence of hearing loss and posttraumatic stress disorder among injured military personnel: a retrospective study

Background

Posttraumatic stress disorder (PTSD) and hearing loss are hallmark public health issues related to military service in Iraq and Afghanistan. Although both are significant individual contributors to disability among veterans, their co-occurrence has not been specifically explored.

Methods

A total of 1179 male U.S. military personnel who sustained an injury between 2004 and 2012 during operations in Iraq or Afghanistan were identified from clinical records. Pre- and postinjury audiometric data were used to define new-onset hearing loss, which was categorized as unilateral or bilateral. Diagnosed PTSD was abstracted from electronic medical records. Logistic regression analysis examined the relationship between hearing loss and PTSD, while adjusting for age, year of injury, occupation, injury severity, injury mechanism, and presence of concussion.

Results

The majority of the study sample were aged 18–25 years (79.9%) and sustained mild-moderate injuries (94.6%). New-onset hearing loss was present in 14.4% of casualties (10.3% unilateral, 4.1% bilateral). Rates of diagnosed PTSD were 9.1, 13.9, and 29.2% for those with no hearing loss, unilateral hearing loss, and bilateral hearing loss, respectively. After adjusting for covariates, those with bilateral hearing loss had nearly three-times higher odds of PTSD (odds ratio = 2.92; 95% CI, 1.47–5.81) compared to those with no hearing loss. Unilateral hearing loss was not associated with PTSD.

Conclusions

Both PTSD and hearing loss are frequent consequences of modern warfare that adversely affect the overall health of the military. Bilateral, but not unilateral, hearing loss was associated with a greater burden of PTSD. This has implications for warfighter rehabilitation and should encourage collaboration between audiology and mental health professionals.