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Long-Term Transcutaneous Stimulation and Essential Tremor: A PET Study

The safety and scientific validity of this study is the responsibility of the study sponsor and investigators. Listing a study does not mean it has been evaluated by the U.S. Federal Government. Know the risks and potential benefits of clinical studies and talk to your health care provider before participating. Read our disclaimer for details. Identifier: NCT03778060
Recruitment Status : Recruiting
First Posted : December 19, 2018
Last Update Posted : February 21, 2022
Cala Health, Inc.
Information provided by (Responsible Party):
Kendall H. Lee, Mayo Clinic

Brief Summary:

Essential tremor (ET) is the most common movement disorder in the United States and affects up to 5% of the population. ET patients experience involuntary shaking of the hands, head and/or voice that can range from mildly limiting to severely disabling.

Treatment options are limited and there are currently no medications specifically designed to treat it, and medications that are prescribed to relieve tremors are often limited by either inadequate efficacy or intolerable side effects. A subset of essential tremor patients whose tremors are inadequately treated by medication choose to undergo deep brain stimulation (DBS) of the ventral intermediate thalamic nucleus. DBS has been shown to be highly effective for tremor suppression. However, DBS carries significant risks. As a result, a very small (less than 3%) percentage of essential tremor patients undergo DBS therapy.

The medical technology company Cala Health has developed a wristband device (the Cala TWO) that offers individuals with essential tremor a novel non-pharmacological, non-invasive alternative, in the form of stimulation of peripheral nerves, to aid in hand tremor relief. This innovative form of therapy has the potential to have important health, quality of life, and economic benefits for essential tremor patients.

The present pilot study (Aim 1) will assess the effectiveness of 3-month twice daily treatment with the Cala TWO device to aid in the relief of hand tremors in adult essential tremor subjects that have been approved to undergo deep brain stimulation surgery at Mayo Clinic - Rochester. This study is a prospective, within subject, non-significant risk study at Mayo Clinic - Rochester, enrolling approximately 20 subjects.

A completely optional component of this study (Aim 2) is seeking to perform three standard PET/CT sessions on a subset of these subjects (n=10) at Mayo Clinic - Rochester to evaluate changes in brain metabolic activity as a result of 3 months treatment with the device. The first session would take place upon a subjects entry into the study (start of month 1) and prior to any treatment with the Cala device, a second the following day after a 40 minute treatment period with the Cala device, and a third session at the end of the third month. This study is a prospective, within subject, greater than minimum risk study.

Condition or disease Intervention/treatment Phase
Essential Tremor Device: Cala TWO stimulator Not Applicable

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Study Type : Interventional  (Clinical Trial)
Estimated Enrollment : 20 participants
Allocation: N/A
Intervention Model: Single Group Assignment
Masking: None (Open Label)
Masking Description: No other parties will be masked
Primary Purpose: Treatment
Official Title: Cala TWO Device: Clinical Efficacy and Effects on Regional Brain Metabolism in Essential Tremor Subjects Scheduled to Undergo Deep Brain Stimulation Surgery
Actual Study Start Date : February 11, 2019
Estimated Primary Completion Date : December 31, 2022
Estimated Study Completion Date : December 31, 2022

Resource links provided by the National Library of Medicine

Arm Intervention/treatment
Experimental: Transcutaneous stimulation
Participants in the clinical study will consist of subjects with essential tremor who are scheduled more than 3 months in advance to undergo deep brain stimulation surgery for treatment of essential tremor at Mayo Clinic. Subjects will wear a Cala TWO stimulator to reduce hand tremors.
Device: Cala TWO stimulator
Treatment intervention will consist of subjects undergoing 40 minute sessions of transcutaneous stimulation with the Cala TWO stimulator twice daily for 3 months to reduce hand tremors prior to their undergoing deep brain stimulation 'surgery for treatment of essential tremor at Mayo Clinic.

Primary Outcome Measures :
  1. Essential Tremor Assessment Following Transcutaneous Stimulation [ Time Frame: Patient assessed at entry to study and at exit of study (3 months). ]
    • The Essential Tremor Rating Assessment Scale (TETRAS) - dominant hand subset mean change (pre-stimulation rating - post-stimulation rating) across visits. Upper limb tremor will be assessed during three maneuvers: forward horizontal reach posture, lateral "wing beating" posture and finger-nose-finger testing. Each upper limb will be assessed and scored individually according to the following scale: 0 = no tremor ; 1 = tremor is barely visible ; 1.5 = tremor is visible, but less than 1 cm ; 2 = tremor is 1- less than 3 cm amplitude ; 2.5 = tremor is 3- less than 5 cm amplitude ; 3 = tremor is 5- less than 10 cm amplitude ; 3.5 = tremor is 10- less than 20 cm amplitude ; 4 = tremor is less than 20 cm amplitude

  2. Assessment of Daily Activities Following Transcutaneous Stimulation [ Time Frame: Patient assessed at entry to study and at exit of study (3 months). ]
    • Bain & Findley Activities of Daily Living (ADL) Scale (pre-stimulation rating - poststimulation rating) across visits. ADL tasks are: Use a spoon to drink soup ; Hold a cup of tea ; Pour milk from a bottle or carton ; Dial a telephone ; Pick up your change in a shop ; Insert an electric plug into a socket ; Unlock your front door with a key. Each task will be rated on a 4-point scale (1-4): 1 = Able to do the activity without difficulty ; 2 = Able to do the activity with a little effort ; 3 = Able to do the activity with a lot of effort ; 4 = Cannot do the activity by yourself

  3. Assessment of Tremor Severity Following Transcutaneous Stimulation [ Time Frame: Patient assessed at entry to study and at exit of study (3 months). ]
    • The Patient Global Impression - Severity scale (PGI-S) on tremor mean improvement change across pre- and post-stimulation sessions. The PGI-S will be a 7-point scale that the participant will use to assess their overall tremor severity of the stimulated hand and consists of: 1 = Normal ; 2 = Hardly perceptible ; 3 = Mild ; 4 = Moderate ; 5 = Marked ; 6 = Severe ; 7 = Extreme

Secondary Outcome Measures :
  1. Daily Changes in Tremor over 3 Months of Transcutaneous Stimulation [ Time Frame: Patient assessed at entry to study, twice daily over the course of 3 months, and at exit of study (3 months). ]
    • Kinematic data mean change in units of meters^2/sec (pre-stimulation tremor power - post-stimulation tremor power) across stimulation sessions.

Information from the National Library of Medicine

Choosing to participate in a study is an important personal decision. Talk with your doctor and family members or friends about deciding to join a study. To learn more about this study, you or your doctor may contact the study research staff using the contacts provided below. For general information, Learn About Clinical Studies.

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Ages Eligible for Study:   21 Years to 70 Years   (Adult, Older Adult)
Sexes Eligible for Study:   All
Accepts Healthy Volunteers:   No

Subject population (children, adults, groups): Adults approved for DBS surgery at Mayo Clinic for treatment of essential tremor

Inclusion Criteria:

  • Prospective subjects must meet all of the following criteria to be eligible for study participation:
  • Must be greater than or equal to 21 years of age. Must be approved for DBS surgery at Mayo Clinic for treatment of essential tremor.
  • Competent and willing to provide signed, informed consent to participate in the study.
  • Stable dose of tremor medications, if applicable, for 30 days prior to study entry.
  • Stable dose of antidepressant medications, if applicable, for 90 days prior to study entry.
  • Willing to comply with study protocol requirements including: remaining on a stable dosage of tremor and antidepressant medications, if applicable, during the duration of the study; no significant alcohol or caffeine consumption within 8 hours of study visits; no usage of the Cala TWO device within 8 hours of study visits.

Exclusion Criteria:

  • Prospective subjects that meet any of the following criteria are not eligible for enrollment in this study:
  • Moderate to severe ethanol dependence as defined by the criteria outlined in the DSM-5 (score of 4 or higher).
  • Implanted electrical medical device, such as a pacemaker, defibrillator, or deep brain stimulator.
  • Previous thalamotomy procedure, including stereotactic thalamotomy, gamma knife radiosurgical thalamotomy, and focused ultrasound for the treatment of tremor.
  • Suspected or diagnosed epilepsy or other seizure disorder. Swollen, infected, inflamed areas, or skin eruptions, open wounds, or cancerous lesions of skin at stimulation site (wrist).
  • Peripheral neuropathy affecting the tested upper extremity. Presence of any other neurodegenerative disease like Parkinson plus syndromes suspected on neurological examination. These include: multisystem atrophy, progressive supranuclear palsy, dementia with Lewy bodies, and Alzheimer's disease.
  • Anyone suspected to have the diagnosis of idiopathic Parkinson's disease (PD). This includes excluding anyone with the presence of parkinsonian features including bradykinesia rigidity, or postural instability. Subjects that exhibit only mild resting tremor but no other symptoms or signs of PD may be included.
  • Botulinum toxin injection for hand tremor within 6 months prior to study enrollment.
  • Are participating or have participated in another interventional clinical trial in the last 30 days which may confound the results of this study, unless approved by the Principal Investigator.
  • Significant alcohol or caffeine consumption within 8 hours of study enrollment, which may confound the results of the study, where significant caffeine is considered more than 95 mg (equivalent to a cup of coffee), and significant alcohol is considered more than 14 g (equivalent to 5 oz of wine, 12 oz of beer, or 1.5 oz of distilled spirits).
  • Subjects unable to communicate with the investigator and staff. Any health condition that in the investigator's opinion should preclude participation in this study.
  • Pregnancy or anticipated pregnancy during the course of the study.

Information from the National Library of Medicine

To learn more about this study, you or your doctor may contact the study research staff using the contact information provided by the sponsor.

Please refer to this study by its identifier (NCT number): NCT03778060

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United States, Minnesota
Mayo Clinic in Rochester Recruiting
Rochester, Minnesota, United States, 55905
Contact: Kendall H Lee, MD, PhD    507-284-7852   
Contact: Kendall L Lee, MD, PhD    507-284-7852   
Sponsors and Collaborators
Mayo Clinic
Cala Health, Inc.
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Principal Investigator: Kendall H Lee Mayo Clinic
Additional Information:
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Responsible Party: Kendall H. Lee, Clinical Professor, Mayo Clinic Identifier: NCT03778060    
Other Study ID Numbers: 18-006984
First Posted: December 19, 2018    Key Record Dates
Last Update Posted: February 21, 2022
Last Verified: February 2022

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Studies a U.S. FDA-regulated Drug Product: No
Studies a U.S. FDA-regulated Device Product: Yes
Keywords provided by Kendall H. Lee, Mayo Clinic:
Transcutaneous Nerve Stimulation
Positron-Emission Tomography
Additional relevant MeSH terms:
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Essential Tremor
Neurologic Manifestations
Nervous System Diseases
Movement Disorders
Central Nervous System Diseases