Multimodal Analyses of the Aging Forehead and Their Clinical Implications.

ABSTRACT

BACKGROUND: Recent research has indicated that in the upper face a delicate arrangement exists between the muscles of facial expression and the skin. This arrangement allows for immediate transmission of movements following muscle contraction, resulting in skin movements and skin rhytid formation. OBJECTIVES: To investigate age-related changes of the biomechanical unit formed by facial muscles, their connective tissue envelope, and the skin of the upper face. METHODS: A total of 76 Caucasian volunteers (30 males, 46 females) with a mean age of 42.2 years (SD 18.6) and a mean body mass index of 24.58 kg/m2 (SD 3.7) were investigated. Three upper facial regions were analyzed for skin firmness and elasticity with cutometric assessment, vertical and horizontal skin vector displacement using 3-dimensional imaging, and muscle activity with surface-derived electromyography. RESULTS: Study participants of older age (>42.2 years), when compared with younger participants (≤42.2 years), showed increased skin firmness, at 0.20 mm vs 0.30 mm (P < .001); decreased skin elasticity at 53.2% vs 69.0% (P < .001); increased vertical (not horizontal) skin mobility at 3.56 mm vs 1.35 mm (P < .001); and decreased surface-derived electromyography (sEMG) signal of the frontalis muscle with 174 µV vs 309 µV (P = .039). CONCLUSIONS: This study reveals that age-related changes occur in each component of the biomechanical unit formed by facial muscles, connective tissue envelope, and skin in the upper face. Knowledge and understanding of such changes can allow for more targeted and individualized surgical and nonsurgical aesthetic treatments.