Eyebrow Height after Botulinum Toxin Type A to the Glabella
Bibliographic record
Abstract
INTRODUCTION: Botulinum toxin type A (BTX-A) has demonstrated impressive safety and efficacy for the treatment of dynamic facial rhytides, particularly in the upper face. Numerous reports have cited an associated brow lift with BTX-A injections in the glabellar complex, presumably caused by deactivation of the brow depressor muscles. Few analyses examining this phenomenon more closely exist, however. OBJECTIVE: The objective was to examine objective changes in eyebrow and eyelid height following BTX-A treatment for glabellar rhytides. METHODS: A retrospective analysis of subjects' photographs taken during a single-center, dose-ranging, parallel-group, double-blind, randomized trial with 1-year follow-up in which women with moderate-to-severe wrinkles at maximum frown received a total of 10, 20, 30, or 40 U BTX-A in seven sites in the glabella alone. Photographs of the eyes and forehead region were taken in repose at baseline and every 2 weeks after treatment for up to 20 weeks. Eyebrow height was measured at midpupillary line ("a"), outer edge ("b"), and medial canthus ("c"). Changes in eyebrow height between baseline and after treatment were recorded for each subject. Brow lift was considered successful if measurements "a" and "b" increased after treatment. RESULTS: A total of 79 women were assessed. Central injections of 20 to 40 U BTX-A into the glabella alone (with the most lateral injection at the midpupillary line) led to an immediate lateral eyebrow elevation, followed by a central and medial eyebrow elevation that peaked at 12 weeks after treatment. The lowest dose of BTX-A (10 U) produced an initial mild brow ptosis and the weakest response. CONCLUSION: Doses of 20 to 40 U BTX-A produced dramatic changes in eyebrow position that may be due to diffusion of BTX-A into and partial inactivation of the medial fibers of the frontalis, with resulting increased muscle tone in the lateral and superior muscle fibers of the frontalis.
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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) | 0.000 | 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".