Article

Effects of deep brain stimulation and levodopa on postural sway in Parkinson's disease

Department of Electronics, Computer Science and Systems, University of Bologna, Bologna, Italy.
Journal of Neurology Neurosurgery & Psychiatry (Impact Factor: 6.81). 10/2002; 73(3):267-74.
Source: PubMed

ABSTRACT

To quantify postural sway in subjects with Parkinson's disease and elderly controls, and determine the effects of Parkinson's disease, deep brain stimulation, levodopa, and their interactions on postural control during quiet stance.
Centre of foot pressure (CoP) displacement under each foot was measured during three 60 s trials of quiet stance with eyes open in 11 controls and six patients with Parkinson's disease. Subjects with Parkinson's disease were tested in four treatment conditions: off both deep brain stimulation and levodopa (off condition); on deep brain stimulation; on levodopa; and on both deep brain stimulation and levodopa. The variables extracted from CoP included: root mean square distance (rms), mean velocity, 95% power frequency (f(95%)), area of the 95% confidence ellipse (ellipse area), direction of its major axis (mdir), and postural asymmetry between the feet.
rms and area of postural sway were larger than normal in subjects with Parkinson's disease in the off condition, increased further with levodopa, and significantly decreased with deep brain stimulation. Mean velocity and f(95%) were also larger than normal but were restored to normal by all treatments, especially by deep brain stimulation. The combined effect of deep brain stimulation and levodopa resulted in a postural sway that was an average of the effect of each treatment individually. Levodopa increased sway more in the mediolateral than in the anterior-posterior direction. Subjects with Parkinson's disease had asymmetrical mean velocity and f(95%) between the feet, and this asymmetry increased with levodopa but decreased with deep brain stimulation. The f(95%) of the CoP correlated with tremor, posture, and gait subcomponents of the unified Parkinson's disease rating scale.
Subjects with Parkinson's disease have abnormal postural sway in stance. Treatment with levodopa increases postural sway abnormalities, whereas treatment with deep brain stimulation improves postural sway. Quantitative evaluation of static posturography may be a useful adjunct to clinical measures in patients with Parkinson's disease.

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    • "The mean center of pressure ( CoP ) signal was also calculated for each analysis . For bipedal and tandem standing , the resultant CoP signal of the ground reaction forces was determined in a 2 - dimensional transverse plane by means of digital moment - of - force calculations for each force plate ( Rocchi et al . , 2002 ; Geurts et al . , 2011 ) . For unipedal adapted standing , the CoP was calculated in a similar manner as for the other conditions , but only for one force plate . In the tandem standing con - dition , the CoP of the limb positioned behind was used for the analysis . The first 10 s of each recording were ignored to avoid potential distu"
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