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: 5.58). 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.

  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: The time course of the center of pressure (CoP) during human quiet standing, corresponding to body sway, is a stochastic process, influenced by a variety of features of the underlying neuro-musculo-skeletal system, such as postural stability and flexibility. Due to complexity of the process, sway patterns have been characterized in an empirical way by a number of indices, such as sway size and mean sway velocity. Here, we describe a statistical approach with the aim of estimating "universal" indices, namely parameters that are independent of individual body characteristics and thus are not "hidden" by the presence of individual, daily, and circadian variations of sway; in this manner it is possible to characterize the common aspects of sway dynamics across healthy young adults, in the assumption that they might reflect underlying neural control during quiet standing. Such universal indices are identified by analyzing intra and inter-subject variability of various indices, after sorting out individual-specific indices that contribute to individual discriminations. It is shown that the universal indices characterize mainly slow components of sway, such as scaling exponents of power-law behavior at a low-frequency regime. On the other hand, most of the individual-specific indices contributing to the individual discriminations exhibit significant correlation with body parameters, and they can be associated with fast oscillatory components of sway. These results are consistent with a mechanistic hypothesis claiming that the slow and the fast components of sway are associated, respectively, with neural control and biomechanics, supporting our assumption that the universal characteristics of postural sway might represent neural control strategies during quiet standing. © 2015 The Authors. Physiological Reports published by Wiley Periodicals, Inc. on behalf of the American Physiological Society and The Physiological Society.
    03/2015; 3(3). DOI:10.14814/phy2.12329
  • [Show abstract] [Hide abstract]
    ABSTRACT: Gait impairment in Parkinson's disease (PD) persists despite the use of dopaminergic therapy. Motor phenotype associated with greater postural instability and gait difficulty is related to a greater risk of motor decline and may be influenced by non-dopaminergic pathology. This study documents the progression of gait impairment over 18 months in an incident cohort of PD with regard to phenotype and medication. Gait characteristics were measured in 121 PD and 184 controls, and 18 months later in 108 PD participants. Sixteen gait characteristics were examined with respect to five broad domains for PD and motor phenotype. Correlations between change in levodopa (l-dopa) equivalent daily dose and gait were used to identify dopa-responsive and nonresponsive characteristics. Pace and rhythm deteriorated over 18 months in people with PD, with other gait domains remaining stable. People with a postural instability and gait difficulty phenotype had more impaired gait at baseline compared with a tremor-dominant phenotype, which was most evident in temporal characteristics. In contrast, pace and variability deteriorated over the subsequent 18 months in the tremor-dominant phenotype only. Weak but statistically significant correlations were found between increased l-dopa medication and less deterioration in pace and asymmetry. Significant gait impairment is evident in very early disease despite optimal medication. Change over 18 months is subtle and discrete, and is more pronounced in the tremor-dominant phenotype. Some features of gait are refractory to dopaminergic therapy, implicating a non-dopaminergic contribution. This may explain more temporal gait disturbance in the postural instability and gait difficulty phenotype. © 2014 International Parkinson and Movement Disorder Society
    Movement Disorders 12/2014; DOI:10.1002/mds.26110 · 5.63 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: The present study addresses the challenge of identifying the features of the centre of pressure (CoP) trajectory that are most sensitive to postural performance, to progress in the process of transforming CoP data into useful information and to promote standardization in quantitative posturography. For this purpose, we singled out the features that characterize postural sway in subjects with Parkinson’s disease (PD) with and without levodopa (on and off states). The feature selection was performed using principal component analysis. Results suggest that CoP in subjects with PD can be primarily characterised by four parameters, in both off and on states, describing: the size of the path over the support surface; the principal sway direction; and the shape and bandwidth of the power spectral density plot. The similarity of the present results with a previous study that considered young healthy subjects, allows us to define more confidently the minimum set of measures to recommend for specific applications as optimal descriptor of CoP sway in quiet stance. Keywords: principal component analysis, posture, Parkinson’s disease. 1 Introduction Body posture is the output of complex interactions between central nervous system control mechanisms and the musculo-skeletal actuators acting against the support surface. Because of its complexity body posture is challenging to
    BIOMEDICINE 2005; 08/2005

Full-text (2 Sources)

Available from
May 17, 2014