Automated and objective action coding of facial expressions in patients with acute facial palsy

Abstract

Aim of the present observational single center study was to objectively assess facial function in patients with idiopathic facial palsy with a new computer-based system that automatically recognizes action units (AUs) defined by the Facial Action Coding System (FACS). Still photographs using posed facial expressions of 28 healthy subjects and of 299 patients with acute facial palsy were automatically analyzed for bilateral AU expression profiles. All palsies were graded with the House-Brackmann (HB) grading system and with the Stennert Index (SI). Changes of the AU profiles during follow-up were analyzed for 77 patients. The initial HB grading of all patients was 3.3 ± 1.2. SI at rest was 1.86 ± 1.3 and during motion 3.79 ± 4.3. Healthy subjects showed a significant AU asymmetry score of 21 ± 11 % and there was no significant difference to patients (p = 0.128). At initial examination of patients, the number of activated AUs was significantly lower on the paralyzed side than on the healthy side (p < 0.0001). The final examination for patients took place 4 ± 6 months post baseline. The number of activated AUs and the ratio between affected and healthy side increased significantly between baseline and final examination (both p < 0.0001). The asymmetry score decreased between baseline and final examination (p < 0.0001). The number of activated AUs on the healthy side did not change significantly (p = 0.779). Radical rethinking in facial grading is worthwhile: automated FACS delivers fast and objective global and regional data on facial motor function for use in clinical routine and clinical trials.

Functional Outcome and Quality of Life After Hypoglossal-Facial Jump Nerve Suture

“…Kochhar et al revealed an objective reduction of facial asymmetry and improved lip excursions for smiling after hypoglossal-facial jump nerve suture. Recently, we have introduced an automated tool based on a machine learning approach for objective facial action coding and another tool for objective grading of patients with facial palsy (28,29). An important next task will be to apply these objective tools also for evaluation of the patients after hypoglossal-facial jump nerve suture.…”

Reliability of grading of facial palsy using a video tutorial with synchronous video recording

“…At minimum, and in particular for scientific purpose, photographic documentation or ideally videography should be prerequisite for objective assessment of facial function using automatic image analysis software . The small sample size limited the statistical power of the study.…”

Chirurgie bei Läsionen des Nervus facialis

“…Der Vorteil dieser Klassifikationssysteme liegt darin, dass diese schnell direkt am Patienten (ungenauer) oder anhand von standardisierten Bildserien erhoben werden können [7]. Neuerdings gibt es auch eine standardisierte Videoinstruktion als Tutorial, welches eine standardisierte Videoaufzeichnung der Fazialisfunktion erlaubt.…”