Disturbances of posture, balance, and gait in Parkinson’s disease

1. Exploring new brain targets to alleviate postural deficits

Disturbances in posture, balance, and walking commonly emerge in advanced stages of Parkinson’s disease.

Instability in a patient’s posture results in reduced mobility, increased risk of falls, and diminished quality of life. For this particular deficit, it is unclear whether stimulation of the brain area usually targeted in Parkinson’s disease (termed the subthalamic nucleus) is effective. Stimulation of alternative brain targets may better address this symptom and preliminary studies have provided promising results. The absence of reliable measures to quantify postural instability adds to the complexity of evaluating this deficit and exploring new treatments. The clinical measure widely used to rate postural instability is subjective and insensitive in determining changes to balance.

The overall aim of this project is to understand the effects of DBS on postural instability in alternative brain targets using new and objective measures of balance and posture. A clinical test of balance is called the ‘pull’ test where the patient is pulled from behind and the clinician assesses the ability to recover balance. We have developed a new instrumented version of this test that provides real-time measures of postural response times when a person is pulled from behind. The first stage of this study has been to test our instrumented test in healthy volunteers and has proved to be very successful.

The long-term goal of this project is to assist clinicians in the treatment of this debilitating symptom, to improve quality of life of patients, and reduce the healthcare costs associated with falls in those living with Parkinson’ disease.

2. Improved clinical assessment of gait

Freezing of gait is a debilitating symptom of Parkinson’s disease associated with a heightened risk of falls.

Current clinical assessment of this symptom involves observation of a patient’s gait during a turning task in addition to self-reporting questionnaires; both these measures are subjective and imprecise. We have therefore developed and tested a system for precise freezing-of-gait assessment using custom-designed shoe insoles that allow precise measurement of turning (duration and speed).

We have recently tested the reliability and validity of this system in people with Parkinson’s disease with freezing of gait. Participants performed 20 on-the-spot 360-degree turns which were captured using the insoles and a video camera. Our instrumented measure correlated highly with clinicians’ rating of the turn, and the system showed high test-retest reliability.

Insoles are worn in shoes and pose no discomfort: in the laboratory setting they must be within two metres of a receiving computer. Our goal is to make this system more convenient so that the insoles can be used for in-home assessment and clinicians can monitor a patient’s treatment and disease progression via telemedicine.

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