Clinicophysiological features of akinesia.

Among the motor tetrad of Parkinson's disease, akinesia is not easy to define and controversies still exist on the nature of akinesia. In 1972 Barbeau first described pure akinesia without rigidity or tremor responsive to L-dopa therapy, that is, akinesia due to striatal dopamine deficiency. Since 1974, Imai and Narabayashi have described a different type of pure akinesia, unresponsive to L-dopa treatment. This new condition exhibits only the freezing symptom, which is a breakdown of repetitive voluntary movements emerging through festination or suddenly, e.g., freezing of gait, micrographia and inaudible speech. Kinésie paradoxale is always accompanied by this type of akinesia. The author suggested that the main pathological structure of the condition was different from the nigrostriatal dopaminergic system and that the condition was different from Parkinson's disease. Subsequently we expanded our experience to more than 30 patients. All patients were sporadic and slowly progressive, and some had been followed for more than 10 years, still without rigidity or tremor. Slowly progressive supranuclear opthalmoplegia appeared later in several patients, in which progressive supranuclear palsy (PSP) was strongly suggested. Autopsy cases associated with this condition have been reported and pathologically revealed PSP. The nosological position and responsible lesion sites of this condition are discussed.