Improving symptom burden in adults with persistent post-concussive symptoms: a randomized aerobic exercise trial protocol

Parental Factors Associated With Recovery After Mild Traumatic Brain Injury: A Systematic Review

While parental factors have been shown to potentially influence recovery after mild traumatic brain injury (mTBI) in children, both the strength and direction of the relationships remain unclear. We performed a systematic review regarding the association between parental factors and recovery after mTBI. PubMed, CINHL, Embase, PsychINFO, Web of Science, ProQuest, Cochrane Central, and Cochrane databases were queried for articles published between September 1, 1970, and September 10, 2022, reporting any parental factor and its association with recovery after mTBI in children younger than 18 years old. The review included both quantitative and qualitative studies published in English. Regarding the directionality of the association, only studies that assessed the effects of parental factors on recovery after mTBI were included. Study quality was assessed using a five-domain scale created by the Cochrane Handbook and the Agency for Healthcare Research and Quality. The study was prospectively registered with PROSPERO (CRD42022361609). Of 2050 studies queried, 40 met inclusion criteria, and 38 of 40 studies used quantitative outcome measures. Across 38 studies, 24 unique parental factors and 20 different measures of recovery were identified. The most common parental factors studied were socioeconomic status/income (SES; n = 16 studies), parental stress/distress (n = 11), parental level of education (n = 9), pre-injury family functioning (n = 8), and parental anxiety (n = 6). Among all associations between parental factors and recovery reported, having a family history of a neurologic disease (i.e., migraine, epilepsy, neurodegenerative disease; 5/6 significant associations reported, 83%), parental stress/distress (9/11, 82%), parental anxiety (4/6, 67%), parental level of education (5/9, 56%), and SES/income (11/19, 57.9%) were shown to have the strongest evidence reporting significant associations with recovery, while a family history of psychiatric disease (3/6, 50%) and pre-injury family functioning (4/9, 44%) showed mixed results. Evidence regarding other parental factors including parental sex, race/ethnicity, insurance status, parental history of concussion, family litigation status, family adjustment levels, and family psychosocial adversity were limited, as studies investigating such factors were few. The current review highlights literature describing several parental factors that significantly influence recovery from mTBI. It will likely be useful for future studies to incorporate parental SES, education, stress/distress, anxiety, quality of parent-child relationships, and parenting style when examining modifying factors in recovery after mTBI. Future studies should also consider how parental factors may serve as potential interventions or policy levers to optimize sport concussion-related policy and return-to-play guidelines.

Interdisciplinary rehabilitation for persisting post-concussion symptoms after mTBI: N=15 single case experimental design

BACKGROUND

Despite clinical guidelines recommending an interdisciplinary approach to persisting post-concussion symptom (PPCS) management, evaluations of interdisciplinary interventions remain scant.

OBJECTIVES

This pilot study aimed to explore the feasibility and preliminary efficacy of an interdisciplinary intervention for PPCSs.

METHOD

A single-case experimental design with randomisation to multiple baselines (2, 4, or 6 weeks) was repeated across 15 participants (53% female) with mild traumatic brain injury (mean age 38.3 years, SD 15.7). The 12-week treatment incorporated psychology, physiotherapy, and medical interventions. Feasibility outcomes included recruitment and retention rates, adverse events, treatment adherence and fidelity. Patient-centred secondary outcomes included the Rivermead Post-Concussion Symptoms Questionnaire (RPQ), assessed 3 times per week during the baseline and treatment phases, and at the 1- and 3-month follow-ups. Other secondary outcomes included measures of mood, sleep and fatigue, physical functioning, health-related quality of life, illness perceptions, and goal attainment. Changes in PPCSs were evaluated using systematic visual analysis and Tau-U. Clinically significant changes in secondary outcomes were explored descriptively.

RESULTS

16/26 individuals assessed for eligibility were enroled (61% recruitment rate); 15 completed the post-treatment follow-ups, and 13 completed the 1- and 3-month follow-up assessments (81% retention rate). High treatment adherence and competence in delivering treatments was observed. Moderate-large effect sizes for reducing PPCSs were observed in 12/15 cases, with 7/15 reaching statistical significance. Improvements were maintained at the 1- and 3-month follow-ups and were accompanied by reductions in fatigue, sleep difficulties, and mood symptoms, and changes in illness perceptions. All participants had clinically significant improvements in at least 1 outcome, with 81% of individual therapy goals achieved.

CONCLUSIONS

This pilot study provided preliminary support for a subsequent randomised controlled trial (RCT), with satisfactory recruitment, retention, treatment compliance, and treatment fidelity. Improvement was evident on participant outcomes including symptom reduction and goal attainment, suggesting that progressing to a phase-II RCT is worthwhile. Findings highlight the potential benefit of individualized interdisciplinary treatments.

Sub-symptom threshold aerobic exercise for patients with persisting post-concussion symptoms and exercise intolerance after mild traumatic brain injury - a study protocol with a nested feasibility study for a randomized controlled trial

BACKGROUND

Persistent post-concussion symptoms (PPCS) affect between 34 and 46% after a mild traumatic brain injury (mTBI). Many also experience exercise intolerance. Sub-symptom threshold aerobic exercise, SSTAE (exercise at an intensity level that does not increase symptoms) is proposed as a treatment to both reduce the symptom burden and increase the exercise tolerance after the injury. It is unclear if this also applies in a more chronic phase after mTBI.

MAIN PURPOSE

The main purpose of this study is to evaluate whether SSTAE in addition to ordinary rehabilitation will lead to clinically meaningful improvement of symptom burden, normalize exercise tolerance, increase physical activity, improve health-related quality of life, and reduce patient-specific activity limitations compared to a control group that only receives ordinary rehabilitation.

DESIGN

Randomized, controlled, single-blind parallel-group study with three measurement times; T0 at baseline, T1 after the intervention and T2 six months after T1.

METHODS

Patients between the ages of 18 and 60 with exercise intolerance and persistent PPCS (> 3 months) will be recruited to the study and randomized to two groups. All patients will receive follow-up at the outpatient TBI clinic. The intervention group will in addition receive SSTAE for 12 weeks with exercise diaries and a retest every 3 weeks for optimal dosage and progression. The Rivermead post-concussion symptoms questionnaire will be the main outcome measure. The secondary outcome measure will be a test of exercise tolerance-the Buffalo Concussion Treadmill Test. Other outcome measures include the patient-specific functional scale that measures patient-specific activity limitations, as well as outcome measures for diagnosis-specific health-related quality of life, anxiety and depression, specific symptoms such as dizziness, headache and fatigue, and physical activity.

DISCUSSION

This study will add knowledge about the effect of SSTAE and whether it should be implemented in rehabilitation for the adult population with persistent PPCS after mTBI. The nested feasibility trial showed that the SSTAE intervention was safe and that the study procedures and delivery of the intervention overall were feasible. However, minor amendments to the study protocol were made prior to the commencement of the RCT.

TRIAL REGISTRATION

Clinical Trials.gov, NCT05086419. Registered on September 5th, 2021.

Efficacy of aerobic exercise following concussion: a narrative review

Concussion is a type of mild traumatic brain injury which results in symptoms within the physical, cognitive, emotional, and sleep domains. Historically, guidelines established by expert opinion have recommended rest during the initial stages of recovery following a concussion until symptom resolution. However, recent recommendations have shifted to advise an initial period of 24-48 h of rest immediately following concussion with the gradual introduction of light-to-moderate intensity aerobic exercise thereafter. Given the relatively recent transition in recommendations, the aim of this review is to provide an overview of the current literature on the efficacy of aerobic exercise following concussion. The current literature is limited to studies assessing the impact of standardized aerobic exercise following concussion. Upon review, literature suggests participating in aerobic exercise below the point of symptom exacerbation is safe in both the acute and chronic post-concussion symptom stages of recovery and does not delay time to medical clearance. Future large-scale randomized controlled trials assessing the impact of aerobic exercise and differences between males and females would help support the current evidence suggesting aerobic exercise could improve time to recovery following concussion and identify any sex differences in response. As well, future studies with the purpose of identifying optimal aerobic exercise volume and intensity in the treatment of concussion could improve the specificity of the current guidelines.

Glutamate, GABA and glutathione in adults with persistent post-concussive symptoms

Persistent post-concussive symptoms (PPCS) are debilitating and endure beyond the usual recovery period after mild traumatic brain injury (mTBI). Altered neurotransmission, impaired energy metabolism and oxidative stress have been examined acutely post-injury but have not been explored extensively in those with persistent symptoms. Specifically, the antioxidant glutathione (GSH) and the excitatory and inhibitory metabolites, glutamate (Glu) and γ-aminobutyric acid (GABA), are seldom studied together in the clinical mTBI literature. While Glu can be measured using conventional magnetic resonance spectroscopy (MRS) methods at 3 Tesla, GABA and GSH require the use of advanced MRS methods. Here, we used the recently established Hadamard Encoding and Reconstruction of MEGA-Edited Spectroscopy (HERMES) to simultaneously measure GSH and GABA and short-echo time point resolved spectroscopy (PRESS) to measure Glu to gain new insight into the pathophysiology of PPCS. Twenty-nine adults with PPCS (mean age: 45.69 years, s.d.: 10.73, 22 females, 7 males) and 29 age- and sex-matched controls (mean age: 43.69 years, s.d.: 11.00) completed magnetic resonance spectroscopy scans with voxels placed in the anterior cingulate and right sensorimotor cortex. Relative to controls, anterior cingulate Glu was significantly reduced in PPCS. Higher anterior cingulate GABA was significantly associated with a higher number of lifetime mTBIs, suggesting GABA may be upregulated with repeated incidence of mTBI. Furthermore, GSH in both regions of interest was positively associated with symptoms of sleepiness and headache burden. Collectively, our findings suggest that the antioxidant defense system is active in participants with PPCS, however this may be at the expense of other glutamatergic functions such as cortical excitation and energy metabolism.

A Remotely Delivered Progressive Walking Intervention for Adults With Persistent Symptoms of a Mild Traumatic Brain Injury: Feasibility and Exploration of Its Impact

Introduction

Persistent post-concussion symptoms following a mild traumatic brain injury (mTBI) can impact function and participation of adults. Physical activity is recommended to reduce symptoms and foster return to normal activities. Adults with a mTBI may have personal factors or experience accessibility issues restricting physical activity. Walking is a physical activity accessible to most that could be delivered remotely.

Objectives

Determine the feasibility, safety, and acceptability of a remotely delivered progressive walking intervention designed for adults with persistent mTBI symptoms and explore its effects on health-related outcomes.

Methodology

This feasibility study using a single-group pre-post mixed methods convergent parallel design was conducted remotely. Adults aged 18–65 years with a mTBI reporting persistent symptoms for ≥3 months were recruited. The 8-week remote progressive walking intervention aimed to increase the weekly number of steps walked by 40% based on a 1-week baseline measured by a Fitbit Inspire 2 activity monitor. Feasibility measures were about the intervention, its remote delivery, safety, and acceptability. Health-related outcomes were post-concussion symptoms, kinesiophobia, mood, sleep, fatigue, and quality of life. Semi-structured exit interviews were recorded and transcribed verbatim. Quantitative and qualitative data were analyzed separately, and results merged, compared, and contrasted. Descriptive statistics and paired samples t-tests were used. The qualitative analyses followed an iterative content analysis approach using reflexivity and triangulation of sources.

Results

Twenty adults (16 women) aged 42.5 ± 11.51 years with persisting symptoms for 9.25 ± 6.43 months participated, adhered to 94.38% of sessions, completed the intervention, and found it to be feasible, safe and acceptable. Participants increased weekly total number of steps walked (change = 14,886 ± 18,283; t = 3.55, p = 0.002). Severity of post-concussion symptoms (change = −6.42 ± 10.69; t = −2.62, p = 0.018), kinesiophobia (change = −5 ± 6.86; t = 3.18, p = 0.005), anxiety (change = −1.53 ± 3.01; t = −2.21, p = 0.04), and fatigue (change = −10.21 ± 10.20; t = −4.37, p < 0.001) were reduced, whilst quality of life improved (change = 10.58 ± 13.35; t = 3.46, p = 0.003). Participants' perceptions corroborate most quantitative results; they felt improved self-efficacy about physical activity and provided five key recommendations.

Discussion

This study demonstrates the feasibility, safety, and acceptability of the remote 8-week progressive walking intervention, a promising approach to reduce persisting symptoms, improve physical activity level health-related outcomes and quality of life of adults with persistent post-concussion symptoms following a mTBI.

Outlining the Invisible: Experiences and Perspectives Regarding Concussion Recovery, Return-to-Work, and Resource Gaps

Appropriate supports and accommodations are necessary to ensure full concussion recovery and return-to-work (RTW). This research investigated barriers and facilitators to concussion recovery and RTW, and resource gaps reported by adults with concussion (‘workers’) and workplace and healthcare professionals (‘workplaces’). Semi-structured interviews and focus groups were conducted with workers (n = 31) and workplaces (n = 16) across British Columbia. Data were analyzed using inductive content analysis. Facilitators to workers’ concussion recovery and RTW included treatment, social support, and workplace and lifestyle modifications. To address barriers, both groups recommended: (a) widespread concussion and RTW education and training (b) standardized concussion recovery guidelines; (c) changing attitudes toward concussion; (d) mental health supports; and (e) increasing awareness that every concussion is unique. Findings can inform best practice for concussion recovery and RTW among professionals in workplaces, healthcare, occupational health and safety, and workers’ compensation boards.

Mental Health Outcomes Across the Lifespan in Individuals With Persistent Post-Concussion Symptoms: A Scoping Review

Objective:

Concussion is a common yet heterogenous injury. Approximately 15–30% of cases present with persistent post-concussion symptoms (PPCS), continuing 4 weeks or more post-injury in children, youth, and adolescents, and 3 months or more in adults. There are known bidirectional links between PPCS and mental health outcomes. The focus of this scoping review is to explore the literature on mental health outcomes in individuals experiencing PPCS. Research objectives were to explore: (1) the mental health outcomes of individuals with PPCS and types of assessments used to identify mental health outcomes this group, and (2) how mental health outcomes compare in terms of similarities and differences among pediatric and adult populations with PPCS.

Method

Ovid MEDLINE; EMBASE; CINAHL, and PsycInfo databases were searched. After title and abstract screening of 11,920 studies, 481 articles were reviewed. Twenty-five papers met inclusion criteria. Results were organized by mental health outcomes of pediatric and adult populations, separately.

Results

There was a significantly higher number of studies devoted to adult populations. Of the 25 studies, 19 (76%) focused on adults, while six (24%) focused on adolescents. In adult populations, studies focused on symptoms of: anxiety (n = 2), depression (n = 8), and anxiety and depression (n = 9). Two studies assessed other emotional outcomes (10.5%). Within pediatric populations, an equal number of studies explored symptoms of: anxiety (n = 2), depression (n = 2), and anxiety and depression (n = 2). No studies focused on other emotional outcomes. Studies ranged greatly in methods, design, and control group. Most studies reported higher psychiatric symptoms of anxiety and/or depression in those with PPCS compared to individuals with recovered concussion or healthy controls.

Discussion

This review contributes to the understanding of mental health outcomes in those experiencing PPCS. Mental health and PPCS requires greater attention in pediatric populations, and consider strategies for those experiencing PPCS and mental health impacts. Future studies should consider including a wider range of emotional outcomes in their design, not limited to anxiety and depression. Study results may lead to improvements and research in the identification, assessment, and management of PPCS and mental health.

Neuro-Visual and Vestibular Manifestations of Concussion and Mild TBI

PURPOSE OF REVIEW

Mild traumatic brain injury, or concussion, is a major cause of disability. Vestibular and visual dysfunction following concussion is common and can negatively affect patients' well-being and prolong recovery. Etiologies of visual and vestibular symptoms are numerous, including ocular, neuro-ophthalmic, otologic, and neuro-vestibular conditions. Some etiologies are benign and may be treatable, while others are potentially vision or life-threatening, making a focused history and examination essential. This review offers an approach to the evaluation and treatment of the most common neuro-visual and vestibular impairments that may result from concussion.

RECENT FINDINGS

Treatment of concussion including exercise, computerized programs, transcranial magnetic stimulation, gene therapy, stem cell therapy, and nanoparticles has shown promise. Many novel therapies are in the pipework for visual and vestibular recovery after concussion; however, the treatment mainstay remains therapy and evaluation for co-existing diseases.

Association of Hemodynamic and Cerebrovascular Responses to Exercise With Symptom Severity in Adolescents and Young Adults With Concussion

BACKGROUND AND OBJECTIVES

Aerobic exercise has become a useful method to assist with post-concussion management. Exercise can exacerbate concussion symptoms even when symptoms are not apparent at rest. Few studies have examined the reasons for symptom exacerbation during exercise following a concussion. We had two primary objectives. 1) To delineate cardiopulmonary and cerebrovascular responses to exercise in adolescents and young adults with a concussion and healthy controls. 2) To determine the association between cerebrovascular responses and symptom burden.

METHODS

We recruited participants with a recent concussion from a sport concussion clinic between 9/1/2018-2/22/2020. They were included if their concussion occurred <3 weeks before initial testing and if they were symptomatic at rest. Participants were excluded if they sustained a concussion in the past year (excluding index injury), reported history of neurological disorders, or were using medications/devices that may alter neurological function. Participants completed a progressive, symptom-limited, sub-maximal exercise protocol on a stationary bike. We assessed heart rate, blood pressure, fraction of end tidal CO2 (FETCO₂) and middle cerebral artery blood flow velocity (CBF) and cerebrovascular function (vasoreactivity and autoregulation) at seated rest and during exercise.

RESULTS

We conducted 107 exercise tests (40 concussed, 37 healthy participants initially; 30 concussed at follow-up). Concussed participants were tested initially (mean=17.6±2.2 [SD] years old; 55% female; mean=12.5±4.7 days post-concussion) and again 8 weeks later (mean=73.3±9.5 days post-concussion). Control participants (mean=18.3±2.4 years; 62% female) were tested once. FETCO₂ increased throughout the exercise protocol as heart rate increased, reached a plateau, and declined at higher exercise intensities. CO₂ explained >25% of the variation in resting CBF (R²>0.25; p<0.01) in most (73% individuals). Within the concussion group, resting symptom severity and the heart rate at which FETCO₂ reached a plateau explained ∼two-thirds of variation in exercise-induced symptom exacerbation (R ² =0.65; FETCO₂ β=-1.210±0.517[S.E.], p<0.05). There was a moderate, statistically significant relationship between cerebrovascular responses to CO₂ at rest (cerebral vasoreactivity) and cerebrovascular responses to exercise-induced changes in FETCO₂ (R²=0.13, p=0.01).

DISCUSSION

The arterial CO₂ response and symptom exacerbation relationship during post-concussion aerobic exercise may be mediated by increased sensitivity of cerebral vasculature to exercise-related increase in CO₂.

Cerebrolysin restores balance between excitatory and inhibitory amino acids in brain following concussive head injury. Superior neuroprotective effects of TiO2 nanowired drug delivery

Concussive head injury (CHI) often associated with military personnel, soccer players and related sports personnel leads to serious clinical situation causing lifetime disabilities. About 3-4k head injury per 100k populations are recorded in the United States since 2000-2014. The annual incidence of concussion has now reached to 1.2% of population in recent years. Thus, CHI inflicts a huge financial burden on the society for rehabilitation. Thus, new efforts are needed to explore novel therapeutic strategies to treat CHI cases to enhance quality of life of the victims. CHI is well known to alter endogenous balance of excitatory and inhibitory amino acid neurotransmitters in the central nervous system (CNS) leading to brain pathology. Thus, a possibility exists that restoring the balance of amino acids in the CNS following CHI using therapeutic measures may benefit the victims in improving their quality of life. In this investigation, we used a multimodal drug Cerebrolysin (Ever NeuroPharma, Austria) that is a well-balanced composition of several neurotrophic factors and active peptide fragments in exploring its effects on CHI induced alterations in key excitatory (Glutamate, Aspartate) and inhibitory (GABA, Glycine) amino acids in the CNS in relation brain pathology in dose and time-dependent manner. CHI was produced in anesthetized rats by dropping a weight of 114.6g over the right exposed parietal skull from a distance of 20cm height (0.224N impact) and blood-brain barrier (BBB), brain edema, neuronal injuries and behavioral dysfunctions were measured 8, 24, 48 and 72h after injury. Cerebrolysin (CBL) was administered (2.5, 5 or 10mL/kg, i.v.) after 4-72h following injury. Our observations show that repeated CBL induced a dose-dependent neuroprotection in CHI (5-10mL/kg) and also improved behavioral functions. Interestingly when CBL is delivered through TiO₂ nanowires superior neuroprotective effects were observed in CHI even at a lower doses (2.5-5mL/kg). These observations are the first to demonstrate that CBL is effectively capable to attenuate CHI induced brain pathology and behavioral disturbances in a dose dependent manner, not reported earlier.

Stakeholder Recommendations to Increase the Accessibility of Online Health Information for Adults Experiencing Concussion Symptoms

Background: Concussion is a global public health problem. In Canada, concussion is among the top five reasons for workplace time-loss. Concussion results in physical, cognitive, and/or emotional symptoms that temporarily worsen with physical and mental exertion, such as viewing electronic screens. The Internet is the primary source of consumer health information. Studies on the end-user needs of adults with brain injuries in regards to digital health technologies largely focus on informational content. There is little to no research on the accessibility of screen-based informational websites and smartphone applications among this population.

Objective: The aim of this research was to involve stakeholders in the design of a comprehensive educational resource to guide concussion recognition, recovery, and return-to-work, called the Concussion Awareness Training Tool for Workers and Workplaces (CATT WW). In order to ensure both relevant content and appropriate delivery of the information to the target groups, participants were asked whether adaptations could increase the accessibility of online health information for the general adult population experiencing concussion symptoms.

Methods: Data have been generated through semi-structured in-depth interviews and focus groups with participants from across British Columbia (BC): workers from various industries who were in the concussion recovery process or had returned to work (n = 31); and healthcare or workplace professionals who support concussion diagnosis, recovery, and return-to-work (n = 16). Data were analyzed using NVivo 12. Before commencing data collection, ethical permission was granted by the University of British Columbia Research Ethics Board (H18-00604), and approval was received from WorkSafeBC Research Services.

Results: Participants (n = 47) recommended twenty adaptations or supplements to electronic screen-based digital health technologies.

Conclusion: Given the high prevalence of concussion among the working adult population, the symptom exacerbation commonly caused by prolonged use of electronic screens, and the demand for online educational resources, these findings can guide clinicians, researchers, technology developers, employers, and occupational health and safety committees to further support adults in concussion recovery and return-to-work.

Neuroimaging and advanced research techniques may lead to improved outcomes in military members suffering from traumatic brain injury

Recent military conflicts in Iraq and Afghanistan have resulted in the significant increase in blast-related traumatic brain injury (TBI), leading to increased Department of Defense interest in its potential long-term effects ranging from the mildest head injuries termed subconcussive trauma to the most debilitating termed chronic traumatic encephalopathy (CTE). Most patients with mild TBI will recover quickly while others report persistent symptoms called postconcussive syndrome. Repeated concussive and subconcussive head injuries result in neurodegenerative conditions that may hinder the injured for years. Fundamental questions about the nature of these injuries and recovery remain unanswered. Clinically, patients with CTE present with either affective changes or cognitive impairment. Genetically, there have been no clear risk factors identified. The discovery that microglia of the cerebral cortex discharged small extracellular vesicles in the injured and adjacent regions to a TBI may soon shed light on the immediate impact injury mechanisms. The combination of neuroimaging and advanced research techniques may, one day, fill critical knowledge gaps and lead to significant TBI research and treatment advancements.

Neuromodulation for Mild Traumatic Brain Injury Rehabilitation: A Systematic Review

Background: Mild traumatic brain injury (mTBI) results from an external force to the head or body causing neurophysiological changes within the brain. The number and severity of symptoms can vary, with some individuals experiencing rapid recovery, and others having persistent symptoms for months to years, impacting their quality of life. Current rehabilitation is limited in its ability to treat persistent symptoms and novel approaches are being sought to improve outcomes following mTBI. Neuromodulation is one technique used to encourage adaptive neuroplasticity within the brain.

Objective: To systematically review the literature on the efficacy of neuromodulation in the mTBI population.

Method: A systematic review was conducted using Medline, Embase, PsycINFO, PsycARTICLES and EBM Review. Preferred Reporting Items for Systematic Reviews and the Synthesis Without Meta-analysis reporting guidelines were used and a narrative review of the selected studies was completed. Fourteen articles fulfilled the inclusion criteria which were published in English, investigating an adult sample and using a pre- and post-intervention design. Studies were excluded if they included non-mild TBI severities, pediatric or older adult populations.

Results: Thirteen of fourteen studies reported positive reductions in mTBI symptomatology following neuromodulation. Specifically, improvements were reported in post-concussion symptom ratings, headaches, dizziness, depression, anxiety, sleep disturbance, general disability, cognition, return to work and quality of life. Normalization of working memory activation patterns, vestibular field potentials, hemodynamics of the dorsolateral prefrontal cortex and excessive delta wave activity were also seen. The studies reviewed had several methodological limitations including small, heterogenous samples and varied intervention protocols, limiting generalisability. Further research is required to understand the context in which neuromodulation may be beneficial.

Conclusions: While these positive effects are observed, limitations included unequal representation of neuromodulation modalities in the literature, and lack of literature describing the efficacy of neuromodulation on the development or duration of persistent mTBI symptoms. Better clarity regarding neuromodulation efficacy could have a significant impact on mTBI patients, researchers, clinicians, and policy makers, facilitating a more productive post-mTBI population. Despite the limitations, the literature indicates that neuromodulation warrants further investigation. PROSPERO registration number: CRD42020161279.