Data extraction tool for studies using neuroimaging
| Study design | Participants | Review of evidence | ||||||
| First author, year | Study type | Modality | Sport | Age/level (mean ± SD, range) | Gender (M/F) | n (control description) | Time from injury to examination | Risk of bias |
| Chen JK, 200411 | PCS | T-fMRI | WR, IH, OT | Control: 27.6±5.2 years; concussed: 26.9±7.2 years | M | 16 C+, 8 C- (age-matched males) | 1–14 months (mean 4.7 months) | High |
| Jantzen KJ, 20046 | PCS | T-fMRI | FB | 20 years; 19–23 years | M | 4 C+, 4 C- | Three athletes examined within 1 week postinjury, 1 at end of season | Moderate |
| Cimatti M, 200626 | CS | MRS | BX, OT | UNK | UNK | 6 C+ | 24–48 hours postinjury | High |
| Gosselin N, 200691 | PCS | EEG | IH, FB SCR | Asymptomatic: 26.1±6.1 years; symptomatic: 25.7±7.0 years; control: 22.0±1.8 years | M/F | 20 C+, 10 C- | Asymptomatic 5.3±3.1 weeks; symptomatic 15.1±16.6 weeks postinjury | Moderate |
| Chen JK, 200749 | PCS | T-fMRI | Any | Low PCS: 26.9±5.6 years; moderate PCS: 30.8±5.8 years; control: 21.9±1.6 years | M | 18 C+, 10 C- | 5±6.4 months postinjury | High |
| Lovell MR, 20075 | PCS | T-fMRI | Any | 16.6±2.4; 13–24 years | M/F | 28 C+, 13 C- (age-matched athletes) | 6.6±4.7 days and 33.3±33.8 days postinjury | Moderate |
| Chen JK, 200850 | PCS | T-fMRI | Any | Control: 20±1.2 years; C+ no depression: 26±5.6 years; C+ mild depression: 29±6.7 years; C+ moderate depression: 30±7.4 years | M | 40 C+, 16 C- (IH and FB controls) | 4.9–7.3 months depending on group | Moderate |
| Vagnozzi R, 200832 | PCS | MRS | RB, BX, OT | 27±4.8 years, 21–35 years | M/F | 14 C+, 5 C- (age-matched controls) | 3, 15 and 30 days postinjury | Moderate |
| Slobounov S, 200963 | PCS | EEG | RB, FB, IH, SCR | Male: 21.3 years; female: 20.8 years; 18–25 years | M/F | 21 C+ | 7, 14 and 21 days postinjury | Moderate |
| Cao C, 201061 | PCS | EEG | RB, FB, IH | Male: 20.9 years; female: 21.4 years; 18–25 years | M/F | 29 C+ | BL, and 7 days postinjury | Moderate |
| Henry LC, 201027 | PCS | MRS | Any | Control: 23±0.71 years; concussed: 22.1±0.77 years | M | 12 C+, 12 C- | Within 6 days postinjury (81.9±46.7 hours) | Moderate |
| Livingston SC, 201092 | PCS | TMS | Any | 20.4±1.3 years | M/F | 9 C+, 9 C- (age, gender, sport, position, concussion history and LD/ADHD matched) | 1, 3, 5 and 10 days postinjury | Moderate |
| McCrea M, 20104 | PCS | qEEG | FB | Col/HS | M | 28 C+, 28 C- (age, years of education, GPA and BL performance matched) | BL, day of injury, 8 days and 45 days postinjury | Moderate |
| Pardini JE, 201093 | PCS | T-fMRI | Any | 16.3 years, 14–23 years | M/F | 16 C+ | 3–12 days postinjury; median: 6.5 days postinjury | Moderate |
| Slobounov SM, 201053 | PCS | T-fMRI | RB, IH, SCR | Control: 21.3 years; concussed: 20.8 years | M/F | 15 C+, 15 C- (age-matched athlete controls) | ≤30 days postinjury | Moderate |
| Vagnozzi R, 201030 | PCS | MRS | RB, SCR, BX, OT | Control: 27.6±3.6 years; concussed: 26.5±5.5 years; 16–35 years | M/F | 40 C+, 30 C- | 3, 15, 22 and 30 days postinjury | Moderate |
| Zhang K, 201048 | PCS | T-fMRI/DTI | RB, IH, SCR | Control: 21.3±1.5 years; concussed: 20.8±1.7 years | M/F | 15 C+, 15 C- (age-matched athlete controls) | 30±2 days postinjury | Moderate |
| Cao C, 201162 | PCS | EEG | RB, FB, IH, SCR | Male: 21.3 years; female: 20.8 years; range: 18–25 years | M/F | 30 C+, 30 C- (age and sex matched athletes from same group without history of concussion) | BL, 30±3 days postinjury | Moderate |
| Cubon VA, 201110 | PCS | DTI | Any | Control: 20.4±1.8 years; concussed: 19.7±1.6 years | M/F | 10 C+, 10 C- (sex and age matched non-contact controls) | At least 1 month postinjury mean: 115±104 days | Moderate |
| Henry LC, 201140 | PCS | DTI | FB | Control: 22.8±1.5 years; concussed: 22.1±1.7 years | M | 16 C+, 8 C- (FB controls without concussion history) | 5 days (mean: 81.9±46.7 hours) and 6 months (mean: 6.4±0.4 months) postinjury | Moderate |
| Henry LC, 201133 | PCS | MRS | FB | 22.5 years | M | 10 C+, 10 C- (athlete controls without concussion history) | 5 days (mean: 81.9±46.7 hours) and 6 months (mean: 6.4±0.4 months) postinjury | Moderate |
| Len TK, 201168 | PCS | CVR | IH, OT | 21.4±1.7 years, 16–25 years | M/F | 10 C+, 21 C- | 4.5±1.1 days postinjury | Moderate |
| Slobounov SM, 201160 | PCS | R-fMRI | RB, IH, SCR | Control: 21.3±1.5 years; concussed: 20.8±1.7 years | M/F | 17 C+, 17 C- | 10±2 days postinjury | Moderate |
| Slobounov S, 201194 | PCS | EEG | RB, FB, IH, LX, OT | Control: 21.3±1.5 years; concussed: 20.8±1.7 years | M/F | 14 C+, 15 C- (student-athletes without history of concussion) | 15 days postinjury and within 24 hours of symptom resolution | Moderate |
| Baillargeon A, 201295 | PCS | EEG | SCR, IH, RB, FB | Control: 9–12 years (11±1.2 years), 13–16 years (14.8±1.1 years), adults (23.3±3.3 years); concussed 9–12 years (10.5.±1.2 years), 13–16 years (14.2±1.0 years), adults (23.4±2.1 years) | M | 48 C+, 48 C- | 6 months postinjury | Moderate |
| Barr WB, 201296 | PCS | EEG | FB | Col/HS | M | 59 C+, 31 C- (age, years of education, GPA and BL performance matched) | Day of injury, 8 days and 45 days postinjury | Moderate |
| Breedlove EL, 201297 | PCS | T-fMRI | FB | Season 1: 17.0 years, 15–18 years; Season 2: 16.8 years, 14–18 years | M | 7 C+ | Preseason and in-season follow-up for concussed athletes | High |
| Chamard E, 201236 | PCS | MRS | IH | 20.21 years, 18–37.2 years | M/F | 45 C+ | 72 hours, 14 days and 2 months postinjury | Moderate |
| Johnson B, 201228 | PCS | MRS | Any | Control: 20.2±0.8 years; concussed: 20.3±1.5 years | M/F | 28 C+, 20 C- (athlete controls) | ≤24 hours of symptom resolution, placed into three groups; subjects recovered within 1 week, 2 weeks or 3+ weeks postinjury | Moderate |
| Johnson B, 201256 | PCS | R-fMRI | Any | Control: 20.4±0.8 years; concussed 20.6±1.2 years; additional concussed: 19.9±1.5 years | M/F | 23 C+, 15 C- (athlete controls) | 14 scanned within 24 hours of symptom resolution (10±2 days postinjury); 9 scanned outside of 24 hours of symptom resolution (10±4 days postinjury) | Moderate |
| Johnson B, 201229 | PCS | MRS | Any | Control: 20.4±0.8 years; concussed: 20.6±1.2 years | M/F | 15 C+, 15 C- (athlete controls) | ≤24 hours of symptom resolution | Moderate |
| Livingston SC, 201298 | PCS | TMS | Any | 20.4±1.3 years | M/F | 9 C+, 9 C- (age, gender, sport, position, concussion history and LD/ADHD matched) | 1, 3, 5 and 10 days postinjury | Moderate |
| Maugans TA, 201237 | PCS | DTI, MRS, ASL | FB, SCR, WR | 11–15 years | M/F | 12 C+, 12 C- (age and gender matched) | ≤72 hours, 14 days and 30 days postinjury | Moderate |
| McAllister TW, 201299 | PCS | DTI | FB, IH | Col/HS | M | 10 C+ | Preseason, ≤10 days of injury | Moderate |
| Slobounov S, 201264 | PCS | EEG | RB, FB, IH, SCR | Male: 21.8 years; female: 20.1 years; 18–25 years | M/F | 49 C+, 383 C- (athletes evaluated at BL) | BL, 7 days, 15 days, 30 days, 6 months and 12 months postinjury | Moderate |
| Zhang K, 2012100 | PCS | R-fMRI | RB, FB, IH, SCR | Control: 20.9±1.1 years; concussed: 20.8±1.5 years | M/F | 14 C+, 17 C- | ≤24 hours of symptom resolution 10±2 days postinjury | Moderate |
| Borich M, 201338 | PCS | DTI | IH | Control: 15.7±0.9; concussed: 15.5±1.2 years | M/F | 12 C+, 10 C- (age, gender and physical activity matched controls) | 35.6±15.0 days postinjury | High |
| Hammeke TA, 2013101 | PCS | T-fMRI | FB | Control: 16.5±0.52 years; concussed: 16.5±0.52 years | M | 12 C+, 12 C- (uninjured teammate; age, education and preseason symptom matched) | 13 hours and 7 weeks postinjury | Moderate |
| Len TK, 201367 | PCS | CVR | IH, OT | 19.7±3.3 years | M/F | 20 C+ | BL, 2, 4 and 7 days postinjury, and end of season | Moderate |
| Prichep LS, 201365 | PCS | EEG | FB | 17.9 years, 15.1–23.2 years | M | 65 C+ | ≤24 hours, 8 and 45 days postinjury | Moderate |
| Vagnozzi R, 201331 | PCS | MRS | Any | Control: 25.9±5.7 years; concussed: 24.6±6.4 years; 16–35 years | M/F | 11 C+, 11 C- (sex and age matched) | 3, 15, 30 and 45 days postinjury | Moderate |
| Virji-Babul N, 201344 | PCS | DTI | IH, RB, OT | 14–17 years | M/F | 12 C+, 10 C- | ≤2 months postinjury | High |
| Bartnik-Olson BL, 201425 | PCS | ASL, DTI, MRS | FB, OT | 8–17 years | M/F | 15 C+, 15 C- (age, gender and BMI matched controls) | Mean: 5.8±4.8 months postinjury | Moderate |
| Chamard E, 201435 | PCS | MRS | Any | Control: 21.1 years; concussed: 21.4 years | F | 11 C+, 10 C- (athletes without history of concussion) | 9.4±4.3 days and 181.9±14.6 days postinjury | Moderate |
| Dettwiler A, 201447 | PCS | T-fMRI | Any | 19.8±0.9 years | M/F | 15 C+, 15 C- (age and sex matched normal controls) | ≤2 days, 2 weeks and 2 months postinjury | Moderate |
| Helmer KG, 2014102 | PCS | SWI | IH | Male: 23±2 years; female: 21±4 years | M/F | 11 C+, 45 C- includes same subjects at BL | BL, 72 hours, 2 weeks, 2 months, and end of season | High |
| Keightley ML, 201451 | PCS | T-fMRI | Any | Control: 14±2.3 years; concussed: 14.5±2.3 years | M/F | 15 C+, 15 C- (age-matched controls) | Range of 9–90 days postinjury | Moderate |
| Kontos AP, 2014104 | PCS | fNIRS | Any | Control: 22±0.3 years; concussed: 22.7±1.3 years | M/F | 9 C+, 5 C- (age-matched healthy controls) | Range of 15–45 days postinjury, while still symptomatic | High |
| Murugavel M, 201445 | PCS | DTI | Any | Control: 19.9±1.7 years; concussed: 20.2±1.0 years; 18–22 years | M | 21 C+, 16 C- (age and sex matched healthy non-contact controls) | 2 days, 2 weeks and 2 months postinjury | Moderate |
| Pasternak O, 201442 | PCS | DTI | IH | 17–26 years | M/F | 11 C+ (7 with usable postinjury scan) | BL, 72 hours postinjury | Moderate |
| Powers KC, 2014105 | PCS | TMS | FB | Control: 20.3±1.5 years; concussed: 20.2±1.2 years | M | 8 C+, 8 C- (age and position matched with healthy teammate controls) | 1–4 weeks postinjury (on symptom resolution) | Moderate |
| Sasaki T, 201443 | PCS | DTI | IH | Control: 21.3±1.8 years; concussed: 21.7±1.5 years | M/F | 16 C+, 18 C- (teammates) | Preseason and postseason, mean time to scan: 95±45 days (range: 42–161 days) | Moderate |
| Sinopoli KJ, 201452 | PCS | T-fMRI | IH, OT | Control: 12.6±1.6 years; concussed: 12.6±1.6 years; 9–15 years | M | 13 C+, 14 C- | 3–6 months postinjury | Moderate |
| Teel EF, 2014106 | PCS | EEG | Any | Control: 21±1 years; concussed: 21±1 years | M/F | 7 C+, 12 C- | ≤8 days (mean: 5±1) | Moderate |
| 107Virji-Babul N, 2014107 | PCS | EEG | IH, SCR | Control: 15.8±1.3 years; concussed: 16±0.9 years | M | 9 C+, 33 C- (soccer player controls) | ≤3 months postinjury | High |
| Balkan O, 2015108 | PCS | EEG | Any | Control: 16 years; concussed: 16.5 years | M | 21 C+, 33 C- (soccer players) | ≤3 months postinjury | Moderate |
| Borich M, 201555 | PCS | R-fMRI | IH | Control: 15.7±0.9 years; concussed: 15.5±1.2 years | M/F | 12 C+, 10 C- (age, gender and physical activity matched controls) | 35.7±15 days postinjury | High |
| Czerniak SM, 201558 | PCS | R-fMRI | Any | Control: 20±0.4 years; concussed: 20.3±0.4 years; 18–22 years | M/F | 9 C+, 12 C- | ≤6 months postinjury (mean: 112±22 days postinjury) | Moderate |
| Gay M, 2015109 | PCS | EEG | Any | Col | UNK | 9 C+, 9 C- (age-matched student athletes) | During return-to-play protocol | High |
| Jing M, 2015103 | DTI | FB | 19–23 years (median: 20 years) | M | 3 C+, 8 C- | Within 24 hours postinjury | High | |
| Johnson B, 201554 | PCS | T-fMRI | Any | 20–22 years | M/F | 9 C+, 9 C- (age and sex matched normal volunteers) | Within 7 days postinjury | Moderate |
| Meier TB, 201566 | PCS | ASL | FB | Control: 20.7±1.4 years; concussed: 20.6±1.2 years | M | 17 C+, 27 C- (healthy football players) | 1 day, 1 week and 1 month postinjury | Moderate |
| Sikoglu EM, 201534 | PCS | MRS | Any | Control: 20.2±0.4 years; concussed: 20.1±0.3 years; 18–22 years | M/F | 14 C+, 13 C- | 76.45±19.3 (mean ± SE) days postinjury (6–185 days) | Moderate |
| Yuan W, 2015110 | PCS | DTI | Any (17/23 sports injury) | 11–16.7 years | M/F | 23 C+, 20 C- (orthopaedically injured controls) | ≤96 hours postinjury | Moderate |
| Zhu DC, 201546 | PCS | R-fMRI, DTI | FB | Control: 20.5±1.8 years; concussed: 20±1.3 years | M | 8 C+, 11 C- (college students of comparable age and physical activity) | 1, 7 and 30 days postinjury | Moderate |
| Broglio SP, 2016111 | PC112S | EEG | Any | Control: 17.1±2.9 years; concussed: 16.3±2.2 years | M/F | 24 C+, 21 C- | While symptomatic, at time of self-reported symptom resolution, at return to play and at 1 month postasymptomatic | Moderate |
| Chamard E, 201639 | PCS | DTI | IH, SCR, OT | Control: 21±1.4 years; concussed: 21.4±1.7 years | F | 10 C+, 8 C- (female athletes without history of concussion) | 6 months postinjury | High |
| Jarrett M, 2016112 | PCS | SWI | IH | Control: 22.9±2.3 years; concussed: 21.2±3.1 years | M/F | 11 C+, 15 C- (college students) | 72 hours, 2 weeks and 2 months postinjury | Moderate |
| Kontos AP, 2016113 | PCS | EEG | Any | Control: 18.3±2.2 years; PTM: 16.5±1.5 years; NO-PTM 16.5±2.3 years; 18–22 years | M/F | 15 PTM, 22 NO-PTM, 20 C- (healthyhealthy age, sex, and concussion history matched) | 1, 2, 3 and 4 weeks postinjury | Moderate |
| Lancaster MA, 201615 | PCS | DTI | FB | Control: 18.0±1.5 years; concussed: 17.6±1.5 years | M | 27 C+, 26 C- (age, sex and sport matched controls) | 24 hours and 8 days postinjury | Moderate |
| Meier TB, 201659 | PCS | R-fMRI | FB, SCR, OT | Control: 20.3±1.4 years; concussed: 20.3±1.3 years | M/F | 43 C+, 51 C- (healthy contact-sport athletes) | 24 hours, 1 week and 1months postinjury | Moderate |
| Meier TB, 201641 | PCS | DTI | FB, SCR, OT | Control: 20.3±1.5 years; concussed: 20.1±1.4 years | M/F | 40 C+, 46 C- (healthy contact-sport athletes) | 24 hours, 1 week and 1 months postinjury | Moderate |
| Militana AR, 201657 | PCS | ASL, T-fMRI, R-fMRI, CVR | SCR, OT | Control: 20±1.6 years; concussed: 19.7±1.2 years | M/F | 7 C+, 11 C- (healthy controls without history of concussion | 3–6 days postinjury | Moderate |
| Mutch AC, 201669 | PCS | CVR | SCR, IH, FB, OT | Control: 18.5 years; concussed: 15.7 years | M/F | 6 C+, 24 C- (normal control atlas) | Between 7 and 279 days postinjury | Moderate |
| Wang Y, 201614 | PCS | ASL | FB | Control: 18±1.76 years; concussed: 17.7±1.5 years | M | 18 C+, 19 C- (age, gender, sport and academic achievement matched controls) | 24 hours and 8 days postinjury | Moderate |
| Wright AD, 2016114 | PCS | DTI | IH | 21.2±3.1 years | M/F | 11 C+, 34 C- | 72 hours, 2 weeks and 2 months postinjury | Moderate |
Definitions and coding table 3.
Author indicates last name of first author. Year refers to year of publication. Study type coded as follows: CS, clinical series; PCS, prospective cohort study.
Modality refers to specific form(s) of neuroimaging used in the study: ASL, arterial spin labelling; CVR, cerebrovascular reactivity; DTI/DKI, diffusion tensor/kurtosis imaging; MRS, magnetic resonance spectroscopy; R-fMRI, resting-state functional MRI; T-fMRI, task-related functional MRI; SWI, susceptibility weighted imaging.
Electrophysiological testing: EEG, electroencephalogram;qEEG, quantitative electroencephalogram; ERP, event-related potential; TMS, transcranial magnetic stimulation.
Other: fNIRS, functional near-infrared spectroscopy; SPECT, single photon emission computed tomography.
Sports coded as follows: BX, boxing; FB, football; FH, field hockey; IH, ice hockey; LX, LaCrosse; OT, other; RB, rugby; SCR, soccer; WR, wrestling.
Age/Level coded as follows: Col, college; HS, high school; P, professional; O, other; Y, youth.F/M indicates gender: F, female; M, male; list both if it applies.
Misc: BL, baseline; LD, learning disability; ADHD attention-deficit/hyperactivity disorder; GPA, grade point average; BMI, body mass index; PTM/NO-PTM, post-traumatic migrain. Risk of bias: overall risk of bias rated as low, moderate, high or unclear, based on modified QUADAS-2 critical appraisal tool (see online supplementary appendix 2).