A biomechanical study of gait initiation in Huntington's disease

Background: Akinesia in basal ganglia disorders is essentially defined by delayed movement initiatiom the reaction time increases and it becomes difficult (or even impossible) for the subject to initiate movement. A biomechanical study of gait initiation would help evaluate the role of akinesia in early stage Huntington's disease (HD) patients. Methods: We recorded kinematic, spatiotemporal and angular parameters (using video motion analysis, a force platform and an optoelectronic system) for the first two steps taken by 15 HD patients and 15 gender- and age-inatched controls. In order to evaluate the influence of an external cue on gait initiation parameters, we studied two movement paradigms: self-triggered initiation and initiation triggered (cued) by a "beep" sound. We analyzed kinematic, spatiotemporal (the speed, length and duration of the two first steps) and angular parameters (range of joint angles) its well as kinetic data (the trajectory of the centre of pressure (COP); the speed and trajectory of the centre of mass (COM)). Results: HD patients presented akinesia in both externally triggered and self-triggered conditions. Patients had more difficulties with self-triggered gait than with triggered gait. In HID, anticipatory Postural adjustments (APAs) were more impaired in self-triggered gait initiation than in cued initiation. Indeed, an alteration in the kinetic parameters revealed a reduction in first step speed in both conditions. Hypokinesia (as assessed by a reduction in the range of angle joints) played all important role in this reduction. Conclusion: Akinesia is a major feature of impaired gait initiation in HID. The deficiencies in self-triggered initiation in HD seen here fit with a hypothesis whereby deficient internal cueing can be replaced by all external trigger. (c) 2006 Elsevier B.V. All rights reserved.