Rest and postural tremors in patients with Parkinson's disease.

The mild tremor of twenty-four patients with Parkinson's disease (PD) was quantified in four conditions: finger-rest, finger-postural, hand-rest and hand-postural. Tremor characteristics such as amplitude, median power frequency, power dispersion, and power percentage within the 4-7 Hz band were correlated across conditions. Results show that all tremor characteristics were well correlated across conditions (Spearman's Rank), signifying that presence of PD rest tremor was accompanied with a postural tremor having similar characteristics to that of rest tremor. The present results suggest that neural mechanisms involved in PD rest tremor do remain active in the postural condition, even in patients with mild tremor.