Eyelid apraxia is an inability to open the eyelids at will, although they may open spontaneously at other times (i.e., voluntary-automatic dissociation). Eyelids may be opened manually or by a backward head thrust.
The term has been criticized on the grounds that this may not always be a true "apraxia", in which case the term "levator inhibition" may be preferred since the open eyelid position is normally maintained by tonic activity of the levator palpebrae superioris. Clinically there is no visible contraction of orbicularis oculi, which distinguishes eyelid apraxia from blepharospasm (however, perhaps paradoxically, the majority of cases of eyelid apraxia occur in association with blepharospasm). Electrophysiological studies do in fact show abnormal muscle contraction in the pre-tarsal portion of orbicularis oculi, which has prompted the suggestion that "focal eyelid dystonia" may be a more appropriate term.
Although the phenomenon may occur in isolation, associations have been reported with:
- Progressive supranuclear palsy (Steele-Richardson-Olszewski syndrome)
- Parkinson’s disease
- Huntington’s disease
- Multiple system atrophy
- MPTP intoxication
- Motor neurone disease
- Acute phase of nondominant hemisphere cerebrovascular event
- Wilson’s disease
The precise neuroanatomical substrate is unknown but the association with basal ganglia disorders points to involvement of this region. The underlying mechanisms may be heterogeneous, including involuntary inhibition of levator palpebrae superioris.
Boghen D. Apraxia of eyelid opening: a review. Neurology 1997; 48: 1491-1494