Publications
Explore our recent publications to learn about the latest research and clinical discoveries in the field of concussion.
2025
Cortel-LeBlanc A, Cortel-LeBlanc M, Webster R, Chen K, Schytz H, Jolliffe K, Dodd A, Terekhov I, Dashti F, and Zemek R for the TRANSCENDENT Concussion Research Team. Post-traumatic headache phenotypes and clinical characteristics.Cephalalgia. 2025.
In December 2025, the research team, led by Dr. Achelle Cortel-LeBlanc, published in Cephalalgia.
Abstract: Background: Post-traumatic headache often resembles migraine or tension-type headache, but distinct phenotype and clinical characteristics necessitate further delineation. We aimed to characterize the clinical phenotype, headache patterns, associated features and comorbidities, medication patterns and functional impact of post-traumatic headache in an adult population following mild traumatic brain injury. Methods: This is a cross-sectional analysis of a cohort of adults with post-traumatic headache after mild traumatic brain injury, by any mechanism, evaluated by a neurologist at an outpatient specialized concussion and headache center in Ontario, Canada between February 2021 and October 2023. Data were collected through standardized pre- and during-visit questionnaires. Descriptive statistics are presented. Results: Among 405 patients assessed by a neurologist for post-traumatic headache, median time since injury was 37 days (IQR: 13–126). Most patients reported headache 26 + days per month (292, 72.1%). Headache was continuous in 114 (28.1%), whereas in 215 (53.1%) it lasted hours to days. Headache location was unilateral in 174 (43.0%) and bilateral in 159 (39.3%). Headache quality was described as pulsating/throbbing in 260 (64.2%). The median severity was 7/10 (IQR 5–8). Aggravation by routine physical activity was reported in 287 (70.9%), nausea/vomiting in 279 (69.0%), photophobia in 358 (88.4%) and phonophobia in 337 (83.2%). There was no positional preference for 147 patients (36.3%), while 216 (53.3%) preferred lying down/reclined. Acute medication use frequency was reported as 3 + days per week in 218 (53.8%) and daily in 143 (35.3%). Within this cohort, 201 (49.6%) endorsed one or more psychiatric comorbidities. Only 66 (16.3%) had returned to full work/school attendance, while 169 (41.7%) were completely off usual occupational activities post-injury. One hundred seventy-eight (44.0%) reported pending litigation or insurance claims related to their injury, and/or having a work-related injury. Among the 183 (45.2%) who had undergone neuroimaging, 160 (87.9%) studies were reportedly normal, while there were 13 (7.1%) incidental findings and eight (4.3%) injury-related. Discussion: While select migraine features such as photophobia, phonophobia and worsening with routine physical activity are common in post-traumatic headache, there are also distinct features, including daily or near daily headache of long duration. The latter may suggest early sensitization in post-traumatic headache. There is an associated high risk of medication overuse headache, given frequent administration of acute medications, as well as high rates of psychiatric comorbidities and functional impairment. Future studies should aim to further delineate the longitudinal clinical, pathophysiological, and treatment response differences between post-traumatic headache and primary migraine.
Dodd A, Silverberg N, Yeates K, Chen K, Kutcher S, Webster R, Johnston S, Cortel-Leblanc M and Terekhov I on behalf of the TRANSCENDENT Concussion Research Program. Concussion Classification in a Multicenter Patient Cohort: The Updated ACRM Diagnostic Criteria and Concordance With Physician Impression of Injury. The Journal of Head Trauma Rehabilitation. 2025.
In October 2025, the research team, led by Andrew Dodd, published in the Journal of Head Trauma Rehabilitation:
Abstract: Objective: The American Congress of Rehabilitation Medicine (ACRM) substantially revised its diagnostic criteria for mild traumatic brain injury (mTBI) in 2023, encompassing acute symptoms and positive clinical and laboratory examinations, in addition to immediate signs of injury. This study aimed to apply these criteria to a large, diverse cohort and compare the diagnostic determination to physician impression of injury. Setting: A network of 3 concussion specialty clinics in Ontario, Canada. Participants: A total of 1447 patients (61.0% female; median age = 26 years [IQR: 15-42 years, range: 3-87 years]; days post-injury (median: 23 IQR: [13-47, 0-349]) completed initial evaluations between June 28, 2024 and June 18, 2025. Design: Prospective observational study. Main Measures: Occurrence rates were calculated, and binary/ordinal logistic regressions were applied to determine if individual criterion endorsement or diagnostic outcome (“Definite,” “Suspected,” and “No mTBI”) was associated with age, sex, symptoms at clinical presentation, or days post-injury. Additionally, concordance with physician impression was assessed similarly. Results: Criteria for signs, symptoms, and clinical examinations were all more likely to be endorsed with increasing symptom severity at presentation, as was an ACRM diagnostic outcome of definite mTBI. Shorter time post-injury was associated with positive clinical/laboratory examinations and the presence of confounding factors, in addition to a definite diagnostic outcome. A total of 18.4% of cases were classified less definitively as mTBI by physician impression than by the updated ACRM diagnosis, with physicians tending toward underdiagnosis, particularly in patients reporting lower current symptom severity. Conclusion: Use of the ACRM criteria clinically to determine if an injury qualifies as mTBI may be less susceptible to bias from ongoing symptom reporting than the physician impression of the injury.
Sicard V, Irani T, Ledoux A, Terekhov I, Webster R, Sucha E, Kutcher S, Duan L, Dashti F, Cortel-Leblanc A, Leddy J, Richer L, Reed N, Connelly K, Anderson C, Johnston S, Zemek R, for the uOttawa Brain-Heart Interconnectome (BHI) and TRANSCENDENT Concussion Integrated Discovery Programs. Prevalence of Orthostatic Autonomic Dysregulation in Pediatric Concussion. JAMA Netw Open. 2025;8(7):e2522309.
In July 2025, the research team, led by Dr. Veronik Sicard, published in JAMA Network Open:
Abstract: Pediatric concussion can affect the autonomic nervous system. Understanding the prevalence and characteristics of physiological autonomic dysregulation (AD) and symptom provocation following concussion is crucial for optimizing recovery and developing targeted interventions. To determine the prevalence of AD and symptom provocation upon postural change and to (1) explore the overlap between AD and symptom provocation, (2) apply adult orthostatic tachycardia criteria (heart rate [HR] ≥30 bpm) to this pediatric population, (3) explore associations of demographic and injury characteristics with AD and symptom provocation, and (4) characterize AD presentation and identify the predominant orthostatic sign. This retrospective cohort study used electronic medical record review of clinical data at tertiary care concussion clinics that operate as a learning health system in Canada. Patients aged 5 to younger than 18 years who presented to those clinics within 45 days of a diagnosed concussion between August 2022 and January 2024 were included. Analysis was conducted from April to October 2024. Primary outcomes were AD presence (defined as the presence of either a decrease in systolic BP [≥20 mm Hg], decrease in diastolic BP [≥10 mm Hg], or increase in HR [≥40 bpm]), and symptom provocation (new or worsening). HR, blood pressure (BP), and symptoms were measured after a 2-minute supine rest and 1 minute of unsupported standing. Of 764 eligible patients, 451 (231 female [51.22%]; 129 [28.60%] aged 5-11 years and 322 [71.40%] aged 12 to <18 years) were included; objective AD was identified in 45 patients (9.98%; 95% CI, 7.54%-13.09%), primarily by HR changes (22 of 45 patients [48.89%]). When applying adult tachycardia criteria, AD prevalence was 23.73% (95% CI, 20.03%-27.88%). Orthostatic symptom provocation occurred in 103 of 445 patients (23.15%; 95% CI, 19.47%-27.28%). Among 134 patients with either AD or symptom provocation, 12 (8.96%) exhibited both. Patients with AD had higher rates of neurodevelopmental disorders than patients without AD (15 of 45 patients [33.33%] vs 75 of 406 patients [18.47%]; P = .02), while symptom provocation was associated with female sex (63 of 103 patients [61.17%] vs 166 of 342 patients [48.54%]; P = .03), preexisting mental health disorders (28 of 103 patients [27.18%] vs 45 of 342 patients [13.16%]; P < .001), higher concussion symptom burden (median [IQR] symptom intensity score, 46.00 [16.00-67.00] vs 21.00 [6.00-46.00]; P < .001), and status of posttraumatic amnesia at injury (22 of 103 patients with posttraumatic amnesia [22.68%] vs 63 of 342 patients without [18.92%]; P = .009). In this cohort study of children and adolescents with concussion, approximately 1 in 10 exhibited AD and 1 in 4 exhibited symptom provocation. The observed low concordance between physiological AD and symptom provocation, along with their distinct clinical profiles, might suggest these represent separate phenomena in pediatric concussion; future research should explore whether incorporating both measures into clinical assessments enhances understanding of concussion and informs targeted interventions to optimize recovery.
Zemek, R., Albrecht, L. M., Johnston, S., Leddy, J., Ledoux, A. A., Reed, N., ... & Wellington, C. L. (2025). TRANSCENDENT (Transforming Research by Assessing Neuroinformatics across the Spectrum of Concussion by Embedding iNterdisciplinary Data-collection to Enable Novel Treatments): protocol for a prospective observational cohort study of concussion patients with embedded comparative effectiveness research within a network of learning health system concussion clinics in Canada. BMJ Open, 15(4), e095292.
In April 2025, the research team, led by Dr. Roger Zemek, published the TRANSCENDENT protocol:
Abstract: Concussion affects over 400 000 Canadians annually, with a range of causes and impacts on health-related quality of life. Research to date has disproportionately focused on athletes, military personnel and level I trauma centre patients, and may not be applicable to the broader community. The TRANSCENDENT Concussion Research Program aims to address patient- and clinician-identified research priorities, through the integration of clinical data from patients of all ages and injury mechanisms, patient-reported outcomes and objective biomarkers across factors of intersectionality. Seeking guidance from our Community Advisory Committee will ensure meaningful patient partnership and research findings that are relevant to the wider concussion community. This prospective observational cohort study will recruit 5500 participants over 5 years from three 360 Concussion Care clinic locations across Ontario, Canada, with a subset of participants enrolling in specific objective assessments including testing of autonomic function, exercise tolerance, vision, advanced neuroimaging and fluid biomarkers. Analysis will be predicated on pre-specified research questions, and data shared with the Ontario Brain Institute’s Brain-CODE database. This work will represent one of the largest concussion databases to date, and by sharing it, we will advance the field of concussion and prevent siloing within brain health research.