Novel Stimulation Patterns for the Treatment of Dystonia

Study Overview
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Brief Summary
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Deep brain stimulation (DBS) is an effective surgical therapy for select Dystonia patients who are refractory to medications or who have generalized symptoms (e.g. patients with Early-Onset Primary Dystonia(DYT1) mutations and other dystonia subtypes). DBS patients typically experience significant improvement in disabling symptoms; however, detailed programming is always required, and stimulation-induced side effects commonly emerge. Clinicians may empirically vary voltage, pulse width, frequency and also the active contacts on the DBS lead to achieve observed optimal benefits. The majority of DBS patients undergo repeat surgeries to replace the implantable pulse generator (IPG) every 2.5 to 5 years. It has been demonstrated that, in dystonia patients, that higher settings are required for adequate symptomatic control, and that neurostimulators have a considerably shorter life when compared to neurostimulators from patients with essential tremor or Parkinson's disease. Additionally, several smaller studies have suggested that alternative pulse stimulation properties and pulse shape modifications can lower IPG battery consumption. Newer patterns of stimulation (regularity of pulses and shapes of pulses) have not been widely tested in clinical practice, and are not part of the current FDA device labeling. Novel patterns of stimulation do however, have the potential to improve symptoms, reduce side effects, and to preserve the neurostimulator life. The current research proposal will prospectively study biphasic pulse stimulation paradigms and its effects on dystonic symptoms. The investigators aim to demonstrate that we can tailor DBS settings to address dystonia symptoms, improve the safety profile, characterize distinct clinical advantages, and carefully document the safety and neurostimulator battery consumption profile for biphasic stimulation.

Detailed Description
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In this research study, different stimulation patterns on the DBS device will be tried for effectiveness against current symptoms. There will be two different stimulation patterns that will be performed and can occur at different clinic dates. Each of the stimulation patterns will have times varying between 2-3 hours per stage. One part of the study will deliver stimulation in a continuous manner, while the other part of the study will deliver stimulation based upon responses obtained from changes in brain wave patterns. These procedures can be performed while in the clinic for regular programming visits or at different visits. The current DBS setting will be recorded and at the end of the session the setting will be reset to back to the previous settings. The participant will have the option of participating in both or just one part. During the visit, the participant will be analyzed for tremor and slowness by using the Trigno wireless Electromyography (EMG) and the Kinesia system. The system includes a unit composed of two modules: a wrist module, which is the size of an I-Pod and will be attached to the wrist over a comfortable wristband, and a sensor module, which will be placed over the index finger. The entire visit will be videotaped and UDRS (Unified Dystonia Disease Rating Scale) and BFMDRS (Burke-Fahn-Marsden Dystonia Rating Scale) scores will be evaluated by two scorers. Pre-DBS off and on scores will also be taken.

Official Title
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Novel Stimulation Patterns and Personalized Deep Brain Stimulation for the Treatment of Dystonia

Conditions
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Dystonia, Cervical Dystonia

Intervention / Treatment
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* Device: Biphasic DBS stimulation
* Other: Unified Dystonia Rating Scale
* Other: Burke-Fahn- Marsden scale


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: Diagnosis of primary generalized dystonia or cervical dystonia Bilaterally implanted globus pallidus interus(GPi) DBS. Minimum of 6 months of chronic stimulation Greater than 60 days on stable DBS settings Exclusion Criteria: Does not have DBS for dystonia or cervical dystonia

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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Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Biphasic DBS stimulations<br>Subjects in this group with have Biphasic DBS stimulation setting performed, Unified Dystonia Rating Scale (UDRS), and Burke-Fahn- Marsden scale (BFMDRS), tremor accelerometer, kinesia accelerometer, and GaitRite walking assessments performed. | Device: Biphasic DBS stimulation<br>* The following protocol will be followed for each subject. In between, baseline and novel stimulation settings there will be a 30-minute washout period with DBS in the off state. Current best/optimized DBS setting (considered baseline) DBS off for 30 minutes Biphasic pulse stimulation mode (immediate assessment) Biphasic pulse stimulation mode (assessment at 1h) Biphasic pulse stimulation mode (assessment at 2h)<br>Other: Unified Dystonia Rating Scale<br>* Neurologist use the UDRS to determine the severity and duration of dystonia on 14 body areas.<br>* Other names: UDRS;Other: Burke-Fahn- Marsden scale<br>* Neurologist use the BFMDRS to rate the severity of dystonia in 9 regions of the body.<br>* Other names: BFMDRS;|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Blinded Unified Dystonia Rating Scale (UDRS) | Neurologist use the UDRS to determine the severity and duration of dystonia on 14 body areas. Each body region is assessed and scores range from 0 (no dystonia) to 4 (extreme dystonia). The maximum UDRS score is 112 and includes severity and duration factors. | Day 1 | 
| Burke-Fahn-Marsden Dystonia Rating Scale (BFMDRS) | Neurologist use the BFMDRS to rate the severity of dystonia in 9 regions of the body. Provoking and severity factors are ranked from 0 (no dystonia) to 4 (extreme dystonia) for each body region and then adjusted scores are summed to give an overall score from 0 to 120. | Day 1 | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Tremor accelerometer to measure motor dysfunction | Tremor accelerometer for the patients with a component of dystonic tremor (device taped or attached to the wrist by an elastic band to record how fast the tremor). | Day 1 | 
| Kinesia accelerometer to measure motor dysfunction | Kinesia accelerometer for the patients with a mobile component of dystonia (device attached to the arms and legs (by an elastic band or tape) to record movements). | Day 1 | 
| Battery Consumption compared between pre and post settings | Battery consumption will be calculated and compared between the NEW settings and patients' baseline settings. The Medtronic battery estimator helpline will be used to calculate battery life, as well as the University of Florida calculator. | Day 2 | 
| GaitRite walking assessment. | The GaitRite is an automated floor that when you walk on the floor it records your gait pattern. | Day 1 | 

 Terms related to the study
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Keywords Provided by Centre Hospitalier Valida
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DBS, Deep brain stimulation, Dystonia, DYT1