Autonomic Dysregulation in Adolescent Concussion: Characterization and Temporal Resolution of Neurological Outcomes
Bibliographic record
Abstract
Although incidence is at epidemic levels, objective indicators of neurologic damage in adolescent concussion remain poorly described. Autonomic markers such as heart rate variability (HRV) have provided equivocal results; however, these predominantly are made under conditions of minimal physiologic stress. The current investigation employs postural stressors to examine underlying neurological outcomes associated with acute concussion and clinical recovery to test the hypothesis that concussion impairs dynamic autonomic adjustments in adolescents. We examined concussed adolescents (CONC; n = 35; 14 males; age 15 ± 1 yrs, range = 12–18 yrs) for up to 6 weekly visits from diagnosis. A group of age and activity level‐matched non‐concussed adolescents (CTRL; n = 35; 19 males; age 14 ± 2 yrs, range = 12–18 yrs) formed the reference control. HRV (root mean square of successive differences in R‐R intervals (RMSSD)) and heart rate were assessed during a sit‐to‐stand protocol (two trials of seated posture (three minutes), followed by two minutes of standing). Measurements were taken during the last minute of sitting and standing, the ten second period following the postural stress of standing, as well as the ten second period from maximum HR. While seated, RMSSD was lower in CONC (41 ± 24 msec) compared with CTRL (60 ± 40 msec; p < 0.05). 31 patients provided weekly data until clinical discharge. Compared with the first visit (43 ± 25 msec), seated RMSSD in CONC increased (51 ± 36 msec; p = 0.05) at the time of clinical discharge. Upon standing (10 seconds following postural change to standing), RMSSD was lower in CONC versus CTRL (13 ± 7 vs. 18 ± 12 msec; p < 0.05). Compared with the first visit, RMSSD following the induced postural stress did not improve in CONC over the six week recovery period. Following maximal HR, CTRL had increased RMSSD versus CONC (46 ± 30 vs. 34 ± 19 msec; p < 0.05). Compared with CTRL, seated HR was higher in CONC. This tachycardia effect persisted throughout the sit‐to‐stand protocol (78 ± 12 vs. 72 ± 12 bpm; p < 0.05) and was maintained until the time of clinical discharge (79 ± 13 vs. 72 ± 12 bpm; p < 0.05). In adolescent concussion, autonomic cardiac impairment is demonstrated by reduced RMSSD in the seated position and throughout the adjustment period in response to postural stress. Further, seated HR is increased following acute concussion and remains elevated by the time of clinical discharge. Seated HRV, but not HR, recovered to levels seen in the control population within three to six weeks. Thus, cardiac adjustments to modest postural stress may represent a measurable neurological impairment in adolescent acute concussion which can be objectively monitored throughout clinical recovery. Support or Funding Information Research supported by the Children's Health Research Institute (London, Canada).
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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 | 0.000 | 0.001 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.001 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| 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".