Gait problems in Parkinson's disease (PD) are complex and not adequately addressed by current medical and surgical options. The focus of this thesis was a desire to optimise the effectiveness of cues after experience of delivering cueing therapy in the context of a multi-centre RCT. Cues provide information on how to adapt the stepping pattern either through external prompts or internally through focussing attention. Cues are known to improve gait in PD but there is a compromise between strategies which have large effects but limited practical application and those which are easily applied in complex situations but have more modest effects. A laboratory study explored the feasibility of a cueing strategy combining an external rhythmical cue with a focussed instruction to increase step size, targeting both temporal and spatial parameters. A group of 15 PD and 12 age and sex matched controls were tested and gait was measured with an instrumented walkway which uses pressure activated sensors. The combination cue was compared with two single parameter cueing strategies, a rhythmical auditory cue and an attentional strategy asking subjects to walk with large steps. Gait was assessed under single and dual tasks to establish the attentional demands of the different cues. Walking speed and step amplitude significantly increased with the attentional strategy and combination cue in single and dual tasks in PD and controls (see chapter 3). The combination cue had an additional benefit in significantly reducing stride time and double limb support time variability in PD subjects, whilst variability increased in controls (see chapter 4). The effects of cues on and off medication was tested in the home in a group of 50 PD subjects using the same dual task paradigm to explore the mechanisms underlying cueing compared to dopamine on gait control. Gait was measured using an in-shoe footswitch system allowing reliable gait data to be collected in the home. Walking speed and stride amplitude significantly improved with all cues in the single and dual tasks on medication and with the attentional strategy and combination cue off medication suggesting that cues have a different mechanism to dopamine. The greatest improvements were seen with the combination of cues and medication. Gait variability responded differently to cues on and off medication. The combination cue reduced variability on and off medication for single and dual tasks, the auditory cue reduced variability in all conditions except for single task on mediation and the attentional strategy increased variability in the single task on mediation and had no effect in other conditions (see chapter 5). Cues which are delivered externally result in different mechanisms of gait control than those generated internally. Measures of gait variability reflect the attentional cost of movement and underlying neural control but there is limited knowledge on their validity. The final stage of the research examined the clinical characteristics associated with increased gait variability to increase understanding of these variables. Non-cued gait variability was strongly associated with disease severity, but cued gait variability was not adequately explained suggesting involvement of more diverse parameters (see chapter 6). These findings provide new knowledge on the mechanism underlying cued gait, the involvement of dopaminergic pathways and the attentional cost of different cues. Focussed instruction can alter the response to an external cue in the form of a rhythmical auditory tone, targeting both temporal and spatial gait parameters and reducing the attentional cost of walking.
|Publication status||Accepted/In press - 13 May 2009|