Quantifying Pediatric Facial Palsy:: Using Digital Image Correlation to Objectively Characterize Pediatric Facial Symmetry

Objective: This study introduces digital image correlation (DIC) as a novel technology to objectively quantify pediatric facial symmetry. Design: Descriptive cohort study of patients' facial symmetry as measured by DIC. Setting: Academic tertiary care hospital. Patients: 9 of 12 identified facial palsy and 13 of 26 identified control subjects participated. Interventions: DIC was used to quantify facial strain and symmetry as patients made the 5 standard Sunnybrook facial expressions. Each subject was evaluated according to the Sunnybrook scale by 4 evaluators, 3 plastic surgeons, and 1 occupational therapist. Main Outcome Measure: The percentage asymmetry values were calculated and compared between the facial palsy and control groups using both DIC and Sunnybrook. Results: Using DIC, facial palsy subjects had 32.99% asymmetry compared with 14.84% in controls (P < .01). Using Sunnybrook, facial palsy subjects had 24.11% asymmetry compared to 3.87% in controls (P < .01). The 2 metrics were positively correlated (P < .01). There was significant variability among the Sunnybrook evaluators (P = .02). Conclusions: DIC is a novel technique of objectively quantifying facial motion of the animated face. As surgical and medical approaches toward facial palsy expand, it is essential to have a means to compare results and improve patient outcomes.