Department of Exercise Sciences


Gait regulation in Parkinson's Disease

GN Lewis, WD Byblow, SE Walt

Introduction

One of the most common symptoms of Parkinson’s disease (Pd) is the development of a shuffling gait pattern with a shortened step length (SL) and a reduced overall velocity of gait. The precise reasons as to why this occurs in Pd patients is unknown at present, however studies have demonstrated that with appropriate visual cues, such as markers placed at intervals along the ground, patients can increase SL and generate a more normal spatiotemporal gait pattern.

It is also uncertain how visual cues such as these lead to the improvements in SL evident. It has been proposed that the cues may draw the attention of the patients and thereby invoke more conscious gait control pathways, bypassing the neural regions affected in Pd.

Methods

  • Fourteen Pd patients and 14 control subjects walked up and down a 10 m runway 20 times in each of three conditions: with a featureless runway (baseline); with a striped runway (SL marker); and with a subject-mounted light device (SMLD). The SMLD was a laser cueing device developed for use in this study as a possible practical rehabilitation tool (above).
  • 3-D kinematic and kinetic gait analysis of the lower limbs and trunk was conducted on all subjects, including electromyographic analysis of soleus and tibialis anterior muscles (left).
  • Subjects performed a probe reaction time task during the walking trails to assess residual processing capacity in the three conditions. Simple reaction time was also collected between trials.
  • Ratings of perceived effort were obtained after all trials in each of the conditions.
  • Results
  • SL and gait velocity were reduced in the patients in baseline conditions. Both of these parameters increased to control levels in the SL marker and SMLD conditions (below).
  • In baseline conditions, Pd gait was characterised by several features of a "crouch" gait pattern, including increased trunk flexion, reduced hip extension, and increased knee flexion. In the less severely affected patients, these profiles were altered towards that of the control subjects in the visually cued conditions, however the more severely affected patients demonstrated further abnormalities in their gait pattern in the visually cued conditions.
  • Reaction time and the perceived effort of walking were both increased in the Pd patients. Both were unchanged from baseline to SL marker conditions, but were increased in the patients and controls in the SMLD condition.
slresult

Conclusions

  • The SMLD may be an effective gait rehabilitation tool for the Pd population.
  • Increased muscle stiffness is likely to play a large role in the gait pattern of Pd patients, and, with disease progression, may limit the effectiveness of rehabilitation strategies.
  • SL reductions in Pd may be due to a deficit in the preparatory motor process specifically relating to the regulation of movement amplitude.
  • As increases in attentional demand were not evident in this study in the SL marker condition, it is alternatively proposed that improvements in SL with visual cues may be due to the availability of visual feedback to regulate movement amplitude.

For more information on this project contact:

Winston Byblow
Email: w.byblow@auckland.ac.nz