Proposal of a video-recording system for the assessment of Bell's Palsy. methodology and preliminary results

Hypothesis: To propose a new objective video-recording procedure to assess and monitor over time the severity of facial nerve palsy. Background: No objective methods for facial palsy (FP) assessment are universally accepted. Methods: The face of subjects presenting with different degrees of facial nerve deficit, as measured by the House-Brackmann (HB) grading system, was videotaped after positioning, at specific points, 10 gray circular markers made of a retroreflective material. Video-recording included the resting position and six ordered facial movements. Editing and data elaboration was performed using a software instructed to assess marker distances. From the differences of the marker distances between the two sides was then extracted a score. Results: The higher the FP degree, the higher the score registered during each movement. The statistical significance differed during the various movements between the different FP degrees, being uniform when closing the eyes gently; whereas when wrinkling the nose, there was no difference between the HB grade III and IV groups and, when smiling, no difference was evidenced between the HB grade IV and V groups. The global range index, which represents the overall degree of FP, was between 6.2 and 7.9 in the normal subjects (HB grade I); between 10.6 and 18.91 in HB grade II; between 22.19 and 33.06 in HB grade III; between 38.61 and 49.75 in HB grade IV; and between 50.97 and 66.88 in HB grade V. Conclusion: The proposed objective methodology could provide numerical data that correspond to the different degrees of FP, as assessed by the subjective HB grading system. These data can in addition be used singularly to score selected areas of the paralyzed face when recovery occurs with a different timing in the different face regions.