Creation and Validation of the Facial Diplegia Scale for Assessment of Bilateral Facial Palsy

<b>Objectives</b>: House-Brackmann (HB) classification and the Sunnybrook Facial Grading System (SFGS), both reference tools for the assessment of facial palsy, are not suitable for bilateral facial palsy. The aim of this study was to develop, standardize, and validate the Facial Diplegia Scale (FDS). <b>Methods</b>: The FDS was standardized in a healthy population (<i>n</i> = 111) and validated in 40 patients with diplegia. Correlations with the SFGS were sought to prove its criterion validity. The comparison between healthy subjects and patients with diplegia was used to test the construct validity. The diagnostic performance of the FDS was verified using an ROC curve based on the HB classification. Internal and external consistency were investigated. <b>Results</b>: The FDS and the SFGS were significantly correlated for the right hemiface [F(39) = 51.51, <i>p</i> < 0.0001, <i>R</i>² = 0.575] as well as for the left one [F(39) = 95.10, <i>p</i> < 0.0001, <i>R</i>² = 0.714]. A significant difference between control subjects and patients with diplegia was found [<i>t</i>(149) = -9.95, <i>p</i> < 0.0001]. Good specificity and sensitivity were confirmed. Finally, internal consistency, inter-rater reliability, and test-retest reliability were largely proven. <b>Conclusions</b>: The FDS has been standardized and validated for the subjective assessment of facial diplegia in adults to improve comprehensive assessment.