Objective The Concussion in Sport Group guidelines recommend a multifaceted approach to help clinicians make return to sport decisions. The purpose of this study was to identify the most common multifaceted measures used to define clinical recovery from sport-related concussion in young athletes (high school and/or college level) and to summarise existing knowledge of criteria used to make return to sport decisions. Design Systematic review. Data sources The PubMed (MEDLINE), SPORTDiscus and Embase electronic databases were searched from 1 January 2000 to 1 March 2017 by three independent reviewers. Eligibility criteria Inclusion criteria: elementary, high school and college age groups, and a specific definition of clinical recovery that required two or more measures. Exclusion criteria: review articles, articles using the same sample population, case studies, non-English language and those that used one measure only or did not specify the recovery measures used. Study quality Study quality was assessed using the Downs and Black Criteria. Results Of 2023 publications, 43 met inclusion criteria. Included articles reported the following measures of recovery: somatic symptom resolution or return to baseline (100%), cognitive recovery or return to baseline (86%), no exacerbation of symptoms on physical exertion (49%), normalisation of balance (30%), normal special physical examination (12%), successful return to school (5%), no exacerbation of symptoms with cognitive exertion (2%) and normalisation of cerebral blood flow (2%). Follow-up to validate the return to sport decision was reported in eight (19%) articles. Most studies were case–control or cohort (level of evidence 4) and had significant risk of bias. Conclusion All studies of sport-related concussion use symptom reports to define recovery. A minority of studies used multiple measures of outcome or had clearly defined recovery criteria, the most common being a combination of a self-reported symptom checklist and a computerised neurocognitive test. Future studies ideally should define recovery a priori using objective physiological measures in addition to symptom reports.

The Buffalo Concussion Treadmill Test (BCTT) is a graded exertion test for assessing exercise tolerance after concussion, but its utility is limited for certain populations. We developed the Buffalo Concussion Bike Test (BCBT) and tested its comparability with the BCTT. We hypothesize that heart rate (HR) at symptom exacerbation on the BCBT will be equivalent to the BCTT. Case-control study. Level 3. Adolescents with acute concussion (AC) (n = 20; mean age, 15.9 ± 1.1 years; 60% male) presenting to a concussion clinic within 10 days of injury and age- and sex-matched healthy controls (n = 20; mean age, 15.9 ± 1.1 years; 60% male) performed the BCTT at first visit and returned within 3 days to perform the BCBT. Test duration, HR, symptom severity (measured using a visual analog scale), and exertion (measured using the Borg Rating of Perceived Exertion) were collected during each test. Adolescents with AC who were exercise intolerant on the BCTT were also intolerant on the BCBT, with symptom exacerbation occurring at a mean 8.1 ± 2.8 minutes on the BCTT versus 14.6 ± 6.0 minutes on the BCBT (P < 0.01). Two 1-sided t tests showed that the HR at symptom exacerbation in AC patients on each test were statistically equivalent (137 ± 28 bpm on BCTT vs 135 ± 25 bpm on BCBT; 95% CI, <0.01-0.03) and at voluntary exhaustion for controls (175 ± 13 bpm on BCTT vs 175 ± 13 bpm on BCBT; 95% CI, 0.03-0.03). The HR at symptom exacerbation on BCBT is equivalent to the BCTT for the assessment of exercise tolerance after concussion in adolescents. The BCBT can be used in patients with limited mobility or for research interventions that require limited participant motion.

The Buffalo Concussion Treadmill Test (BCTT) identifies the heart rate threshold (HRt) of exercise tolerance in concussed patients. A previous study found that an absolute HRt of < 135 bpm was associated with prolonged recovery (>30 days) from sport-related concussion (SRC). In this study, we assessed the relationship of ΔHR (difference between resting HR and HRt) and recovery from SRC. Using a retrospective cohort design, we compared acutely (30 days) in RG (p = 0.01) and PG (p = 0.04). A ΔHR of ≤50 bpm on the BCTT is 73% sensitive and 78% specific for predicting prolonged recovery in concussed adolescents who were prescribed the current standard of care (i.e., cognitive and physical rest).

Context: Emerging research supports the use of mild to moderate aerobic exercise for treating sport-related concussion (SRC) and persistent postconcussive symptoms (PPCS), yet the current standard of care remains to be strict rest. The purpose of this review is to summarize the existing literature on physical activity and prescribed exercise for SRC and PPCS. Evidence Acquisition: PubMed and Embase were searched in April of 2019 for studies assessing rest or prescribed exercise for SRC and PPCS. No specific search syntax was used. Study Design: Clinical review. Level of Evidence: Level 4. Results: A majority of studies show that spontaneous physical activity is safe after SRC and that subsymptom threshold aerobic exercise safely speeds up recovery after SRC and reduces symptoms in those with PPCS. Exercise tolerance can safely be assessed using graded exertion test protocols within days of injury, and the degree of early exercise tolerance has diagnostic and prognostic value. Conclusion: Subsymptom threshold aerobic exercise is safe and effective for the treatment of SRC as well as in athletes with PPCS. Further research is warranted to establish the most effective method and dose of aerobic exercise for the active treatment of SRC and whether early exercise treatment can prevent PPCS in athletes. Strength of Recommendation Taxonomy: 2.

Objective: Intracranial pressure (ICP) after mild traumatic brain injury (mTBI) is poorly studied due to lack of sensitive non-invasive methods. The purpose of this review was to summarize the existing knowledge of changes in ICP after mTBI. Literature selection: PubMed, Embase, CINAHL, and Scopus were searched by three reviewers independently up to December 2016. Inclusion criteria: animal and human studies measuring ICP and brain oedema after an mTBI. Exclusion criteria: moderate and severe forms of traumatic brain injury, repeat samples, and studies that measured ICP at the time of impact but not after. Study quality was assessed using Downs and Black criteria. Results: Of 1067 papers, 9 studies were included. In human studies, one provided direct evidence on increased, one provided indirect evidence of increased, and two provided indirect evidence of decreased ICP. In animal studies, three studies provided direct evidence of increased, one provided indirect evidence of increased, and one provided indirect evidence of no change in ICP. Conclusion: The existing research suggests that there may be increased ICP after mTBI and animal studies suggest an elevation for days which returns to baseline, which corresponds with functional and symptomatic recovery. Future human studies using sensitive indirect methods to measure ICP longitudinally after mTBI are needed.

Objective: The goals of this study were to assess the ability of salivary non-coding RNA (ncRNA) levels to predict post-concussion symptoms lasting ≥ 21 days, and to examine the ability of ncRNAs to identify recovery compared to cognition and balance.Methods: RNA sequencing was performed on 505 saliva samples obtained longitudinally from 112 individuals (8–24-years-old) with mild traumatic brain injury (mTBI). Initial samples were obtained ≤ 14 days post-injury, and follow-up samples were obtained ≥ 21 days post-injury. Computerized balance and cognitive test performance were assessed at initial and follow-up time-points. Machine learning was used to define: (1) a model employing initial ncRNA levels to predict persistent post-concussion symptoms (PPCS) ≥ 21 days post-injury; and (2) a model employing follow-up ncRNA levels to identify symptom recovery. Performance of the models was compared against a validated clinical prediction rule, and balance/cognitive test performance, respectively.Results: An algorithm using age and 16 ncRNAs predicted PPCS with greater accuracy than the validated clinical tool and demonstrated additive combined utility (area under the curve (AUC) 0.86; 95% CI 0.84–0.88). Initial balance and cognitive test performance did not differ between PPCS and non-PPCS groups (p > 0.05). Follow-up balance and cognitive test performance identified symptom recovery with similar accuracy to a model using 11 ncRNAs and age. A combined model (ncRNAs, balance, cognition) most accurately identified recovery (AUC 0.86; 95% CI 0.83–0.89).Conclusions: ncRNA biomarkers show promise for tracking recovery from mTBI, and for predicting who will have prolonged symptoms. They could provide accurate expectations for recovery, stratify need for intervention, and guide safe return-to-activities.