Radiologic Measurement of Submandibular Gland Ptosis
24 July 2013 (online)
Objective Ptosis of the submandibular glands is a well-recognized yet poorly quantified element of the aging face and neck. The goal of this study is to describe and quantify the rate and extent of age-related submandibular gland ptosis. A novel grading system is proposed to quantify the degree of descent of the submandibular gland in relation to the inferior border of the mandible. Implications for facial rejuvenation surgery are discussed.
Study Design Retrospective review.
Methods Consecutive computed tomography (CT) imaging studies performed at a university-affiliated hospital were selected for review. Using cross-referenced images in the coronal and axial planes, distance measurements were obtained from the bottom of the submandibular gland to the plane of the inferior border of the mandible. These data points were plotted against subject age for statistical analysis. The position of the submandibular gland was then categorized as grade I when distance below the mandible was < 20 mm, grade II for 20 to 25 mm, grade III for 25 to 30 mm, and grade IV for > 30 mm. Volumetric analysis was performed in a subset of subjects to assess for the possibility of age-related submandibular gland volume changes as a potential confounding factor in distance measurements.
Results One hundred consecutive CT imaging studies were selected for review (50 men, 50 women). A statistically significant linear relationship was identified between subject age and ptosis of the submandibular gland (r = 0.52, p < 0.001), as measured by the distance from the bottom of the submandibular gland from the plane of the inferior border of the mandible. The average rate of descent was 0.17 mm per year. Overall, the position of the submandibular gland was categorized as grade I in 18% of patients, grade II in 27% of patients, grade III in 32% of patients, and grade IV in 23% of patients. No statistically significant gender differences were identified in any of the data points. Volumetric analysis did not demonstrate any age-related changes in submandibular gland volume, and as such, this was excluded as a potential confounding factor in distance measurements.
Conclusion A linear relationship exists between patient age and submandibular gland ptosis, as measured by the distance of the gland from the inferior border of the mandible. To our knowledge, this is the first quantification of the rate and extent of submandibular gland ptosis. A novel grading system for submandibular gland ptosis has been proposed.