Handedness as a predictor of side of onset of Parkinson's disease.

The prevalence and predictive factors of asymmetry in Parkinson's disease have hardly been investigated. The aim of this study was to determine the rate of asymmetric features in patients with Parkinson's disease. The study group consisted of 307 patients with idiopathic Parkinson's disease. The dominant hand was recorded in each case, and right-left differences in tremor, bradykinesia, and rigidity was defined as a difference of more than 4 points on the Unified Parkinson Disease Rating Scale. Asymmetric presentation was noted in 260 patients [84.7%]. The initial symptoms appeared on the right side in 47% of the right-handed patients [on the left side in 38% of the right-handed patients], and on the left side in 52% of the left-handed patients [on the right side in 36% of them] [p=0.06]. In conclusion, Parkinson's disease appears to be characterized by asymmetry of symptoms. There was a trend toward symptoms onset on the dominant side.