Postural stability in Parkinson's disease: the effects of disease severity and acute levodopa dosing.

We systematically assessed the potential effects of disease severity and acute levodopa dosing on body balance by a stable force measuring platform in 56 patients with Parkinson's disease, and compared them to 34 healthy volunteers. Postural sway variables were significantly higher in both patient groups without (Hoehn and Yahr 1-2) and with (Hoehn and Yahr 3-4) a clinically evident deficit of postural stability compared to controls. Levodopa dosing significantly increased postural sway 1 and 2 hours post-dose. The standardization of static posturography with respect to the clinical characteristics and drug schedule of patients may improve the sensitivity of the test, disclosing abnormalities of postural stance even at the early stages of the disease and revealing possible acute drug effects.