Diagnosis and classification of blepharospasm: Recommendations based on empirical evidence

Background: Blepharospasm is one of the most common subtypes of dystonia, and often spreads to other body regions. Despite published guidelines, the approach to diagnosis and classification of affected body regions varies among clinicians. Objective: To delineate the clinical features used by movement disorder specialists in the diagnosis and classification of blepharospasm according to body regions affected, and to develop recommendations for a more consistent approach. Methods: Cross-sectional data for subjects diagnosed with all types of isolated dystonia were acquired from the Dystonia Coalition, an international, multicenter collaborative research network. Data were evaluated to determine how examinations recorded by movement disorder specialists were used to classify blepharospasm as focal, segmental, or multifocal. Results: Among all 3222 participants with isolated dystonia, 210 (6.5%) had a diagnosis of focal blepharospasm. Among these 210 participants, 34 (16.2%) had dystonia outside of upper face region. Factors such as dystonia severity across different body regions and number of body regions affected influenced the classification of blepharospasm as focal, segmental, or multifocal. Conclusions: Although focal blepharospasm is the second most common type of dystonia, a high percentage of individuals given this diagnosis had dystonia outside of the eye/upper face region. These findings are not consistent with existing guidelines for the diagnosis and classification of focal blepharospasm, and point to the need for more specific guidelines for more consistent application of existing recommendations for diagnosis and classification.