Objective: Determine if there is a motor control hypothesis that could explain movement kinematics of Huntington’s disease (HD) chorea and Parkinson’s disease (PD) levodopa-induced dyskinesia (LID).

Background: HD chorea and PD LID have distinct pathological causes. Yet, they present with similar kinematic patterns. Very few studies have tried to understand why these different basal ganglia insults lead to movement patterns that are kinematically similar.

Method: We analyzed data from 20 subjects with HD chorea and 10 subjects with PD LID. The three-dimensional velocity time-series of involuntary movements of both hands were segmented into one-dimensional point-to-point sub-movements based on velocity zero-crossings. These sub-movements were then normalized and several features were extracted and compared to those from healthy individuals performing voluntary movements. Finally, data from involuntary movement following a reflex response was analyzed using the same approach.

Results: Our results show that sub-movements extracted from HD chorea, PD LID,  voluntary movements of healthy individuals, and involuntary reflex movements exhibit a bell-shaped velocity profile characteristic of human movement. While there were small differences in statistical features of the sub-movements between groups, the largest difference was observed in the slope of the relationship between maximum velocity and duration of the sub-movements. Specifically, the slope of this relationship was approximately 0.94 for the reflex movements, 0.91 for HD chorea, and 0.95 for PD LID while it is approximately 0.66 for voluntary movements of healthy individuals.

Conclusion: This work highlights that HD chorea and PD LID possess some characteristics that more closely resemble those observed from reflex activity. Accordingly, we believe that it is too simplistic to state that those involuntary movements are merely the involuntary release of motor programs normally used for voluntary movements. We hypothesize that our results could be consistent with the equilibrium-point hypothesis where the abnormal descending signals from the central nervous system caused by the basal ganglia dysfunction associated with HD chorea and PD LID activate/modify muscle spring properties while the ascending sensory information of limb position and joint torques lead to a constant search of an equilibrium point. Further studies are required to address this hypothesis.

« Back to 2023 International Congress

MDS Abstracts - https://www.mdsabstracts.org/abstract/levodopa-induced-dyskinesia-and-huntingtons-chorea-link-to-current-motor-control-theories/