A Prospective Transcranial Doppler Ultrasound-Based Evaluation of the Acute and Cumulative Effects of Sport-Related Concussion on Neurovascular Coupling Response Dynamics
Bibliographic record
Abstract
Sport-related concussion has been shown to alter cerebral blood flow (CBF) both acutely and chronically, and may exert cumulative effects across multiple injuries. Such dysfunction may be mediated by trauma-induced deficits to CBF control mechanisms, though our understanding of these effects is limited, including dynamics of neurovascular coupling (NVC) responses (i.e., CBF responses to neurologic demand). A total of 179 junior-level contact sport athletes completed preseason testing; 42 reported never having experienced a concussion (Hx−) while 31 had endured three or more (Hx3+). A total of 18 athletes suffered concussions during the study period and were re-tested 3 days, 2 weeks, and 1 month post-injury. NVC dynamics were indexed via CBF velocity in the posterior (PCAv) and middle (MCAv) cerebral arteries during cycles of 20 sec eyes closed and 40 sec eyes open to a visual stimulus (reading). Acutely following concussion, peak rate of PCAv increase during the activation phase was delayed by over 50% and PCAv response magnitude was elevated by over 30%, compared with preseason. Response magnitude remained elevated at 2 weeks despite symptom resolution. Independent medical clearance for full return-to-play was inversely related to the magnitude of increase in the NVC response at 3 days post-injury. No post-injury changes were observed in MCAv, blood pressure, or end-tidal carbon dioxide levels during visual stimulation. No NVC metric differences were observed between the Hx− and Hx3+ groups at preseason. Via multiple potential mechanisms, acute sport-related concussion may induce compensatory alterations in NVC response dynamics that may be related to clinical recovery. Such effects do not appear to be persistent across multiple injuries.
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.001 | 0.001 |
| Meta-epidemiology (narrow) | 0.001 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.001 | 0.000 |
| Science and technology studies | 0.001 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.001 | 0.001 |
| Insufficient payload (model declined to judge) | 0.001 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".