A study of subtle motor signs in early Parkinson's disease

BACKGROUND: The UPDRS is the most widely used rating scale for Parkinson's disease (PD). However, subtle features of early disease stages may be missed. METHODS: We studied 25 early PD patients using a newly compiled battery of motor tests focusing on subtle motor features. Focal dystonia patients (n = 31) and healthy individuals (n = 26) served as controls. Specifically, asymmetric shoulder null position and delayed shoulder shrugs, reduced arm swing, subtle tremor, and timed finger taps were assessed. Spiral drawings and writing were also studied. RESULTS: With a total mean of 9.8 ± 4.9 (possible range: 0-94), PD patients scored significantly higher than dystonia patients (2.9 ± 2.0) and healthy controls (1.9 ± 2.0) (P < 0.001). Reduced arm swing and tremor of individual fingers best distinguished PD from the other groups. CONCLUSIONS: The battery was sensitive to detect subtle motor features missed by the UPDRS. For future revisions of an international motor score, further assessment of these items may be worthwhile.