Alternating DBS for Stepping Control in Parkinson's Disease

Study Overview
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Brief Summary
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Parkinson's disease (PD) is a disabling, progressive condition characterised by severe problems with movement for which medical treatment in the longer term can be unsatisfactory. Deep brain stimulation (DBS) is a treatment, which directly stimulates the nerve cells affected inside the brain to help overcome the difficulties with movement. Classically, DBS stimulates in a manner that is constant. Many patients develop severe problems with walking, so-called freezing of gait, which can be unresponsive to constant DBS. In this study the investigators will test if left-right alternating DBS helps to improve gait problems by potentially promoting left-right alternating up- and down-modulated brain activity, which was found during walking in a previous study. The investigators will test if alternating DBS improves the ability to adjust walking speed and to walk freely compared to constant DBS.

Official Title
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Studying Stepping Control in Parkinson's Disease Using Alternating DBS

Conditions
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Parkinson Disease

Intervention / Treatment
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* Device: Alternating DBS


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: PD patients with bilateral subthalamic nucleus DBS electrodes and stimulators implanted for at least 6 months Able to give consent. Exclusion Criteria: Lack of capacity to consent Cognitive impairment/lack of capacity to perform experimental task. The investigators will additionally conduct a short (10 min) quantitative assessment of cognitive function using a validated test (MMSE). Patients with a score < 20 will be excluded from the study.

Ages Eligible for Study
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Minimum Age: 18 Years
Maximum Age: 80 Years

Sexes Eligible for Study
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All

Accepts Healthy Volunteers
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No

Study Plan
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How is the study designed?
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Design Details

Primary Purpose: Basic Science
Intervention Model: Single Group Assignment
Masking: None (Open Label)


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Experimental: Within-subjects comparison of constant and alternating DBS<br> | Device: Alternating DBS<br>* Constant DBS will be changed to DBS that is up- and downmodulated alternating between the left and right stimulation side.<br>|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Stepping control will be assessed as the ability to adjust the stepping speed (m/s) in each stimulation condition. | Stepping speed (m/s) will be assessed. | Immediate recording | 
| Stepping control will be assessed as the ability to limit the variance in stepping speed (m/s) in each stimulation condition. | Stepping variance (m/s) will be assessed. | Immediate recording | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| The investigators will test if patients automatically adjust to the stimulation rhythm | Stepping entrainment | Immediate recording | 
| The investigators will how well other motor symptoms including tremor, rigidity and bradykinesia are controlled with alternating DBS. | United Parkinsons Disease Rating Scale motor (Part III) scores will be compared between stimulation conditions. | Immediate recording |