Pain effects of glutamate injections into human jaw or neck muscles.
Bibliographic record
Abstract
AIMS: To document and compare the intensity, localization, and quality of pain evoked by glutamate injections into the human masseter or splenius muscles and to determine the effect of glutamate-evoked pain on the pressure pain thresholds (PPTs) in both jaw and neck muscles. METHODS: Twenty-six healthy men were given painful injections of glutamate (1.0 mol/L) and control injections of isotonic saline (0.165 mol/L) into the masseter and splenius muscles. The subjects rated the perceived intensity of pain on a visual analog scale (VAS), drew the area of the pain on maps of the face and neck, and filled out a Danish version of the McGill Pain Questionnaire (MPQ). PPTs were used to assess the sensitivity of the masseter and splenius muscles to mechanical stimuli (n = 11). RESULTS: Glutamate injection into the masseter or splenius evoked pain lasting almost 10 minutes. Peak pain intensity usually occurred within 2 minutes of the injection, and VAS scores of peak pain were significantly higher for the masseter muscle compared with the splenius muscle (paired t test, P = .003). The pain area from the masseter injections did not extend into the neck region, although in some subjects the pain from the neck region extended into the temporal region. There were no significant relationships between the area of perceived pain and the VAS pain scores (Pearson correlation, P > .297). Glutamate-evoked pain in either the masseter or splenius muscles was associated with significant decreases in masseter or splenius PPTs, respectively (2-wayANOVAs, P < .016). Isometric saline injections were almost pain-free and caused no PPT changes. CONCLUSION: The data suggest that the masseter muscle is more sensitive to glutamate injections and mechanical stimuli than the splenius muscle. The relatively limited overlap between the sensory manifestations of pain from masseter and splenius muscles may have potential implications for diagnosis and management of myofascial pain complaints in the craniofacial and neck region.
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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 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 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) | 0.002 | 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".