Investigating the correlation between the blepharospasm disability index and botulinum neurotoxin dosage for benign essential blepharospasm and hemifacial spasm.

Purpose: The purpose of this study is to evaluate the association between the blepharospasm disability index (BSDI) and botulinum neurotoxin (BTX) dosage for patients affected by either benign essential blepharospasm or hemifacial spasm.

Methods: Cross-sectional cohort study evaluating adult patients diagnosed with benign essential blepharospasm or hemifacial spasm who completed a BSDI evaluation prior to receiving same-day therapeutic BTX injections. Primary outcome measures included BSDI score and number of BTX units. Simple and multivariable linear regression analyses were utilized to assess the relationship between BSDI score and BTX dosage.

Results: For patients with benign essential blepharospasm, BTX dosage was significantly and positively correlated to BSDI score (R²=0.16, β=1.15, p=0.007). This relationship remained robust when controlling for age, sex, disease duration, interval since previous BTX injection, and injecting provider (β=1.11, p=0.010). No significant correlation was identified between BSDI score and BTX dosage for patients affected by hemifacial spasm (R²=0.05, β=0.39, p=0.379).

Conclusions: This study demonstrates that BTX dosage is significantly and positively correlated to BSDI score for patients affected by benign essential blepharospasm, but not for those affected by hemifacial spasm. Incorporating BSDI score may support more individualized and efficient clinical management of benign essential blepharospasm.