Hypoalgesia in the Referred Pain Areas After Bilateral Injections of Hypertonic Saline Into the Trapezius Muscles of Men and Women: A Potential Experimental Model of Gender-Specific Differences
Bibliographic record
Abstract
OBJECTIVE: The study was to assess the local pain intensity, referred pain patterns, and changes in the pressure pain thresholds of the local and referred pain areas following bilateral injections of hypertonic saline into trapezius muscles and to delineate gender differences in pain profile and the possible modulation of pressure pain thresholds. METHODS: Fifteen healthy men and women each participated. Pain intensity and areas were assessed after bilateral injections. The pressure pain thresholds in the trapezius and posterolateral neck muscles (referred pain areas) were measured before and 7.5 and 15 minutes postinjection. RESULTS: The time to maximal pain intensity was significantly shorter after the second injection than after the first injection. Patients exhibited a bilaterally symmetrical distribution of pain areas that included the neck to shoulder angle and the posterolateral neck. Bilateral injections significantly elevated pressure pain thresholds in the right and left posterolateral neck muscles 7.5 and 15 minutes postinjection. In men but not women, the pressure pain thresholds measured in the posterolateral neck muscles 7.5 and 15 minutes after the second injection were higher than those after the first injection and also higher than those after the second injection in women, men tolerated more pressure than women at all time points. DISCUSSION: These findings indicate that both excitatory and inhibitory mechanisms modulate pain response characteristics in bilateral neck-shoulder pain conditions and suggest that there may be a more potent inhibitory control mechanism in men than women. This experimental model may be potentially used to detect gender differences in descending inhibition.
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How this classification was reachedexpand
Full frame distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.005 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.001 | 0.000 |
| Bibliometrics | 0.000 | 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) | 0.000 | 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 teacher head, 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".