Postoperative Forehead Elongation Linked to Frontalis Relaxation Not Tissue Migration

Frontalis Dynamics and the Aesthetics of the Upper Face

Endoscopic brow lift remains a primary surgical intervention for correcting brow ptosis, achieving pooled long-term elevation of 3.25 mm medially and 4.35 mm laterally [1]. While the procedure is favored for its minimally invasive nature, longitudinal data show a discrepancy in outcomes, with 70% of patients reporting satisfaction compared to only 50% of surgeons regarding long-term results [2]. These aesthetic shifts are complicated by the preoperative hyper-contraction of the frontalis muscle, a compensatory mechanism where the forehead muscle overworks to lift sagging tissues [3]. Despite the use of various fixation methods, such as bone tunnels which demonstrate a lower complication profile than screw-based systems, objective quantification of postoperative rejuvenation has remained difficult [4]. Recent analysis using convolutional neural networks (a type of artificial intelligence that identifies patterns in visual data to estimate age) indicates that brow lifts independently reduce perceived age by an average of 1.432 years (p =.031) [5].

AI-Assisted Morphometric Analysis of the Upper Face

The researchers evaluated a cohort of 35 patients who underwent endoscopic brow lift surgery to determine if the procedure causes actual tissue migration or merely a change in muscle tone. This study is classified as Therapeutic, Level IV evidence, providing a clinical assessment of surgical outcomes through retrospective analysis. To ensure objective quantification of facial changes, the investigators utilized an artificial intelligence technique for precise measurement to assess whether the forehead is enlarged post-procedure. Specifically, they employed the SPIGA model, which is an artificial intelligence framework for facial landmark detection (a system that automatically identifies specific anatomical points on the face to allow for a standardized and reproducible assessment of the upper third of the face that minimizes human error in manual marking). The measurement protocol was designed to isolate the influence of the frontalis muscle, which is the primary muscle responsible for lifting the eyebrows and wrinkling the forehead. To achieve this, the researchers recorded preoperative and postoperative measurements of forehead height and brow position in two distinct conditions: the open-eye state and the closed-eye state. By comparing these states, the study aimed to differentiate between the physical displacement of the hairline and the functional relaxation of the frontalis muscle. In the open-eye state, patients often exhibit compensatory muscle contraction to counteract brow ptosis, whereas the closed-eye model effectively eliminates frontalis muscle contraction. This dual-state analysis allowed the team to assess whether the forehead is truly enlarged post-procedure or if the perceived elongation is a byproduct of altered muscle dynamics.

Distinguishing Functional Relaxation from Structural Elongation

As endoscopic brow lift surgery is increasingly performed in clinical practice, concerns have persisted regarding a potential increase in forehead height and the posterior migration of the hairline position following the procedure. To address these concerns, the researchers investigated perceived changes in forehead dimensions using a closed-eye model, which effectively eliminates frontalis muscle contraction (the primary muscle responsible for elevating the brow and wrinkling the forehead). The analysis of 35 patients revealed that significant increases in forehead height were observed postoperatively in the open-eye state (P < 0.001). However, when the same patients were measured in the closed-eye state, no significant changes in forehead height were observed (P > 0.05). These data indicate that the forehead itself does not physically elongate postoperatively, suggesting that the perceived change is not a result of structural tissue migration. The researchers hypothesized that frontalis muscle contraction is a primary factor in determining perceived forehead height. In the preoperative state, patients often exhibit chronic contraction of the frontalis muscle to compensate for brow ptosis (drooping of the upper eyelid or brow), which effectively bunches the skin and reduces the vertical distance between the brow and the hairline. The study findings suggest that endoscopic brow lift surgery does not inherently cause a structural increase in forehead size. Instead, the perceived increase in forehead size is attributed to the comparison of these contracted preoperative states with relaxed postoperative states. Because the surgery successfully addresses the underlying ptosis, the compensatory need for frontalis activity is removed. Consequently, the perception of forehead elongation is likely due to the relaxation of the frontalis muscle after surgery rather than a physical shift in the hairline.

References

1. Şibar S, Dikmen AU, Erdal AI. Long-term Stability in Endoscopic Brow Lift: A Systematic Review and Meta-Analysis of the Literature. Aesthetic Surgery Journal. 2024. doi:10.1093/asj/sjae225

2. Chiu ES, Baker DC. Endoscopic Brow Lift: A Retrospective Review of 628 Consecutive Cases over 5 Years. Plastic & Reconstructive Surgery. 2003. doi:10.1097/01.prs.0000071042.11435.2e

3. Lei BVD, Fechner MF. Does the Eyebrow Sag with Aging? An Anthropometric Study of 95 Caucasians from 20 to 79 Years of Age. Plastic & Reconstructive Surgery. 2016. doi:10.1097/prs.0000000000002577

4. Caceres H, Raza SN, Katta T, et al. Fixation Techniques Across Endoscopic Brow Lifts: A Scoping Review.. Aesthetic plastic surgery. 2025. doi:10.1007/s00266-025-05114-1

5. Kreh C, Roider L, Firouzbakht PK, et al. Artificial Intelligence Analysis of Periorbital Rejuvenation. Aesthetic Surgery Journal. 2024. doi:10.1093/asj/sjae201