Early targeted heart rate exercise is safe and May hasten return-to-duty in service members with acute concussion, a preliminary study.

OBJECTIVE: To evaluate the feasibility of an exercise tolerance assessment and intervention added to the Progressive Return to Activity Clinical Recommendations (PRA-CR) in acutely concussed service members (SMs). METHODS: This non-randomized, pilot trial was performed at one center. SMs in the experimental group (ERG) performed the Buffalo Concussion March-in-place Test (BCMT) at every clinic visit and were prescribed at least 20 minutes/day of targeted exercise in addition to PRA-CR. Data for the control group (SCG) were extracted from the same clinic immediately prior to ERG. SMs in both groups were assessed by the same clinician to determine return-to-duty. RESULTS: BCMT identified concussion-related exercise intolerance in 100% (n = 14) at screening visit (mean 3.4 days after injury) and in 0% (n = 7) who had recovered. No adverse effects were associated with BCMT. The estimated recovery time for ERG who performed the exercise intervention (n = 12) was 17.0 (12.8, 21.2) days and for SCG (n = 15) was 23.7 (19.9, 27.5) days (p = 0.039). CONCLUSION: Assessment of exercise tolerance was feasible and could be incorporated into the PRA-CR. Future definitive, randomized controlled trials should be performed to assess the effectiveness of exercise reset program for SMs after concussion.

Early Identification and Management of Cervical Impairments in Pediatric Patients With Concussion May Reduce Risk of Delayed Recovery.

OBJECTIVE: Previous research, including high-quality systematic reviews, has found that cervical injury, which often accompanies concussive head injury, can delay recovery from concussion. One pilot randomized controlled trial found that focused cervical assessment and appropriate intervention in children and young adults with persisting postconcussive symptoms (PPCS) improved recovery outcomes. Our sports medicine clinics adopted this approach early (within 2 weeks) in children (aged 10-18 years) after concussion. This study describes our clinical management protocol and compares the recovery trajectories in children after concussion with and without a concomitant cervical injury. DESIGN: Prospective cohort study. SETTING: Three university-affiliated outpatient sports medicine clinics from September 2016 to December 2019. PATIENTS: One-hundred thirty-four concussed children with cervical impairment (mean age 14.9 years, 65% male, and 6.2 days since concussion) were compared with 130 concussed children without cervical impairment (mean age 14.9 years, 57% male, and 6.0 days since concussion). INDEPENDENT VARIABLES: Examination findings related to the cervical spine (range of motion, cervical spasm, and cervical tenderness). MAIN OUTCOME MEASURES: Recovery time (measured in days), concussion symptom burden (Postconcussion Symptom Scale), and incidence of PPCS. RESULTS: Children with cervical impairment reported a higher initial symptom burden; however, there were no differences in recovery time (33.65 [28.20-39.09] days vs 35.98 [27.50-44.45] days, P = 0.651) or incidence of PPCS (40.0% vs 34.3%, P = 0.340). CONCLUSIONS: We conclude that within this pediatric population, early identification and management of cervical injuries concomitant with concussion may reduce the risk of delayed recovery.

An Exploratory Analysis of Physical Examination Subtypes in Pediatric Athletes With Concussion.

OBJECTIVE: Pediatric athletes with concussion present with a variety of impairments on clinical assessment and require individualized treatment. The Buffalo Concussion Physical Examination is a brief, pertinent clinical assessment for individuals with concussion. The purpose of this study was to identify physical examination subtypes in pediatric athletes with concussion within 2 weeks of injury that are relevant to diagnosis and treatment. DESIGN: Secondary analysis of a published cohort study and clinician consensus. SETTING: Three university-affiliated sports medicine centers. PARTICIPANTS: Two hundred seventy children (14.9 ± 1.9 years). INDEPENDENT VARIABLES: Orthostatic intolerance, horizontal and vertical saccades, smooth pursuits, vestibulo-ocular reflex, near-point convergence, complex tandem gait, neck range of motion, neck tenderness, and neck spasm. MAIN OUTCOME MEASURES: Correlations between independent variables were calculated, and network graphs were made. k-means and hierarchical clustering were used to identify clusters of impairments. Optimal number of clusters was assessed. Results were reviewed by experienced clinicians and consensus was reached on proposed subtypes. RESULTS: Physical examination clusters overlapped with each other, and no optimal number of clusters was identified. Clinician consensus suggested 3 possible subtypes: (1) visio-vestibular (horizontal and vertical saccades, smooth pursuits, and vestibulo-ocular reflex), (2) cervicogenic (neck range of motion and spasm), and (3) autonomic/balance (orthostatic intolerance and complex tandem gait). CONCLUSIONS: Although we identified 3 physical examination subtypes, it seemed that physical examination findings alone are not enough to define subtypes that are both statistically supported and clinically relevant, likely because they do not include symptoms, assessment of mood or cognitive problems, or graded exertion testing.

Does Physiologic Post-Concussion Disorder Cause Persistent Post-Traumatic Headache?

PURPOSE OF REVIEW: One system classifies patients with symptoms after concussion into physiologic, vestibulo-ocular, cervicogenic, and mood/cognition post-concussion disorders (PCD) based upon the preponderance of specific symptoms and physical impairments. This review discusses physiologic PCD and its potential relationship to the development of persistent post-traumatic headaches (PPTH). RECENT FINDINGS: Headache is the most reported symptom after a concussion. Headaches in physiologic PCD are suspected to be due to abnormal cellular metabolism, subclinical neuroinflammation, and dysfunction of the autonomic nervous system (ANS). These abnormalities have been linked to the development of migraine-like and neuralgia-related PPTH. Physiologic PCD is a potential cause of PPTH after a concussion. Future research should focus on how to prevent PPTH in patients with physiologic PCD.

Practical Management: A Standardized Aerobic Exercise Program for Adolescents With Concussion in the Absence of Graded Exercise Testing.

ABSTRACT: Aerobic exercise is safe and beneficial for adolescent athletes recovering from sport-related concussion (SRC). The results of systematic graded exercise testing are used to create individualized, subsymptom heart rate threshold (HRt) aerobic exercise treatment programs for adolescents after SRC. Many clinicians, however, do not have access to graded exercise tests. This article presents a safe, systematic, evidence-based exercise program that clinicians can prescribe, progress, and modify to help manage acute pediatric SRC without the need for formal exercise testing. The exercise prescription accounts for sex and days since injury but not age because our analysis indicates age does not significantly affect the HRt on graded exercise testing. This article provides clinicians without access to graded exercise testing a viable option for prescribing exercise treatment to adolescents in the early phase after SRC.

Exercise-Induced Vision Dysfunction Early After Sport-Related Concussion Is Associated With Persistent Postconcussive Symptoms.

OBJECTIVE: The purpose of this study was to determine if exercise-induced vision dysfunction [reduced performance and/or symptom exacerbation on a post-exercise King-Devick (KD) test] in adolescents early after sport-related concussion was associated with increased risk of persistent post-concussive symptoms (PPCS, recovery >28 days). We used exercise as a provocative maneuver before the KD test, hypothesizing that concussed adolescents with exercise-induced vision dysfunction would be more likely to develop PPCS. DESIGN: Secondary analysis of data from a multi-center, randomized clinical trial comparing KD test performance before and after the Buffalo Concussion Treadmill Test in adolescents within 10 days of sport-related concussion who were randomized to aerobic exercise or placebo stretching program. SETTING: Three university-associated sports medicine clinical programs. PARTICIPANTS: Ninety-nine adolescents with sport-related concussion (exercise group: n = 50, 15.3 ± 1 years, 60% M, 22% with PPCS; stretching group: n = 49, 15.9 ± 1 years, 65% M, 35% with PPCS) tested a mean of 6 ± 2 days from injury. INDEPENDENT VARIABLE: King-Devick test performed immediately before and 2 minutes after Buffalo Concussion Treadmill Test. MAIN OUTCOME MEASURE: Persistent post-concussive symptoms. RESULTS: Adolescents who demonstrated exercise-induced vision dysfunction upon initial evaluation developed PPCS at a significantly greater rate when compared with adolescents who did not (71% vs 34%, P < 0.001). Exercise-induced vision dysfunction corresponded to a relative risk of 3.13 for PPCS. CONCLUSIONS: Adolescents with exercise-induced vision dysfunction had a 3-fold greater relative risk of developing PPCS than those without exercise-induced vision dysfunction.

Association of Concussion History and Prolonged Recovery in Youth.

OBJECTIVE: To determine the number of prior concussions associated with increased incidence of persistent postconcussive symptoms (PPCS) in a cohort of acutely concussed pediatric patients. DESIGN: Prospective observational cohort study. SETTING: Three university-affiliated concussion clinics. PARTICIPANTS: Two hundred seventy participants (14.9 ± 1.9 years, 62% male, 54% with prior concussion) were assessed within 14 days of concussion and followed to clinical recovery. Participants with a second head injury before clinical recovery were excluded. MEASURES AND MAIN OUTCOME: Concussion history, current injury characteristics, recovery time, and risk for prolonged recovery from current concussion. RESULTS: There was no statistically significant change in PPCS risk for participants with 0, 1 or 2 prior concussions; however, participants with 3 or more prior concussions had a significantly greater risk of PPCS. Twelve participants sustained a subsequent concussion after clinical recovery from their first injury and were treated as a separate cohort. Our secondary analysis found that these participants took longer to recover and had a greater incidence of PPCS during recovery from their latest concussion. CONCLUSION: Pediatric patients with a history of 3 or more concussions are at greater risk of PPCS than those with fewer than 3 prior concussions.

Rehabilitation of Concussion and Persistent Postconcussive Symptoms.

Concussion and persistent postconcussive symptoms (PPCS) are encountered by clinicians in sports medicine, pediatrics, neurology, physiatry, emergency medicine, and primary care. Clinical management may require a multidisciplinary approach. This article presents a structured method for the diagnosis of concussion and PPCS in the outpatient setting, which includes a history, physical examination, and additional tests as clinically indicated to help identify underlying symptom generators. Treatment for concussion and PPCS should be individualized, based on predominant signs and symptoms, and can include subsymptom threshold aerobic exercise, cervical physical therapy, vestibulo-ocular rehabilitation, behavioral and cognitive psychotherapy, and some symptom-specific pharmacological therapies.

Symptoms upon postural change and orthostatic hypotension in adolescents with concussion.

Objective: Concussion is associated with dysautonomia, altered blood pressure (BP) control, and may cause Orthostatic Hypotension (OH). We measured prevalence of OH using the 1-minute supine-to-standing OH Test in adolescents with concussion and controls.Participants: Adolescents within 10 days of injury (Concussion Group, n = 297, 15.0 ± 1.7 years, 59% male) were compared with controls (Control Group, n = 214, 15.0 ± 1.5 years, 58% male).Methods: BP, heart rate (HR), and complaints of lightheadedness/dizziness were measured after 2-minute supine and 1-minute standing. Control Group was assessed once. Concussion Group was assessed twice; (1) initial visit (mean 6.0 ± 3 days-since-injury) and (2) after clinical recovery (mean 46.3 ± 42 days-since-injury).Results: Initial visit; Concussion Group reported feeling lightheaded/dizzy on postural change more often than the Control Group (37% vs 4%, p < .001) but did not differ in meeting standard OH criteria (3% vs 5%, p = .32). Experiencing symptoms did not correlate with meeting OH criteria, but correlated with abnormal vestibulo-ocular reflex. After clinical recovery; Concussion Group did not differ in experiencing lightheaded/dizziness on postural change than controls (4%, p = .65).Conclusion: Adolescents commonly experience orthostatic intolerance after concussion without meeting the standard criteria for OH.

Practical Management: Prescribing Subsymptom Threshold Aerobic Exercise for Sport-Related Concussion in the Outpatient Setting.

ABSTRACT: Exercise intolerance is an objective biomarker of the physiological dysfunction after sport-related concussion (SRC). Several trials have established the safety and clinical efficacy of subsymptom threshold aerobic exercise prescribed within 1 week of injury as treatment for SRC. Clinicians, however, may not be comfortable prescribing aerobic exercise after SRC. This article presents 3 methods of exercise prescription for patients with SRC. The first requires a graded exertion test plus a home-based exercise program requiring a heart rate (HR) monitor. The second requires a graded exertion test but no HR monitor for home-based exercise. The third requires solely an HR monitor to safely progress through the home-based exercise prescription. Patients are encouraged to keep a symptom and exercise diary and return for re-evaluation every 1 to 2 weeks. Delayed recovery should prompt the clinician to evaluate for other potential symptom generators (eg, cervical, vestibular, oculomotor, mood, or migraine disorders).

A preliminary investigation of cognitive intolerance and neuroimaging among adolescents returning to school after concussion.

PRIMARY OBJECTIVE: To introduce the concept of cognitive intolerance. A test is proposed to measure this concept and pilot data are presented to support this measure and future research to develop this concept into a construct. Research design: Three-group comparison to protect larger study blinding. Methods and procedures: Two groups of student athletes (n = 13, n = 13) between 13 and 17 (mean 15.1 ± 1.1 years; 58% male) who sustained a sport-related concussion within 10 days and one group (n = 13) of age-matched healthy controls were recruited for a comparison of correlations between self and observer ratings of cognitive difficulties and DTI fractional anisotropy (FA) using tract-based spatial statistics (TBSS) analysis at two time points. Main outcomes and results: Significant negative only associations (higher cognitive difficulty and lower FA) with DTI FA were found in white matter tracts. These included the anterior corpus callosum, frontal-parietal longitudinal fasciculi, and cortical-subcortical pathways at only the second time point. Several working memory networks would likely involve connections using the above-identified white matter tracts. Conclusions: Cognitive intolerance can be defined as symptom exacerbation from prolonged cognitive activity. Cognitive intolerance could be measured by the n-back working memory task and time to symptom exacerbation.

Practical Management: Brief Physical Examination for Sport-Related Concussion in the Outpatient Setting.

This article presents a brief, focused physical examination [PE, the Buffalo Concussion Physical Examination (BCPE)] for sport-related concussion (SRC) to be considered for use in the outpatient setting by sports medicine physicians, pediatricians, and primary-care physicians. This companion paper describes how to perform the PE, which was derived in a separate study presented in this journal. It is envisioned for use at the initial and follow-up outpatient visits both for acute concussions and in patients with prolonged symptoms. A pertinent PE, combined with other assessments, can help identify specific treatment targets in those with persistent symptoms after SRC. The BCPE includes orthostatic vital signs and examinations of the cranial nerves, oculomotor/ophthalmologic, cervical, and vestibular systems. Supplementary tests, including testing for exercise tolerance and neurocognitive function, may be performed if indicated. It is recommended that a PE be performed at the initial visit and every 1 to 2 weeks after SRC. On return of symptoms, cognition, and the PE to baseline, as well as normalization of any supplementary tests, patients can begin a return to play program.

Comparison of Rest to Aerobic Exercise and Placebo-like Treatment of Acute Sport-Related Concussion in Male and Female Adolescents.

OBJECTIVE: To compare a sample of adolescents with sport-related concussion (SRC) who were prescribed rest with 2 arms of a randomized controlled trial comparing aerobic exercise with placebo-like stretching. We also compared sex differences across the 3 approaches to treatment. DESIGN: Quasi-experimental trial. SETTING: University concussion management clinics. PARTICIPANTS: Adolescent athletes (aged 13-18 years) presenting within 10 days of SRC (mean, 5 days after injury) received a recommendation for rest (rest group [RG], n=48, 15.4±1y, 25% female). Their outcomes were compared with matched samples of adolescents assigned to aerobic exercise (exercise group [EG], n=52, 15.3±2y, 46% female) or placebo-like stretching (placebo group [PG], n=51, 15.4±2y, 47% female) (N=151). MAIN OUTCOME MEASURES: The primary outcome was median days from injury to recovery. The secondary outcome was proportion classified as normal recovery (<30d) or delayed recovery (≥30d). RESULTS: The RG recovered in 16 days (interquartile range, 9.25-23.25d), which was significantly delayed (P=.020) compared with EG (13d; interquartile range, 10-18.5d). The PG recovered in 17 days (interquartile range, 13-23d). Four percent of the EG, 14% of the PG, and 13% of the RG had delayed recovery (P=.190). There was no difference in recovery time or delayed recovery between male participants and female participants across groups. Female participants prescribed rest experienced an increase in symptoms vs the other groups (P=.013). CONCLUSION: Relative rest and a placebo-like stretching program were very similar in days to recovery and symptom improvement pattern after SRC. Both conditions were less effective than subsymptom threshold aerobic exercise. Female adolescents appear to be susceptible to symptom increase when prescribed rest.

Integrating Neuropsychology Services in a Multidisciplinary Concussion Clinic.

OBJECTIVE: To describe the integration of neuropsychology services in a multidisciplinary concussion clinic and provide descriptive information on patients, services, and initial health status. SETTING: A university-based outpatient sports medicine concussion clinic. PARTICIPANTS: A consecutive sample of 338 patients ages 8 to 84 years (median 23.5 years, 35% 13-18 years), 49.1% male, seen between 2014 and 2018. Patients' injuries included sports 42%, work 28.4%, and vehicular 12.1% and 48.5% were students. DESIGN: Descriptive statistics with group comparisons. MAIN MEASURES: 12-Item Short Form Health Survey (SF-12) T scores (mean = 50, SD = 10) referenced to US population. RESULTS: Half of the patients were seen within 24 days of their injury and showed reduced physical functioning (40.2) and average mental (emotional) functioning (48.8). Patients seen after 24 days showed even more reduced physical functioning (33.9) and reduced mental functioning (41.0), both P < .0001. Average treatment time was also longer, 88.1 (173.9) versus 186.8 (211.1) days, P < .0001. Two-thirds of patients were referred for cervical or vestibular physical therapy at their initial visit. CONCLUSION: Early referral for specialized care, including neuropsychology services, may be beneficial.

A Preliminary Study of the Effect of Early Aerobic Exercise Treatment for Sport-Related Concussion in Males.

OBJECTIVE: To study the effect of early prescribed aerobic exercise versus relative rest on rate of recovery in male adolescents acutely after sport-related concussion (SRC). DESIGN: Quasi-experimental design. SETTING: University sports medicine centers. PARTICIPANTS: Exercise group (EG, n = 24, 15.13 ± 1.4 years, 4.75 ± 2.5 days from injury) and rest group (RG, n = 30, 15.33 ± 1.4 years, 4.50 ± 2.1 days from injury). INTERVENTIONS: Exercise group performed a progressive program of at least 20 minutes of daily subthreshold aerobic exercise. Rest group was prescribed relative rest (no structured exercise). Both groups completed daily online symptom reports (Postconcussion Symptom Scale) for 14 days. MAIN OUTCOME MEASURES: Days to recovery after treatment prescription. Recovery was defined as return to baseline symptoms, exercise tolerant, and judged recovered by physician examination. RESULTS: Recovery time from initial visit was significantly shorter in EG (8.29 ± 3.9 days vs 23.93 ± 41.7 days, P = 0.048). Mixed-effects linear models showed that all symptom clusters decreased with time and that there was no significant interaction between treatment group and time. No EG participants experienced delayed recovery (>30 days), whereas 13% (4/30) of RG participants experienced delayed recovery. CONCLUSIONS: These preliminary data suggest that early subthreshold aerobic exercise prescribed to symptomatic adolescent males within 1 week of SRC hastens recovery and has the potential to prevent delayed recovery.

Active recovery from concussion.

PURPOSE OF REVIEW: Recent studies are challenging the utility of prolonged rest as treatment for concussion and postconcussion syndrome (PCS). The purpose of this paper is to review the evidence for active recovery from concussion and PCS. RECENT FINDINGS: Emerging data identify the central role of autonomic nervous system (ANS) dysfunction in concussion pathophysiology. The exercise intolerance demonstrated by athletes after sport-related concussion may be related to abnormal ANS regulation of cerebral blood flow. As aerobic exercise training improves ANS function, sub-symptom threshold exercise treatment is potentially therapeutic for concussion. A systematic assessment of exercise tolerance using the Buffalo Concussion Treadmill Test has been safely employed to prescribe a progressive, individualized subthreshold aerobic exercise treatment program that can return patients to sport and work. Multiple studies are demonstrating the efficacy of an active approach to concussion management. SUMMARY: Sustained rest from all activities after concussion, so-called 'cocoon therapy', is not beneficial to recovery. Evidence supports the safety, tolerability, and efficacy of controlled sub-symptom threshold aerobic exercise treatment for PCS patients. Further study should determine the efficacy and optimal timing, dose, and duration of subthreshold aerobic exercise treatment acutely after concussion because early intervention has potential to prevent PCS.

A Preliminary Study of Early-Onset Dementia of Former Professional Football and Hockey Players.

OBJECTIVE: To provide an overview of 3 studies of the same population of retired professional contact sport athletes compared with age-matched noncontact sport athlete controls on cognition, executive function, behavior, and advanced brain imaging. SETTING: University Concussion Management Clinic. PARTICIPANTS: Twenty-two retired professional hockey and football athletes (average age 56 years) and 21 age-matched noncontact sport athlete controls. DESIGN: Case control. MAIN MEASURES: Participants were assessed on a broad range of neuropsychological measures that are associated with identification of mild cognitive impairment and executive function. Athletes were also assessed using self-report measures of executive function and personality. Advanced structural and functional imaging techniques were utilized as well. RESULTS: The former National Football League and National Hockey League athletes perceived themselves to have impaired executive function, but this was not confirmed by objective neurocognitive assessment. No significant differences were found when comparing contact-sport athletes with controls on the presence of mild cognitive impairment or brain structural and functional tissue injury. Contact sport athletes were more anxious and more likely to report unusual beliefs and experiences. CONCLUSION: None of the retired contact sport athletes qualified as having early-onset dementia consistent with chronic traumatic encephalopathy. There were no remarkable differences in imaging, cognition, behavior, or executive function from noncontact sport athletes. The results underscore an apparent disconnect between public perceptions and evidence-based conclusions about the inevitability of chronic traumatic encephalopathy and the potential neurodegenerative effect on former athletes from contact sports.

Evaluation of Executive Function and Mental Health in Retired Contact Sport Athletes.

OBJECTIVE: To compare retired professional contact sport athletes with age-matched noncontact sport athletes on measures of executive function and mental health. SETTING: The University Concussion Management Clinic. PARTICIPANTS: Twenty-one retired National Football League (NFL) and National Hockey League (NHL) players (mean age 56 years) and 21 age-matched noncontact sport athlete controls. DESIGNS: Case control. MAIN MEASURE: The self- and informant-reported Behavior Rating Inventory of Executive Function-Adult form (BRIEF-A); Wisconsin Card Sorting Test; Delis-Kaplan Executive Function System; Trail Making Part A and B; Wechsler Adult Intelligence Scale; Neuropsychological Assessment Battery; List Learning; Controlled Oral Word Association Test; Beck Depression Inventory; Beck Anxiety Inventory; and Personality Inventory of the DSM-5. RESULTS: Former NFL and NHL players perceived themselves to have some impairment in 2 of the 9 domains of executive function on the BRIEF-A; however, their informants reported no difference when compared with informants of noncontact athletes. No significant differences were found when comparing contact sport athletes with noncontact athletes on objective neuropsychological testing. Contact sport athletes qualified as clinically anxious and had more "unusual beliefs and experiences," although they remained within with age-based norms. CONCLUSION: Participation in contact sports at the professional level may not lead to later-life executive dysfunction, as the popular media and some research currently suggest.

An Exploratory Study of Mild Cognitive Impairment of Retired Professional Contact Sport Athletes.

OBJECTIVE: To test the hypothesis that mild cognitive impairment (MCI) rates are higher among retired professional contact sport athletes than in noncontact athlete controls and compare history of contact sports with other MCI risk factors. SETTING: University Concussion Management Clinic. PARTICIPANTS: Twenty-one retired National Football League and National Hockey League players and 21 aged-matched noncontact athlete controls. DESIGNS: Case-control. MAIN MEASURES: Comprehensive criteria were used to assess MCI based on the following: Wisconsin Card Sorting Test, Delis-Kaplan Executive Function System; Trail Making Parts A and B; Wechsler Adult Intelligence Scale-Third Edition subtests; Neuropsychological Assessment Battery Memory Module List Learning, Story Learning, and Naming subtests; and Controlled Oral Word Association Test. The Wide Range Achievement Test was used as a proxy measure for IQ. Atherosclerotic cardiovascular disease risk factors were self-reported and blood cholesterol was measured. Depression was measured by the Beck Depression Inventory-II (BDI). RESULTS: Eight contact sport athletes (38%) and 3 noncontact athletes (14%) met MCI criteria (P = .083). Contact sport athletes' scores were significantly worse on Letter Fluency and List B Immediate Recall. Contact athletes were more obese, had more vascular risk factors, and had higher scores on the BDI than controls. CONCLUSION: Athletes with a history of playing professional contact sports had more vascular risk factors and higher depression scores. MCI rates were somewhat higher, though not significant.

Multimodal Imaging of Retired Professional Contact Sport Athletes Does Not Provide Evidence of Structural and Functional Brain Damage.

BACKGROUND: Long-term consequences of playing professional football and hockey on brain function and structural neuronal integrity are unknown. OBJECTIVES: To investigate multimodal metabolic and structural brain magnetic resonance imaging (MRI) differences in retired professional contact sport athletes compared with noncontact sport athletes. METHODS: Twenty-one male contact sport athletes and 21 age-matched noncontact sport athletes were scanned on a 3 tesla (3T) MRI using a multimodal imaging approach. The MRI outcomes included presence, number, and volume of focal white matter signal abnormalities, volumes of global and regional tissue-specific brain structures, diffusion-tensor imaging tract-based spatial statistics measures of mean diffusivity and fractional anisotropy, quantitative susceptibility mapping of deep gray matter, presence, number, and volume of cerebral microbleeds, MR spectroscopy N-acetyl-aspartate, glutamate, and glutamine concentrations relative to creatine and phosphor creatine of the corpus callosum, and perfusion-weighted imaging mean transit time, cerebral blood flow, and cerebral blood volume outcomes. Subjects were also classified as having mild cognitive impairment. RESULTS: No significant differences were found for structural or functional MRI measures between contact sport athletes and noncontact sport athletes. CONCLUSIONS: This multimodal imaging study did not show any microstructural, metabolic brain tissue injury differences in retired contact versus non-contact sport athletes.