Clinical Evidence


Essential Tremor

Essential tremor (ET) is one of the most common movement disorders that is well classified in its physiologic and phenotypic mechanisms.

The largest therapeutic clinical trial in ET, PROSPECT, was conducted using the Cala Trio™ device. Studies have shown that commonly prescribed medications benefit about half of patients with essential hand tremor which is similar to Cala Trio therapy. The electrical stimulation uses the same pathways as brain implants.

The FDA-cleared, wearable Cala Trio therapy avoids common side-effects and risks associated with traditional ET treatment options.


Cala TrioTM delivers significant tremor reduction in clinician-rated, patient-rated and objective accelerometer measurements.

The largest therapeutic essential tremor study ever conducted, PROspective study for SymPtomatic relief of Essential tremor with Cala Therapy (PROSPECT)

Per-patient tremor power* reduction demonstrated in home-use therapy sessions

Per-Patient median tremor power reduction

* Tremor power is a calculation of amplitude and frequency. Tremor power decreases with lower amplitude motions and lower frequency motions.

Tremor reduction of 50% is comparable to first-line pharmacotherapies: propranolol and primidone, but without their side effect profile.2,3 Some patients had tremor reduction as large as 55-90%, similar to surgical outcomes, but without the risk of permanent side effects.2,4


TETRAS Improvement at Clinic Visits

TETRAS Improvement at Clinic Visits

* p < 0.0001


ADL Improvement at Clinic Visits

ADL improvement at clinic visits


TETRAS Dominant Hand Rating

TETRAS Dominant Hand Rating charts


ADL Dominant Hand Rating

ADL Dominant Hand Rating diagrams

Mechanism of Action

The Cala Trio has electrodes on the inside of the wrist band which deliver electrical stimulation to the median and radial nerves. This desynchronizes tremulous activity in the brain. This new approach of peripheral surface stimulation is thought to disrupt pathological tremor frequency signals in the central neural network and show meaningful reduction of tremor in the patient’s treated hand.

Now you can treat your patients’ specific tremor patterns using advanced targeted therapy for more personalized care.

Variability of Essential Tremor

Essential tremor is a progressive and clinically heterogeneous condition with sporadic and familial forms. Tremor amplitude increases with age, accounting for substantial disability in older people.5

The clinical sub-types of essential tremor are not well understood at this time. This may explain the variance in the magnitude of response seen in patients using Cala Trio. On average, 54% of patients improved by at least 50% and 25% of patients improved by at least 70%, measured by tremor power.* Use of the device is the best way to assess if Cala Trio is effective for any individual patient.

* Tremor power is a calculation of amplitude and frequency. Tremor power decreases with lower amplitude motions and lower frequency motions.

5 Dietrich Haubenberger, M.H.Sc., M.D., and Mark Hallett, M.D., D.M.,N Engl J Med 378;19 May 10, 2018

An Effective, Safe Tremor Therapy

A non-surgical solution that alleviates fear patients may have of surgery or permanent side effects

Tremor reduction without systemic side effects and drug interactions

Users of Cala Trio experienced only mild to moderate skin irritation including electrical stimulation burns, redness, and/or itching.

Early Research

Several multicenter clinical trials have studied the effectiveness of Cala Trio in treating essential tremor. Physician-rated and patient-rated improvements are shown below.

TETRAS dominant hand upper limb tremor score
(Physician rating)

TETRAS dominant hand upper limb tremor score (Physician rating)

Bain & Findley Activity of Daily Living (ADL) tasks
(Patient rating)

Bain & Findley Activity of Daily Living (ADL) tasks (Patient rating)

Randomized controlled study of 77 subjects who received either treatment (N=40) or sham (N=37). Tremor was evaluated before and immediately after the end of a single 40-minute stimulation session.6

6 Pahwa, et al. An Acute Randomized Controlled Trial of Noninvasive Peripheral Nerve Stimulation in Essential Tremor, Neuromodulation 2019.

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Indication for Use

The Cala Trio therapy is prescribed by a physician and is indicated to aid in the transient relief of hand tremors in the treated hand following stimulation in adults with essential tremor. Refer to Safety Information for a complete list of warnings, precautions, and contraindications.

Safety Information

This section lists general Warnings and Cautions related to using Cala Trio.


  • To avoid the risk of electric shock, burns, electrical interference, or death, do not use Cala Trio if you have:
    • A pacemaker
    • An implanted defibrillator
    • Other implanted electronic devices, or implanted metal in the wrist
  • Do not use Cala Trio while:
    • Sleeping
    • Driving
    • Bathing
    • Operating machinery
    • Doing any activity in which possible involuntary muscle contractions due to therapy may cause undue risk of injury.
  • Do not use Cala Trio:
    • Near the head
    • Directly on the eyes
    • Covering the mouth
    • On your upper back
    • Over the heart area
    • On diseased skin
  • Do not use Cala Trio on the neck.
    • Doing so can cause severe muscle spasm, resulting in closure of the airway, difficulty with breathing, or adverse effects on heart rhythm.
  • Do not use Cala Trio on the chest.
    • Introduction of electric current into the chest may cause rhythm disturbances to the heart, which could cause death.
  • Do not apply Cala Trio near the chest.
    • This may increase the risk of abnormal heart rhythm (arrhythmia).
  • Do not apply Cala Trio over open wounds or rashes, or over swollen, red, infected, or inflamed areas or skin eruptions (e.g., phlebitis, thrombophlebitis, varicose veins, etc.).
  • Do not apply Cala Trio over—or in proximity to—cancerous lesions.
  • To prevent electrical shock, do not immerse Cala Trio in water.
  • Do not wear Cala Trio while performing activities where Cala Trio is under water (e.g., swimming or bathing).
  • Do not use Cala Trio simultaneously with:
    • High-frequency surgical equipment, as this may result in electrical burns and/or possible damage to Cala Trio
    • Electronic- monitoring equipment (e.g., cardiac monitors, ECG alarms), which may not operate properly when Cala Trio is in use
  • To prevent an explosion hazard and possible injury, stop Cala Trio therapy when at a refueling place (e.g., gas station).
  • Do not use Cala Trio near flammable fuel, fumes, or chemicals.
  • Physician approval should be obtained by your prescribing physician before using Cala Trio if you have any implanted devices at the site of stimulation.
  • Cala Trio provides chronic electrical stimulation, the long-term effects of which are unknown.
  • To prevent uncomfortable therapy, skin irritation and/or shock, the user should wet their wrist before donning Cala Trio.
  • Therapy at an intensity that is too high can cause discomfort in your wrist and/or hand, muscle contraction, or skin irritation.
  • Some may experience skin irritation, an allergic reaction, or hypersensitivity to the therapy or the band.
  • Avoid removing Cala Trio from your wrist during therapy.
  • To charge Cala Trio, use only the Cala Trio Base Station.
  • The cord on the charger may present a choking hazard. Keep away from children.


  • Use Cala Trio only as directed by this Patient Guide or your physician.
  • Do not use Cala Trio if you have suspected or diagnosed epilepsy or other seizure disorder.
  • Do not use Cala Trio if you are pregnant.
  • Higher stimulation levels may be associated with potential for increase in skin irritation, including electrical stimulation burns of the skin, which may cause focal pinpoint edema, erosion and crusting.
  • Store Cala Trio in the included microfiber bag to prevent exposure to dust and pests.
  • To prevent damage and/or performance issues to Cala Trio:
    • Keep Cala Trio dry. Cala Trio can withstand some splashing.
    • Do not use in places with high humidity (e.g., the bathroom).
    • Do not store or transport Cala Trio or its accessories in temperatures that exceed the recommended storage temperature range: -20°C to 45°C (-4°F to 113°F).
    • Do not operate in temperatures that exceed the recommended operation temperature range of 5°C to 40°C (41°F to 104°F). Temperature extremes can damage the device and accessories.
    • Do not tamper with, modify, or attempt to perform maintenance or servicing on Cala Trio.
    • Do not use Cala Trio within 3 ½ feet of shortwave or microwave equipment.
  • To prevent damage, performance issues, increased emissions, or decreased immunity of Cala Trio, only use the accessories recommended by Cala Health with the device.
  • Use Cala Trio with caution:
    • If you tend to bleed following an injury.
    • Over areas of the skin that lack normal sensation.
  • Keep out of the reach of children and pets.
  • Cala Trio is single-patient use by the individual for whom it has been prescribed.
    • It should not be worn by anyone else, or on any other part of your body.
  • To avoid interfering with diagnostic assessments, do not wear Cala Trio during x-ray examinations.
  • To prevent Cala Trio band damage, do not pinch, pull, or twist the Band with too much force.
  • Should any technical problem occur that is not covered in the Patient Guide, please contact Cala Health at 888-699-1009 or

Adverse Reactions

The following are possible minor risks or adverse reactions that you may experience with the use of Cala Trio:

  • Discomfort with stimulation (e.g. stinging, sensation of weakness, etc.)
  • Allergic reaction to electrodes or other materials
  • Skin irritation, including electrical stimulation burns, redness and/or itching

In the unlikely event that any of the following more significant issues happen, immediately stop using Cala Trio and contact your physician.

  • Signs of significant persistent skin irritation, sores, electrical stimulation burns, or lesions at the site of the stimulation
  • Significant and persistent increase in muscle tightness or stiffness
  • A feeling of chest pressure during stimulation
  • Swelling of your arm, wrist, or hand

Skin Care Guidelines

The device works by electrically stimulating nerves through the skin. It is important to inspect your skin where it contacts the electrodes to minimize risk of irritation. To promote good electrode connection and healthy skin, try some of these skin care guidelines:

  • Wet your wrist before donning Cala Trio
  • If there is any excess oil or lotion on your wrist, wash with soap and water and rinse well before wearing Cala Trio
  • Always check your skin for irritation, redness, or rash when putting on and taking off Cala Trio