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.

Essential Tremor

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.

Cala TWO stimulator

Mayo Clinic in Rochester

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

Cala TWO Device: Clinical Efficacy and Effects on Regional Brain Metabolism in Essential Tremor Subjects Scheduled to Undergo Deep Brain Stimulation Surgery

• 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

• 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

• 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

• Kinematic data mean change in units of meters^2/sec (pre-stimulation tremor power - post-stimulation tremor power) across stimulation sessions.

essential tremor/carbohydrate

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

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