Identification of Clinically Relevant Markers of Deep Brain Stimulation Electrode Impedance

Study Overview
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Brief Summary
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The study will look into the changes of Deep Brain Stimulation (DBS) measured impedances in patients of Parkinson disease (PD) as a function of their functional state (lying, sitting and walking) and dopaminergic medication intake (levodopa or dopamine agonists). The goal is to use DBS measured impedance as a surrogate of the functional and medication states of PD patients.

Detailed Description
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Subjects will be recruited from the population of patients who are already implanted with DBS for treatment of PD. At the patient's follow up visit they will be asked to come to the clinic in the off medication state. Off medication is defined as at least 8 hours since the last medication dosing. Data will be collected during three phases: OFF state, transitioning state, and ON state. Subjects will be asked to assume different functional states (lying, sitting or walking) for 1 minute each. During these functional states, multiple measures of impedance will be collected. OFF state data collection: The subject will be examined to assess his motor examination score using the UPDRS-III. Measurements of impedance will be collected multiple times in the lying down and sitting up states. Transition state data collection: The subject will be asked to take their dopamine medication. The medication will take approximately 1 hour to take full effect. Measurements of impedance will be collected every 10 minutes during this transition from the OFF state to the ON state. Patients will be asked to report at what point they felt the ON: state (they can report the state as OFF, unsure, transition or ON). ON state data collection: The ON state examination will start after 1 hour from medication administration. Subjects will be examined using the UPDRS-III. Measurements of impedance will be collected in the lying down, sitting and walking states. Summary of the study protocol: OFF state Transition state ON' state UPDRS-III x x Impedance Lying down x x Sitting up x x x Walking x UPDRS I and II x Hoehn and Yahr x x

Official Title
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Identification of Clinically Relevant Markers of Deep Brain Stimulation Electrode Impedance

Conditions
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Parkinson Disease

Intervention / Treatment
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* Other: Impedance measurements


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: Idiopathic Parkinson's patients with DBS (unilateral or bilateral) Must be taking dopamine agonist or levodopa regimen Medtronic Neurostimulator Activa SC, PC or PC+S (IPG) Exclusion Criteria: Hoehn and Yahr (H&Y) 4 and above History of DBS revision or lead replacement surgery Current or prior non-Medtronic Activa SC, PC or PC+S IPG Historical information of more than 1 hour delay to ON state as average

Ages Eligible for Study
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Minimum Age: 25 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: Other
Intervention Model: Single Group Assignment
Masking: None (Open Label)


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Experimental: PD patients with implanted DBS<br>Impedance measurements at different time points. | Other: Impedance measurements<br>* Refer to study description<br>|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Change in impedance value as it relates to the functional state. | Functional state is defined as either: lying, sitting or walking. | 1 hour (for both outcomes) | 
| Change in impedance value as it relates to the dopaminergic medication state. | Dopaminergic medications are defined as either levodopa containing or dopamine agonist containing medications. The state is defined as the OFF state (medication effect is not present) and ON state (medication effect noted). | 1 hour (for both outcomes) | 

 Terms related to the study
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Keywords Provided by Centre Hospitalier Valida
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Deep Brain Stimulation, Electric Impedance, Parkinson disease