Development of a Clinical Rating Scale for the Severity of Apraxia of Eyelid Opening, Either Isolated or Associated with Blepharospasm

Background: Apraxia of eyelid opening is a movement disorder characterized by an inability to raise the eyelids without any overt contractions of the orbicularis oculi muscle. There is currently no clinical scale to rate the severity of this condition. Objectives: To develop and validate a novel scale that considers phenomenological aspects relevant to the severity of the condition. Methods: The study sample included 20 patients with apraxia of eyelid opening, either isolated (9 patients) or associated with blepharospasm (11 patients). To validate the scale, selected features were checked for reliability, reliable items were combined to generate the scale, and clinimetric properties were evaluated. Results: The novel severity scale yielded acceptable reliability, scaling assumptions, internal consistency, and sensitivity to change; a lack of floor and ceiling effects; and no correlation with the blepharospasm severity rating scale. Conclusions: We propose a severity scale that considers the most relevant apraxia of eyelid opening motor abnormalities based on objective criteria. This scale can be reliably administered by general neurologists after a brief training.