Variations in axial, proximal, and distal motor response to L-dopa in multisystem atrophy and Parkinson's disease

The purpose of this study was to quantitatively compare the motor response to L-dopa in Parkinson's disease (PD) and striatonigral-type multisystem atrophy (MSA) patients. Ten consecutive MSA patients were compared with nine PD patients selected to have similar overall motor compromise, age, and mental state. The performance of simple repetitive axial movements plus bilateral proximal and distal limb movements; overall motor response assessed by the Unified Parkinson Disease Rating Scale (UPDRS); as well as scores from the UPDRS items evaluating speech/facial expression, postural stability, and posture/gait were assessed 90 min and 12 h (baseline) after L-dopa administration. The total UPDRS score, all subcategory scores, and all body movements improved significantly 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 loss 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 putamen.