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LEVODOPA INFLUENCES THE REGULARITY OF THE ANKLE JOINT
KINEMATICS IN INDIVIDUALS WITH PARKINSON'S DISEASE
Max J. Kurz1, Ashley Hickerson1, Chris Arellano1, J. G. Gabriel Hou2, and Eugene C. Lai2 1 Laboratory of Integrated Physiology, Department of Health and Human Performance, University of Houston, Houston, TX, USA, mkurz@uh.edu 2 Parkinson's Disease Research, Education & Clinical Center, Michael E. DeBakey VA Medical Center, Baylor College of Medicine, Houston, TX, USA
INTRODUCTION
Parkinson's disease (PD) is a progressive, results mainly from a loss of dopaminergic while "off" and then "on" their levodopa therapy. Characteristics of the participants nuclei, together with other related brain are detailed in Table 1. All participants were structures, compose the basal ganglia, which initially assessed in the morning without are largely attributed to controlling the amplitude and timing of movement patterns. functions appears to be the cause for the larger amount of stride-to-stride variability seen in PD patients (Schaafsma et al., 2003). levodopa to be turned "on" before having the participant repeat the walking bout. including gait. It was demonstrated that Hz) was used to collect the right leg's ankle, levodopa therapy reduced the magnitude of knee and hip joint sagittal plane kinematics. the variations present in the stride time interval dynamics (Schaafsma et al., 2003). variations present in the respective joint's improved regulation of the lower extremity angle kinematics (Pincus, 1981; Equation 1). joint kinematics. However, the influence of levodopa on the regularity of the structural variations found in the joint kinematics is The purpose of this investigation was to Table 1. Participants' characteristics.
regularity of the structural variations present in the lower extremity joint kinematics. We hypothesized that levodopa will reduce the variations of the lower extremity kinematics where Cm(r) is the number of data points of length m that are similar, Cm+1(r) is the number of data points of length m+1 that are similar, and r is the similarity criterion. For this investigation, m was 2 and r was 20% of the standard deviation of the time series (Pincus, 1991). A lower ApEn value indicates a greater regularity in the structural variations present in the joint kinematics. We used a two factor repeated measures Figure 1. ApEn values for the respective
joints while "on" and "off" levodopa. post-hoc to evaluate the effect of levodopa on the regularity of the structural variations the fact that our investigation was conducted present in the joint kinematics. All statistical on a treadmill. Potentially, the treadmill may tests were performed at a 0.05 alpha level. have acted as an external cueing device that reduced the structural variations present in RESULTS AND DISCUSSION
investigation that found that the magnitude significant joint-medication interactive of the stride-to-stride variations is reduced effect (F(2,14) = 6.74; p = 0.009; Figure 1). Our post-hoc analysis indicated that the structural variations present in the ankle joint kinematics were more regular while being "on" levodopa (p < 0.0001). No significant differences in the regularity of Levodopa influences the regularity of the the structural variations were found in the structural variations present in the ankle knee (p >0.05) and hip (p>0.05) joints' joint kinematics of individuals with PD. We suggest that an impaired ability to regulate According to the above results, levodopa abnormalities in PD. Future investigations improves the Parkinsonian motor symptoms the variations present in the Parkinsonian by regulating the performance of the ankle previously noted in the magnitude of the stride-to-stride variations by levodopa may REFERENCES
be related to the ankle joint's ability to regulate a consistent muscular performance Frenkel-Toledo et al. (2005). Mov Disord, (Schaafsma et al., 2003). This notion is supported by a previous investigation that demonstrated that individuals with PD have a decreased amount of ankle power at push- off if not taking levodopa (Morris et al., 1999). The perceived resistance of the knee Schaafsma JD et al. (2003). J Neuro Sci, and hip joints to levodopa may be related to

Source: http://ww.asbweb.org/conferences/2008/abstracts/396.pdf