The control of hand movements in a case of hemianaesthesia following a parietal lesion.

A 46-year-old patient with a lesion limited to the left retrorolandic area without involvement of the prerolandic motor strip was examined. Anaesthesia to tactile, warm, cold, and painful stimuli was complete for the right hand and wrist. Position sense was abolished for the right wrist and finger joints. Performance of the right hand in motor tasks was severely impaired. Simple visual and auditory reaction times were lengthened. Sustaining a constant level of force was impossible. In the absence of visual feedback, only simple, monoarticular movements could be correctly executed; more complex movements requiring coordination between several joints, such as prehension, were poorly, or not, performed. The role of somatosensory cortex in conveying kinaesthetic input to the motor areas and the importance of vision in substituting for kinaesthetic loss, are discussed.