mTBI evaluation, management, and referral to allied healthcare: practices of first-line healthcare professionals.

PRIMARY OBJECTIVE: To gain an understanding of current evaluation practices, post-injury recommendations, and referrals to allied healthcare professions (AHP) by first-line healthcare professionals (FHPs) providing care for people with mild traumatic brain injury (mTBI). RESEARCH DESIGN: Survey study. METHODS AND PROCEDURES: Physicians, physician assistants, nurse practitioners, nurses, and athletic trainers (n = 126) completed an online survey, including Likert scale and free response question relating to mTBI evaluation, management, and referral practices. MAIN OUTCOMES AND RESULTS: FHPs surveyed reported being confident in their ability to evaluate patients with suspected mTBI, relying most heavily on patient-reported symptoms and physical signs as methods of evaluation. Most FHPs reported making recommendations to compensate for the symptoms experienced following mTBI diagnosis. In contrast, FHPs expressed challenges in the evaluation and management of symptoms associated with mTBI along with limited knowledge of and referrals to AHPs. CONCLUSIONS: Overall, FHPs feel confident in the diagnosis of mTBI but experience assessment and management challenges. AHPs are underutilized on mTBI management teams calling for a need for multidisciplinary collaboration on research, education, and rehabilitation efforts to optimally care for people experiencing mTBI symptoms.

Implementation of telehealth and hybrid service delivery of interdisciplinary rehabilitation for military populations with traumatic brain injury.

BACKGROUND: The COVID-19 pandemic necessitated the implementation of telehealth and hybrid service delivery models and provided an opportunity to study the impact of this care model in military populations with history of traumatic brain injury (TBI). OBJECTIVE: To present telehealth service utilization rates across rehabilitation specialties, treatment outcome indicators, and patient satisfaction outcomes from a retrospective clinical sample. METHODS: The study sample consists of 34 patients who underwent telehealth/hybrid Intensive Outpatient Programming (IOP) at a major rehabilitation hospital. Retrospective chart review and clinical data extraction were performed. A historical cohort receiving in-person care was used as a comparison group. Statistical analyses included partial correlations, mixed method analysis of variance (ANOVA), and independent sample t-tests. RESULTS: Medical, behavioral health, physical, occupational, and speech-language therapy providers exhibited similar rates of telehealth service delivery (35 to 41% of all sessions). No significant association was found between percent telehealth sessions and the global treatment outcome indicator. Comparison of treatment effects across cohorts revealed similar benefits of IOP. No between-group differences were noted in satisfaction ratings. CONCLUSION: The comparable treatment-related gains and reports of positive patient experience support the use of a telehealth and hybrid delivery model for military service members and veterans with TBI.

Level of Evidence of Telehealth Rehabilitation and Behavioral Health Services for Traumatic Brain Injury: A Scoping Review.

Traumatic brain injury (TBI) can result in significant impairments in functioning associated with partial or permanent disabilities. Examining the evidence for domain-specific telehealth interventions is necessary to guide the development of effective clinical and research programs for this population. The present scoping review characterizes the level of evidence across a range of TBI-related disabilities and impairments. A literature search was performed across comprehensive databases using search terms related to TBI, rehabilitation, telehealth, and outcome. A total of 19 publications from 17 studies met inclusion criteria. Articles focused on telehealth interventions to improve global, cognitive, emotional, and physical functioning post-TBI. Levels of evidence ranged from 1 to 4 across domains, with predominantly experimental designs (level 1). Outcomes demonstrating improvement or benefit from telehealth treatments were reported across all functional domains (50-80% of studies). Results highlight the potential of telehealth interventions across the span of comprehensive interdisciplinary rehabilitation care. Expanded research is needed on remote treatment options for physical symptoms, for subgroups within TBI populations (i.e., mild TBI, military populations), as well as on remote and hybrid comprehensive rehabilitation programs.

Longitudinal Assessment of Postconcussion Driving: Evidence of Acute Driving Impairment.

BACKGROUND: Current medical practices and recommendations largely ignore the safety of postconcussion driving, even though commonly used measures of neurocognition, balance, and vestibulo-ocular function show impairment. PURPOSE: To compare simulated driving between patients with concussion and controls throughout concussion recovery using a case-control design. STUDY DESIGN: Cohort study; Level of evidence, 2. METHODS: A total of 26 concussed and 23 control Division I collegiate athletes completed a driving simulation assessment at 3 time points (within 72 hours, asymptomatic, and return to sport). Cumulative driving simulation outcome variables included total number of collisions, speed exceedances, stop signs missed, lane excursions, total drive time, percentage of time over the speed limit, and percentage of time out of the lane. The mean speed, standard deviation of speed (SDS), lateral lane position, and standard deviation of lateral lane position (SDLP) were examined for each of the 11 drive segments. Outcomes were compared using generalized linear mixed models with random intercepts by participant with Poisson or normal distributions. RESULTS: Within 72 hours of injury, the concussion group committed more lane excursions (median difference, 2; P = .003), exhibited greater SDS while avoiding a child pedestrian crossing the road (Cohen d = 0.73; P = .011), drove ~7 inches (~18 cm) closer to the centerline during a residential left curve (d = 0.90; P = .015), and had greater SDLP while navigating around a car crash compared with controls (d = 0.72; P = .016). When asymptomatic, the concussion group committed fewer speed exceedances (median difference, 2; P = .002) and had lower SDLP while navigating through a traffic light compared with controls (d = 0.60; P = .045). No differences were evident at return to sport. Groups did not differ in total collisions at any time point. CONCLUSION: The concussion group showed more impaired driving patterns within 72 hours of injury, drove more conservatively once asymptomatic, and had similar driving performance at the time they returned fully to sport. Clinicians should consider these findings when discussing driving with patients acutely after concussion. Further research is needed to determine whether on-road collision risk is elevated after concussion.

Visuo-vestibular and cognitive connections of the vestibular neuromatrix are conserved across age and injury populations.

BACKGROUND AND PURPOSE: Given the prevalence of vestibular dysfunction in pediatric concussion, there is a need to better understand pathophysiological disruptions within vestibular and associated cognitive, affective, and sensory-integrative networks. Although current research leverages established intrinsic connectivity networks, these are nonspecific for vestibular function, suggesting that a pathologically guided approach is warranted. The purpose of this study was to evaluate the generalizability of the previously identified "vestibular neuromatrix" in adults with and without postconcussive vestibular dysfunction to young athletes aged 14-17. METHODS: This retrospective study leveraged resting-state functional MRI data from two sites. Site A included adults with diagnosed postconcussive vestibular impairment and healthy adult controls and Site B consisted of young athletes with preseason, postconcussion, and postseason time points (prospective longitudinal data). Adjacency matrices were generated from preprocessed resting-state data from each sample and assessed for overlap and network structure in MATLAB. RESULTS: Analyses indicated the presence of a conserved "core" network of vestibular regions as well as areas subserving visual, spatial, and attentional processing. Other vestibular connections were also conserved across samples but were not linked to the "core" subnetwork by regions of interest included in this study. CONCLUSIONS: Our results suggest that connections between central vestibular, visuospatial, and known intrinsic connectivity networks are conserved across adult and pediatric participants with and without concussion, evincing the significance of this expanded, vestibular-associated network. Our findings thus support this network as a workable model for investigation in future studies of dysfunction in young athlete populations.

The effects of sports-related concussion history on female adolescent brain activity and connectivity for bilateral lower extremity knee motor control.

Sports-related concussions (SRCs) are associated with neuromuscular control deficits in athletes following return to play. However, the connection between SRC and potentially disrupted neural regulation of lower extremity motor control has not been investigated. The purpose of this study was to investigate brain activity and connectivity during a functional magnetic resonance imaging (fMRI) lower extremity motor control task (bilateral leg press) in female adolescent athletes with a history of SRC. Nineteen female adolescent athletes with a history of SRC and nineteen uninjured (without a history of SRC) age- and sport-matched control athletes participated in this study. Athletes with a history of SRC exhibited less neural activity in the left inferior parietal lobule/supramarginal gyrus (IPL) during the bilateral leg press compared to matched controls. Based upon signal change detected in the brain activity analysis, a 6 mm region of interest (seed) was defined to perform secondary connectivity analyses using psychophysiological interaction (PPI) analyses. During the motor control task, the left IPL (seed) was significantly connected to the right posterior cingulate gyrus/precuneus cortex and right IPL for athletes with a history of SRC. The left IPL was significantly connected to the left primary motor cortex (M1) and primary somatosensory cortex (S1), right inferior temporal gyrus, and right S1 for matched controls. Altered neural activity in brain regions important for sensorimotor integration and motor attention, combined with unique connectivity to regions responsible for attentional, cognitive, and proprioceptive processing, indicate compensatory neural mechanisms may underlie the lingering neuromuscular control deficits associated with SRC.

The SUCCESS Peer Mentoring Program for College Students with Concussion: Preliminary Results of a Mobile Technology Delivered Intervention.

Concussions are caused by a hit or blow to the head that alters normal brain functioning. The Success in College after Concussion with Effective Student Supports (SUCCESS) program was developed to provide students with psychosocial support and resources-both key components of concussion management-to assist in recovery and return-to-learn following concussion. In this preliminary evaluation of intervention efficacy, SUCCESS was delivered through a mobile application connecting mentors (students who have recovered from concussion and successfully returned to school) with mentees who were currently recovering. Mentor-mentee pairs met virtually through the app, using chat and videoconferencing features to share support, resources, and program-specific educational materials. Results from 16 mentoring pairs showed that mentee symptoms (V = 119, p = 0.009) and academic problems decreased (V = 114.5, p = 0.002), while academic self-efficacy increased (V = 13.5, p = 0.009) following mentoring. As expected, mentor measures were stable, indicating that providing mentoring did not exacerbate previously resolved concussion complaints. Virtual peer mentoring provided through a mobile application may be a feasible intervention to support academic success and psychosocial processing during recovery for college students with concussion.

Eagle-449: A volumetric, whole-brain compilation of brain atlases for vestibular functional MRI research.

Human vestibular processing involves distributed networks of cortical and subcortical regions which perform sensory and multimodal integrative functions. These functional hubs are also interconnected with areas subserving cognitive, affective, and body-representative domains. Analysis of these diverse components of the vestibular and vestibular-associated networks, and synthesis of their holistic functioning, is therefore vital to our understanding of the genesis of vestibular dysfunctions and aid treatment development. Novel neuroimaging methodologies, including functional and structural connectivity analyses, have provided important contributions in this area, but often require the use of atlases which are comprised of well-defined a priori regions of interest. Investigating vestibular dysfunction requires a more detailed atlas that encompasses cortical, subcortical, cerebellar, and brainstem regions. The present paper represents an effort to establish a compilation of existing, peer-reviewed brain atlases which collectively afford comprehensive coverage of these regions while explicitly focusing on vestibular substrates. It is expected that this compilation will be iteratively improved with additional contributions from researchers in the field.

Use of person-centered goals to direct interdisciplinary care for military service members and Veterans with chronic mTBI and co-occurring psychological conditions.

Objective: To explore the use of person-centered goals (PCGs) to direct interdisciplinary care to support PCG attainment in military service members and Veterans (SM/Vs) with chronic mild traumatic brain injury (mTBI) and co-occurring psychological conditions. Methods: A retrospective chart review was completed for 146 United States military SM/Vs reporting chronic symptoms following mTBI and co-occurring psychological conditions who received care in the SHARE Military Initiative intensive outpatient program, a donor-funded program administered by a not-for-profit hospital, between April 1, 2015 and March 31, 2019. PCGs were used to direct care consisting of individual and group-based interventions and therapies delivered by an interdisciplinary, co-located team including behavioral health, case management, neurology or physiatry, nursing, occupational therapy, physical therapy, recreation therapy, speech-language pathology, and transition support. The primary outcome measure was PCG attainment measured via goal attainment scaling. Results: Increased PCG attainment was demonstrated at program discharge and throughout the first year following program discharge. Predictors of goal attainment at discharge included longer participation in treatment, greater reduction in depressive symptoms and greater improvement in adjustment at discharge, male gender, and higher cognitive and physical abilities on admission. Conclusions: This sample of military SM/Vs with mTBI and co-occurring psychological conditions who received intensive, interdisciplinary, PCG directed care demonstrated increased PCG attainment at program discharge which further increased with transition support over the year post-discharge. Results suggest PGC goal directed care is a feasible, promising methodology of individualizing treatment in this population. This exploratory study lays a foundation for future prospective, controlled, comparative effectiveness research that will further understanding of the effectiveness of intensive, interdisciplinary, PCG directed care.

Implementation of a Mobile Technology-Supported Diaphragmatic Breathing Intervention in Military mTBI With PTSD.

BACKGROUND: Diaphragmatic breathing is an evidence-based intervention for managing stress and anxiety; however, some military veterans with mild traumatic brain injury (mTBI) and posttraumatic stress disorder (PTSD) report challenges to learning and practicing the technique. BreatheWell Wear assists performance of breathing exercises through reminders, biofeedback, and visual, tactile, and auditory guidance. OBJECTIVE: To evaluate feasibility of implementing BreatheWell Wear, a mobile smartwatch application with companion smartphone app, as an intervention for stress management in military veterans with mTBI and PTSD. METHODS: Thirty veterans with chronic symptoms of mTBI and PTSD recruited from an interdisciplinary, intensive outpatient program participated in this pilot pragmatic clinical trial. Participants were randomly assigned to the experimental (BreatheWell Wear and conventional care) and control (conventional care) groups for 4 weeks. Conventional care included instruction on relaxation breathing and participation in behavioral health therapy. Effects on goal attainment, treatment adherence, diaphragmatic breathing technique knowledge, and stress were measured through surveys and diaries. Changes in symptoms, mood, and well-being were measured pre/postintervention via the Posttraumatic Checklist for DSM-5, Beck Anxiety Inventory, Beck Depression Inventory, and Flourishing Scale. RESULTS: Person-centered goal attainment (t = 4.009, P < .001), treatment adherence (t = 2.742, P = .001), diaphragmatic breathing technique knowledge (t = 1.637, P < .001), and reported ease of remembering to practice (t = -3.075, P = .005) were significantly greater in the experimental group. As expected, measures of PTSD, anxiety, depression, and psychological well-being showed clinically meaningful change in both groups, and both groups demonstrated reduced stress following diaphragmatic breathing. CONCLUSION: These preliminary findings indicate that BreatheWell Wear may be a clinically feasible tool for supporting diaphragmatic breathing as an intervention in veterans with mTBI and PTSD, and a future effectiveness trial is warranted.

Technology-enhanced visual desensitization home exercise program for post-concussive visually induced dizziness: a case series.

PURPOSE: Post-concussive visually induced dizziness (VID), in which symptoms are provoked by exposure to complex visual motion, is associated with protracted recovery. Although vestibular rehabilitation therapy (VRT) is recommended to treat post-concussive dizziness, there is sparse literature reporting on specific VRT interventions treating VID. METHODS: A consecutive series of 26 individuals referred for VRT post-concussion were retrospectively assessed for inclusion in this case series. Each participant underwent a combination of conventional VRT and a technology-enhanced visual desensitization home exercise program (HEP). Self-report and objective measures were recorded from initial and discharge therapy evaluations. Twenty-three individuals (mean age 23.1 ± 12.4) with post-concussive dizziness (mean 109 ± 56 days post-injury) and no evidence for peripheral vestibular dysfunction were included. Treatment duration averaged 6.9 ± 2.5 weeks. RESULTS: There were significant improvements in post-intervention on subjective and objective measures of dizziness and gait (p < .05). The response to intervention was independent of pre-injury migraine history but pre-injury depression/anxiety increased self-report of post-treatment anxiety. Concurrent treatment with medications did not influence response to treatment. CONCLUSIONS: The combination therapy intervention improved outcome measures consistent with VRT treatment outcomes in both concussion and non-traumatic vestibular conditions. Individuals referred for VRT post-concussion warrant assessment for VID and may benefit from the addition of technology-enhanced visual desensitization.

The "vestibular neuromatrix": A proposed, expanded vestibular network from graph theory in post-concussive vestibular dysfunction.

Convergent clinical and neuroimaging evidence suggests that higher vestibular function is subserved by a distributed network including visuospatial, cognitive-affective, proprioceptive, and integrative brain regions. Clinical vestibular syndromes may perturb this network, resulting in deficits across a variety of functional domains. Here, we leverage structural and functional neuroimaging to characterize this extended network in healthy control participants and patients with post-concussive vestibular dysfunction (PCVD). Then, 27 healthy control subjects (15 females) and 18 patients with subacute PCVD (12 female) were selected for participation. Eighty-two regions of interest (network nodes) were identified based on previous publications, group-wise differences in BOLD signal amplitude and connectivity, and multivariate pattern analysis on affective tests. Group-specific "core" networks, as well as a "consensus" network comprised of connections common to all participants, were then generated based on probabilistic tractography and functional connectivity between the 82 nodes and subjected to analyses of node centrality and community structure. Whereas the consensus network was comprised of affective, integrative, and vestibular nodes, PCVD participants exhibited diminished integration and centrality among vestibular and affective nodes and increased centrality of visual, supplementary motor, and frontal and cingulate eye field nodes. Clinical outcomes, derived from dynamic posturography, were associated with approximately 62% of all connections but best predicted by amygdalar, prefrontal, and cingulate connectivity. No group-wise differences in diffusion metrics or tractography were noted. These findings indicate that cognitive, affective, and proprioceptive substrates contribute to vestibular processing and performance and highlight the need to consider these domains during clinical diagnosis and treatment planning.

A Novel Neuropsychological Tool for Immersive Assessment of Concussion and Correlation with Subclinical Head Impacts.

Mild traumatic brain injury (mTBI) remains a diagnostic challenge and therefore strategies for objective assessment of neurological function are key to limiting long-term sequelae. Current assessment methods are not optimal in austere environments such as athletic fields; therefore, we developed an immersive tool, the Display Enhanced Testing for Cognitive Impairment and mTBI (DETECT) platform, for rapid objective neuropsychological (NP) testing. The objectives of this study were to assess the ability of DETECT to accurately identify neurocognitive deficits associated with concussion and evaluate the relationship between neurocognitive measures and subconcussive head impacts. DETECT was used over a single season of two high school and two college football teams. Study participants were instrumented with Riddell Head Impact Telemetry (HIT) sensors and a subset tested with DETECT immediately after confirmed impacts for different combinations of linear and rotational acceleration. A total of 123 athletes were enrolled and completed baseline testing. Twenty-one players were pulled from play for suspected concussion and tested with DETECT. DETECT was 86.7% sensitive (95% confidence interval [CI]: 59.5%, 98.3%) and 66.7% specific (95% CI: 22.3%, 95.7%) in correctly identifying athletes with concussions (15 of 21). Weak but significant correlations were found between complex choice response time (processing speed and divided attention) and both linear (Spearman rank correlation coefficient 0.262, p = 0.02) and rotational (Spearman coefficient 0.254, p = 0.03) acceleration on a subset of 76 players (113 DETECT tests) with no concussion symptoms. This study demonstrates that DETECT confers moderate to high sensitivity in identifying acute cognitive impairment and suggests that football impacts that do not result in concussion may negatively affect cognitive performance immediately following an impact. Specificity, however, was not optimal and points to the need for additional studies across multiple neurological domains. Given the need for more objective concussion screening in triage situations, DETECT may provide a solution for mTBI assessment.

Alterations in Resting-State Functional Brain Connectivity and Correlations with Vestibular/Ocular-Motor Screening Measures in Postconcussion Vestibular Dysfunction.

BACKGROUND AND PURPOSE: Vestibular symptoms after concussion are common and associated with protracted recovery. The purpose of this study is to define resting-state functional MRI (rs-fMRI) brain connectivity alterations in patients with postconcussion vestibular dysfunction (PCVD) and correlations between rs-fMRI connectivity and symptoms provoked during Vestibular/Ocular-Motor Screening (VOMS) assessment. METHODS: Prospective IRB approved study. STUDY GROUP: 12 subjects with subacute PCVD (2-10 weeks); control group: 10 age-matched subjects without history of concussion or vestibular impairment. Both groups underwent clinical vestibular assessment. rs-fMRI was acquired on 3.0T Siemens Trio with a 12-channel head coil. rs-fMRI data analysis included independent component analysis-based functional connectivity group differences, graph theory analysis, and ROI-to-ROI connectivity correlation analysis with VOMS clinical derivatives. Group difference maps between resting-state networks were calculated using dual regression method and corrected for multiple comparisons. Correlation analysis between ROI-to-ROI rs-fMRI brain activation and VOMS assessment ratings was performed using Pearson correlation coefficient, with a significance threshold of P ≤ .05. RESULTS: Compared to controls, PCVD group demonstrated significantly increased rs-fMRI connectivity between the default-mode network and right middle frontal gyrus and right postcentral gyrus; and between a vestibular-sensorimotor network and right prefrontal cortex. Significant positive correlations were found between clinical derivative VOMS scores and components of the vestibular, visual networks, and multisensory processing cortical representations. CONCLUSION: Altered rs-fMRI brain connectivity with increased connectivity of visual input, multisensory processing, and spatial memory in PCVD is correlative with clinical derivative VOMS scores, suggesting maladaptive brain plasticity underlying vestibular symptomatology.

Intubation Containment System for Improved Protection From Aerosolized Particles During Airway Management.

OBJECTIVES: Worldwide efforts to protect front line providers performing endotracheal intubation during the COVID-19 pandemic have led to innovative devices. Authors evaluated the aerosol containment effectiveness of a novel intubation aerosol containment system (IACS) compared with a recently promoted intubation box and no protective barrier. METHODS: In a simulation center at the authors' university, the IACS was compared to no protective barrier and an intubation box. Aerosolization was simulated using a commercial fog machine and leakage of aerosolize mist was visually assessed. RESULTS: The IACS appeared to contain the aerosolized mist, while the intubation box allowed for mist to contact the laryngoscopist and contaminate the clinical space through arm port holes and the open caudal end. Both devices protected the laryngoscopist better than no protective barrier. DISCUSSION: The IACS with integrated sleeves and plastic drape appears to offer superior protection for the laryngoscopist and assistant providers from aerosolized particles.

ASB clinical biomechanics award winner 2016: Assessment of gaze stability within 24-48hours post-concussion.

BACKGROUND: Approximately 90% of athletes with concussion experience a certain degree of visual system dysfunction immediately post-concussion. Of these abnormalities, gaze stability deficits are denoted as among the most common. Little research quantitatively explores these variables post-concussion. As such, the purpose of this study was to investigate and compare gaze stability between a control group of healthy non-injured athletes and a group of athletes with concussions 24-48hours post-injury. METHODS: Ten collegiate NCAA Division I athletes with concussions and ten healthy control collegiate athletes completed two trials of a sport-like antisaccade postural control task, the Wii Fit Soccer Heading Game. During play all participants were instructed to minimize gaze deviations away from a central fixed area. Athletes with concussions were assessed within 24-48 post-concussion while healthy control data were collected during pre-season athletic screening. Raw ocular point of gaze coordinates were tracked with a monocular eye tracking device (240Hz) and motion capture during the postural task to determine the instantaneous gaze coordinates. This data was exported and analyzed using a custom algorithm. Independent t-tests analyzed gaze resultant distance, prosaccade errors, mean vertical velocity, and mean horizontal velocity. FINDINGS: Athletes with concussions had significantly greater gaze resultant distance (p=0.006), prosaccade errors (p<0.001), and horizontal velocity (p=0.029) when compared to healthy controls. INTERPRETATION: These data suggest that athletes with concussions had less control of gaze during play of the Wii Fit Soccer Heading Game. This could indicate a gaze stability deficit via potentially reduced cortical inhibition that is present within 24-48hours post-concussion.

Risk for broad-spectrum neuropsychiatric disorders after mild traumatic brain injury in a cohort of US Air Force personnel.

BACKGROUND: Military personnel are at increased risk for traumatic brain injury (TBI) from combat and non-combat exposures. Sequelae of moderate-to-severe TBI are well described, but the literature remains conflicted regarding whether mild TBI (mTBI) results in lasting brain injury and functional impairments. This study assessed risk for a range of neuropsychiatric disorders presenting after mTBI while adjusting for the potential confounds of depression and post-traumatic stress disorder (PTSD). METHODS: A historical prospective association study was conducted utilising electronic demographic, medical and military-specific data for over 49,000 active duty US Air Force service members (Airmen). This study utilised diagnostic codes considered by an expert panel to be indicative of mTBI to identify cases. Cox proportional hazards modelling calculated HRs for neuropsychiatric outcomes while controlling for varying lengths of follow-up and potentially confounding variables. RESULTS: Airmen with mTBI were at increased risk for specific neuropsychiatric disorders compared with a similarly injured non-mTBI control group. HRs for memory loss/amnesia, cognitive disorders, schizophrenia, PTSD, and depression were significantly elevated and remained so for at least 6 months post-mTBI, even after eliminating those with previous neuropsychiatric diagnoses. CONCLUSIONS: mTBI was positively associated with neuropsychiatric disorders in this population of primarily young adult males; with increased HRs 6 months post-mTBI. The results support that mTBI is distinguished from moderate-to-severe TBI in terms of risk for developing neuropsychiatric disorders. Further, these findings suggest the importance of screening for psychiatric and cognitive disorders post-mTBI in general medical practice.

Functional recordings from awake, behaving rodents through a microchannel based regenerative neural interface.

OBJECTIVE: Neural interface technologies could provide controlling connections between the nervous system and external technologies, such as limb prosthetics. The recording of efferent, motor potentials is a critical requirement for a peripheral neural interface, as these signals represent the user-generated neural output intended to drive external devices. Our objective was to evaluate structural and functional neural regeneration through a microchannel neural interface and to characterize potentials recorded from electrodes placed within the microchannels in awake and behaving animals. APPROACH: Female rats were implanted with muscle EMG electrodes and, following unilateral sciatic nerve transection, the cut nerve was repaired either across a microchannel neural interface or with end-to-end surgical repair. During a 13 week recovery period, direct muscle responses to nerve stimulation proximal to the transection were monitored weekly. In two rats repaired with the neural interface, four wire electrodes were embedded in the microchannels and recordings were obtained within microchannels during proximal stimulation experiments and treadmill locomotion. MAIN RESULTS: In these proof-of-principle experiments, we found that axons from cut nerves were capable of functional reinnervation of distal muscle targets, whether regenerating through a microchannel device or after direct end-to-end repair. Discrete stimulation-evoked and volitional potentials were recorded within interface microchannels in a small group of awake and behaving animals and their firing patterns correlated directly with intramuscular recordings during locomotion. Of 38 potentials extracted, 19 were identified as motor axons reinnervating tibialis anterior or soleus muscles using spike triggered averaging. SIGNIFICANCE: These results are evidence for motor axon regeneration through microchannels and are the first report of in vivo recordings from regenerated motor axons within microchannels in a small group of awake and behaving animals. These unique findings provide preliminary evidence that efferent, volitional motor potentials can be recorded from the microchannel-based peripheral neural interface; a critical requirement for any neural interface intended to facilitate direct neural control of external technologies.

Neurologically-related sequelae associated with mild traumatic brain injury.

OBJECTIVE: Mild traumatic brain injury (mTBI) accounts for more than 75% of traumatic brain injuries every year. This study examines the temporal association between non-blast mTBI and the onset of neurologic sequelae to illuminate risks of post-concussive syndrome, epilepsy and chronic pain. METHODS: A large historical prospective study was conducted utilizing electronically-recorded demographic, medical and military-specific data for over half a million active duty US Air Force Airmen. This study utilized diagnostic codes to identify mTBI exposures, two control groups and three post-mTBI time periods. Adjusted hazard ratios (HRs) were calculated using Cox proportional hazards modelling. RESULTS: HRs were higher when mTBI exposed Airmen were compared with the full cohort and lower when compared with the other injured group. When compared to the other injured group, mTBI was positively associated with epilepsy/recurrent seizure outcomes, post-concussive syndrome and pain disorders. HRs tended to be highest within the first 30 days and decreased over time. CONCLUSIONS: Findings support that mTBI may have a prolonged neurological impact. Findings are also likely generalizable to young adult populations with exposure to non-blast related mTBI, including civilians, as those included in this study were young adults with a high prevalence of recreational/sports and motor vehicle injuries.

Microchannel-based regenerative scaffold for chronic peripheral nerve interfacing in amputees.

Neurally controlled prosthetics that cosmetically and functionally mimic amputated limbs remain a clinical need because state of the art neural prosthetics only provide a fraction of a natural limb's functionality. Here, we report on the fabrication and capability of polydimethylsiloxane (PDMS) and epoxy-based SU-8 photoresist microchannel scaffolds to serve as viable constructs for peripheral nerve interfacing through in vitro and in vivo studies in a sciatic nerve amputee model where the nerve lacks distal reinnervation targets. These studies showed microchannels with 100 µm × 100 µm cross-sectional areas support and direct the regeneration/migration of axons, Schwann cells, and fibroblasts through the microchannels with space available for future maturation of the axons. Investigation of the nerve in the distal segment, past the scaffold, showed a high degree of organization, adoption of the microchannel architecture forming 'microchannel fascicles', reformation of endoneurial tubes and axon myelination, and a lack of aberrant and unorganized growth that might be characteristic of neuroma formation. Separate chronic terminal in vivo electrophysiology studies utilizing the microchannel scaffolds with permanently integrated microwire electrodes were conducted to evaluate interfacing capabilities. In all devices a variety of spontaneous, sensory evoked and electrically evoked single and multi-unit action potentials were recorded after five months of implantation. Together, these findings suggest that microchannel scaffolds are well suited for chronic implantation and peripheral nerve interfacing to promote organized nerve regeneration that lends itself well to stable interfaces. Thus this study establishes the basis for the advanced fabrication of large-electrode count, wireless microchannel devices that are an important step towards highly functional, bi-directional peripheral nerve interfaces.