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Background: Organizations recommend that athletes should be asymptomatic or symptom-limited before initiating a graduated return-to-play (GRTP) protocol after sports-related concussion, although asymptomatic or symptom-limited is not well-defined., Hypotheses: (1) There will be a range (ie, beyond zero as indicator of "symptom-free") in symptom severity endorsement when athletes are deemed ready to initiate a GRTP protocol. (2) Baseline symptom severity scores and demographic/preinjury medical history factors influence symptom severity scores at the commencement of the GRTP protocol. (3) Greater symptom severity scores at GRTP protocol initiation will result in longer protocol duration. (4) Symptom severity scores will not differ between those who did and did not sustain a repeat injury within 90 days of their initial injury., Study Design: Cohort study; Level of evidence, 2., Methods: Across 30 universities, athletes (N = 1531) completed assessments at baseline and before beginning the GRTP protocol, as determined by local medical staff. Symptom severity scores were recorded with the symptom checklist of the Sport Concussion Assessment Tool-3rd Edition. Nonparametric comparisons were used to examine the effect of medical, demographic, and injury factors on symptom endorsement at GRTP protocol initiation, as well as differences in symptom severity scores between those who did and did not sustain a repeat injury within 90 days. A Cox regression was used to examine the association between symptom severity scores at GRTP protocol initiation and protocol duration., Results: Symptom severity scores at the time when the GRTP protocol was initiated were as follows: 0 to 5 (n = 1378; 90.0%), 6 to 10 (n = 76; 5.0%), 11 to 20 (n = 42; 3.0%), and ≥21 (n = 35; 2.0%). Demographic (sex and age), medical (psychiatric disorders, attention-deficit/hyperactivity disorder, learning disorder), and other factors (baseline symptom endorsement and sleep) were significantly associated with higher symptom severity scores at the GRTP initiation ( P < .05). The 4 GRTP initiation time point symptom severity score groups did not significantly differ in total time to unrestricted RTP, χ 2 (3) = 1.4; P = .73. When days until the initiation of the GRTP protocol was included as a covariate, symptom severity scores between 11 and 20 ( P = .02; hazard ratio = 1.44; 95% CI, 1.06-1.96) and ≥21 ( P < .001; hazard ratio = 1.88; 95% CI, 1.34-2.63) were significantly associated with a longer GRTP protocol duration as compared with symptom severity scores between 0 and 5. Symptom severity scores at GRTP initiation did not significantly differ between those who sustained a repeat injury within 90 days and those who did not ( U = 29,893.5; P = .75)., Conclusion: A range of symptom severity endorsement was observed at GRTP protocol initiation, with higher endorsement among those with higher baseline symptom endorsement and select demographic and medical history factors. Findings suggest that initiation of a GRTP protocol before an absolute absence of all symptoms is not associated with longer progression of the GRTP protocol, although symptom severity scores >10 were associated with longer duration of a GRTP protocol. Results can be utilized to guide clinicians toward optimal GRTP initiation (ie, balancing active recovery with avoidance of premature return to activity).

Purpose A recent systematic review determined that the physiological effects of concussion may persist beyond clinical recovery. Preclinical models suggest that these physiological effects are accompanied by a window of cerebral vulnerability that is associated with risk for subsequent, more severe injury. This study examined the association between persistent diffusion tensor imaging signal following clinical recovery of sport-related concussion and risk of re-injury. Methods Average mean diffusivity (MD) was obtained in a region-of-interest (ROI) in which concussed athletes showed significantly elevated MD acutely after injury (<48 hours), at an asymptomatic timepoint, 7-days post-return to play, and 6 months post-injury relative to controls. The relationship between MD in the identified ROI and risk of sustaining a subsequent concussion over a 1-year period was examined with a binary logistic regression (re-injured, yes/no). Results Eleven of 83 concussed athletes suffered a second concussion within a 1-year period. The relationship between MD at 7-days post return to play and risk of sustaining a secondary injury within 1-year showed a non-significant trend (X2(1)=4.17, p=.057, B=0.03, SE=0.017; Nagelkerke R2=0.16). Mean differences in MD between the repeat injury and non-reinjured group at 7-days post return to play produced a large effect, d=.75. MD in the a priori ROI at the other recovery time points did not predict elevated risk of re-injury. Conclusion These preliminary findings suggest that a large effect size was present in the relationship between persistent diffusion signal abnormalities and risk for subsequent re-injury. This provides support for a window of cerebral vulnerability following concussion, though further examination is needed. [ABSTRACT FROM AUTHOR]