[Akinesia and associated motor involvement in Parkinson's disease and basal ganglia lesions].

The paralysis due to lesions of the cortico-spinal tract disturb movements in their different modes while dissociated paralysis result from cortical and particular biopercular lesions. Movements cannot be executed on command whereas they are accomplished in their total complexity when they accompanied certain emotional states or when they are part of an automatic activity. Such a dissociation suggest that the motor program which does not respond to voluntary command will eventually be applied thanks to emotional or affective stimuli. Basal ganglia lesions induce other symptoms. The first to be observed concern the movements and postures implied in automatic series after learning. Akinesias which results from these lesions can be partially controlled by a voluntary command, particularly when helped by sensori stimuli. Such symptoms are observed sometimes from its beginning in the Parkinson's disease. Emotion and sleep are also able to improve these akinesias: therefore they appear either on a deficitary form implying a sensitive reinforcement or on a hyperactive form, which is alleviated by hypotonia and sleep. The localized lesions of striatum or of pallidum provoke identical symptoms but at the interruption of akinesia, a distortion of movement appears, contrary to what is observed in Parkinson's disease. Mechanisms of anticipation and adjustment of postural reaction are disturbed concerning not only the body axis but also the different segments of the limbs. This disturbance provokes unsteadiness and sometimes falls. At the level of the limbs the anomaly of postural reactions slows down the movement and disturbs specially the repetitive gestures.(ABSTRACT TRUNCATED AT 250 WORDS)