Validation of the Hemifacial Spasm Grading Scale: a clinical tool for hemifacial spasm

Background: To create an objective rating tool for hemifacial spasm (HFS) and validate it on a cohort of patients. Methods: A panel of movement disorders specialists elaborated, through the Delphi method, the Hemifacial Spasm Grading Scale (HSGS). The validity of the scale was tested in a longitudinal, prospective observational study, with standardized video recording protocol before and after botulinum neurotoxin (BoNT) treatment. The video recordings obtained from each patient were then independently assessed with HSGS by three blinded raters. The scale was compared to patient-reported HFS-7 scale and to the clinical grading of spasm intensity scale. Results: Intra-rater reproducibility ranged between ICC 0.73 (95% CI = 0.54–0.86) and 0.83 (0.68–0.92) and inter-rater reproducibility between 0.62 (95% CI = 0.44–0.77) and 0.82 (0.69–0.90). HSGS scores correlated with clinical grading of spasm intensity scale scores, but not with HFS-7. HSGS confirmed BoNT efficacy, with scores lowering at 1 month from treatment. Conclusions: HSGS represents an objective, quick and reliable scale for the assessment of HFS, and might be useful to monitor BoNT treatment efficacy over time.