Medical Policy

This document addresses a wrist-worn external upper limb tremor stimulator of the peripheral nerves. This non-pharmacological/non-surgical treatment option is proposed to aid in the temporary relief of essential tremor (also known as, familial essential tremor or hereditary tremor) of the hand as well as Parkinson’s disease.

Please see the following related document for additional information:

• SURG.00026 Deep Brain, Cortical, and Cerebellar Stimulation

Investigational and Not Medically Necessary:

Wrist-worn external upper limb tremor stimulator is considered investigational and not medically necessary for all indications, including but not limited to the treatment of essential tremor of the hands and Parkinson’s disease.

Essential tremor (ET) is the most common neurological disorder among adults and is the most prevalent tremor disorder. The exact mechanisms of ET are not fully understood, however recent studies suggest that ET may be a neurodegenerative disorder.

External upper limb tremor stimulation devices (Cala Trio/Cala kIQ^™ [Cala Health, Inc. Burlingame, CA]), are  on-demand, non-invasive, wrist-worn devices that deliver individualized electrical stimulation to the median and radial nerves of the arm in people with ET. One such device is the Cala Trio Therapy. The proposed action of this device is the delivery of transcutaneous afferent patterned stimulation (TAPS) to the ventral intermediate nucleus thalamus, a key relay point in the central tremor network, and one target of deep brain stimulation (DBS), an invasive treatment of ET. Noninvasive TAPS stimulation to the upper limb using the Cala Trio device is calibrated to an individual’s tremor pattern and the user can adjust its strength to account for daily variations in tremor activity. Cala kIQ is the next generation device subsequently developed by the manufacturer to treat action hand tremor for individuals with ET and Parkinson’s disease. Cala kIQ is also wrist-worn and utilizes TAPS technology. Cala kIQ is purported to sense an individual’s unique tremor and deliver individualized therapy; one therapy session lasts for 40 minutes and sessions may be completed as often as five times daily.

In October 2021, the U.S. Food and Drug Administration (FDA) granted 510k clearance for Cala Trio Therapy with the indication to aid in the temporary relief of hand tremors in the treated hand following stimulation in adults with ET. The device stimulates the nerves in the arm to disrupt the neural signals that cause essential tremor. In November 2022, the FDA granted 510k clearance for the Cala kIQ as a substantially equivalent device. The indications for use are to aid in the temporary relief of hand tremors in the treated hand following stimulation in adults with ET, and to aid in the temporary relief of postural and kinetic hand tremor symptoms that impact activities of daily living in the treated hand following stimulation in adults with Parkinson’s disease. Clearance of the Cala kIQ device for Parkinson’s disease was based on a single-arm, non-significant risk study that evaluated calibrated therapy in patients with Parkinson’s Disease who also had postural hand tremor. A total of 40 individuals were enrolled in the study. Across visits, individuals were assessed using an unvalidated subset of the Movement Disorder Society-Unified Parkinson’s Disease Rating Scale (MDS-UPDRS) dominant hand tasks, and activities of daily living (ADLs) based on an unvalidated subset of Bain and Finley-ADL (BF-ADL) tasks. There were no reports of device-related serious adverse events, and all were resolved with minimal intervention. As noted in the FDA 510(k) Premarket Notification summary:

These results were descriptive in nature, different patients showed improvement in different tasks tested. None of the patients showed improvement in all of the tasks tested and some of the patients showed no improvement in any of the tasks tested.

There is no data comparing the Cala kIQ device vs. a sham-control device in individuals with Parkinson’s disease, and insufficient evidence to assess how the device affects health outcomes.

The predicate device to the Cala Trio and the Cala kIQ was the CalaONE, which obtained De Novo designation from the FDA in May 2017 (DEN170028). According to the De Novo summary document, the CalaONE failed to show a benefit versus placebo (FDA, 2017).The FDA clearance for the Cala Trio therapy was supported by data from the Prospective Study for Symptomatic Relief of ET with Cala Therapy (PROSPECT; NCT03597100), a prospective, post-clearance, multicenter, single-arm, open-label clinical trial evaluating the safety and efficacy of wrist worn TAPS therapy over a 3-month period. Isaacson and colleagues (2020) reported findings for 205 of 263 participants who enrolled in and completed the study. Participants were instructed to use Cala Trio therapy twice daily (in 40-minute sessions) for 3 months, including three in-clinic visits. The co-primary endpoints were clinician-related Tremor Research Essential Tremor Rating Assessment Scale (TETRAS) and patient-rated Bain & Findley Activities of Daily Living (BF-ADL) dominant hand score. Other study measures included “improvement in the tremor power detected by an accelerometer on the therapeutic device, Clinical and Patient Global Impression scores (CGI-I, PGI-I), and Quality of Life in Essential Tremor (QUEST) survey.” Eligibility criteria included participants ≥ 22 years of age, a confirmed diagnosis of ET by a movement specialist, a tremor severity score of 2 or above in the dominant hand or arm by any of the TETRAS upper limb items, and a minimum score of 6 across all upper limb items. A BF-ADL score of 3 or more in any one of the upper limb items, a mi­nimum subset score of 8 across all upper limb items, and stable dose of tremor and antidepressant medications were inclusion criteria. Participants were excluded if they had significant alcohol or caffeine consumption within 8 hours prior to the study enrollment, any implanted medical devices or implanted metal in the wrist to be stimulated, presence of other neurodegenerative disease like Parkinson-plus syndrome on neurological exam, suspected idiopathic Parkinson’s disease, including presence of parkinsonian features, suspected or diagnosed epilepsy or other seizure disorder, or previous thalamotomy procedure, including stereotactic thalamotomy, gamma knife radiosurgical thalamotomy, and focused ultrasound for the treatment of tremor. The authors reported that the study co-primary endpoints were met (p<0.00001), with 62% (TETRAS) and 68% (BF-ADL) of ‘severe’ or ‘­­­moderate’ individuals reported improving to ‘mild’ or slight’. These results excluded 58 participants that withdrew from the study. There were no serious adverse events reported. Device-related adverse events were reported to have occurred in 18% of participants, with 64% rated mild (itchiness, discomfort), 34% as moderate (electrical burn, significant discomfort), and 2% as severe (1 event, a fall, which was possibly device-related). The study did not find a relationship between concurrent ET medication usage and response to TAPS therapy (66% of participants were on a medication to treat tremor). While initial results look promising for use of TAPs therapy in individuals with ET of the upper extremities the mechanism of therapy remains unclear, and limitations of the study include lack of blinding, absence of a control group (or randomization), and a short duration of follow-up. The authors concluded “future work examining how these clinical trial results translate into the real-world setting would be valuable” and to “establish robust methods to longitudinally maintain a patient blind for peripheral neuromodulation therapies.” Two additional manufacturer sponsored clinical trials (NCT05540626, NCT05480215) regarding the Cala Trio device were completed in 2022, however, no results have been published as of the time of this review.

Barath and colleagues (2020) reported an interventional, open-label, single-group study investigating the changes in brain metabolism over 3 months of TAPS use in 5 ET (n=5) participants. Each participant received 40 minutes of TAPS treatment twice daily for 90 days. Brain metabolic activity and tremor severity were measured at baseline, and after 90 days using F-fluorodeoxyglucose (FDG) PET/CT and TETRAS. The participant’s tremor power and frequency were measured before and after therapy sessions. Inclusion criteria were ≥ 21 years of age and approved for DBS surgery by the Mayo Clinic DBS Committee for treatment of ET. Participants were excluded if they had alcohol dependence or had an implanted pacemaker, defibrillator, or deep brain stimulator. The mean age of the study participants was 70.2 ± 5.2 years, and the duration of ET ranged from 10 to 57 years (mean 32 ± 16.8 years). Participants enrolled for approximately 89.2 days ± 4.8 days and completed 136.2 ± 41.3 TAPS sessions; participant compliance was 77.3 ± 25.6 %. The FDG PET/CT results demonstrated areas of increased metabolism in the ipsilateral cerebellar hemisphere and decreased metabolism in the contralateral hemisphere following 90 days of therapy, compared to day 1 (p<0.05). Comparison of pre- and post-therapy measurements over 90 days showed decreased tremor power (p<0.0001), but no change in frequency. The day 1 TETRAS scores decreased from 6.5 to 4.1 following TAPS (p=0.05). The 90-day pre- and post-TETRAS scores also decreased from 4.9 to 4.1 (p=0.14 and p=0.05, respectively). No adverse events were reported. The authors concluded that longitudinal TAPS of the median and radial nerves affect brain metabolism in areas necessary for motor coordination which may cause ET. Study limitations included its small study population and weak power. Additional studies with robust methodology and power are needed to further elucidate the clinical mechanism of TAPS.

Yu and colleagues (2020) reported a single-arm, open-label study, of 15 individuals with ET who received TAPS therapy. The aim was to evaluate the duration of tremor reduction. Inclusion criteria were individuals 22 years of age and older diagnosed with ET by an internist or neurologist. Participants performed four hand tremor-specific tasks (postural hold, spiral drawing, finger-to-nose reach, and pouring) from the Fahn-Tolosa-Marin Clinical Rating Scale (FTM-CRS) prior to, during, and 0, 30, and 60 minutes following TAPS therapy. Tremor severity was rated using the FTM-CRS, and simultaneously with wrist-worn accelerometers. The duration of tremor reduction was measured by improvement in the mean FTM-CRS score across all four tasks compared to baseline, and reduction in accelerometer-measured tremor power compared to baseline for each task. The results demonstrated that mean FTM-CRS scores improved for at least 60 minutes beyond the end of TAPS for 80% of participants. For the assessed tasks, tremor power improved for at least 60 minutes beyond the end of TAPS for over 70% of participants. The postural hold task had the most significant reduction in tremor power (median 5.9-fold peak reduction in tremor power) and had at least 60 minutes of improvement relative to baseline beyond the end of TAPS therapy for 73% of participants. No adverse events were reported. The authors concluded that tremor power is a valid, objective assessment metric, and that TAPS therapy may improve upper limb tremor symptoms for at least 1 hour post therapy which may improve ability to perform ADL’s in individuals with ET. The authors also noted that 5 of the 15 subjects in this study who were on pharmacologic treatment for ET, may have ingested medication that could have influenced the duration of effect. The NIH considers TETRAS the superior ET assessment measure compared to FTM, stating “TETRAS has two main advantages over FTM in the assessment of tremor severity: (1) the absence of a ceiling effect in patients with severe ET, and (2) the inclusion of wing‐beating tremor” (2017). While the results of this study are promising, larger cohorts with similar ET tremor scales are needed to further evaluate the clinical utility of TAPS.

The American Academy of Neurology (AAN) has an evidence-based guideline update for the treatment of essential tremor that was last reaffirmed July 2017 (Zesiewicz, 2017). This document includes recommendations for pharmacologic agents and surgical interventions for individuals with ET. No recommendations for use of external upper limb tremor stimulator device as a treatment of ET are provided.

The International Essential Tremor Foundation’s (IETF) Essential Tremor in Adult Patients Guideline Advisory document (2021) recognizes Cala Trio therapy as a “optional add-on non-pharmacological/non-surgical treatment” in combination with first-line pharmacological approaches (propranolol, primidone), or prior to or in conjunction with second- or third-line pharmacotherapies (topiramate, gabapentin, other beta blockers, or benzodiazepines). However, the recommendations which were updated in 2023, remain based on expert consensus for Cala Trio therapy and are not supported by any evidence-based explanation.

Lu and colleagues (2023) published a 3.4 year retrospective analysis of the TAPS device. A registry was utilized to identify 1,233 individuals that were prescribed TAPS for ET and had used the device beyond 90-days. The study evaluated the usage, effectiveness, safety, and durability of TAPS. The inclusion criteria were the prescriber indicated a diagnosis of ET and the individual had used TAPS beyond the 90-day trial period. Exclusion criteria for all analyses, except the survey, were; 1) individuals that completed an insufficient number of sessions, defined as having completed fewer than 10 sessions that were at least 20 minutes in duration, 2) individuals that had not completed 10 sessions of TAPS with accelerometry measurements free of motion artifact that could be used to measure effectiveness before and after therapy, and 3) accelerometry that was measured no longer than 15 minutes before or 15 minutes after therapy, and was started at least 120 minutes after a prior session (to minimize carry-over effects). Eight hundred eight individuals passed the exclusion criteria. However, another 81 were excluded for having no postural hold data and another 334 were excluded for having fewer than 10 sessions of postural hold data. Final effectiveness analysis was derived from data for the remaining 386 individuals. The results showed the average tremor power improvement ratio was 2.8, (64.3% reduction) based upon accelerometry data. Additionally, 49.8% of individuals showed at least 50% tremor reduction, and 88.1% had at least 50% of sessions with a tremor improvement ratio. Average device usage was 5.6 sessions per week and no habituation was reported. Sixty two percent of the survey respondents reported reduced medication utilization (no p-values provided). One safety-related complaint was reported in 10.2% of individuals (discomfort 5.3%, skin irritation 6.9%, and physical symptoms 1.9%) but no serious safety events were reported. The authors concluded that the results reinforced and extended prior efficacy findings regarding the safety, usage, and durability of TAPS for tremor management in patients with ET. However, the study is limited by several factors, including the wrist-worn accelerometry provided a proxy assessment of hand tremor amplitude, only adverse events that were reported by participants to the manufacturer were recorded, and the low response rate to the voluntary survey. 

Isaacson (2023) performed a review of seven studies that assessed the response to TAPS in the high unmet need subgroup (defined as a severe tremor, non-responsive to medication, age ≥65 years) and early responders (defined as substantial TAPS tremor improvement in the first month). Two of the studies were randomized controlled trials (RCT [Lin, 2018 and Pahwa, 2019]) that delivered a single session of TAPS treatment or sham in 23 and 93 enrolled ET participants, respectively. Additionally, there were three open label single-arm studies (Yu, 2020,  Isaacson, 2020, and Barath, 2021) which evaluated a single TAPS session in 15 participants, as well as two home-use studies that evaluated twice-daily TAPS sessions over 3 months in 263 and 5 participants, respectively. Two real-world evidence analyses were also performed using a device registry database in 321 participants (Brillman, 2022) and 1,223 participants (Lu, 2023), with participants using TAPS therapy as-needed in the home setting. The analyses were performed using previously collected TETRAS scores, BF-ADL scores, and tremor power. Differences in BF-ADL and TETRAS improvement were observed with TAPS over sham for the high unmet need subgroup in a RCT (p<0.001). Analysis of previous evidence demonstrated that early responders maintained effectiveness and usage at 3 and 12 months (p<0.001). The authors concluded that compared to the original study population, similar or superior effectiveness was shown in the high unmet need sub group. Additionally, individuals who exhibited an early response to therapy achieved tremor reduction without developing therapy habituation over long-term usage. The studies addressed in this review were discussed above and found to have methodological weaknesses.

Dai and colleagues (2023) reported a non-blinded, randomized, prospective study that evaluated the clinical benefit of adding TAPS treatment to Standard of Care (SOC) versus SOC alone. It is notable that this may have included anti-tremor medication therapies in some participants. Individuals received a TAPS device and were randomized 1:1 to either 1 month adding TAPS therapy to usual care (treatment arm, n=119), or usual care with tremor assessment only (SOC arm, n=123). Inclusion criteria were individuals diagnosed with ET, defined as having at least two medical claims with an ET diagnosis code at least 7 days apart in the last 3 years, or one claim with an ET diagnosis code followed by at least one dispensed pharmaceutical treatment that can be used for ET; aged 22 years or older; and individuals with health insurance. Exclusion criteria were a diagnosis of Parkinson’s, Alzheimer’s, dementia, epilepsy, thyroid disorders, implanted pacemaker, defibrillator, or deep brain stimulator, individuals who had undergone ET-related neurosurgery or magnetic resonance-guided focused ultrasound, used botulinum toxin in the upper extremity in the last 6 months, were pregnant, or had hand lesions at the stimulation site. The outcomes assessed were changes in tremor power measured by motion sensors on the device, and improvement in BF-ADL upper limb scores between treatment and SOC groups. The results demonstrated tremor power, expressed as a geometric mean, in the treatment arm (0.017 m/s^2/2) was lower than tremor power in the SOC arm (0.08 m/s²)² in the modified intention to treat group (p< 0.0001), as well as in the per protocol analysis, (p< 0.0001). One hundred thirty four of the 276 individuals completed the BF-ADL ratings at baseline and 1 month. The changes in BF-ADL scores from baseline to 1 month in the treatment arm (1.6, n=51) were greater than the changes observed in the SOC arm (0.22, n=83), (p=0.0187). One hundred fourteen of the 242 individuals in the per-protocol analysis completed the BF-ADL ratings at baseline and 1 month. The changes in BF-ADL scores in the treatment arm (1.5, n=47) were greater than changes observed in the SOC arm (–0.1, n=67) (p=0.0077). The BF-ADL scores improved from baseline to 1 month by 2.4 points in the treatment arm (p=0.0006), whereas no significant improvements were observed in the SOC arm (p=0.55). While this study is promising, distal endpoints are needed to establish durability of the intervention. The contributory effects of medication therapies used during the study on the tremor power measurements is unknown.

In summary, the available evidence in peer-reviewed medical literature is insufficient to evaluate the effect of TAPS therapy with Cala Trio on health outcomes in individuals with ET. Additional evidence in the form of well-designed and conducted studies measuring longer follow-up times are needed to evaluate the clinical utility of this treatment approach.

According to the National Organization for Rare Disorders (NORD) rare disease database for essential tremor, nearly 7 million Americans are currently diagnosed with ET. The incidence of ET increases with age and more than 4% of individuals over age 40 have ET (NORD, 2022). The National Institute of Neurological Disorders and Stroke (NINDS) considers ET a chronic, progressive, and disabling neurological disease that causes uncontrolled rhythmic shaking. It is characterized by the presence of an action tremor (shaking during voluntary muscle movements), most often the hands or arms. In individuals with ET, other motor symptoms may be present including an unsteady manner of walking due to an inability to coordinate voluntary movements (ataxia), and in some cases, a variety of non-motor symptoms including cognitive impairment, depression or anxiety may develop. Population-based studies in the U.S. estimate that 2.2% of the U.S. population suffers from ET, and although most common among the elderly, the prevalence is increasing across age groups. Individuals with ET have higher rates of anxiety and depression than the general population, and difficulties with normal daily activities can potentially dramatically impact quality of life (NINDS, 2022).

There is no cure for ET and only a handful of pharmacologic or surgical treatments exist to help individuals manage their symptoms. First-line treatment consists of pharmacotherapies, such as propranolol and primidone. Second and third-line pharmacological approaches include topiramate, gabapentin, other beta-blockers, or benzodiazepines. However, response to pharmacotherapies varies, and high doses are often required for effective tremor reduction, increasing the burden of side effects for individuals and reducing tolerability and compliance. Deep brain stimulation surgery and magnetic resonance imaging (MRI)-guided focused ultrasound ablation are additional treatment options for tremor. However, not all individuals are appropriate candidates for such surgical procedures.

Essential tremor (ET): A chronic, incurable condition with unknown cause characterized by involuntary, rhythmic movement of a body part, most typically the hands and arms.

The following codes for treatments and procedures applicable to this document are included below for informational purposes. Inclusion or exclusion of a procedure, diagnosis or device code(s) does not constitute or imply member coverage or provider reimbursement policy. Please refer to the member's contract benefits in effect at the time of service to determine coverage or non-coverage of these services as it applies to an individual member.

When services are Investigational and Not Medically Necessary:
For the following procedure codes, or when the code describes a procedure indicated in the Position Statement section as investigational and not medically necessary.

Peer Reviewed Publications:

1. Barath AS, Rusheen AE, Min HK, et al. Brain metabolic changes with longitudinal transcutaneous afferent patterned stimulation in essential tremor subjects. Tremor Other Hyperkin Mov. (2020; 10(1):52.
2. Brillman S, Colletta K, Borucki S, et al. Real-world evidence of Transcutaneous Afferent Patterned Stimulation for Essential Tremor. Tremor and Other Hyperkin Mov. 2022; 12:1–11.
3. Dai D, Fernandes J, Kim H, et al. Comparative effectiveness of Transcutaneous Afferent Patterned Stimulation therapy for Essential Tremor: A randomized pragmatic clinical trial. Tremor and Other Hyperkin Mov. 2023;16 (13):38. Epub: Available at: https://pubmed.ncbi.nlm.nih.gov/37869579/. Accessed on March 15, 2024.
4. Isaacson SH, Peckham E, Tse W, et al. Prospective home-use study on non-invasive neuromodulation therapy for essential tremor. Tremor Other Hyperkin Mov. 2020; 10:1-16.
5. Isaacson S, Pahwa R, Brillman S, et al. Clinical benefit of transcutaneous afferent patterned stimulation (TAPS) in essential tremor patients with high unmet need: a secondary analysis of TAPS studies, Expert Rev Med Devices. 2023 Oct 25; [Epub ahead of print]. Available at: https://doi.org/10.1080/17434440.2023.2274604. Accessed on March 15, 2024.
6. Lin PT, Ross EK, Chidester, et al. Non-invasive neuromodulation in essential tremor demonstrates relief in a sham-controlled pilot trial. Mov Disord. 2018; 33:1182-1183.
7. Lu C, Khosla D, Kent A, et al. Transcutaneous Afferent Patterned Stimulation for Essential Tremor: real-world evidence with long term follow-up. Tremor and Other Hyperkin Mov. 2023;13:1–13.
8. Pahwa R, Dhall R, Ostrem J, et al. An acute randomized controlled trial of noninvasive peripheral nerve stimulation in essential tremor. Neuromodulation. 2019; 22:537-545.
9. Yu JY, Rajagopal A, Syrkin-Nikolau J, et al. Transcutaneous Afferent Patterned Stimulation (TAPS) therapy reduces hand tremor for one hour in essential tremor patients. Front. Neurosci. 2020; 14:530300.

Government Agency, Medical Society, and Other Authoritative Publications:

1. Cala Health, Inc. A Pilot Study of the Cala ONE Device for Essential Tremor. NLM Identifier: NCT03152136. Last updated April 30, 2019. Available at: https://clinicaltrials.gov/study/NCT03152136. Accessed on March 15, 2024.
2. Cala Health, Inc. Cala ONE Device for Essential Tremor. NLM Identifier: NCT02629614 Available at: https://clinicaltrials.gov/study/NCT02629614. Accessed on March 15, 2024.
3. Cala Health, Inc. Long-Term Transcutaneous Stimulation and Essential Tremor: A PET Study. NLM Identifier: NCT03778060. Available at: https://clinicaltrials.gov/study/NCT03778060. Accessed on March 15, 2024.
4. Cala Health, Inc. Prospective Study for Symptomatic Relief of ET with Cala Therapy (PROSPECT). NLM Identifier: NCT03597100. Last updated October 12, 2023. Available at: https://clinicaltrials.gov/ct2/show/NCT03597100. Accessed on March 15, 2024.
5. Cala Health, Inc. RWE Study Utilizing the Cala Trio Device in Patients With Essential Tremor. NLM Identifier: NCT05540626. Last updated November 14, 2022. Available at: https://clinicaltrials.gov/study/NCT05540626. Accessed on March 15, 2024.
6. Cala Health, Inc. Symptomatic Relief of Action Tremor With Cala Trio Using Trio+ Bands. NLM Identifier: NCT05480215. Available at: https://clinicaltrials.gov/study/NCT05480215. Accessed on March 15, 2024.
7. Cala Health, Inc. Transcutaneous Afferent Patterned Stimulation (TAPS) for Reduction of Parkinson's Disease (PD) Related Action Tremor. NLM Identifier: NCT05012579. Available at: https://clinicaltrials.gov/study/NCT05012579. Accessed on March 15, 2024.
8. Centers for Medicare and Medicaid Services (CMS). National Coverage Determination: Treatment of motor function disorders with electric nerve stimulation. NCD#160.2. Effective April 1, 2003. Available at: https://www.cms.gov/medicare-coverage-database/view/ncd.aspx?ncdid=22&ncdver=2&keyword=essential%20tremor&keywordType=starts&areaId=all&docType=NCD,F&contractOption=all&sortBy=relevance&bc=1.
9. International Essential Tremor Foundation Consensus and Physician Experts. Essential tremor in adult patients. Available at: https://www.guidelinecentral.com/guideline/502775/. Accessed on March 15, 2024.
10. U.S Food and Drug Administration (FDA). 510k Summary. K2032088. Cala Health, Inc. Cala Trio. Available  at: https://www.accessdata.fda.gov/cdrh_docs/pdf20/K203288.pdf. Accessed on March 15, 2024.
11. U.S Food and Drug Administration (FDA). 510k Summary. K222237. Cala Health, Inc. Cala kIQ. Available at: https://www.accessdata.fda.gov/cdrh_docs/pdf22/K222237.pdf. Accessed on March 15, 2024.
12. Zesiewicz TA, Elble RJ, Louis ED, et al. Evidence-based guideline update: Treatment of essential tremor. Report of the Quality Standards Subcommittee of the American Academy of Neurology. Last reaffirmed on July 29, 2017. Available at: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3208950/ Accessed on March 15, 2024.

1. National Institute of Neurological Disorders and Stroke. Tremor fact sheet. Last reviewed June 7, 2023. Available at: https://www.ninds.nih.gov/health-information/disorders/essential-tremor?search-term=essential%20tremor%20fact%20sheet. Accessed on March 15, 2024.
2. National Library of Medicine. Medical Encyclopedia. Essential tremor. Available at: https://medlineplus.gov/ency/article/000762.htm#:~:text=Essential%20tremor%20(ET)%20is%20a,stop%20the%20shaking%20at%20will. Accessed on March 15, 2024.
3. National Library of Medicine. Journal list. Ondo W, Hashem V, LeWitt PA, et al. Comparison of the Fahn-Tolosa-Marin Clinical Rating Scale and the Essential Tremor Rating Assessment Scale. Mov Disord Clin Pract. 2017 23;5(1):60-65. Available at: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6174461/. Accessed on March 15, 2024.
4. National Organization for Rare Disorders. Rare disease database. Essential tremor. Available at: https://rarediseases.org/?s=essential+tremor&rdb-search=true&post_type%5B%5D=rare-diseases&post_type%5B%5D=gard-rare-disease. Accessed on March 15, 2024.

Cala Trio
External upper limb tremor stimulator

The use of specific product names is illustrative only. It is not intended to be a recommendation of one product over another, and is not intended to represent a complete listing of all products available.