Investigators/Authors: Mark Hallett, MD; Codrin Lungu, MD
Objective/Rationale: Difficulties with walking is often a significant problem for patients with Parkinson disease. Not only is walking slow, but there are also occasional falls and freezing (getting “stuck” in place). Freezing, in particular, is often refractory to medication and even Deep Brain Stimulation (DBS). Freezing is sometimes precipitated by visual stimuli (like encountering a doorway) or relieved by visual stimuli. One of the difficulties in understanding this is that there is no information on where patients are looking while they are walking. With this project, we will study where patients are looking and determine how that influences walking.
Project Description/Methods/Design: The aim is to see where patients with Parkinson disease look when walking. An eye tracking device will be used that allows patients to walk freely. The system will record a video of what is in front of the patient and then indicate exactly what the eyes are focused on in that scene. A comparison will be done between patients and age/sex matched healthy subjects. Exploratory studies will be done first to develop detailed hypotheses. We will study subjects walking in various situations including a plain corridor, a corridor with many objects, a corridor with horizontal lines on the floor, and a corridor with a door to go through. A door often makes walking more difficult, while horizontal lines on the floor might be helpful. Some variability of influence might depend on where the patient is looking.
Relevance to Treatment of Parkinson’s Disease: It is clearly critical in walking to know what lies ahead and how to deal with it. If it is determined that there are systematic abnormalities in where patients are looking, then it might be possible to improve walking by training patients to look differently. The biggest impact could be on freezing of gait where visual stimuli are known to be important.
Expected Outcome: The first outcome is basic knowledge about the coupling of vision and walking in patient with Parkinson disease. Certain types of visual-motor coordination are known to be impaired in patients, and this might be another example, with bad consequences. The second outcome is a set of ideas of how to improve physical therapy gait training. It might also be possible to develop new ideas for devices that would aid vision to help improve gait.
September 2014 Project Update:
Study Progress: By using an eye-tracker while walking, our project explores the presence of visual exploration differences between patients with Parkinson’s disease (PD) and healthy volunteers (HV). The participants are asked to wear the SMI Eye Tracking Glasses while waking through a corridor. Information regarding the areas of visual fixation is obtained and the percentages of time spent looking at specific areas are compared between different populations (Healthy Volunteers, patients with Parkinson’s Disease with and without Freezing of Gait).
Our study has enrolled a total of 24 participants:
15 patients with PD without freezing of gait
2 patients with PD and freezing of gait
7 healthy volunteers
Preliminary results: Our preliminary analysis demonstrates increased fixation duration and decreased saccade velocity on patients with PD when compared with HVs. More importantly, there are sight differences on the percentages of time spent looking at specific areas between the two populations. The differences are not statistically significant at this time, likely due to the small sample size.
- Continue patient enrollment and analysis.
- Evaluate differences on area scanned in different static environments and the translation into dynamic tasks (walking). Additionally, assess the influence of therapeutic visual exploration strategies.
- Development of detailed hypothesis based on our current explorations.
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