VARIATIONS IN AXIAL, PROXIMAL, AND DISTAL MOTOR RESPONSE TO L-DOPA INMULTISYSTEM ATROPHY AND PARKINSONS-DISEASE

The purpose of this study was to quantitatively compare the motor resp onse to L-dopa in Parkinson's disease (PD) and striatonigral-type mult isystem atrophy (MSA) patients. Ten consecutive MSA patients were comp ared with nine PD patients selected to have similar overall motor comp romise, age, and mental state. The performance of simple repetitive ax ial movements plus bilateral proximal and distal limb movements; overa ll motor response assessed by the Unified Parkinson Disease Rating Sca le (UPDRS); as well as scores from the UPDRS items evaluating speech/f acial expression, postural stability, and posture/gait were assessed 9 0 min and 12 h (baseline) after L-dopa administration. The total UPDRS score, all subcategory scores, and all body movements improved signif icantly in the PD group. Proximal and distal limb akinesias and speech /facial expression improved in some MSA patients. Lack of response of axial akinesia to L-dopa in MSA correlates with a presumed greater los s of postsynaptic dopaminergic receptors in the dorsolateral putamen, while improvement in distal and proximal limb muscle akinesias in MSA patients may be related to relative preservation of the ventral putame n.