Predictors of response to botulinum toxin treatment in patients with primary hemifacial spasm: A prospective cohort study.

[INTRODUCTION] Hemifacial spasm (HFS) is a disabling movement disorder characterized by involuntary, unilateral facial muscle contractions. Botulinum toxin (BTX) is the standard non-surgical treatment, but response variability exists, and predictors of outcomes remain underexplored, especially in the Asian subcontinent. This study aimed to identify clinical and neuroimaging predictors of BTX response in primary HFS.

[METHODS] A prospective cohort study at a tertiary care centre in North India enrolled 90 BTX-naïve primary HFS patients from September 2022 to June 2024. Clinical assessments included the Hemifacial Spasm Grading Scale (HSGS), HFS-7 Quality of Life scale (HFS-7), and the Depression, Anxiety, and Stress Scale (DASS-21). THE FIESTA MRI evaluated neurovascular compression (NVC) at the facial nerve root exit zone. Outcomes were classified as good (JFG ≥3) or poor responders (JFG<3). Univariate analysis and logistic regression identified predictors of response.

[RESULTS] The mean age was 51.5 ± 11.2 years; 67.8% were female. At 3 months, 76.7% had good outcomes, increasing to 85.6% after dose titration at the second visit. Poor response (14.4%) was significantly associated with hypertension (OR, 17.55; p = 0.009) and NVC (OR, 9.37; p = 0.044). These patients also exhibited worse depression, anxiety, stress scores, poorer quality of life, and required higher BTX doses.

[CONCLUSION] HFS responds well to BTX, but hypertension and NVC are independent predictors of poor response. Patients show higher psychiatric burden and lower quality of life. Early dose escalation may improve outcomes. The prospective study guides personalized HFS management by integrating clinical, radiological, and comorbid psychiatric predictors.