Background Botulinum neurotoxin (BoNT) is widely used for forehead rejuvenation, but risks complications like brow ptosis with conventional pan-frontalis injections. Recent study highlights the frontalis muscle’s bidirectional movement, demarcated by the line of convergence (C-line): The upper segment depresses the hairline and the lower segment elevates the brows. This study evaluates the efficacy and safety of a super-high BoNT injection technique, selectively targeting the upper frontalis above the C-line to reduce forehead lines while preserving brow position and mobility. Methods Forty-one East Asian participants (35–50 years) received BoNT injections (20 U/ml) at two midline points above the C-line (upper 1/5 of the forehead). Doses varied by gender (1.5–2 U/point). Three-dimensional stereophotogrammetry quantified brow position (BP), maximal brow height (MBH), and brow movement range (BMR) at baseline , 4 weeks, and 16 weeks. Forehead Wrinkle Scale (FWS) scores and patient-reported outcomes were analyzed. Results At T1, static FWS improved by 51% (1.00 ± 0.70 to 0.49 ± 0.50, p < 0.01) and dynamic FWS by 63% (2.51 ± 0.64 to 0.92 ± 0.64, p < 0.01), with 100% patient satisfaction. BP decreased marginally (left: 60.83 ± 3.21 mm to 60.44 ± 3.22 mm; right: 61.06 ± 2.95 mm to 60.69 ± 3.12 mm; p < 0.05), but BMR remained stable (p > 0.1), indicating preserved dynamic function. No brow ptosis or eyelid heaviness occurred. Static and dynamic FWS scores decreased by 51% (1.00 ± 0.70 to 0.49 ± 0.50, p < 0.01) and 63% (2.51 ± 0.64 to 0.92 ± 0.64, p < 0.01), respectively. Conclusion The super-high injection technique effectively reduces forehead wrinkles without disrupting brow dynamics, offering a safe alternative to pan-frontalis approaches. The absence of complications and preserved movement validated this anatomically guided approach as an alternative option for forehead rejuvenation. Level of Evidence IV This journal requires that authors assign a level of evidence to each article. For a full description of these Evidence-Based Medicine ratings, please refer to the Table of Contents or the online Instructions to Authors  <a href="http://www.springer.com/00266">www.springer.com/00266</a>.

Harnessing the Bidirectional Feature of the Frontalis Muscle: The Super-High Injection Technique

期刊论文
发表日期：

2025年9月22日

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Lehao Wu,
Hengyuan Ma,
Binghang Li,
Yihao Xu,
Jianjun You,
Tailing Wang

摘要

Background

Botulinum neurotoxin (BoNT) is widely used for forehead rejuvenation, but risks complications like brow ptosis with conventional pan-frontalis injections. Recent study highlights the frontalis muscle’s bidirectional movement, demarcated by the line of convergence (C-line): The upper segment depresses the hairline and the lower segment elevates the brows. This study evaluates the efficacy and safety of a super-high BoNT injection technique, selectively targeting the upper frontalis above the C-line to reduce forehead lines while preserving brow position and mobility.

Methods

Forty-one East Asian participants (35–50 years) received BoNT injections (20 U/ml) at two midline points above the C-line (upper 1/5 of the forehead). Doses varied by gender (1.5–2 U/point). Three-dimensional stereophotogrammetry quantified brow position (BP), maximal brow height (MBH), and brow movement range (BMR) at baseline , 4 weeks, and 16 weeks. Forehead Wrinkle Scale (FWS) scores and patient-reported outcomes were analyzed.

Results

At T1, static FWS improved by 51% (1.00 ± 0.70 to 0.49 ± 0.50, p < 0.01) and dynamic FWS by 63% (2.51 ± 0.64 to 0.92 ± 0.64, p < 0.01), with 100% patient satisfaction. BP decreased marginally (left: 60.83 ± 3.21 mm to 60.44 ± 3.22 mm; right: 61.06 ± 2.95 mm to 60.69 ± 3.12 mm; p < 0.05), but BMR remained stable (p > 0.1), indicating preserved dynamic function. No brow ptosis or eyelid heaviness occurred. Static and dynamic FWS scores decreased by 51% (1.00 ± 0.70 to 0.49 ± 0.50, p < 0.01) and 63% (2.51 ± 0.64 to 0.92 ± 0.64, p < 0.01), respectively.

Conclusion

The super-high injection technique effectively reduces forehead wrinkles without disrupting brow dynamics, offering a safe alternative to pan-frontalis approaches. The absence of complications and preserved movement validated this anatomically guided approach as an alternative option for forehead rejuvenation.

Level of Evidence IV

This journal requires that authors assign a level of evidence to each article. For a full description of these Evidence-Based Medicine ratings, please refer to the Table of Contents or the online Instructions to Authors www.springer.com/00266.