Apraxia of eyelid opening and the variable motor phenomenology of blepharospasm.

Apraxia of eyelid opening (AEO) is characterized by a transient inability to initiate eyelid elevation following voluntary or involuntary closure, in the absence of visible contraction of the orbicularis oculi muscle. This condition is frequently associated with blepharospasm (BSP); however, the relationship between AEO and the variable motor presentations of BSP remains unknown. In this study, we analyzed 104 patients with isolated, idiopathic, adult-onset BSP for the presence of AEO, the type of orbicularis oculi muscle spasms, and other relevant demographic and clinical characteristics. Comparison of patients with and without AEO revealed significant associations between AEO and the presence, frequency, and duration of prolonged (>3 s) orbicularis oculi spasms leading to complete eyelid closure. This finding was specific, as no association was observed between AEO and brief (<3 s) orbicularis oculi spasms. Additionally, no other demographic or clinical parameters were significantly associated with AEO in BSP patients. We propose that AEO and BSP with prolonged spasms may share common pathophysiological mechanisms. This observation could have important therapeutic implications for the management of patients with AEO.