The syndrome of 'pure akinesia' and its relationship to progressive supranuclear palsy.

Five patients developed a stereotyped syndrome of progressive akinesia of gait, speech, and hand-writing without rigidity, tremor, or dementia. The symptoms did not improve with levodopa. These clinical findings conform to a syndrome described repeatedly in Japan since 1974 as "pure akinesia." Evidence has indicated that pure akinesia often represents a pre-ocular motor, and in some cases an ocular motor-sparing, form of progressive supranuclear palsy (PSP). Although we found disorders of eyelid movements, none of the patients demonstrated a gaze palsy on clinical examination. Four patients underwent eye movement recordings. The two patients with the longest disease duration had slow or small vertical saccades. These findings support the notion that patients with pure akinesia may develop a vertical gaze palsy, similar to that in PSP, late in their course. Our patients show that pure akinesia occurs in North America as well as in Japan. Recognition of the syndrome of pure akinesia may suggest the diagnosis of PSP before the development of abnormalities of ocular movement.