title: Facial thirds-based evaluation of facial asymmetry using stereophotogrammetric devices: Application to facial palsy subjects.
abstract: Many conditions can compromise facial symmetry, resulting in an impairment of the affected person from both esthetic and functional points of view. For these reasons, a detailed, focused, and objective evaluation of facial asymmetry is needed, both for surgical planning and for treatment evaluation. In this study, we present a new quantitative method to assess symmetry in different facial thirds, objectively defined on the territories of distribution of trigeminal branches. A total of 70 subjects (40 healthy controls and 30 patients with unilateral facial palsy) participated. A stereophotogrammetric system and the level of asymmetry of the subjects' hemi-facial thirds was evaluated, comparing the root mean square of the distances (RMSD) between their original and mirrored facial surfaces. Results show a high average reproducibility of area selection (98.8%) and significant differences in RMSD values between controls and patients (p = 0.000) for all of the facial thirds. No significant differences were found on different thirds among controls (p > 0.05), whereas significant differences were found for the upper, middle, and lower thirds of patients (p = 0.000). The presented method provides an accurate, reproducible, and local facial symmetry analysis that can be used for different conditions, especially when only part of the face is asymmetric.
authors.affiliation: Department of Biomedical Sciences for Health (Director: Prof. Francesco Auxilia), Facoltà di Medicina e Chirurgia, Università degli Studi di Milano, Milano, Italy.
authors.forename: Marina
authors.initials: M
authors.lastname: Codari
authors.affiliation: Department of Biomedical Sciences for Health (Director: Prof. Francesco Auxilia), Facoltà di Medicina e Chirurgia, Università degli Studi di Milano, Milano, Italy.
authors.forename: Valentina
authors.initials: V
authors.lastname: Pucciarelli
authors.affiliation: Department of Biomedical Sciences for Health (Director: Prof. Francesco Auxilia), Facoltà di Medicina e Chirurgia, Università degli Studi di Milano, Milano, Italy.
authors.forename: Fabiano
authors.initials: F
authors.lastname: Stangoni
authors.affiliation: Department of Biomedical Sciences for Health (Director: Prof. Francesco Auxilia), Facoltà di Medicina e Chirurgia, Università degli Studi di Milano, Milano, Italy.
authors.forename: Matteo
authors.initials: M
authors.lastname: Zago
authors.affiliation: Maxillo-Facial Surgery Unit, San Paolo University Hospital, San Paolo Hospital, Department of Health Sciences (Director: Prof. Silvio Scarone), Facoltà di Medicina e Chirurgia, Università degli Studi di Milano, Milano, Italy.
authors.forename: Filippo
authors.initials: F
authors.lastname: Tarabbia
authors.affiliation: Maxillo-Facial Surgery Unit, San Paolo University Hospital, San Paolo Hospital, Department of Health Sciences (Director: Prof. Silvio Scarone), Facoltà di Medicina e Chirurgia, Università degli Studi di Milano, Milano, Italy.
authors.forename: Federico
authors.initials: F
authors.lastname: Biglioli
authors.affiliation: Department of Biomedical Sciences for Health (Director: Prof. Francesco Auxilia), Facoltà di Medicina e Chirurgia, Università degli Studi di Milano, Milano, Italy. Electronic address: chiarella.sforza@unimi.it.
authors.forename: Chiarella
authors.initials: C
authors.lastname: Sforza
mesh_terms: D000328:Adult; D016022:Case-Control Studies; D005145:Face / Q000000981:diagnostic imaging / Q000473:pathology; D005146:Facial Asymmetry / Q000175:diagnosis* / Q000000981:diagnostic imaging / Q000473:pathology; D005158:Facial Paralysis / Q000175:diagnosis* / Q000000981:diagnostic imaging / Q000473:pathology; D005260:Female; D006801:Humans; D008297:Male; D010780:Photogrammetry / Q000295:instrumentation / Q000379:methods*
keywords: Facial asymmetry; Facial paralysis; Photogrammetry