"The nasolabial fold: A micro-computed tomography study."

Abstract

BACKGROUND The nasolabial fold (NLF) is known to be a challenging midface feature for aesthetic physicians. However, the steric conformation of the structures related to the NLF has remained undefined since the composition and topography of this region is highly intricate. Therefore, this study aimed to clarify the three-dimensional structures of the NLF using micro-computed tomography and verify their detailed composition via histological observation. METHODS Twenty-four specimens were collected from the area beside the alar nasi to the area above the oral angle of 12 cadavers (mean age, 80.3 years) bilaterally. Twelve specimens were evaluated via phosphotungstic acid contrast staining, and the rest were evaluated via histological staining. All specimens were divided into three regions and comprehensively analyzed. RESULTS The medial region of the NLF had dense irregular connective tissue intermingled with muscle fibers; the lateral region of NLF had numerous fibrous septa with abundant adipose tissue. The levator labii alaeque nasi and the zygomaticus minor were attached to the medial part of the NLF, and the fascial septa were intermittently tethered to the dermis, lateral to the NLF. The extension of the adipose tissue within the fascial septa was limited by the lateral border of the muscle attachment. CONCLUSIONS Dimensional and distributional alterations of the adipose tissues with senescence could render the NLF deeper by increasing the depth of the subcutaneous layer, lateral to the fold. Hence, to ameliorate the fold, the adipose tissue, lateral to the fold, or the muscle traction, medial to the fold, should be altered.