Vestibular consequences of mild traumatic brain injury and blast exposure: a review

Understanding factors influencing the return to physical activity, perspectives of adults with concussion/mild traumatic brain injury: A qualitative study

Understanding the factors that influence the return to physical activity can help to modify behaviour to enhance the recovery of symptoms and physical activity. We conducted 14 semi-structured interviews to explore the barriers and facilitators to returning to physical activity in adults following a mild traumatic brain injury (TBI). The study design was informed by the Theoretical Domains Framework and Capability, Opportunity and Motivation-Behaviour model. Ten key factors were identified in the analysis: four factors consistently acted as barriers (fatigue, sensory overload, symptoms, social expectations), four as facilitators (physical activity, assistive items, social support, health professional support), and two demonstrated a more complex, bidirectional influence (mental health, environment). These ten factors were organized to four overarching thematic groups: intrinsic factors, environmental and adaptive factors, social influences and symptom management. Adults with symptoms lasting greater than 10 days post-mild TBI report that a combination of symptoms, including fatigue and sensory overload prevent their ability to return to physical activity. The environment, social support structures, and access to health professional support facilitated individuals with returning to their physical activities. These findings should be considered when providing interventions to patients in clinical practice to enhance patients' recovery of symptoms and physical activity.

Current and prospective roles of magnetic resonance imaging in mild traumatic brain injury

There is unmet clinical need for biomarkers to predict recovery or the development of long-term sequelae of mild traumatic brain injury, a highly prevalent condition causing a constellation of disabling symptoms. A substantial proportion of patients live with long-lasting sequelae affecting their quality of life and ability to work. At present, symptoms can be assessed through clinical tests; however, there are no imaging or laboratory tests fully reflective of pathophysiology routinely used by clinicians to characterize post-concussive symptoms. Magnetic resonance imaging has potential to link subtle pathophysiological alterations to clinical outcomes. Here, we review the state of the art of MRI research in adults with mild traumatic brain injury and provide recommendations to facilitate transition into clinical practice. Studies utilizing MRI can inform on pathophysiology of mild traumatic brain injury. They suggest presence of early cytotoxic and vasogenic oedema. They also show that mild traumatic brain injury results in cellular injury and microbleeds affecting the integrity of myelin and white matter tracts, all processes that appear to induce delayed vascular reactions and functional changes. Crucially, correlates between MRI parameters and post-concussive symptoms are emerging. Clinical sequences such as T1-weighted MRI, susceptibility-weighted MRI or fluid attenuation inversion recovery could be easily implementable in clinical practice, but are not sufficient, in isolation for prognostication. Diffusion sequences have shown promises and, although in need of analysis standardization, are a research priority. Lastly, arterial spin labelling is emerging as a high-utility research as it could become useful to assess delayed neurovascular response and possible long-term symptoms.

The Neurobehavioral Symptom Inventory: Psychometric Properties and Symptom Comparisons in Women With and Without Brain Injuries Due to Intimate Partner Violence

This study psychometrically evaluated the Neurobehavioral Symptom Inventory (NSI) among women survivors of intimate partner violence (IPV) and compared symptoms between women with no brain injury history (n = 93) and women with IPV-related brain injury history (n = 112). Women completed the NSI and questionnaires on traumatic brain injury (TBI), hypoxic-ischemic brain injury (HI-BI), and lifetime IPV history. A four-factor NSI model, including affective, somatosensory, cognitive, and vestibular factors, had the best fit (comparative fit index = 0.970, root mean square error of approximation = 0.064), with strong reliability for the total score (ω = .93) and subscale scores (ω range = .72-.89). In group comparisons, women with IPV-related brain injuries reported greater total, affective, and cognitive symptom severity after adjusting for age and education; however, no group differences were observed after adjusting for IPV severity. When examining lifetime number of brain injuries, HI-BI count was independently predictive of total, cognitive, and vestibular symptom severity after adjusting for age, education, and IPV severity; whereas TBI count did not independently predict any NSI scores after adjusting for these covariates. The NSI had acceptable psychometric properties for measuring neurobehavioral symptoms among women survivors of IPV. The association between HI-BI count and cognitive and vestibular symptoms may indicate the importance of studying repetitive nonfatal strangulation as an injury mechanism in this population.

Unveiling the predictive power of biomarkers in traumatic brain injury: A narrative review focused on clinical outcomes

Traumatic brain injury (TBI) has long-term consequences, including neurodegenerative disease risk. Current diagnostic tools are limited in detecting subtle brain damage. This review explores emerging biomarkers for TBI, including those related to neuronal injury, inflammation, EVs, and ncRNAs, evaluating their potential to predict clinical outcomes like mortality, recovery, and cognitive impairment. It addresses challenges and opportunities for implementing biomarkers in clinical practice, aiming to improve TBI diagnosis, prognosis, and treatment.

Evidence of Peripheral Vestibular Impairment Among Adults With Chronic Moderate-Severe Traumatic Brain Injury

PURPOSE

Traumatic brain injury (TBI) is a leading cause of death and disability among adults in the United States. There is evidence to suggest the peripheral vestibular system is vulnerable to damage in individuals with TBI. However, there are limited prospective studies that describe the type and frequency of vestibular impairment in individuals with chronic moderate-severe TBI (> 6 months postinjury).

METHOD

Cervical and ocular vestibular evoked myogenic potentials (VEMPs) and video head impulse test (vHIT) were used to assess the function of otolith organ and horizontal semicircular canal (hSCC) pathways in adults with chronic moderate-severe TBI and in noninjured comparison (NC) participants. Self-report questionnaires were administered to participants with TBI to determine prevalence of vestibular symptoms and quality of life associated with those symptoms.

RESULTS

Chronic moderate-severe TBI was associated with a greater degree of impairment in otolith organ, rather than hSCC, pathways. About 63% of participants with TBI had abnormal VEMP responses, compared to only ~10% with abnormal vHIT responses. The NC group had significantly less abnormal VEMP responses (~7%), while none of the NC participants had abnormal vHIT responses. As many as 80% of participants with TBI reported vestibular symptoms, and up to 36% reported that these symptoms negatively affected their quality of life.

CONCLUSIONS

Adults with TBI reported vestibular symptoms and decreased quality of life related to those symptoms and had objective evidence of peripheral vestibular impairment. Vestibular testing for adults with chronic TBI who report persistent dizziness and imbalance may serve as a guide for treatment and rehabilitation in these individuals.

Comparison of Vestibular/Ocular Motor Screening (VOMS) and Computerized Eye-tracking to Identify Exposure to Repetitive Head Impacts

INTRODUCTION

Military service members (SMs) are exposed to repetitive head impacts (RHIs) in combat and training that are purported to adversely affect brain health, including cognition, behavior, and function. Researchers have reported that RHI from blast-related exposure may affect both vestibular and ocular function, which in turn may be related to symptomology. As such, an examination of the effects of RHI on exposed military SMs should incorporate these domains. To date, researchers have not compared groups of exposed special operations forces (SOF) operators on combined clinical vestibular/ocular and eye-tracker-based outcomes. Therefore, the primary purpose of this study was to compare participant-reported symptoms and performance on the Vestibular/Ocular Motor Screening (VOMS) tool with performance on the computerized RightEye tracking system between SOF operators exposed to blast-related RHI and healthy controls without blast-related exposure. In addition, the study aimed to compare subgroups of snipers and breachers exposed to RHI to controls on the preceding metrics, as well as identify a subset of individual (demographic) factors, participant-reported symptoms, and performance metrics on VOMS and RightEye that best identify SOF operators exposed to RHI from unexposed controls.

MATERIALS AND METHODS

The study involved a cross-sectional design including 25 Canadian SOF SMs comprised of breachers (n = 9), snipers (n = 9), and healthy, unexposed controls (n = 7). The former 2 groups were combined into an RHI group (n = 18) and compared to controls (n = 7). Participants provided demographics and completed a self-reported concussion-related symptom report via the Military Acute Concussion Evaluation 2, the VOMS, and RightEye computerized eye-tracking assessments. Independent samples t-tests and ANOVAs were used to compare the groups on the outcomes, with receiver operating characteristic curve and area under the curve (AUC) analyses to identify predictors of blast exposure. This study was approved by the Defence Research Development Canada Human Research Ethics Committee and the Canadian Forces Surgeon General/Special Forces Command.

RESULTS

The results from t-tests supported group differences for age (P = .012), participant-reported symptoms (P = .006), and all VOMS items (P range = <.001-.02), with the RHI group being higher than healthy controls on all variables. ANOVA results supported group differences among snipers, breachers, and controls for age (P = .01), RightEye saccades (P = .04), participant-reported total symptom severity (P = .03), and VOMS total scores (P = .003). The results of the receiver operating characteristic curve analyses supported age (AUC = 0.81), Military Acute Concussion Evaluation 2 participant-reported total symptom severity (AUC = 0.87), and VOMS total scores (AUC = 0.92) as significant predictors of prior blast exposure.

CONCLUSIONS

Participant-reported concussion symptoms, VOMS scores, and age were useful in identifying SOF operators exposed to RHI from controls. RightEye metrics were not useful in differentiating RHI groups from controls. Differences between snipers and breachers warrant further research. Overall, the findings suggest that VOMS may be a useful tool for screening for the effects of exposure to RHI in SOF operators. Future investigations should be conducted on a larger sample of military SMs, consider additional factors (e.g., RHI exposure levels, medical history, and sex), and include additional assessment domains (e.g., balance, cognitive, and psychological).

Repetitive subconcussion results in disrupted neural activity independent of concussion history

Concussion is a public health crisis that results in a complex cascade of neurochemical changes that can have life-changing consequences. Subconcussions are generally considered less serious, but we now realize repetitive subconcussions can lead to serious neurological deficits. Subconcussions are common in contact sports and the military where certain personnel are exposed to repetitive occupational blast overpressure. Post-mortem studies show subconcussion is a better predictor than concussion for chronic traumatic encephalopathy-a progressive and fatal neurodegenerative tauopathy, only diagnosable post-mortem-thus, an in vivo biomarker would be transformative. Magnetoencephalography captures the dynamics of neuronal electrochemical action, and functional MRI shows that functional connectivity is associated with tauopathy patterns. Therefore, both imaging modalities could provide surrogate markers of tauopathy. In this cross-sectional study, we examined the effects of repetitive subconcussion on neuronal activity and functional connectivity using magnetoencephalography and functional MRI, and on neurological symptoms and mental health in a military sample. For magnetoencephalography and outcome analyses, 81 participants were split into 'high' and 'low' blast exposure groups using the generalized blast exposure value: n = 41 high blast (26.4-65.7 years; 4 females) and n = 40 low blast (28.0-63.3 years; 8 females). For functional MRI, two high blast male participants without data were excluded: n = 39 (29.6-65.7 years). Magnetoencephalography revealed disrupted neuronal activity in participants with a greater history of repetitive subconcussions, including neural slowing (higher delta activity) in right fronto-temporal lobes and subcortical regions (hippocampus, amygdala, caudate, pallidum and thalamus), and functional dysconnectivity in the posterior default mode network (lower connectivity at low and high gamma). These abnormalities were independent of concussion or traumatic stress history, and magnetoencephalography showed functional dysconnectivity not detected in functional MRI. Besides magnetoencephalography changes, those with higher blast exposure had poorer somatic and cognitive outcomes, with no blast-related differences in mental health or associations between neurological symptoms and neuronal activity. This study suggests that repetitive subconcussions have deleterious effects on brain function and that magnetoencephalography provides an avenue for both treatment targets by identifying affected brain regions and in prevention by identifying those at risk of cumulative subconcussive neurotrauma.

Biofluid, Imaging, Physiological, and Functional Biomarkers of Mild Traumatic Brain Injury and Subconcussive Head Impacts

Post-concussive symptoms are frequently reported by individuals who sustain mild traumatic brain injuries (mTBIs) and subconcussive head impacts, even when evidence of intracranial pathology is lacking. Current strategies used to evaluate head injuries, which primarily rely on self-report, have a limited ability to predict the incidence, severity, and duration of post-concussive symptoms that will develop in an individual patient. In addition, these self-report measures have little association with the underlying mechanisms of pathology that may contribute to persisting symptoms, impeding advancement in precision treatment for TBI. Emerging evidence suggests that biofluid, imaging, physiological, and functional biomarkers associated with mTBI and subconcussive head impacts may address these shortcomings by providing more objective measures of injury severity and underlying pathology. Interest in the use of biomarker data has rapidly accelerated, which is reflected by the recent efforts of organizations such as the National Institute of Neurological Disorders and Stroke and the National Academies of Sciences, Engineering, and Medicine to prioritize the collection of biomarker data during TBI characterization in acute-care settings. Thus, this review aims to describe recent progress in the identification and development of biomarkers of mTBI and subconcussive head impacts and to discuss important considerations for the implementation of these biomarkers in clinical practice.

Multifunctional redox modulator prevents blast-induced loss of cochlear and vestibular hair cells and auditory spiral ganglion neurons

Blast wave exposure, a leading cause of hearing loss and balance dysfunction among military personnel, arises primarily from direct mechanical damage to the mechanosensory hair cells and supporting structures or indirectly through excessive oxidative stress. We previously reported that HK-2, an orally active, multifunctional redox modulator (MFRM), was highly effective in reducing both hearing loss and hair cells loss in rats exposed to a moderate intensity workday noise that likely damages the cochlea primarily from oxidative stress versus direct mechanical trauma. To determine if HK-2 could also protect cochlear and vestibular cells from damage caused primarily from direct blast-induced mechanical trauma versus oxidative stress, we exposed rats to six blasts of 186 dB peak SPL. The rats were divided into four groups: (B) blast alone, (BEP) blast plus earplugs, (BHK-2) blast plus HK-2 and (BEPHK-2) blast plus earplugs plus HK-2. HK-2 was orally administered at 50 mg/kg/d from 7-days before to 30-day after the blast exposure. Cochlear and vestibular tissues were harvested 60-d post-exposure and evaluated for loss of outer hair cells (OHC), inner hair cells (IHC), auditory nerve fibers (ANF), spiral ganglion neurons (SGN) and vestibular hair cells in the saccule, utricle and semicircular canals. In the untreated blast-exposed group (B), massive losses occurred to OHC, IHC, ANF, SGN and only the vestibular hair cells in the striola region of the saccule. In contrast, rats treated with HK-2 (BHK-2) sustained significantly less OHC (67%) and IHC (57%) loss compared to the B group. OHC and IHC losses were smallest in the BEPHK-2 group, but not significantly different from the BEP group indicating lack of protective synergy between EP and HK-2. There was no loss of ANF, SGN or saccular hair cells in the BHK-2, BEP and BEPHK-2 groups. Thus, HK-2 not only significantly reduced OHC and IHC damage, but completely prevented loss of ANF, SGN and saccule hair cells. The powerful protective effects of this oral MFRM make HK-2 an extremely promising candidate for human clinical trials.

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.

Dizziness Directly Influences Postconcussion Symptoms and Is Predictive of Poorer Mental Health in UK Military Personnel: A Retrospective Analysis

OBJECTIVE

To investigate the contribution of dizziness to postconcussion symptoms, depression, and anxiety symptoms.

SETTING

Mild traumatic brain injury (mTBI) service, Defence Medical Rehabilitation Centre, Stanford Hall.

PARTICIPANTS

Two hundred eighty-three UK military personnel from the Royal Navy, Royal Airforce, Royal Marines, and British Army.

DESIGN

A retrospective analysis of data from the Ministry of Defence medical records database.

MAIN MEASURES

Sixteen-item Rivermead Post Concussion Symptoms Questionnaire, Generalized Anxiety Disorder 7-item scale, Patient Health Questionnaire-9, The Dizziness Handicap Inventory.

RESULTS

Injuries from sports or falls were the most common mechanism of mTBI, accounting for 23%, respectively. Chi-square analysis indicated that individuals with dizziness and postconcussion symptoms (PCS) had greater severity of PCS, depression, and anxiety than those with PCS alone. Mediation analysis showed dizziness directly and independently influenced the severity of PCS, despite the indirect effects of mediating depression and anxiety symptoms.

CONCLUSION

Comorbid dizziness and PCS were predictive of poorer mental health compared with PCS alone. In addition, dizziness directly influenced the severity of PCS irrespective of the indirect effects of mental health symptoms. These observations suggest that treating dizziness with vestibular rehabilitation may improve PCS and mental health.

Association of Head Injury, Neck Injury or Acoustic Trauma on Phenotype of Ménière's Disease

The aim of the present study was to investigate adverse effects of head injury, neck trauma, and chronic noise exposure on the complaint profile in people with Ménière's disease (MD). The study used a retrospective design. Register data of 912 patients with MD from the Finnish Ménière Federation database were studied. The data comprised case histories of traumatic brain injury (TBI), neck trauma and occupational noise exposure, MD specific complaints, impact related questions, and the E-Qol health-related quality of life instrument. TBI was classified based on mild, moderate, and severe categories of transient loss of consciousness (TLoC). The mean age of the participants was 60.2 years, the mean duration of the disease was 12.6 years, and 78.7% were females. Logistic regression analysis, linear correlation, and pairwise comparisons were used in evaluating the associations. 19.2% of the participants with MD had a history of TBI. The phenotype of participants with TBI was associated with frequent vestibular drop attacks (VDA), presyncope, headache-associated vertigo, and a reduction in the E-QoL. Logistic regression analysis explained the variability of mild TBI in 6.8%. A history of neck trauma was present in 10.8% of the participants. Neck trauma associated with vertigo (NTwV) was seen in 47 and not associated with vertigo in 52 participants. The phenotype of NTwV was associated with balance problems, VDA, physical strain-induced vertigo, and hyperacusia. Logistic regression analysis explained 8.7% of the variability of the complaint profile. Occupational noise exposure was recorded in 25.4% of the participants and correlated with the greater impact of tinnitus, hyperacusis, and hearing loss. Neither the frequency, duration, or severity of vertigo or nausea were significantly different between the baseline group and the TBI, NTwV, or noise-exposure groups. The results indicate that TBI and NTwV are common among MD patients and may cause a confounder effect.

Leveraging Technology for Vestibular Assessment and Rehabilitation in the Operational Environment: A Scoping Review

INTRODUCTION

The vestibular system, essential for gaze and postural stability, can be damaged by threats on the battlefield. Technology can aid in vestibular assessment and rehabilitation; however, not all devices are conducive to the delivery of healthcare in an austere setting. This scoping review aimed to examine the literature for technologies that can be utilized for vestibular assessment and rehabilitation in operational environments.

MATERIALS AND METHODS

A comprehensive search of PubMed was performed. Articles were included if they related to central or peripheral vestibular disorders, addressed assessment or rehabilitation, leveraged technology, and were written in English. Articles were excluded if they discussed health conditions other than vestibular disorders, focused on devices or techniques not conducive to the operational environment, or were written in a language other than English.

RESULTS

Our search strategy yielded 32 articles: 8 articles met our inclusion and exclusion criteria whereas the other 24 articles were rejected.

DISCUSSION

There is untapped potential for leveraging technology for vestibular assessment and rehabilitation in the operational environment. Few studies were found in the peer-reviewed literature that described the application of technology to improve the identification of central and/or peripheral vestibular system impairments; triage of acutely injured patients; diagnosis; delivery and monitoring of rehabilitation; and determination of readiness for return to duty.

CONCLUSIONS

This scoping review highlighted technology for vestibular assessment and rehabilitation feasible for use in an austere setting. Such technology may be leveraged for prevention; monitoring exposure to mechanisms of injury; vestibular-ocular motor evaluation; assessment, treatment, and monitoring of rehabilitation progress; and return-to-duty determination after vestibular injury.

FUTURE DIRECTIONS

The future of vestibular assessment and rehabilitation may be shaped by austere manufacturing and 3D printing; artificial intelligence; drug delivery in combination with vestibular implantation; organ-on-chip and organoids; cell and gene therapy; and bioprinting.

TBICoE approach to concussion rehabilitation in service members and veterans

BACKGROUND

Concussion, also known as mild traumatic brain injury (mTBI), is a condition with unique ties to military service. Service members (SMs) are inherently at a higher risk for concussive injuries due to the intense physical training environment and combat operational tempo required to serve. The Traumatic Brain Injury Center of Excellence (TBICoE) is the US Department of Defense authority on this condition and provides a thorough approach to management of concussion and associated symptom sequela.

OBJECTIVES

This article seeks to review the TBICoE approach to the management and rehabilitation of military SMs with mTBI, and highlight resources available to military medical providers.

METHODS

The authors reviewed evidence and TBICoE resources to provide this comprehensive overview of the TBICoE approach to management and rehabilitation of concussion in military SMs.

RESULTS

A progressive return to activity protocol in conjunction with symptom-guided management of common post-concussive sequelae, including headache, vestibular and oculomotor issues, sleep dysfunction, cognitive rehabilitation, and behavioral health comorbidities are essential for concussion management in the acute, post-acute and chronic phases of injury.

CONCLUSION

The TBICoE approach to the rehabilitation of military SMs is comprehensive, and includes initial management with a stepwise return to duty protocol and an objective return to duty screening. The mainstays of treatment for SMs with post-acute and chronic post-concussion symptoms are headache management, vestibular and oculomotor rehabilitation, sleep interventions, cognitive rehabilitation, and early intervention for behavioral health comorbidities. These evidence-based strategies may be applied in the treatment of SMs in the US and internationally.

Blast-related mild TBI: LIMBIC-CENC focused review with implications commentary

BACKGROUND

A significant factor for the high prevalence of traumatic brain injury (TBI) among U.S. service members is their exposure to explosive munitions leading to blast-related TBI. Our understanding of the specific clinical effects of mild TBI having a component of blast mechanism remains limited compared to pure blunt mechanisms.

OBJECTIVE

The purpose of this review is to provide a synopsis of clinical research findings on the long-term effects of blast-related mild TBI derived to date from the Long-Term Impact of Military-Relevant Brain Injury Consortium - Chronic Effects of Neurotrauma Consortium (LIMBIC-CENC).

METHODS

Publications on blast-related mild TBI from LIMBIC-CENC and the LIMBIC-CENC prospective longitudinal study (PLS) cohort were reviewed and their findings summarized. Findings from the broader literature on blast-related mild TBI that evaluate similar outcomes are additionally reviewed for a perspective on the state of the literature.

RESULTS

The most consistent and compelling evidence for long-term effects of blast-related TBI is for poorer psychological health, greater healthcare utilization and disability levels, neuroimaging impacts on brain structure and function, and greater headache impact on daily life. To date, evidence for chronic cognitive performance deficits from blast-related mild TBI is limited, but futher research including crucial longitudinal data is needed.

CONCLUSION

Commentary is provided on: how LIMBIC-CENC findings assimilate with the broader literature; ongoing research gaps alongside future research needs and priorities; how the scientific community can utilize the LIMBIC-CENC database for independent or collaborative research; and how the evidence from the clinical research should be assimilated into clinical practice.

Blast Overpressures as a Military and Occupational Health Concern

PURPOSE

This tutorial reviews effects of environmental stressors like blast overpressures and other well-known acoustic contaminants (continuous, intermittent, and impulsive noise) on hearing, tinnitus, vestibular, and balance-related functions. Based on the overall outcome of these effects, detailed consideration is given to the health and well-being of individuals.

METHOD

Because hearing loss and tinnitus are consequential in affecting quality of life, novel neuromodulation paradigms are reviewed for their positive abatement and treatment-related effects. Examples of clinical data, research strategies, and methodological approaches focus on repetitive transcranial magnetic stimulation (rTMS) and electrical stimulation of the vagus nerve paired with tones (VNSt) for their unique contributions to this area.

RESULTS

Acoustic toxicants transmitted through the atmosphere are noteworthy for their propensity to induce hearing loss and tinnitus. Mounting evidence also indicates that high-level rapid onset changes in atmospheric sound pressure can significantly impact vestibular and balance function. Indeed, the risk of falling secondary to loss of, or damage to, sensory receptor cells in otolith organs (utricle and saccule) is a primary reason for this concern. As part of the complexities involved in VNSt treatment strategies, vocal dysfunction may also manifest. In addition, evaluation of temporospatial gait parameters is worthy of consideration based on their ability to detect and monitor incipient neurological disease, cognitive decline, and mortality.

CONCLUSION

Highlighting these respective areas underscores the need to enhance information exchange among scientists, clinicians, and caregivers on the benefits and complications of these outcomes.

Exploring the relationship between sleep apnea and vestibular symptoms following traumatic brain injury

BACKGROUND

Traumatic brain injury (TBI) is a complex health problem in military veterans and service members (V/SM) that often involves comorbid vestibular impairment. Sleep apnea is another comorbidity that may exacerbate, and/or be exacerbated by, vestibular dysfunction.

OBJECTIVE

To examine the relationship between sleep apnea and vestibular symptoms in V/SM diagnosed with TBI of any severity.

DESIGN

Multicenter cohort study; cross-sectional sample.

SETTING

In-patient TBI rehabilitation units within five Veterans Affairs (VA) Polytrauma Rehabilitation Centers.

PARTICIPANTS

V/SM with a diagnosis of TBI (N = 630) enrolled in the VA TBI Model Systems study.

INTERVENTION

Not applicable.

METHODS

A multivariable regression model was used to evaluate the association between sleep apnea and vestibular symptom severity while controlling for relevant covariates, for example, posttraumatic stress disorder (PTSD).

MAIN OUTCOME MEASURES

Lifetime history of sleep apnea was determined via best source reporting. Vestibular disturbances were measured with the 3-item Vestibular subscale of the Neurobehavioral Symptom Inventory (NSI).

RESULTS

One third (30.6%) of the sample had a self-reported sleep apnea diagnosis. Initial analysis showed that participants who had sleep apnea had more severe vestibular symptoms (M = 3.84, SD = 2.86) than those without sleep apnea (M = 2.88, SD = 2.67, p < .001). However, when the data was analyzed via a multiple regression model, sleep apnea no longer reached the threshold of significance as a factor associated with vestibular symptoms. PTSD severity was shown to be significantly associated with vestibular symptoms within this sample (p < .001).

CONCLUSION

Analysis of these data revealed a relationship between sleep apnea and vestibular symptoms in V/SM with TBI. The significance of this relationship was affected when PTSD symptoms were factored into a multivariable regression model. However, given that the mechanisms and directionality of these relationships are not yet well understood, we assert that in terms of clinical relevance, providers should emphasize screening for each of the three studied comorbidities (sleep apnea, vestibular symptoms, and PTSD).

Prevalence and Risk Factors of Self-reported Dizziness in Post-9/11 Service Members and Veterans

INTRODUCTION

Dizziness is prevalent in the general population, but little is known about its prevalence in the U.S. military population. Dizziness is commonly associated with blast exposure and traumatic brain injury (TBI), but the potential independent contributions of blast and TBI have yet to be evaluated. This study's goal was to estimate the prevalence of dizziness among post-9/11 service members and Veterans and to examine independent and joint associations between military TBI history, blast exposure, and self-reported dizziness.

MATERIALS AND METHODS

The study sample consisted of service members (n = 424) and recently separated (< ∼2.5 years) Veterans (n = 492) enrolled in the Noise Outcomes in Service members Epidemiology (NOISE) Study. We examined associations between self-reported history of probable TBI and blast exposure and recent dizziness using logistic regression. Models were stratified by service member versus Veteran status and adjusted to account for potentially confounding demographic and military characteristics.

RESULTS

Overall, 22% of service members and 31% of Veterans self-reported dizziness. Compared to those with neither TBI nor blast exposure history, both service members and Veterans with TBI (with or without blast) were three to four times more likely to self-report dizziness. Those with blast exposure but no TBI history were not more likely to self-report dizziness. There was no evidence of an interaction effect between blast exposure and a history of TBI on the occurrence of dizziness.

CONCLUSION

Self-reported dizziness was prevalent in this sample of service members and Veterans. Probable TBI history, with or without blast exposure, was associated with dizziness, but blast exposure without TBI history was not. This suggests that treatment guidelines for TBI-related dizziness may not need to be tailored to the injury mechanism. However, future efforts should be directed toward the understanding of the pathophysiology of TBI on self-reported dizziness, which is fundamental to the design of treatment strategies.

Self-Reported Symptoms of Vertigo and Imbalance Are Prevalent Among Adults With Chronic Moderate-Severe Traumatic Brain Injury: A Preliminary Analysis

PURPOSE

Dizziness and imbalance are common symptoms during the acute phase of traumatic brain injury (TBI). However, there is evidence to suggest that these symptoms persist into the chronic phase of injury. Few prospective studies have examined the frequency and type of dizziness and imbalance in adults with chronic moderate-severe TBI. The aim of this preliminary analysis was to investigate the prevalence of these symptoms in adults with chronic moderate-severe TBI.

METHOD

Twenty-four adults with chronic moderate-severe TBI and a group of 19 age-, sex-, and education-matched noninjured comparison participants were recruited. Self-reported dizziness and imbalance were measured using a modified version of a standard case history form. Significant associations between group (TBI group or noninjured comparison [NC] participants) and self-reports of dizziness, imbalance, and related symptoms (endorsed "yes" or "no") were explored.

RESULTS

The TBI group most reported lightheadedness (75%), vertigo (38%), and imbalance and/or falling (46%). The most common related symptom reported by the TBI group was headache (63%) and nausea (46%). Significant associations revealed that the TBI group responded "yes" in higher percentages than the NC group across all categories (dizziness, imbalance, and related symptoms). There were no statistically significant relationships among dizziness, imbalance, or headache symptoms within the TBI group.

CONCLUSIONS

These preliminary findings suggest that dizziness and imbalance are prevalent in adults with chronic moderate-severe TBI. Persistent vertiginous symptoms may point to an underlying vestibular impairment. However, further research is needed to characterize vestibular function in chronic moderate-severe TBI.

Normative Ranges for, and Interrater Reliability of, Rotational Vestibular and Balance Tests in U.S. Military Service Members and Veterans

PURPOSE

The objectives of this study were to (a) describe normative ranges-expressed as reference intervals (RIs)-for vestibular and balance function tests in a cohort of Service Members and Veterans (SMVs) and (b) to describe the interrater reliability of these tests.

METHOD

As part of the Defense and Veterans Brain Injury Center (DVBIC)/Traumatic Brain Injury Center of Excellence 15-year Longitudinal Traumatic Brain Injury (TBI) Study, participants completed the following: vestibulo-ocular reflex suppression, visual-vestibular enhancement, subjective visual vertical, subjective visual horizontal, sinusoidal harmonic acceleration, the computerized rotational head impulse test (crHIT), and the sensory organization test. RIs were calculated using nonparametric methods and interrater reliability was assessed using intraclass correlation coefficients between three audiologists who independently reviewed and cleaned the data.

RESULTS

Reference populations for each outcome measure comprised 40 to 72 individuals, 19 to 61 years of age, who served either as noninjured controls (NIC) or injured controls (IC) in the 15-year study; none had a history of TBI or blast exposure. A subset of 15 SMVs from the NIC, IC, and TBI groups were included in the interrater reliability calculations. RIs are reported for 27 outcome measures from the seven rotational vestibular and balance tests. Interrater reliability was considered excellent for all tests except the crHIT, which was found to have good interrater reliability.

CONCLUSION

This study provides clinicians and scientists with important information regarding normative ranges and interrater reliability for rotational vestibular and balance tests in SMVs.

Research Letter: Rate of BPPV in Patients Diagnosed With Concussion

OBJECTIVE

The purpose of this study was to investigate the incidence of benign paroxysmal positional vertigo (BPPV) specifically among patients with dizziness in the rehabilitation phase of concussion recovery and to provide evidence regarding the importance of BPPV assessment in physical therapy concussion evaluations.

SETTING

Outpatient neurologic rehabilitation center at a suburban comprehensive rehabilitation hospital.

PARTICIPANTS

Fifty patients diagnosed with concussion and referred to vestibular physical therapy with complaints of dizziness were tested for BPPV within their first 3 visits.

DESIGN

In this prospective cohort study, a positive Dix-Hallpike test or Horizontal Roll test indicated the presence of BPPV.

MAIN MEASURES

The primary outcome measure was the presence of BPPV. Additional demographic and injury-specific variables were also considered. Among secondary outcomes, patient characteristics and Dizziness Handicap Inventory scores were compared on the basis of presence or absence of BPPV.

RESULTS

Eleven participants, 22%, tested positive for BPPV. Only fall, as the mechanism of injury, was statistically significant ( P < .05), with 72.7% of those who tested positive for BPPV reporting having been injured in a fall compared with 30.8% in the negative group. Nearly half, 45%, of the participants who were positive for BPPV had resolution of their BPPV within 1 visit.

CONCLUSION

This study is unique in its focus on mild traumatic brain injury in the rehabilitation phase of recovery. The results provide evidence regarding the importance of BPPV assessment in physical therapy concussion evaluations.

The impact of the war in Ukraine on the reproductive health of female military personnel

OBJECTIVE

To explore the link between mental health, physical well-being, and reproductive system pathology in females who suffered war-related concussions.

METHODS

A study was conducted at the Kyiv Center of Reproductive and Perinatal Medicine with 715 participants. The group included 457 female military personnel with concussions (211 with post-concussive syndrome (PCS), 246 without), 208 women from occupied/deoccupied areas (103 with PCS, 105 without), and 50 civilians from safe zones. Average deployment time (mean ± standard deviation) was 60.26 ± 42.21 months, and trauma occurred 18.81 ± 9.221 months ago. Medical history and physical examinations were performed.

RESULTS

Female soldiers with PCS had a 1.3 times higher likelihood (P < 0.015) of experiencing longer menstrual periods. Painful menstruation was 1.47 times more frequent (P < 0.001), and heavy periods were 1.64 times more common (P < 0.003). Infertility duration in concussed women was 5.36 ± 0.13 years, whereas those with PCS experienced 1.29 times longer duration (6.02 ± 0.21 years) (P < 0.001) compared with women without PCS (4.69 ± 0.13 years). Among concussed soldiers, 69.27% had endometrial structural pathology, with PCS occurring 1.64 times more often (P < 0.001).

CONCLUSIONS

The health decline in female veterans and active-duty personnel extends beyond medical implications and has social significance. The well-being of these Ukrainian women affects the country's defense, demographic patterns, socio-political landscape, and social stability.

Clinical Theragnostic Signature of Extracellular Vesicles in Traumatic Brain Injury (TBI)

Traumatic brain injury (TBI) is a common cause of disability and fatality worldwide. Depending on the clinical presentation, it is a type of acquired brain damage that can be mild, moderate, or severe. The degree of patient's discomfort, prognosis, therapeutic approach, survival rates, and recurrence can all be strongly impacted by an accurate diagnosis made early on. The Glasgow Coma Scale (GCS), along with neuroimaging (MRI (Magnetic Resonance Imaging) and CT scan), is a neurological assessment tools used to evaluate and categorize the severity of TBI based on the patient's level of consciousness, eye opening, and motor response. Extracellular vesicles (EVs) are a growing domain, explaining neurological complications in a more detailed manner. EVs, in general, play a role in cellular communication. Its molecular signature such as DNA, RNA, protein, etc. contributes to the status (health or pathological stage) of the parental cell. Brain-derived EVs support more specific screening (diagnostic and prognostic) in TBI research. Therapeutic impact of EVs are more promising for aiding in TBI healing. It is nontoxic, biocompatible, and capable of crossing the blood-brain barrier (BBB) to transport therapeutic molecules. This review has highlighted the relationships between EVs and TBI theranostics, EVs and TBI-related clinical trials, and related research domain-associated challenges and solutions. This review motivates further exploration of associations between EVs and TBI and develops a better approach to TBI management.

Global research trends in benign paroxysmal positional vertigo: a bibliometric analysis

Background

Benign paroxysmal positional vertigo is the most common disease in which vertigo is the main clinical manifestation, and it has become a global medical problem, affecting a wide range of areas and seriously affecting the quality of human life.

Objective

This article presents an analysis of the current characteristics of BPPV-related research and summarizes the current hot topics and trends, with the goal of inspiring future research into the prevention and treatment of BPPV, thereby improving the differential diagnosis and prevention of peripheral vertigo.

Methods

A bibliometric approach was used to collect 1,219 eligible studies on BPPV from four databases-PubMed, Embase, Scopus, and Web of Science-published between 1974 and 2022. The characteristics and status of the accumulated scientific output were processed using R and VOSviewer so that we could visualize any trends or hotspots.

Results

The results showed a significant increase in the annual number of publications, with an average annual growth rate of 21.58%. A possible reason for the especially pronounced peak in 2021 was an increase in the prevalence of BPPV as a result of COVID-19. The new coronavirus became a focus of research in 2021. A total of 3,876 authors (of whom 1,097 were first authors) published articles in 307 different journals; 15.7% of the articles were published in Acta Oto-Larygologica, Otology and Neurotology, and Frontiers in Neurology. Acta Oto-Laryngologica was well ahead of the other journals in terms of growth rate and number of articles published. American scholars generated the largest number of articles overall, and the USA was involved in the greatest number of international collaborations, followed by Italy and China. The themes of the research centered around three topics, namely the treatment of BPPV, its influencing factors, and diagnosis.

Conclusions

There has been a major increase in BPPV-related research over the last 50 years, leading to an increase in related articles and rapid development of the field. Key directions for future research include the improvement of individualized treatment for residual symptoms after initial treatment of BPPV among the elderly; effective control of comorbidities such as osteoporosis; and secondary inner ear disease, such as Ménière's disease.

Volitional Head Movement Deficits and Alterations in Gait Speed Following Mild Traumatic Brain Injury

OBJECTIVE

Unconstrained head motion is necessary to scan for visual cues during navigation, for minimizing threats, and to allow regulation of balance. Following mild traumatic brain injury (mTBI) people may experience alterations in head movement kinematics, which may be pronounced during gait tasks. Gait speed may also be impacted by the need to turn the head while walking in these individuals. The aim of this study was to examine head kinematics during dynamic gait tasks and the interaction between kinematics and gait speed in people with persistent symptoms after mTBI.

SETTING

A clinical assessment laboratory.

DESIGN

A cross-sectional, matched-cohort study.

PARTICIPANTS

Forty-five individuals with a history of mTBI and 46 age-matched control individuals.

MAIN MEASURES

All participants were tested at a single time point and completed the Functional Gait Assessment (FGA) while wearing a suite of body-mounted inertial measurement units (IMUs). Data collected from the IMUs were gait speed, and peak head rotation speed and amplitude in the yaw and pitch planes during the FGA-1, -3, and -4 tasks.

RESULTS

Participants with mTBI demonstrated significantly slower head rotations in the yaw ( P = .0008) and pitch ( P = .002) planes. They also demonstrated significantly reduced amplitude of yaw plane head rotations ( P < .0001), but not pitch plane head rotations ( P = .84). Participants with mTBI had significantly slower gait speed during normal gait (FGA-1) ( P < .001) and experienced a significantly greater percent decrease in gait speed than healthy controls when walking with yaw plane head rotations (FGA-3) ( P = .02), but not pitch plane head rotations (FGA-4) ( P = .11).

CONCLUSIONS

Participants with mTBI demonstrated smaller amplitudes and slower speeds of yaw plane head rotations and slower speeds of pitch plane head rotations during gait. Additionally, people with mTBI walked slower during normal gait and demonstrated a greater reduction in gait speed while walking with yaw plane head rotations compared with healthy controls.

A mathematical model for mechanical activation and compound action potential generation by the utricle in response to sound and vibration

Introduction

Calyx bearing vestibular afferent neurons innervating type I hair cells in the striolar region of the utricle are exquisitely sensitive to auditory-frequency air conducted sound (ACS) and bone conducted vibration (BCV). Here, we present experimental data and a mathematical model of utricular mechanics and vestibular compound action potential generation (vCAP) in response to clinically relevant levels of ACS and BCV. Vibration of the otoconial layer relative to the sensory epithelium was simulated using a Newtonian two-degree-of-freedom spring-mass-damper system, action potential timing was simulated using an empirical model, and vCAPs were simulated by convolving responses of the population of sensitive neurons with an empirical extracellular voltage kernel. The model was validated by comparison to macular vibration and vCAPs recorded in the guinea pig, in vivo.

Results

Transient stimuli evoked short-latency vCAPs that scaled in magnitude and timing with hair bundle mechanical shear rate for both ACS and BCV. For pulse BCV stimuli with durations <0.8 ms, the vCAP magnitude increased in proportion to temporal bone acceleration, but for pulse durations >0.9 ms the magnitude increased in proportion to temporal bone jerk. Once validated using ACS and BCV data, the model was applied to predict blast-induced hair bundle shear, with results predicting acute mechanical damage to bundles immediately upon exposure.

Discussion

Results demonstrate the switch from linear acceleration to linear jerk as the adequate stimulus arises entirely from mechanical factors controlling the dynamics of sensory hair bundle deflection. The model describes the switch in terms of the mechanical natural frequencies of vibration, which vary between species based on morphology and mechanical factors.

Deployment-related concussion and long-term health-related quality of life among US military personnel

PURPOSE

To examine the relationship between deployment-related concussion and long-term health-related quality of life (HRQoL) among injured US military personnel.

METHODS

The study sample included 810 service members with deployment-related injuries between 2008 and 2012 who responded to a web-based longitudinal health survey. Participants were categorized into three injury groups: concussion with loss of consciousness (LOC; n = 247), concussion without LOC (n = 317), or no concussion (n = 246). HRQoL was measured using the 36-Item Short Form Health Survey physical and mental component summary (PCS and MCS) scores. Current post-traumatic stress disorder (PTSD) and depression symptoms were examined. Multivariable linear regression models assessed the effects of concussion on PCS and MCS scores, while controlling for covariates.

RESULTS

A lower PCS score was observed in participants with concussion with LOC (B =  - 2.65, p = 0.003) compared with those with no history of concussion. Symptoms of PTSD (PCS: B =  - 4.84, p < 0.001; MCS: B =  - 10.53, p < 0.001) and depression (PCS: B =  - 2.85, p < 0.001; MCS: B =  - 10.24, p < 0.001) were the strongest statistically significant predictors of lower HRQoL.

CONCLUSION

Concussion with LOC was significantly associated with lower HRQoL in the physical domain. These findings affirm that concussion management should integrate physical and psychological care to improve long-term HRQoL and warrant a more detailed examination of causal and mediating mechanisms. Future research should continue to incorporate patient-reported outcomes and long-term follow-up of military service members to further define the lifelong impact of deployment-related concussion.

Adults are not older adolescents: comparing physical therapy findings among adolescents, young adults and older adults with persistent post-concussive symptoms

OBJECTIVE

Individuals with persistent post-concussive symptoms (PPCS) may present with a myriad of physical symptoms. There is limited research available comparing the presence of examination findings among individuals with PPCS from different age groups.

METHODS

Retrospective case-control chart review of 481 patients with PPCS and 271 non-trauma controls. Physical assessments were categorized as ocular, cervical, and vestibular/balance. Differences in presentation were compared between PPCS and controls as well as between individuals with PPCS in three age groups: adolescents, young adults, and older adults.

RESULTS

All three PPCS groups had more abnormal oculomotor findings than their age-matched counterparts. When comparing PPCS patients from different age groups, no differences were seen in prevalence of abnormal smooth pursuits or saccades; however, adolescents with PPCS had more abnormal cervical findings and a lower prevalence of abnormal NPC, vestibular and balance findings.

CONCLUSION

Patients with PPCS presented with a different constellation of clinical findings based on their age. Adolescents were more likely to demonstrate evidence of cervical injury compared to younger and older adults, and adults were more likely to present with vestibular findings and impaired NPC. Adults with PPCS were more likely to present with abnormal oculomotor findings compared to adults with non-traumatic causes of dizziness.

The Prevalence of Symptom Reporting for Benign Paroxysmal Positional Vertigo in a Traumatic Brain Injury Population

OBJECTIVE

To assess the prevalence of benign paroxysmal positional vertigo (BPPV) in traumatic brain injury population.

STUDY DESIGN

In this cross-sectional design, each subject completed screening for BPPV, which included subjective questioning and positional testing. Subjects were asked if they experienced dizziness with bed mobility. All were tested with the Dix-Hallpike and the roll test to determine if nystagmus consistent with BPPV was present.

SETTING

Brain injury inpatient rehabilitation unit.

PARTICIPANTS

Subjects admitted to the rehabilitation unit during a 6-month time frame who had a traumatic mechanism of brain injury or experienced a fall resulting from a neurologic event.

INTERVENTIONS

Diagnostic interventions included the Dix-Hallpike and roll tests.

MAIN MEASURES

The primary outcomes of this study were the prevalence of BPPV and symptom reports.

RESULTS

Seventy-six subjects met the inclusion criteria. Three subjects were transferred to acute care before screening for BPPV could be completed. Of the 73 subjects who completed the screening process, 42 (58%) tested positive for BPPV, of which only 7 (10%) reported subjective symptoms of dizziness and/or vertigo. χ2 Analysis of the two screening methods demonstrated a statistically significant difference in the positivity rate between tests (χ21 = 5.715, p = 0.017, Cohen's W = 0.279). If subjects responded yes to both screening questions, they were significantly more likely to test positive for BPPV with a moderate effect size of 0.279.

CONCLUSION

There was a high prevalence of BPPV within an inpatient rehabilitation facility in subjects with traumatic brain injury, with a small percentage of patients reporting dizziness with subjective questioning.

Multi-Modal Neurorehabilitation for Persisting Post-Concussion Symptoms

Treatment of the chronic sequela that persist after a mild traumatic brain injury has been challenging with limited efficacy. The aim of this work was to report outcomes obtained from persons who met the criteria of persisting post-concussive symptoms (PPCS), utilizing a novel combination of modalities in a structured neurorehabilitation program. This work was designed as a retrospective, pre-post chart review of objective and subjective measures collected from 62 outpatients with PPCS a mean of 2.2 years post-injury, before and after a multi-modal 5-day treatment protocol. The subjective outcome measure was the 27-item modified Graded Symptom Checklist (mGSC). Objective outcome measures were motor speed/reaction time, coordination, cognitive processing, visual acuity, and vestibular function. Interventions included non-invasive neuromodulation, neuromuscular re-education exercises, gaze stabilization exercises, orthoptic exercises, cognitive training, therapeutic exercises, and single/multi-axis rotation therapy. Pre-post differences in measures were analyzed using the Wilcoxon signed-rank test, with effect size determined by the rank-biserial correlation coefficient. Pre-post treatment comparisons for the subjective mGSC overall, combined symptom measures, individual components of the mGSC, and cluster scores significantly improved for all items. Moderate strength relationships were observed for the mGSC composite score, number of symptoms, average symptom score, feeling in a "fog," "don't feel right," irritability, and physical, cognitive, and affective cluster scores. Objective symptom assessment significantly improved for trail making, processing speed, reaction time, visual acuity, and Standardized Assessment of Concussion. Patients suffering from PPCS ∼2 years after injury may have significant benefits with some moderate effect sizes from an intensive, multi-modal neurorehabilitation program.

Multisensory integration and white matter pathology: Contributions to cognitive dysfunction

The ability to simultaneously process and integrate multiple sensory stimuli is paramount to effective daily function and essential for normal cognition. Multisensory management depends critically on the interplay between bottom-up and top-down processing of sensory information, with white matter (WM) tracts acting as the conduit between cortical and subcortical gray matter (GM) regions. White matter tracts and GM structures operate in concert to manage both multisensory signals and cognition. Altered sensory processing leads to difficulties in reweighting and modulating multisensory input during various routine environmental challenges, and thus contributes to cognitive dysfunction. To examine the specific role of WM in altered sensory processing and cognitive dysfunction, this review focuses on two neurologic disorders with diffuse WM pathology, multiple sclerosis and mild traumatic brain injury, in which persistently altered sensory processing and cognitive impairment are common. In these disorders, cognitive dysfunction in association with altered sensory processing may develop initially from slowed signaling in WM tracts and, in some cases, GM pathology secondary to WM disruption, but also because of interference with cognitive function by the added burden of managing concurrent multimodal primary sensory signals. These insights promise to inform research in the neuroimaging, clinical assessment, and treatment of WM disorders, and the investigation of WM-behavior relationships.

Central sensorimotor integration assessment reveals deficits in standing balance control in people with chronic mild traumatic brain injury

Imbalance is common following mild Traumatic Brain Injury (mTBI) and can persist months after the initial injury. To determine if mTBI subjects with chronic imbalance differed from healthy age- and sex-matched controls (HCs) we used both the Central SensoriMotor Integration (CSMI) test, which evaluates sensory integration, time delay, and motor activation properties and the standard Sensory Organization Test (SOT). Four CSMI conditions evoked center-of-mass sway in response to: surface tilts with eyes closed (SS/EC), surface tilts with eyes open viewing a fixed visual surround (SS/EO), visual surround tilts with eyes open standing on a fixed surface (VS/EO), and combined surface and visual tilts with eyes open (SS+VS/EO). The mTBI participants relied significantly more on visual cues during the VS/EO condition compared to HCs but had similar reliance on combinations of vestibular, visual, and proprioceptive cues for balance during SS/EC, SS/EO, and SS+VS/EO conditions. The mTBI participants had significantly longer time delays across all conditions and significantly decreased motor activation relative to HCs across conditions that included surface-tilt stimuli with a sizeable subgroup having a prominent increase in time delay coupled with reduced motor activation while demonstrating no vestibular sensory weighting deficits. Decreased motor activation compensates for increased time delay to maintain stability of the balance system but has the adverse consequence that sensitivity to both internal (e.g., sensory noise) and external disturbances is increased. Consistent with this increased sensitivity, SOT results for mTBI subjects showed increased sway across all SOT conditions relative to HCs with about 45% of mTBI subjects classified as having an “Aphysiologic” pattern based on published criteria. Thus, CSMI results provided a plausible physiological explanation for the aphysiologic SOT pattern. Overall results suggest that rehabilitation that focuses solely on sensory systems may be incomplete and may benefit from therapy aimed at enhancing rapid and vigorous responses to balance perturbations.

Rationale and methodology for examining the acute effects of aerobic exercise combined with varying degrees of virtual reality immersion on cognition in persons with TBI

Persons with Traumatic Brain Injury (TBI) commonly present with long-term cognitive deficits in executive function, processing speed, attention, and learning and memory. While specific cognitive rehabilitation techniques have shown significant success for deficits in individual domains, aerobic exercise training represents a promising approach for an efficient and general treatment modality that might improve many cognitive domains concurrently. Existing studies in TBI report equivocal results, however, and are hampered by methodological concerns, including small sample sizes, uncontrolled single-group designs, and the use of suboptimal exercise modalities for eliciting cognitive improvements in this population. One particularly promising modality involves the application of environmental enrichment via virtual reality (VR) during aerobic exercise in persons with TBI, but this has yet to be investigated. One approach for systematically developing an optimal aerobic exercise intervention for persons with TBI involves the examination of single bouts of aerobic exercise (i.e., acute aerobic exercise) on cognition. Acute exercise research is a necessary first step for informing the development of high-quality exercise training interventions that are more likely to induce meaningful beneficial effects. To date, such an acute exercise paradigm has yet to be conducted in persons with TBI. To that end, we propose an acute exercise study that will investigate the acute effects of aerobic exercise with incremental degrees of environmental enrichment (VR) relative to a control comparison condition on executive function (divided attention and working memory) and processing speed in 24 people with TBI.

Sensory Phenotypes for Balance Dysfunction After Mild Traumatic Brain Injury

BACKGROUND AND OBJECTIVES

Recent team-based models of care use symptom subtypes to guide treatments of individuals with chronic effects of mild traumatic brain injury (mTBI). However, these subtypes, or phenotypes, may be too broad, particularly for balance (e.g., vestibular subtype). To gain insight into mTBI-related imbalance, we (1) explored whether a dominant sensory phenotype (e.g., vestibular impaired) exists in the chronic mTBI population, (2) determined the clinical characteristics, symptomatic clusters, functional measures, and injury mechanisms that associate with sensory phenotypes for balance control in this population, and (3) compared the presentations of sensory phenotypes between individuals with and without previous mTBI.

METHODS

A secondary analysis was conducted on the Long-Term Impact of Military-Relevant Brain Injury Consortium-Chronic Effects of Neurotrauma Consortium. Sensory ratios were calculated from the sensory organization test, and individuals were categorized into 1 of the 8 possible sensory phenotypes. Demographic, clinical, and injury characteristics were compared across phenotypes. Symptoms, cognition, and physical function were compared across phenotypes, groups, and their interaction.

RESULTS

Data from 758 Service Members and Veterans with mTBI and 172 individuals with no lifetime history of mTBI were included. Abnormal visual, vestibular, and proprioception ratios were observed in 29%, 36%, and 38% of people with mTBI, respectively, with 32% exhibiting more than 1 abnormal sensory ratio. Within the mTBI group, global outcomes (p < 0.001), self-reported symptom severity (p < 0.027), and nearly all physical and cognitive functioning tests (p < 0.027) differed across sensory phenotypes. Individuals with mTBI generally reported worse symptoms than their non-mTBI counterparts within the same phenotype (p = 0.026), but participants with mTBI in the vestibular-deficient phenotype reported lower symptom burdens than their non-mTBI counterparts (e.g., mean [SD] Dizziness Handicap Inventory = 4.9 [8.1] for mTBI vs 12.8 [12.4] for non-mTBI, group × phenotype interaction p < 0.001). Physical and cognitive functioning did not differ between the groups after accounting for phenotype.

DISCUSSION

Individuals with mTBI exhibit a variety of chronic balance deficits involving heterogeneous sensory integration problems. While imbalance when relying on vestibular information is common, it is inaccurate to label all mTBI-related balance dysfunction under the vestibular umbrella. Future work should consider specific classification of balance deficits, including specific sensory phenotypes for balance control.

Testosterone treatment restores vestibular function by enhancing neuronal survival in an experimental closed-head repetitive mild traumatic brain injury model

Repetitive mild traumatic brain injury (rmTBI) results in a myriad of symptoms, including vestibular impairment. The mechanisms underlying vestibular dysfunction in rmTBI patients remain poorly understood. Concomitantly, acute hypogonadism occurs following TBI and can persist chronically in many patients. Using a repetitive mild closed-head animal model of TBI, the role of testosterone on vestibular function was tested. Male Long Evans Hooded rats were randomly divided into sham or rmTBI groups. Significant vestibular deficits were observed both acutely and chronically in the rmTBI groups. Systemic testosterone was administered after the development of chronic vestibular dysfunction. rmTBI animals given testosterone showed improved vestibular function that was sustained for 175 days post-rmTBI. Significant vestibular neuronal cell loss was, however, observed in the rmTBI animals compared to Sham animals at 175 days post-rmTBI and testosterone treatment significantly improved vestibular neuronal survival. Taken together, these data demonstrate a critical restorative role of testosterone in vestibular function following rmTBI. This study has important clinical implications because it identifies testosterone treatment as a viable therapeutic strategy for the long-term recovery of vestibular function following TBI.

Using Body-worn Accelerometers to Detect Physiological Changes During Periods of Blast Overpressure Exposure

Repetitive exposure to non-concussive blast expo-sure may result in sub-clinical neurological symptoms. These changes may be reflected in the neural control gait and balance. In this study, we collected body-worn accelerometry data on individuals who were exposed to repetitive blast overpressures as part of their occupation. Accelerometry features were gener-ated within periods of low-movement and gait. These features were the eigenvalues of high-dimensional correlation matrices, which were constructed with time-delay embedding at multiple delay scales. When focusing on the gait windows, there were significant correlations of the changes in features with the cumulative dose of blast exposure. When focusing on the low-movement frames, the correlation with exposure were lower than that of the gait frames and statistically insignificant. In a cross-validated model, the overpressure exposure was predicted from gait features alone. The model was statistically significant and yielded an RMSE of 1.27 dB. With continued development, the model may be used to assess the physiological effects of repetitive blast exposure and guide training procedures to minimize impact on the individual.

'I had nothing. It's just life experience that helped me through that situation': Australian audiologists' perspectives on audiological clinical practice for traumatic brain injury and rehabilitation

OBJECTIVE

Australian Audiologists' perspectives on standard non-specialized clinical practice in the context of Traumatic Brain Injury (TBI) were examined, including the perceived barriers to optimal service provision.

DESIGN

A qualitative research design utilizing semi-structured interviews was conducted using purposive sampling. Nine participants were interviewed about their understanding of the impact of TBI on hearing and balance; identification, diagnosis and management of auditory and vestibular dysfunction following TBI; barriers to service delivery; training relating to complex clients (i.e., TBI); and awareness of referral pathways.

RESULTS

Three major themes, each with subthemes, were evident in the data. The major themes reflected general considerations of audiological professional culture and specific issues related to knowledge of TBI and clinical practice with patients. Analysis revealed that professional culture seemed to act as a contextual barrier and interacted with the perceived lack of TBI related knowledge to hinder optimal clinical practice in this patient population.

CONCLUSION

Application of the biopsychosocial model, including interdisciplinary care in the management of patients with TBI, is needed. An improvement in theoretical and practical knowledge encompassing the wide-ranging effects of TBI is critical for the optimal audiological service delivery.

Challenging the Vestibular System Affects Gait Speed and Cognitive Workload in Chronic Mild Traumatic Brain Injury and Healthy Adults

People with persistent symptoms after mild traumatic brain injury (mTBI) report imbalance during walking with head movements. The purpose of this study was (1) to compare usual walk gait speed to walking with head turns (HT) between people with mTBI and controls, (2) to compare the cognitive workload from usual walk to HT walk between groups, and (3) to examine if gaze stability deficits and mTBI symptoms influence gait speed. Twenty-three individuals (mean age 55.7 ± 9.3 years) with persistent symptoms after mTBI (between 3 months to 2 years post-injury) were compared with 23 age and sex-matched controls. Participants walked a 12-inch wide, 60-foot walkway when looking ahead and when walking with HT to identify letters and their colors. Gait speed during usual walk and HT walk were calculated. Pupillary responses during both walks were converted to the Index of Cognitive Activity (ICA) as a measure of cognitive workload. Gaze stability was examined by the dynamic visual acuity (DVA) test in the yaw plane. The post-concussion symptom scale (PCSS) was used to collect symptom severity. Within group analysis showed that gait speed was lower during HT walk compared to usual walk in the people with mTBI (p < 0.001) as well as in controls (p < 0.001). ICA was higher with HT compared to usual walk in the mTBI group in the right eye (p = 0.01) and left eye (p = 0.001), and in controls in the right eye (p = 0.01) and left eye (p = 0.01). Participants in the mTBI group had slower usual (p < 0.001), and HT gait speed (p < 0.001) compared to controls. No differences were noted in ICA in the right or left eye during usual walk and HT walk between groups (p > 0.05). DVA loss in the yaw plane to the right and left was not different between groups (p > 0.05) and were not correlated with gait speed. PCSS scores were correlated with usual walk (r = −0.50, p < 0.001) and HT gait speed (r = −0.44, p = 0.002). Slower gait speed, poorer stability, and higher cognitive workload during walking with head turns may reduce community participation in people with mTBI and persistent symptoms.

The Non-Concordance of Self-Reported and Performance-Based Measures of Vestibular Dysfunction in Military and Civilian Populations Following TBI

As a predominately young, physically active, and generally healthy population, service members (SMs) with vestibular dysfunction (VD) following a TBI may not be accurately represented by the current civilian reference ranges on assessments of VD. This study enrolled SMs who were referred for vestibular rehabilitation following a mild/moderate TBI. The participants self-reported VD using the Activities-specific Balance Confidence (ABC) scale and the Dizziness Handicap Inventory (DHI) followed by evaluation of vestibular performance using computerized dynamic posturography sensory organizational test (CDP−SOT). Retrospective analysis of these outcomes comparing the study sample of SMs to the reported civilian samples revealed SMs self-reported lower VD with significantly higher balance confidence (ABC: 77.11 ± 14.61, p < 0.05) and lower dizziness (DHI: 37.75 ± 11.74, p < 0.05) than civilians. However, the SMs underperformed in performance-based evaluations compared to civilians with significantly lower CDP−SOT composite and ratio scores (COMP: 68.46 ± 13.46, p < 0.05; VIS: 81.36 ± 14.03, p < 0.01; VEST: 55.63 ± 22.28, p < 0.05; SOM: 90.46 ± 10.17, p < 0.05). Correlational analyses identified significant relationships between the ABC and CDP−SOT composite (r = 0.380, p < 0.01) and ratio scores (VIS: r = 0.266, p < 0.05; VEST: r = 0.352, p < 0.01). These results highlight the importance of recognizing and understanding nuances in assessing VD in SMs to ensure they have access to adequate care and rehabilitation prior to returning to duty.

Vestibulo-ocular dysfunction in mTBI: Utility of the VOMS for evaluation and management – A review

BACKGROUND: Individuals who have suffered a concussion/mild traumatic brain injury (mTBI) frequently report symptoms associated with vestibular and/or oculomotor dysfunction (VOD) like dizziness, nausea, fatigue, brain fog, headache, gait and neurocognitive impairments which are associated with the development of chronic symptoms. The Vestibular/Ocular Motor Screening (VOMS) tool has been established as a reliable and clinically relevant complement to use alongside a battery of post-concussion tests to improve screening and referral for further evaluation and treatment of VOD. OBJECTIVES: This paper will review the pathoanatomy and symptomatology of common vestibular and oculomotor disorders after concussion, as well as the utility of the VOMS to assist in diagnosis, referral, and management. METHODS: Primary articles were identified using a search via PubMed, Google Scholar, OneSearch, and CINAHL. Search key terms were combinations of “mild traumatic brain injury” or “concussion” or “pursuit” or “accommodation” or “vergence” or “convergence insufficiency” or “saccades” or “vestibulo-ocular reflex” or “vestibular ocular motor screen” or “vestibular rehabilitation”, or “vision rehabilitation” including adult and pediatric populations that were published in print or electronically from 1989 to 2021 in English. Classic papers on anatomy of eye movements, vestibular system and pathological changes in mTBI were also included, regardless of publication date. RESULTS: Objective impairments are commonly found during testing of smooth pursuit, saccades, vergence, accommodation, vestibular ocular reflex, and visual motion sensitivity after mTBI. These deficits can be actively treated with vestibular physical therapy and oculomotor/neuro-optometric vision therapy. VOMS is an efficient and reliable tool that can be used by all healthcare and rehabilitation providers to aid in diagnosis of post-concussion VOD, to help facilitate the decision to refer for further evaluation and treatment to expedite symptomatic post-concussion recovery. CONCLUSIONS: VOD is common after concussion in acute, post-acute, and chronic phases. Once areas of impairments are identified through proper assessment, clinicians can maximize recovery by referring to vestibular physical therapy and/or neuro-optometry to design a targeted treatment program to address individual deficits.

A Comparison of Generalized and Individualized Vestibular Rehabilitation Therapy in a Military TBI Sample

OBJECTIVE

To compare clinical outcomes between active duty service members receiving generalized versus individualized vestibular rehabilitation treatment (GVRT and IVRT, respectively) for persistent vestibular-related symptoms following mild traumatic brain injury (mTBI).

SETTING

An outpatient TBI rehabilitation clinic.

PARTICIPANTS

Fifty-seven participants with persistent vestibular-related symptoms following mTBI were randomly assigned to the GVRT (n = 28) or IVRT (n = 29) group, stratified by dizziness-related impairment severity. Forty-two participants (n = 21 per group) completed the posttreatment evaluation and were included in analyses.

DESIGN

We employed a single-site, randomized, pre-/posttest experimental design. The GVRT program consisted of eight 45-minute group-based treatment sessions and IVRT consisted of three 30-minute one-on-one treatment sessions both to be completed within 8 weeks. Group assignment was not blinded to study personnel or participants. Research evaluations were completed approximately 2 weeks prior to treatment initiation and following treatment completion.

MAIN MEASURES

Outcome measures included Dizziness Handicap Inventory (DHI) and Activities-specific Balance Confidence Scale (ABC) total scores, Sensory Organization Test (SOT) composite equilibrium and sensory input ratio scores, Head Shake SOT (HS-SOT) conditions 2 and 5, and horizontal and vertical Dynamic Visual Acuity. Separate mixed-effects models were used to compare clinical outcomes between the GVRT and IVRT groups.

RESULTS

Both groups demonstrated significant improvement from pre- to posttreatment on self-reported dizziness-related impairment (DHI [F(1,41) = 16.28, P < .001]) and balance performance with and without head movement (composite equilibrium score [F(1,41) = 16.58, P < .001, effect size [ES] = 0.43], somatosensory [F(1,41) = 6.79, P = .013, ES = 0.26], visual [F(1,41) = 6.49, P = .015, ES = 0.29], vestibular [F(1,41) = 22.31, P < .001, ES = 0.55], and HS-SOT condition 5 [F(1,38) = 23.98, P < .001, ES = 0.64]). Treatment effects did not differ between groups on any of the outcome measures.

CONCLUSIONS

We provide preliminary evidence that differences in clinical outcomes do not exist between participants receiving generalized versus individualized VR. Further research is needed to determine comparative effectiveness between these 2 treatment approaches for persistent vestibular-related symptoms following mTBI.

[Lesions of the cortical part of the auditory analyzer in explosive injury]

A survey of 48 victims aged 19-36 years with explosive trauma and combined damage to the auditory system was conducted to assess the level of damage to nerve structures by analyzing the bioelectric activity of the cerebral cortex. All patients underwent electroencephalography (EEG). It is established that akubarotrauma of explosive genesis almost always leads to lesions of the function of the cortical part of the auditory analyzer. Desynchronized activity on the EEG after acubarotrauma is a favorable prognostic sign, indicating only functional disorders of the cortical part of the auditory analyzer. On the contrary, EEG changes of an organic type of cortical or stem nature are an unfavorable prognostic factor, usually accompanied by sensorineural hearing loss with prolonged and incomplete hearing recovery. Promising drugs for the treatment of otoneurological disorders are antihypoxants, in particular, derivatives of triazine indole, which affect the molecular mechanisms of hypoxia development.

Perception, knowledge, and attitude of medical doctors in Saudi Arabia about the role of physiotherapists in vestibular rehabilitation: a cross-sectional survey

Objectives

There is compelling scientific evidence about the role of physiotherapists in vestibular rehabilitation. However, patients with vestibular-associated dizziness and balance disturbances are seldom referred to physiotherapists in Saudi Arabia. Therefore, this study aims to achieve insight into perceptions, knowledge, attitudes, and referral practices among Saudi Arabian medical doctors relating to the role of physiotherapists in vestibular rehabilitation.

Methods

A sample of 381 medical doctors practicing in Saudi Arabia participated in this nationwide cross-sectional study. The sample was obtained from 226 hospitals across 13 provinces of Saudi Arabia by stratified sampling method. The 23-item questionnaire developed by a team of experts was emailed to medical doctors practicing in various hospitals across Saudi Arabia.

Results

Out of 1,231 medical doctors invited, 381 medical doctors responded, giving a response rate of 30.9%. One hundred ninety-three (50.6%) medical doctors reported managing patients with vestibular rehabilitation. The most preferred specialist for managing patients with vestibular disorders was an Ear Nose Throat (ENT) specialist (n = 173, 89.6%). Related Sample Cochran's Q test showed statistically significant difference between preferred specialist for managing patients with vestibular disorders (ENT specialists, physiotherapists, nurses, occupational therapists and audiologists) (χ2(4) = 482.476, p = 0.001). Out of 193 medical doctors, 153 (79.2%) reported no role of the physiotherapist in vestibular rehabilitation. One hundred forty-five (75.1%) of medical doctors reported that they were not aware of the role of physiotherapists in vestibular rehabilitation. Only 27 (15.5%) medical doctors reported referring patients with vestibular disorders to physiotherapists.

Conclusion

The study reports that physiotherapy services are underutilized in vestibular rehabilitation due to limited referral from Saudi Arabian medical doctors. Therefore, there is a need to increase the awareness among Saudi Arabian doctors about the physiotherapist's role in vestibular rehabilitation.

Vestibular Rehabilitation Effectiveness for Adults With Mild Traumatic Brain Injury/Concussion: A Mini-Systematic Review

OBJECTIVE

Millions of people suffer from traumatic brain injuries every year with common sequelae, including dizziness, disequilibrium, compromised vision, and gait abnormalities. Individuals suffering a mild traumatic brain injury (mTBI) or concussion may be prescribed bed rest, but for some, symptoms may persist and require different treatment options. The aim of this mini-systematic review was to synthesize the best available evidence regarding the effectiveness of vestibular rehabilitation therapy (VRT) as a treatment option for adults with mTBIs.

METHOD

A systematic review of the literature was performed following the PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) guidelines. Search term concepts were VRT and mTBI. Records meeting the inclusion criteria were extracted from the following databases: PubMed and CINAHL. A manual search of reference lists identified additional studies. Inclusion criteria were (a) participants with mTBI/concussion characterized by dizziness, balance, and/or other vestibular symptoms; (b) VRT as the primary treatment; and (c) self-reported and/or performance-based outcome measures. Data were extracted using a standardized tool, and studies were critically appraised.

RESULTS

Five studies were included in the systematic review: one randomized controlled trial, two retrospective chart reviews, one pre-/post-intervention study, and one case series. Four of the five studies found VRT to be effective at reducing postconcussion symptoms after head injury. Self-reported measures were included in all studies; performance-based measures were included in four out of five studies. None of the studies reported adverse effects of intervention.

CONCLUSIONS

Results suggest VRT is an effective treatment option for patients with persistent/lingering symptoms after concussion/mTBI, as demonstrated by self-reported and performance-based outcome measures. Results of this study emphasize the need for audiologists to be thoroughly familiar with VRT as an effective treatment for patients with persistent symptoms following mTBI.

Post-concussive Dizziness: A Review and Clinical Approach to the Patient

Dizziness is a frequent complaint after head trauma. Among patients who suffer a concussion (mild traumatic brain injury or mTBI), dizziness is second only to headache in symptom frequency. The differential diagnosis of post-concussive dizziness (PCD) can be divided into non-vestibular, central vestibular and peripheral vestibular causes with growing recognition that patients frequently exhibit both central and peripheral findings on vestibular testing. Symptoms that traditionally have been ascribed to central vestibular dysfunction may be due to peripheral dysfunction. Further, our ability to test peripheral vestibular function has improved and has allowed us to identify peripheral disorders that in the past would have remained unnoticed. The importance of the identification of the peripheral component in PCD lies in our ability to remedy the peripheral vestibular component to a much greater extent than the central component. Unfortunately, many patients are not adequately evaluated for vestibular disorders until long after the onset of their symptoms. Among the diagnoses seen as causes for PCD are (1) Central vestibular disorders, (2) Benign Paroxysmal Positional Vertigo (BPPV), (3) Labyrinthine dehiscence/perilymph fistula syndrome, (4) labyrinthine concussion, (5) secondary endolymphatic hydrops, (6) Temporal bone fracture, and (7) Malingering (particularly when litigation is pending). These diagnoses are not mutually exclusive and PCD patients frequently exhibit a combination of these disorders. A review of the literature and a general approach to the patient with post-concussive dizziness will be detailed as well as a review of the above-mentioned diagnostic categories.

The Marcus Institute for Brain Health: an integrated practice unit for the care of traumatic brain injury in military veterans

PRIMARY OBJECTIVE

Traumatic brain injury (TBI) is a signature wound of recent Unites States military conflicts. The National Intrepid Center of Excellence (NICoE) has demonstrated that interdisciplinary care is effective for active-duty military personnel with TBI and related psychological health conditions. This paper details how the Marcus Institute for Brain Health (MIBH), established in 2017 as an Integrated Practice Unit (IPU), is founded on the NICoE model and is dedicated to interdisciplinary care for Veterans with persistent symptoms due to TBI and psychological comorbidities.

RESEARCH DESIGN

A highly integrated group of clinicians from diverse disciplines combine their expertise to offer comprehensive evaluation, intensive outpatient treatment, and program outcomes evaluation.

METHODS AND PROCEDURES

The role of each discipline in the provision of care, and the regular interaction of all clinicians, are delineated. A strong connection to academic medicine is maintained so that clinical research and education complement patient care.

MAIN OUTCOMES AND RESULTS

Over three hundred veterans and family members have received treatment at the MIBH. Program evaluation is underway.

CONCLUSIONS

As the understanding of TBI and related psychological conditions continues its rapid evolution, the expert interdisciplinary care at the MIBH has great promise as a Veteran counterpart of the NICoE.

Evaluating the Vestibulo-Ocular Reflex Following Traumatic Brain Injury: A Scoping Review

Purpose:To identify the tests and tools used to evaluate vestibulo-ocular reflex (VOR) function after traumatic brain injury (TBI) in all age groups and across TBI severity.Methods: An electronic search was conducted to include relevant peer-reviewed literature published up to November 2019. Studies included those done with humans, of all ages, and had assessments of oculomotor and/or vestibulo-ocular function in TBI.Results: Of the articles selected (N = 48), 50% were published in 2018/2019. A majority targeted mild TBI, with equal focus on non-computerized versus computerized measures of VOR. Computerized assessment tools used were videonystagmography, dynamic visual acuity/gaze stability, rotary chair, and caloric irrigation. Non-computerized tests included the head thrust, dynamic visual acuity, gaze stability, head shaking nystagmus, rotary chair tests and the vestibular/oculomotor screening tool. High variability in administration protocols were identified. Namely: testing environment, distances/positioning/equipment used, active/passive state, procedures, rotation frequencies, and variables observed.Conclusions: There is a rapid growth of literature incorporating VOR tests in mild TBI but moderate and severe TBI continues to be under-represented. Determining how to pair a clinical test with a computerized tool and developing standardized protocols when administering tests will help in developing an optimal battery assessing the VOR in TBI.

Normative data for ages 18-45 for ocular motor and vestibular testing using eye tracking

OBJECTIVE

Eye tracking technology has been employed in assessing ocular motor and vestibular function following vestibular and neurologic conditions, including traumatic brain injury (TBI). Assessments include tests that provide visual and motion (rotation) stimuli while recording horizontal, vertical, and torsional eye movements. While some of these tests have shown diagnostic promise in previous studies, their use in clinical practice is limited by the lack of normative data. The goal of this study was to construct normative reference ranges to be used when comparing patients' results.

METHODS

Optokinetic response, subjective visual horizontal and vertical, and rotation tests were administered to male and female volunteers, ages 18-45, who were free from neurological, vestibular disorders, or other head injuries. Tests were administered using either a rotatory chair or a portable virtual reality-like goggle equipped with video-oculography.

RESULTS

Reference values for eye movements in response to different patterns of stimuli were analyzed from 290 to 449 participants. Analysis of gender (self-reported) or age when grouped as pediatric (late adolescent; 18-21 years of age) and adult (21-45 years of age) revealed no effects on the test metrics. Data were pooled and presented for each test metric as the 95% reference interval (RI) with 90% confidence intervals (CI) on upper and lower limits of the RI.

CONCLUSIONS

This normative database can serve as a tool to aid in diagnosis, treatment, and/or rehabilitation protocols for vestibular and neurological conditions, including mild TBI (mTBI). This database has been cleared by the FDA for use in clinical practice (K192186).

LEVEL OF EVIDENCE

2b.

The development and the inter-rater agreement of a treatment protocol for vestibular/oculomotor rehabilitation in children and adolescents post-moderate-severe TBI

Introduction:There is limited evidence investigating the effect of vestibular/oculomotor rehabilitation programs in children and adolescents post moderate-severe TBI at the sub-acute stage.Objective:To describe the development of a treatment protocol for vestibular/oculomotor interventions in this population, and to assess the inter-rater agreement of this protocol as an initial step of a clinical trial.Method:The protocol was developed by 10 health professionals, address the high variability of balance performance, the high prevalence of vestibular/oculomotor abnormalities and the low prevalence of symptoms reported in this population.Results:The protocol enables the clinician to use the assessment during the treatment exercise selection. The training position was defined by the Pediatric Balance Scale. Vestibular/oculomotor exercises were selected using a quantified version of the Vestibular/Ocular Motor Screening. The exercise protocol was selected based on impairment in function or reproduction of symptoms. The protocol planning was implemented by two assessors in 27 children and adolescents post-moderate-severe TBI (median age 14.1 [6-18.4] years) in the sub-acute stage (median 40 [14-162] days since injury). Very high agreement was found (k > 0.72) in all the parameters.Conclusion: This protocol could reliably be used in a randomized control trial that assesses the effect of vestibular/oculomotor rehabilitation program in children and adolescents post moderate-severe TBI at the sub-acute stage.

Altered Vestibular Balance Function in Combat Sport Athletes

Combat sports pose a risk for accumulative injuries to the nervous system, yet fighters have remained an understudied population. Here, our purpose was to determine whether repetitive blows to the head have an effect on vestibular balance reflexes in combat sports athletes. We compared lower-limb muscle responses evoked with electrical vestibular stimuluation (EVS) between fighters (boxing/muay thai) and non-fighter controls. Each participant received stochastic vestibular stimulation (0-25 Hz, ±3 mA) over their mastoid processes while they stood relaxed with their head to the left or right. Surface electromyography was recorded from the medial gastrocnemius and soleus muscles bilaterally. Short and medium latency response (SLR/MLR) peaks were significantly delayed in the fighter group compared to controls. SLR and MLR peak amplitudes were also significantly lower in fighters. Fighter-estimated cumulative repetitive head impact (RHI) events demonstrated strong positive correlations with the timing of SLR and MLR peaks. Cumulative RHI events also negatively correlated with peak MLR amplitude and response gain at frequencies above 5 Hz. Our results provide evidence of a progressive vestibular impairment in combat sports athletes, potentially resulting from blows to the head accumulated in sparring practice and competitive bouts throughout their careers. Taken together, EVS-based vestibular assessments may provide a valuable clinical diagnostic tool and help better inform "return-to-play" and career-length decisions for not only combat sports athletes, but potentially other populations at risk of RHIs.