A quantitative evaluation of the effects of L-dopa on Parkinson's disease.

Clinical estimation of the degree of muscular rigidity and akinesia in cases of Parkinson’s disease is difficult, as both produce slowing of voluntary movements. However, while akinesia interferes mainly with the speed at which the movement is initiated following extereoceptive and propioceptive demands, muscular rigidity interferes only with the speed at which a body segment is transferred in the space. The present report describes a series of tests for an objective and quantitative evaluation of the initiation of movement and the transference of a body segment in the space. The tests allow comparative analysis between different patients and within the same patient at different time. In a group of Parkinsonian patients treated with L-DOPA, tests were performed to follow patients’ improvement. Results showed that patients receiving L-DOPA significantly improved in the performance of tests that measure transference of a body segment in space, but not in tests that measure initiation of movements. Tremor frequency was decreased and amplitude increased by treatment with L-DOPA although not in a significant way. In agreement a careful clinical evaluation demonstrated improvement mainly in cogwheel sign and less in other clinical manifestations of rigidity. It is concluded that L-DOPA improves the clinical picture of Parkinson’s disease by relieving muscular rigidity and its secondary negative symptoms, but has limited effect on akinesia. These results may explain why L-DOPA has not been useful in the treatment of akinesia when due to other causes (progressive supranuclear palsy).