Teaching NeuroImages: awakening ptosis (unilateral hypnopompic eyelid palsy).

A healthy 68-year-old woman presented with 2 years of recurrent episodes of right ptosis, constantly present after waking from sleep (figure 1). Clinical examination, brain MRI, EMG, and polysomnography were unremarkable (figure 2). In particular, there was no cranial nerve impairment. Few cases of idiopathic ptosis on awakening have been described, and they have been attributed to eyelid opening apraxia. This disorder needs to be differentiated from myasthenia gravis and other neuromuscular disorders. We propose that the term apraxia is not suitable to describe this clinical phenomenon, which could result from an abnormal, transient persistence of focal sleep-related muscular atonia.