Electroencephalography Markers of Brain Stimulation in Post-Concussion Patients (Stim-PPCS)

November 6, 2026 updated by: Nicolas LEJEUNE, University of Liege

Identification of EEG Biomarkers Associated With Transcranial Direct Current Stimulation in Patients With Persistent Post-Concussion Symptoms

In this randomized, sham-controlled, two-group, parallel, single-session study, the investigators aim to identify EEG biomarkers associated with cerebellar transcranial direct current stimulation (tDCS) in patients with persistent post-concussion symptoms (PPCS). Cerebellar tDCS will be used to modulate brain network connectivity, which is known to be altered in PPCS. The study will include 38 participants, each completing a single session including EEG recordings before and after stimulation. Participants will be randomly assigned to one of two conditions: 1) active cerebellar tDCS, or 2) sham stimulation.By focusing on EEG functional connectivity and related signal metrics, this study aims to better understand the neural mechanisms of cerebellar tDCS and support the development of targeted interventions for patients with PPCS.

Study Overview

Status

Status

Indicates the current recruitment status or the expanded access status.
Not yet recruiting

Conditions

Conditions

The disease, disorder, syndrome, illness, or injury that is being studied. On ClinicalTrials.gov, conditions may also include other health-related issues, such as lifespan, quality of life, and health risks.

Intervention / Treatment

Intervention / Treatment

A process or action that is the focus of a clinical study. Interventions include drugs, medical devices, procedures, vaccines, and other products that are either investigational or already available. Interventions can also include noninvasive approaches, such as education or modifying diet and exercise.

Study Type

Study Type

Describes the nature of a clinical study. Study types include interventional studies (also called clinical trials), observational studies (including patient registries), and expanded access.
Interventional

Enrollment (Estimated)

Enrollment

The number of participants in a clinical study. The "anticipated" enrollment is the target number of participants that the researchers need for the study.
38

Phase

Phase

The stage of a clinical trial studying a drug or biological product, based on definitions developed by the U.S. Food and Drug Administration (FDA). The phase is based on the study's objective, the number of participants, and other characteristics. There are five phases: Early Phase 1 (formerly listed as Phase 0), Phase 1, Phase 2, Phase 3, and Phase 4. Not Applicable is used to describe trials without FDA-defined phases, including trials of devices or behavioral interventions.
  • 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

The name and contact information for the person who can answer enrollment questions for a clinical study. Each location where the study is being conducted may also have a specific contact, who may be better able to answer those questions.

Study Locations

  • Belgium
    • Liege
      • Tinlot, Liege, Belgium, 4557
        • Centre Neurologique et de réadaptation Fonctionnelle
        • 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

Eligibility Criteria

The key requirements that people who want to participate in a clinical study must meet or the characteristics they must have. Eligibility criteria consist of both inclusion criteria (which are required for a person to participate in the study) and exclusion criteria (which prevent a person from participating). Types of eligibility criteria include whether a study accepts healthy volunteers, has age or age group requirements, or is limited by sex.

Ages Eligible for Study

18 years and older (Adult, Older Adult)

Accepts Healthy Volunteers

No

Genders Eligible for Study

All

Description

Inclusion Criteria:

  • Be aged 18 years or older;
  • Have received a medical diagnosis of concussion within the 12 months prior to recruitment;
  • Exhibit persistent post-concussion symptoms (PPCS) with a score ≥16 on the Rivermead Post-Concussion Symptoms Questionnaire

Exclusion Criteria:

  • Identified risk for tDCS exposure according to the Transcranial Direct Current Stimulation Safety Screening Tool
  • Neurological or psychiatric disorders with a prior medical diagnosis that could alter brain network connectivity before the concussion
  • Use of medications (antidepressants, anxiolytics, antipsychotics, antiepileptics) that may affect brain connectivity.

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: Other
  • Allocation: Randomized
  • Interventional Model: Parallel Assignment
  • Masking: Quadruple

Arms and Interventions

Participant Group / Arm

Participant Group / Arm

A group or subgroup of participants in a clinical trial that receives a specific intervention/treatment, or no intervention, according to the trial's protocol.
Intervention / Treatment

Intervention / Treatment

A process or action that is the focus of a clinical study. Interventions include drugs, medical devices, procedures, vaccines, and other products that are either investigational or already available. Interventions can also include noninvasive approaches, such as education or modifying diet and exercise.
Active Comparator: Active tDCS

Active tDCS participants will receive high-definition cerebellar transcranial direct current stimulation using a multi-electrode montage optimized to target bilateral cerebellar regions. The electrode configuration is identical across conditions and has been defined using computational modeling to maximize focality while limiting current spread to adjacent areas. The stimulation consists of a 30-second ramp-up phase, followed by 20 minutes of continuous stimulation, and a 30-second ramp-down phase.
Device: tDCS 8 channels

Transcranial direct current stimulation is a non-invasive brain stimulation technique that delivers a weak direct electrical current through scalp electrodes to modulate neuronal excitability (<2mA). Cerebellar tDCS will be administered using an 8-channel montage optimized with the Stimweaver software (Neuroelectrics, Barcelona, Spain) to maximize current density over the cerebellum while minimizing off-target effects. A constant direct current will be applied for 20 minutes, with a 30-second ramp-up at the beginning and a 30-second ramp-down at the end. Other Name:
Sham Comparator: Sham tDCS

Sham tDCS participants will undergo the same high-definition cerebellar electrode montage as the active tDCS group, ensuring identical setup and participant experience. However, no sustained current is delivered to the scalp. The protocol includes brief ramp-up and ramp-down phases at the beginning and end of the session to mimic the sensations of real stimulation, while preventing any meaningful modulation of cortical excitability. This approach, established in previous studies, maintains blinding of participants to the stimulation condition. The investigator administering the stimulation will also be blinded, as the tDCS device allows double blinding, with identical screen displays in both sham and active conditions.
Device: sham tDCS 8 channels

Transcranial direct current stimulation is a non-invasive brain stimulation technique that delivers a weak direct electrical current through scalp electrodes to modulate neuronal excitability (<2 mA). The device used has a sham setting that allows sham stimulation to be delivered while the interventionist remains blinded.Other Name:

What is the study measuring?

Primary Outcome Measures

Primary Outcome Measures

In a clinical study's protocol, the planned outcome measure that is the most important for evaluating the effect of an intervention/treatment. Most clinical studies have one primary outcome measure, but some have more than one.
Outcome Measure
Measure Description
Time Frame
EEG Functional Connectivity in the Alpha Band (dwPLI)
Time Frame: EEG functional connectivity will be assessed at two time points: immediately before and immediately after the stimulation session.

EEG functional connectivity will be assessed using the debiased weighted Phase Lag Index (dwPLI) in the alpha frequency band (8-12 Hz). This metric quantifies the consistency of phase relationships between EEG signals across brain regions while minimizing the effects of volume conduction. It will be used to evaluate changes in large-scale brain network connectivity associated with cerebellar transcranial direct current stimulation (tDCS) in patients with persistent post-concussion symptoms (PPCS). Differences in connectivity patterns between pre- and post-stimulation recordings, as well as between active and sham groups, will be analyzed.
EEG functional connectivity will be assessed at two time points: immediately before and immediately after the stimulation session.

Secondary Outcome Measures

Secondary Outcome Measures

In a clinical study's protocol, a planned outcome measure that is not as important as the primary outcome measure for evaluating the effect of an intervention but is still of interest. Most clinical studies have more than one secondary outcome measure.
Outcome Measure
Measure Description
Time Frame
Permutation entropy (PE)
Time Frame: Immediately before and immediately after the stimulation session

Permutation Entropy (PE) will be calculated from EEG signals to quantify the temporal irregularity and unpredictability of brain activity. PE is a dimensionless measure.
Immediately before and immediately after the stimulation session
Normalized Lempel-Ziv Complexity (LZC)
Time Frame: Immediately before and immediately after the stimulation session

Normalized Lempel-Ziv Complexity (LZC) will be calculated from EEG signals to quantify the diversity and complexity of brain activity patterns. LZC is a dimensionless measure.
Immediately before and immediately after the stimulation session
EEG microstate
Time Frame: Immediately before and immediately after the stimulation session

EEG microstate analysis will be conducted to examine temporal dynamics of large-scale brain networks. Metrics will include microstate duration, coverage, and occurrence. These will be computed from resting-state EEG recordings acquired before and after stimulation to explore modulation of brain network organization.
Immediately before and immediately after the stimulation session
EEG spectral analysis (alpha peak and spectral slope)
Time Frame: Immediately before and immediately after the stimulation session

Spectral properties of EEG signals will be analyzed, including alpha peak frequency and spectral slope. These measures provide insight into oscillatory activity and excitation-inhibition balance. Analyses will be performed on resting-state EEG recordings collected pre- and post-intervention.
Immediately before and immediately after the stimulation session
Phase-amplitude coupling
Time Frame: Immediately before and immediately after the stimulation session

Analyses will assess phase-amplitude coupling and coherence to evaluate cross-frequency interactions and synchronization between brain regions. These measures will be derived from resting-state EEG recordings before and after stimulation.
Immediately before and immediately after the stimulation session
Alpha band participation coefficient
Time Frame: Immediately before and immediately after the stimulation session

The participation coefficient in the alpha band will be computed to assess the integration of brain regions within large-scale networks. This will be derived from resting-state EEG data collected pre- and post-intervention.
Immediately before and immediately after the stimulation session
Rivermead Post-Concussion Symptoms Questionnaire
Time Frame: Pre-intervention (baseline)

Post-concussion symptoms will be assessed using the French version of the Rivermead Post-Concussion Symptoms Questionnaire (total score range: 0-64, with higher scores indicating greater symptom severity). This self-reported measure evaluates the severity of common post-concussion symptoms and will be used to characterize baseline symptom burden.
Pre-intervention (baseline)
Simple Reaction Time Task
Time Frame: Pre-intervention and immediately post-intervention

Participants will complete a computerized simple reaction time task to assess processing speed and motor responsiveness. Performance will be compared before and after stimulation.
Pre-intervention and immediately post-intervention
Sport concussion assessment tool 6 (SCAT6)
Time Frame: Pre-intervention and immediately post-intervention

The SCAT6 symptom evaluation (Step 2) will be used to assess immediate concussion-related symptoms (total score range: 0-132, with higher scores indicating greater symptom severity). This questionnaire will be administered before and after the intervention to explore changes in symptom severity.
Pre-intervention and immediately post-intervention
Sustained Attention Task (TAP)
Time Frame: Pre-intervention and immediately post-intervention

A computerized cognitive task assessing attention will be administered pre- and post-intervention. Performance metrics will be analyzed to evaluate potential cognitive effects of the stimulation.
Pre-intervention and immediately post-intervention
Blinding assessment
Time Frame: Immediately post-intervention

A blinding questionnaire will be completed by both the participant and the interventionist to assess the effectiveness of blinding between active and sham stimulation conditions.
Immediately post-intervention
Adverse events reporting
Time Frame: Immediately post-intervention

Adverse events will be assessed using a standardized questionnaire as described in Reckow et al. This will capture any discomfort or side effects associated with the intervention.
Immediately post-intervention
Sociodemographic characteristics and medical history
Time Frame: Pre-intervention (baseline)

Sociodemographic data will be collected to characterize the study population, including age, gender, level of education, employment status, physical activity level, and substance use (alcohol, tobacco, and drugs). Participants' medical history and current medication use will be recorded to characterize baseline health status and control for potential confounding factors in analyses.
Pre-intervention (baseline)

Collaborators and Investigators

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

Sponsor

Sponsor

The organization or person who initiates the study and who has authority and control over the study.
University of Liege

Collaborators

Collaborators

An organization other than the sponsor that provides support for a clinical study. This support may include activities related to funding, design, implementation, data analysis, or reporting.
Centre Hospitalier Universitaire de Liege

Investigators

Investigators

A researcher involved in a clinical study. Related terms include site principal investigator, site sub-investigator, study chair, study director, and study principal investigator.
  • Principal Investigator: Nicolas Lejeune, University of Liege - CHU Liege
  • Study Chair: Géraldine Martens, University of Liege
  • Study Director: Fanny Montulet, University of Liege

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)

Study Start

The actual date on which the first participant was enrolled in a clinical study. The "anticipated" study start date is the date that the researchers think will be the study start date.
December 1, 2026

Primary Completion (Estimated)

Primary Completion

The date on which the last participant in a clinical study was examined or received an intervention to collect final data for the primary outcome measure. Whether the clinical study ended according to the protocol or was terminated does not affect this date. For clinical studies with more than one primary outcome measure with different completion dates, this term refers to the date on which data collection is completed for all the primary outcome measures. The "anticipated" primary completion date is the date that the researchers think will be the primary completion date for the study.
December 1, 2027

Study Completion (Estimated)

Study Completion

The date on which the last participant in a clinical study was examined or received an intervention/treatment to collect final data for the primary outcome measures, secondary outcome measures, and adverse events (that is, the last participant's last visit). The "anticipated" study completion date is the date that the researchers think will be the study completion date.
December 1, 2027

Study Registration Dates

First Submitted

First Submitted

The date on which the study sponsor or investigator first submitted a study record to ClinicalTrials.gov. There is typically a delay of a few days between the first submitted date and the record's availability on ClinicalTrials.gov (the first posted date).
October 19, 2026

First Submitted That Met QC Criteria

First Submitted That Met QC Criteria

The date on which the study sponsor or investigator first submits a study record that is consistent with National Library of Medicine (NLM) quality control (QC) review criteria. The sponsor or investigator may need to revise and submit a study record one or more times before NLM's QC review criteria are met. It is the responsibility of the sponsor or investigator to ensure that the study record is consistent with the NLM QC review criteria.
October 19, 2026

First Posted (Actual)

First Posted

The date on which the study record was first available on ClinicalTrials.gov after National Library of Medicine (NLM) quality control (QC) review has concluded. There is typically a delay of a few days between the date the study sponsor or investigator submitted the study record and the first posted date.
October 26, 2026

Study Record Updates

Last Update Posted (Actual)

Last Update Posted

The most recent date on which changes to a study record were made available on ClinicalTrials.gov. There may be a delay between when the changes were submitted to ClinicalTrials.gov by the study's sponsor or investigator (the last update submitted date) and the last update posted date.
November 12, 2026

Last Update Submitted That Met QC Criteria

Last Update Submitted That Met QC Criteria

The most recent date on which the study sponsor or investigator submitted changes to a study record that are consistent with National Library of Medicine (NLM) quality control (QC) review criteria. It is the responsibility of the sponsor or investigator to ensure that the study record is consistent with the NLM QC review criteria.
November 6, 2026

Last Verified

Last Verified

The most recent date on which the study sponsor or investigator confirmed the information about a clinical study on ClinicalTrials.gov as accurate and current. If a study with a recruitment status of recruiting; not yet recruiting; or active, not recruiting has not been confirmed within the past 2 years, the study's recruitment status is shown as unknown.
November 1, 2026

More Information

Terms related to this study

Keywords

Additional Relevant MeSH Terms

Other Study ID Numbers

Other Study ID Numbers

Identifiers or ID numbers other than the NCT number that are assigned to a clinical study by the study's sponsor, funders, or others. These numbers may include unique identifiers from other trial registries and National Institutes of Health grant numbers.
  • Stim-PPCS : 2026-183

Plan for Individual participant data (IPD)

Plan to Share Individual Participant Data (IPD)?

YES

IPD Plan Description

De-identified individual participant data will be made available to qualified researchers whose requests are methodologically sound and for legitimate scientific purposes, following publication of the primary study results.

IPD Sharing Time Frame

IPD and supporting information will be made available after publication of the primary study results upon reasonable request and subject to approval. Data will be stored in Dataverse ULiège under restricted access for an indefinite period.

IPD Sharing Access Criteria

Access to the anonymized individual participant data (IPD) and supporting information, including the study protocol, data dictionary, and statistical analysis code, will be granted to qualified researchers upon reasonable request.

Requests will be evaluated by the principal investigator based on scientific validity, methodological quality, and compliance with the original ethical approval and informed consent.

Approved users will receive access through a secure institutional repository (e.g., ULiège Dataverse)

Only de-identified data will be shared.

IPD Sharing Supporting Information Type

  • STUDY_PROTOCOL

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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