"Apraxia" of eyelid opening: an involuntary levator inhibition.

Apraxia of lid opening was described by Goldstein and Cogan as "a non paralytic motor abnormality characterized by the patient's difficulty in initiating the act of lid elevation." We studied six such patients with this finding accompanied by vigorous frontalis contraction and no evidence of ongoing orbicularis oculi contraction, dysfunction of the oculomotor nerve, or loss of ocular sympathetic innervation. Four patients had Parkinson's disease or atypical parkinsonism, one had progressive supranuclear palsy, and one had Shy-Drager syndrome. At onset of ocular symptoms, mean age was 64 years, and the mean duration of extrapyramidal symptoms was 9.7 years. By definition, the motor system must be intact in any apraxia. Therefore, this disorder of lid opening in patients with extrapyramidal motor dysfunction is not an apraxia, but rather involuntary levator palpebrae inhibition of supranuclear origin.