A quantitative surface electromyogram analysis for diagnosis and therapy control in Parkinson's disease.

Computer analysis of EMG data on tonic and phasic activities of mm. biceps and triceps brahii was performed to evaluate objectively Parkinson's disease (PD) symptoms and to quantify levodopa therapy effects. Fifteen patients were evaluated in the OFF and eleven in the ON states. Ten healthy controls were also studied. The following EMG parameters were examined: average and maximal amplitudes at rest, occurrence of burst muscle discharges (BMD) with a frequency of 4-7Hz, phasic activation coefficients (PhAC) of the voluntarily contracting flexors and reflex agonist/antagonist muscle involvement under voluntary movement or tonic strain. Statistically significant correlations of resting EMG amplitudes and PhACs with the part III UPDRS motor scores were found. However, the level of antagonist muscle involvement correlated specifically with the part II UPDRS and dyskinesia (disability) scores. Treatment with levodopa produced a clear positive effect on resting amplitudes, PhAC values and BMD occurrence. But in some cases levodopa caused an enhancement of agonist and antagonist muscle involvement, which may be an objective indicator of the risk for developing drug-induced dyskinesia in PD patients.