Efficacy of botulinum toxin treatment in older adults with hemifacial spasm: A retrospective pilot study using the Hemifacial Spasm Severity Score

Background: Hemifacial spasm (HFS) is a chronic and disabling movement disorder commonly affecting older adults. Although botulinum toxin (BoNT) is an established treatment, standardized and multidimensional assessments of severity remain limited. Aim: This study evaluates the therapeutic efficacy of the HFS Severity Score (HFSS), a newly developed scale incorporating five symptom domains, and compares its responsiveness with that of the Jankovic Rating Scale (JRS). Methods: This retrospective study included 18 patients aged 65 years or older who were treated with 10 units of BoNT. HFSS and JRS were assessed at baseline and 4 weeks post-injection by two blinded neurosurgeons. Inter-rater reliability (intraclass correlation coefficient [ICC]) and internal consistency (Cronbach’s α) were calculated. Pre–post differences were evaluated using the Wilcoxon signed-rank test. Convergent validity was examined using Spearman correlation between baseline HFSS and JRS. Responsiveness was assessed using change–score correlations and standardized response means (SRMs). Scatter plots were generated to visualize relationships between the scales. Results: Mean HFSS improved significantly from 9.39 to 3.72 (p