Optimizing Parameters of Transcranial Temporal Interference Stimulation for Spinocerebellar Ataxia Type 3

August 3, 2026 updated by: Xinyuan Chen, First Affiliated Hospital of Fujian Medical University

Efficacy and Safety of Transcranial Temporal Interference Stimulation of the Cerebellar Dentate Nucleus Using Individualized Head Modeling in Patients With Spinocerebellar Ataxia Type 3

The purpose of this research study is to identify the optimal biological dose for tTIS that targets DN in SCA3 while achieving the best possible balance between therapeutic efficacy and safety.

Study Overview

Status

Not yet recruiting

Conditions

Intervention / Treatment

Detailed Description

Spinocerebellar ataxia type 3 (SCA3), also known as Machado-Joseph disease, is an autosomal dominant neurodegenerative disorder caused by CAG repeat expansion in the ATXN3 gene. Selective degeneration of neurons in the cerebellar dentate nucleus (DN) leads to abnormal cerebellar outflow circuitry and impaired motor control, resulting in progressive gait ataxia, dysarthria and other motor symptoms. Current treatments are symptomatic only, with no disease-modifying therapies available. Deep brain stimulation targeting the dentate nucleus has shown efficacy but is invasive and associated with significant adverse events.

Transcranial temporal interference stimulation (tTIS) enables non-invasive, deep and spatially precise neuromodulation. It has been applied in various neurological and psychiatric disorders with favorable safety and efficacy, demonstrating potential for neuromodulation of deep cerebellar circuits.

This phase I/II adaptive dose-finding prospective interventional study evaluates the safety and efficacy of tTIS targeting the cerebellar dentate nucleus in patients with spinocerebellar ataxia type 3. Using MRI-derived individualized head models and real-time neuronavigation, the study employs a utility-based Bayesian optimal interval (U-BOIN) design with three difference frequencies: 30 Hz, 40 Hz, and 70 Hz. Patients are enrolled in sequential cohorts of three, with dose escalation guided by a utility-based approach integrating safety and efficacy data. Each patient receives ten tTIS sessions over two consecutive weeks, with one session daily. Motor function, balance function, activities of daily living, and multimodal magnetic resonance imaging are evaluated before the first treatment session and after the final treatment session.

Study Type

Interventional

Enrollment (Estimated)

24

Phase

  • Not Applicable

Contacts and Locations

This section provides the contact details for those conducting the study, and information on where this study is being conducted.

Study Contact

Study Contact Backup

Study Locations

  • China
    • Fujian
      • Fuzhou, Fujian, China
        • Department of Rehabilitation Medicine, The First Affiliated Hospital of Fujian Medical University
        • Contact:

Participation Criteria

Researchers look for people who fit a certain description, called eligibility criteria. Some examples of these criteria are a person's general health condition or prior treatments.

Eligibility Criteria

Ages Eligible for Study

  • Adult
  • Older Adult

Accepts Healthy Volunteers

No

Description

Inclusion Criteria:

  1. A physician-diagnosed SCA3 according to diagnostic criteria, with definite clinical symptoms and confirmed genetic testing;
  2. Age 18-75 years;
  3. Baseline total score of SARA: 8-30 points (inclusive); SARA gait function subscore: 2-6 points (inclusive);
  4. Willing to participate and provide informed consent;
  5. Have a reliable caregiver available;
  6. No severe cognitive impairment that would preclude reliable reporting of adverse events or efficacy during treatment.

Exclusion Criteria:

  1. History of seizures or convulsions, or a seizure within 6 months prior to enrolment;
  2. History of severe traumatic brain injury or intracranial neurosurgery;
  3. Presence of cardiac pacemakers, cochlear implants, intracranial implanted electronic devices, or other MRI-contraindicated ferromagnetic implants;
  4. Severe cognitive impairment (Mini-Mental State Examination [MMSE] score ≤ 9) or severe visual, auditory, or speech dysfunction preventing cooperation with scale assessments and study procedures;
  5. Pregnant or lactating women, or women of childbearing age not using reliable contraception;
  6. Previous neuromodulation treatment (e.g., rTMS or tDCS) within the past year;
  7. Skin breakdown or inflammation at the electrode placement site, or known allergy to conductive gel or electrode patch adhesives;
  8. Currently participating in other interventional clinical trials, or planning to participate in other trials that might affect the outcome assessment of this study during the study period.

Study Plan

This section provides details of the study plan, including how the study is designed and what the study is measuring.

How is the study designed?

Design Details

  • Primary Purpose: Treatment
  • Allocation: Non-Randomized
  • Interventional Model: Sequential Assignment
  • Masking: Single

Arms and Interventions

Participant Group / Arm
Intervention / Treatment
Experimental: 30 Hz Difference Frequency tTIS
Transcranial Temporal Interference Stimulation (tTIS) uses a difference frequency (Δf) of 30 Hz.
Device: Transcranial Temporal Interference Stimulation (tTIS)

Participants assigned to this intervention arm receive transcranial temporal interference stimulation (tTIS) with a difference frequency (Δf) of 30Hz/40Hz/70 Hz.

Before treatment, individualized electric field modeling is performed based on each participant's 3D-T1 MRI data to optimize electrode placement and stimulation parameters. The stimulation target is the bilateral cerebellar dentate nuclei. A personalized finite element head model is generated, and electrode positions are determined through simulation-based optimization to achieve focused interference electric fields at the target region.

During each treatment session, tTIS is delivered using two carrier frequencies of 2000 Hz and 2030Hz/2040Hz/2070 Hz, with a current intensity of 2.0 mA (zero-to-peak). Each session lasts 20 minutes. Treatment is administered twice daily, 5 days per week, for a total of 10 sessions.
Experimental: 40 Hz Difference Frequency tTIS
Transcranial Temporal Interference Stimulation (tTIS) uses a difference frequency (Δf) of 40 Hz.
Device: Transcranial Temporal Interference Stimulation (tTIS)

Participants assigned to this intervention arm receive transcranial temporal interference stimulation (tTIS) with a difference frequency (Δf) of 30Hz/40Hz/70 Hz.

Before treatment, individualized electric field modeling is performed based on each participant's 3D-T1 MRI data to optimize electrode placement and stimulation parameters. The stimulation target is the bilateral cerebellar dentate nuclei. A personalized finite element head model is generated, and electrode positions are determined through simulation-based optimization to achieve focused interference electric fields at the target region.

During each treatment session, tTIS is delivered using two carrier frequencies of 2000 Hz and 2030Hz/2040Hz/2070 Hz, with a current intensity of 2.0 mA (zero-to-peak). Each session lasts 20 minutes. Treatment is administered twice daily, 5 days per week, for a total of 10 sessions.
Experimental: 70 Hz Difference Frequency tTIS
Transcranial Temporal Interference Stimulation (tTIS) uses a difference frequency (Δf) of 70 Hz.
Device: Transcranial Temporal Interference Stimulation (tTIS)

Participants assigned to this intervention arm receive transcranial temporal interference stimulation (tTIS) with a difference frequency (Δf) of 30Hz/40Hz/70 Hz.

Before treatment, individualized electric field modeling is performed based on each participant's 3D-T1 MRI data to optimize electrode placement and stimulation parameters. The stimulation target is the bilateral cerebellar dentate nuclei. A personalized finite element head model is generated, and electrode positions are determined through simulation-based optimization to achieve focused interference electric fields at the target region.

During each treatment session, tTIS is delivered using two carrier frequencies of 2000 Hz and 2030Hz/2040Hz/2070 Hz, with a current intensity of 2.0 mA (zero-to-peak). Each session lasts 20 minutes. Treatment is administered twice daily, 5 days per week, for a total of 10 sessions.

What is the study measuring?

Primary Outcome Measures

Outcome Measure
Measure Description
Time Frame
Safety: Incidence of Dose-Limiting Toxicity (DLT)
Time Frame: At any point during or immediately following intervention on day of tTIS application

DLT event is defined as any one of the following 5 categories:

  1. Grade Ⅱ (moderate) or higher adverse events per the NCI-CTCAE grading criteria[1] that require topical or non-invasive intervention, such as skin burns (skin breakdown, blister formation);
  2. Clinically observable seizures during stimulation;
  3. Severe headache with vomiting, confusion, or severe dizziness leading to syncope;
  4. Severe sleep disturbance with psychiatric abnormalities (anxiety, depression, hallucinations, etc.);
  5. New brain lesions on imaging, or decreased apparent diffusion coefficient (ADC) values in the subcortex beneath the stimulation site.

References [1] Antal A, et al. Low intensity transcranial electric stimulation: Safety, ethical, legal regulatory and application guidelines (2017-2025: An update) - endorsed by the European Society for Brain Stimulation (ESBS) and by the International Federation for Clinical Neurophysiology (IFCN). Clin Neurophysiol. 2026. 184: 2111436
At any point during or immediately following intervention on day of tTIS application
Efficacy: To assess the proportion of patients with SARA improvement (decrease) of at least 1.5 from baseline after 5 days
Time Frame: Baseline and within 24 hours after completing the 5-day tTIS treatment

The Scale for the Assessment and Rating of Ataxia (SARA) evaluates the severity of ataxia symptoms, including gait, posture, speech, and limb kinetic functions.

Score range: 0-40 Higher scores indicate more severe ataxia. Response is defined as a reduction of ≥1.5 points from baseline.
Baseline and within 24 hours after completing the 5-day tTIS treatment
Comprehensive Benefit-Risk: Utility
Time Frame: Within 24 hours after completing the 5-day tTIS treatment

Utility is a composite measure integrating dose-limiting toxicity (DLT) and efficacy response to quantify the overall benefit-risk balance for each dose group.

During the trial, the Utility value for each dose group is dynamically calculated using the U-BOIN design platform. In Stage II, the Utility value determines dose allocation for subsequent cohorts. At study completion, the dose group with the highest Utility value is identified as the optimal biological dose.
Within 24 hours after completing the 5-day tTIS treatment

Other Outcome Measures

Outcome Measure
Measure Description
Time Frame
The International Cooperative Ataxia Rating Scale (ICARS)
Time Frame: Baseline and within 24 hours after completing the 5-day tTIS treatment

The International Cooperative Ataxia Rating Scale (ICARS) assesses the severity of cerebellar ataxia across four subscales: posture and gait disturbances, limb kinetic functions, speech disorders, and oculomotor disorders.

Total score range: 0-100 Higher scores indicate more severe ataxia impairment.
Baseline and within 24 hours after completing the 5-day tTIS treatment
The European Quality of Life 5-Dimension (EQ-5D)
Time Frame: Baseline and within 24 hours after completing the 5-day tTIS treatment

The European Quality of Life 5-Dimension Utility Index Score (EQ-5D Utility Index) assesses health-related quality of life across five dimensions: mobility, self-care, usual activities, pain/discomfort, and anxiety/depression.

Participants' health states are described using a five-digit code, with values ranging from 11111 (no problems in any dimension) to 33333 (extreme problems in all dimensions). The health state code is converted into a utility index score using population-specific preference weights. The score is anchored at 1.0 for full health, with lower values indicating poorer health status; values below 0 may occur for health states considered worse than death depending on the applicable value set.
Baseline and within 24 hours after completing the 5-day tTIS treatment
Patient Global Impression of Change (PGI-C)
Time Frame: Within 24 hours after completing the 5-day tTIS treatment

The Patient Global Impression of Change (PGI-C) is a patient-reported scale assessing perceived change in overall condition after treatment.

Score range: 1-7 Lower scores indicate greater improvement
Within 24 hours after completing the 5-day tTIS treatment
Clinical Global Impression of Change (CGI-C)
Time Frame: Within 24 hours after completing the 5-day tTIS treatment

The Clinical Global Impression of Change (CGI-C) is a clinician-rated scale assessing overall change in the patient's clinical status.

Score range: 1-7 Lower scores indicate greater improvement
Within 24 hours after completing the 5-day tTIS treatment
Change in Multimodal Magnetic Resonance Imaging (MRI) Parameters
Time Frame: Baseline and within 24 hours after completing the 5-day tTIS treatment
Multimodal magnetic resonance imaging (MRI), including structural MRI (sMRI), resting-state fMRI (rs-fMRI) and diffusion tensor imaging (DTI), is performed to evaluate cerebral structural and functional alterations.
Baseline and within 24 hours after completing the 5-day tTIS treatment
Functional Near-Infrared Spectroscopy (fNIRS) assesses hemodynamic changes
Time Frame: Baseline and within 24 hours after completing the 5-day tTIS treatment

Functional Near-Infrared Spectroscopy (fNIRS) assesses hemodynamic changes by measuring regional cerebral oxygenation in the cerebellar and motor cortical regions.

Changes in oxygenation signals reflect alterations in regional neural activity through neurovascular coupling.
Baseline and within 24 hours after completing the 5-day tTIS treatment

Collaborators and Investigators

This is where you will find people and organizations involved with this study.

Sponsor

First Affiliated Hospital of Fujian Medical University

Study record dates

These dates track the progress of study record and summary results submissions to ClinicalTrials.gov. Study records and reported results are reviewed by the National Library of Medicine (NLM) to make sure they meet specific quality control standards before being posted on the public website.

Study Major Dates

Study Start (Estimated)

August 7, 2026

Primary Completion (Estimated)

November 30, 2026

Study Completion (Estimated)

February 28, 2027

Study Registration Dates

First Submitted

July 29, 2026

First Submitted That Met QC Criteria

July 31, 2026

First Posted (Actual)

August 4, 2026

Study Record Updates

Last Update Posted (Actual)

August 5, 2026

Last Update Submitted That Met QC Criteria

August 3, 2026

Last Verified

July 1, 2026

More Information

Terms related to this study

Keywords

Additional Relevant MeSH Terms

Other Study ID Numbers

  • MRCTA,ECFAH of FMU[2026]803

Plan for Individual participant data (IPD)

Plan to Share Individual Participant Data (IPD)?

NO

Drug and device information, study documents

Studies a U.S. FDA-regulated drug product

No

Studies a U.S. FDA-regulated device product

No

This information was retrieved directly from the website clinicaltrials.gov without any changes. If you have any requests to change, remove or update your study details, please contact register@clinicaltrials.gov. As soon as a change is implemented on clinicaltrials.gov, this will be updated automatically on our website as well.

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