Motor asymmetry over time in Parkinson's disease.

BACKGROUND: Motor symptoms in Parkinson's disease (PD) patients are usually asymmetric at onset. The literature on change in asymmetry over time has mixed results, with some studies suggesting a retained asymmetry and others suggesting a progression towards symmetry. The aim of this study was to assess change in asymmetry over time.

METHODS: Charts of 109 consecutive patients who had been followed in a movement disorders clinic for routine PD care were retrospectively reviewed. All patients had been treated for PD symptoms and had been seen during at least 2 annual time points over 5 years. Interval absolute differences in Unified PD rating scale (UPDRS) scores for bradykinesia, rigidity, and tremor between the right and left sides were calculated for annual time points.

RESULTS: Neither bradykinesia, rigidity, nor tremor became more symmetric over a 5-year period; there was not a statistically significant change in asymmetry at any annual time point for these motor symptoms.

CONCLUSIONS: The lack of observed change in UPDRS score difference suggests that motor symptoms in PD patients remain asymmetric. This is important to consider clinically when predicting the natural course of PD and considering alternative diagnoses to PD. These results may also be important in developing hypotheses for disease progression.