Quantitative analysis of facial palsy using a three dimensional facial motion measurement system.
OBJECTIVE The prognosis for facial nerve palsy (FNP) depends on its severity. Currently, many clinicians use the Yanagihara, House Brackmann, and/or Sunnybrook grading systems to assess FNP. Although these assessments are performed by experts, inter and intra observer disagreements have been demonstrated. The quantitative and objective analyses of the degree of FNP would be preferred to monitor functional changes and to plan and evaluate therapeutic interventions in patients with FNP. Numerous two dimensional (2 D) assessments have been proposed, however, the limitations of 2 D assessment have been reported. The purpose of this study was to introduce a three dimensional (3 D) image generation system for the analysis of facial nerve palsy (FNP) and to show the correlation between the severity of FNP assessed by this method and two conventional systems. METHODS Five independent facial motions, resting, eyebrow raise, gentle eye closure, full smile with lips open and whistling were recorded with our system and the images were then analyzed using our software. The regional and gross facial symmetries were analyzed. The predicted scores were calculated and compared to the Yanagihara and H B grading scores. We analyzed 15 normal volunteers and 42 patients with FNP. RESULTS The results showed that 3 D analysis could measure mouth movement in the anteroposterior direction, whereas two dimensional analysis could not. The system results showed good correlation with the clinical results from the Yanagihara (r(2)=0.86) and House Brackmann (r(2)=0.81) grading scales. CONCLUSION This objective method can produce consistent results that align with two conventional systems. Therefore, this method is ideally suited for use in a routine clinical setting.
Auris, nasus, larynx