Ataxia in Essential Tremor: Describing the Differences Between Disease Process and Treatment Effect

Study Overview
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Brief Summary
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The proposed study aims to characterize ataxia occurring in essential tremor and essential tremor with DBS.

Detailed Description
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Objectives: In recent years, there has been a growing amount of evidence tying Essential Tremor (ET) to cerebellar dysfunction. This has been clinically observed, demonstrated through specific gait measures of ataxia (often involving tandem gait), and confirmed through Positron emission tomography (PET) imaging. Deep Brain stimulation for ET has become a widely utilized therapeutic intervention for patients, and the bilateral thalamic ventralis intermedius (VIM) is most commonly implanted. However, it has been noted that in some patients gait ataxia significantly worsens post-op. This initially was thought to be a result of disease progression, but recent studies have in fact shown that this is a DBS related phenomenon. Methods: Participants will have two visits to either the Portland VA or Oregon Health & Science University (OHSU). At each visit, several assessments of balance, tremor, gait and balance, and DBS settings will be made. The gait and balance assessments will be performed by a unblinded and a blinded rater.

Official Title
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Ataxia in Essential Tremor: Describing the Differences Between Disease Process and Treatment Effect (ATAX)

Conditions
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Essential Tremor, Deep Brain Stimulation, Ataxia, Cerebellar Diseases

Intervention / Treatment
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* Other: No intervention


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: Essential Tremor diagnosis at least 3 years duration Absence of other neurological signes (such as dystonia, ataxia, or Parkinsonism) Patients must be able to walk 2 minutes unassisted. Patients must be able to understand and consent to be in the study. Exclusion Criteria: Patients who have had changes in DBS settings within the last 3 months. Patients who have had no initial improvement or response to DBS. ET medication changes in the last month. Actively abusing alcohol. A neurologic diagnosis other than ET that in the investigator's opinion could affect gait and/or balance. Atypical tremor disorder including by not limited to tremor due to multiple sclerosis, medication-induced tremor, Parkinson's disease, or parkinsonian syndrome. Dementia

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 |
| --- | --- |
| ET (DBS-, Ataxia+)<br>Essential Tremor without DBS with Ataxia on examination | Other: No intervention<br>* No interventions - Observational study<br>|
| ET (DBS-, Ataxia-)<br>Essential Tremor without DBS and without Ataxia on examination | Other: No intervention<br>* No interventions - Observational study<br>|
| ET (DBS+, Ataxia+)<br>Essential Tremor with DBS with Ataxia on examination | Other: No intervention<br>* No interventions - Observational study<br>|
| ET (DBS+, Ataxia-)<br>Essential Tremor with DBS without Ataxia | Other: No intervention<br>* No interventions - Observational study<br>|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Ataxia Differences between DBS and no DBS | Compare the Scale of the Assessment and Rating of Ataxia (SARA) total score between DBS and no DBS participants with essential tremor. This 8-item scale rates gait (0-8 points), stance (0-6 points), sitting (0-4 points), speech disturbance (0-6 points), finger chase (0-4 points), nose-finger test (0-4 points), fast alternating hand movements (0-4 points), and heel-shin slide (0-4 points). Motor activists of the four extremities (items 5-8) assessments are performed bilaterally, mean values to obtain a total score. Cumulative score ranges from 0 (no ataxia) to 40 (most severe ataxia). | Visit 2 (after DBS has been turned off for 3-10 days) | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Balance Confidence | The Activities-Specific Balance Confidence Scale (ABC) is a subjective measure of confidence in performing various ambulatory activities without falling or experiencing a sense of unsteadiness. The ABC scale is a 16-item self-report measure in which participants rate their balance confidence on a 0-100 scale (0 = 0 no confidence, 100 = 100 complete confidence). Overall score is calculated by adding item scores and dividing by the total number of items. | Visit 2 (after DBS has been turned off for 3-10 days) | 

 Terms related to the study
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Keywords Provided by Centre Hospitalier Valida
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essential tremor, dbs