Disorder of ConsciousnessNCT07699055
tACS Alters EEG Microstates in DoC
A study testing Transcranial Alternating Current Stimulation in people with Disorder of Consciousness, run by Istanbul Medipol University Hospital at 1 site in Turkey (Türkiye).
Trial summary
Disorders of consciousness (DoC), including unresponsive wakefulness syndrome (UWS) and minimally conscious state (MCS), remain difficult to diagnose at the bedside. Electroencephalography (EEG) microstate analysis provides a high-temporal-resolution approach for characterizing large-scale resting-state brain… Read more about this study
- Who is it for?
- Ages 18 years and older
- Conditions the study is for
- Disorder of Consciousness
- What is being tested?
- Transcranial Alternating Current Stimulation
- Type of treatment
- Medical device
- Could I receive a placebo?
- No, everyone receives an active treatment
- How many people
- 31 participants
- Where
- 1 siteTurkey (Türkiye)
- Study dates
- 1 Dec 2020to 12 Sep 2024
- Phase
- Interventional
- Are there results?
- None posted in the registry
Key requirements
Who can take part, as listed by the sponsor. Only the study team can confirm whether you are eligible, so take this list to your doctor.
- Ages 18 years and older
- All sexes
- No healthy volunteers
- Adult, Older adult
Who may be able to join
- Adults aged 18 years or older.
- Medically stable at the time of assessment.
- No administration of sedative or hypnotic medication within the previous 24 hours.
- Preserved wakefulness (spontaneous or elicited by stimulation) with reduced or absent awareness, consistent with Unresponsive Wakefulness Syndrome (UWS) or Minimally Conscious State (MCS).
- Diagnosis confirmed by an experienced neurologist using repeated clinical assessments with the Coma Recovery Scale-Revised (CRS-R) and the Simplified Evaluation of CONsciousness Disorders (SECONDs) performed on different days and at different times during periods of wakefulness.
Who cannot join
- Acute phase of brain injury (within the first 28 days after injury).
- Administration of sedative or hypnotic medication within the previous 24 hours.
- Medical instability (e.g., active infection or hemodynamic instability).
- Epileptic seizures uncontrolled despite anticonvulsant therapy.
- Serious systemic illnesses that could affect the level of consciousness (e.g., sepsis or end-stage organ failure).
- Brain death or coma without any evidence of wakefulness.
- A previous history of developmental disorders, major neurological disorders, or severe psychiatric disorders associated with significant functional impairment.
Trial locations and contacts
1 site in 1 country.
Turkey (Türkiye)1 site
Medipol Mega University Hospital
Istanbul, Bağcılar
About this study
Official title: Transcranial Alternating Current Stimulation Is Associated With Changes in EEG Microstate Dynamics in Disorders of Consciousness
Disorders of consciousness (DoC), including unresponsive wakefulness syndrome (UWS) and minimally conscious state (MCS), remain difficult to diagnose at the bedside. Electroencephalography (EEG) microstate analysis provides a high-temporal-resolution approach for characterizing large-scale resting-state brain dynamics, and its application in neuromodulation studies remains under investigation.
This study is designed to investigate the effects of a single 20-minute session of 40 Hz transcranial alternating current stimulation (tACS) applied over the bilateral dorsolateral prefrontal cortex (DLPFC) on resting-state EEG microstate parameters in patients with DoC. Participants undergo resting-state EEG recordings immediately before and after a 2 mA, 40 Hz bilateral DLPFC tACS session. EEG microstate maps (A-G) are identified by back-fitting to individual recordings, and microstate parameters including mean duration, occurrence, coverage, and global explained variance (GEV) are calculated. Behavioral assessments are performed using the Coma Recovery Scale-Revised (CRS-R) and the Simplified Evaluation of CONsciousness Disorders (SECONDs). The study aims to characterize changes in EEG microstate dynamics following tACS and to examine their associations with behavioral measures of consciousness.
- Conditions
- Disorder of Consciousness
- Being tested
- Transcranial Alternating Current Stimulation
- Keywords
- transcranial alternating current stimulation, gamma oscillations, EEG microstate analysis, consciousness biomarker, dorsolateral prefrontal cortex, disorders of consciousness
- Medical subject headings
- Consciousness Disorders
What participants receive
What participants receive. In a randomised study each person is assigned to one group by chance.
Transcranial Alternating Current StimulationDevice
After completion of the first 20-minute resting-state EEG, tACS was applied using a Neurosoft / Neurostim device. Stimulation was performed at the 40 Hz gamma frequency, with two stimulation electrodes placed bilaterally over the DLPFC. According to the international 10-20 system, this placement corresponded to the F3 (left DLPFC) and F4 (right DLPFC) electrode positions. The stimulation lasted 20 minutes, and a constant current intensity of 2 mA was used throughout. The current was delivered as a sinusoidal waveform without phase shifting or modulation. The electrodes were sponge-based pads measuring 5 × 7 cm each. To improve conductivity and ensure homogeneous skin contact, the sponge electrodes were moistened with 0.9% isotonic sodium chloride (saline). Electrodes were secured to the skin to optimize contact quality and homogenize current distribution.
| Study group | Role | What they receive |
|---|---|---|
| Disorders of Consciousness and TACS | Experimental | We evaluated the effect of a single 20-minute session of 40 Hz transcranial alternating current stimulation (tACS) over the bilateral dorsolateral prefrontal cortex (DLPFC) on resting-state EEG microstate parameters in DoC and their relationships with behavioral consciousness scores. Receives: Device: Transcranial Alternating Current Stimulation |
What is being measured
The primary outcome is the main question the study is designed to answer.
Resting-State EEG Microstate Parameters
EEG recordings were obtained in different settings according to the patient's physical condition. From every individual, a total of 20 minutes of resting-state EEG was obtained. EEG recordings were performed using a Neurosoft NEURON-SPECTRUM-4 device and Neuron-Spectrum.NET software. Recordings were obtained from 19 electrode channels positioned according to the international 10-20 system: Fp1, Fp2, F7, F3, Fz, F4, F8, T7, C3, Cz, C4, T8, P7, P3, Pz, P4, P8, O1, O2. Data were digitized at a sampling rate of 500 Hz. Resting-state electroencephalography (EEG) microstate parameters, including mean duration, occurrence, coverage, and global explained variance (GEV) of microstate classes A-G, derived from 19-channel scalp EEG recordings using microstate analysis.
Measured: Baseline and immediately after the 20-minute tACS session.
Coma Recovery Scale-Revised (CRS-R)
The CRS-R is a standardized clinical assessment tool used to evaluate the level of consciousness in patients with disorders of consciousness. It consists of six subscales: auditory, visual, motor, oromotor/verbal, communication, and arousal. The total score ranges from 0 to 23, with higher scores indicating a higher level of consciousness. Diagnostic interpretation is based not only on the total score but also on the highest behavioral responses observed within each subscale.
Measured: Baseline and immediately after the 20-minute tACS session.
Simplified Evaluation of CONsciousness Disorders (SECONDs)
The SECONDs is a brief bedside assessment designed for the rapid evaluation of patients with disorders of consciousness. It assesses arousal and behavioral responses to simple commands and environmental stimuli. The total score ranges from 0 to 8, with higher scores indicating a better level of consciousness. It is a practical tool for screening and longitudinal clinical monitoring.
Measured: Baseline and immediately after the 20-minute tACS session.
Timeline
From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.
- First posted13 Jul 2026
- Study start1 Dec 2020
- Primary completion12 Dec 2021
- Study completion12 Sep 2024
Resources
- Official record on ClinicalTrials.govThe registry entry this page is built from, with its full change history.
- Other trials for Disorder of ConsciousnessStudies of the same condition, open and under way.
- What the trial phases meanHow a treatment moves from first tests in people to approval.
More details
For doctors and researchers: how the study is designed, who runs it, and its registry IDs.
Study design
- Study type
- Interventional
- Phase
- Phase N/A
- Primary purpose
- Treatment
- Allocation
- Not applicable
- Intervention model
- Single group
- Masking
- None (open label)
- Enrolment
- 31 participants (actual)
Sponsor and investigators
- Lead sponsor
- Istanbul Medipol University Hospital
- Sponsor type
- University, hospital or other
- Responsible party
- Principal investigator, eren toplutas, Istanbul Medipol University Hospital
IDs, dates and publications
- ClinicalTrials.gov ID
- NCT07699055
- Sponsor's protocol ID
- 10840098-772.02-47943
- Status last verified
- Dec 2020
- First submitted
- 1 Jul 2026
- Last updated
- 13 Jul 2026
- Results posted
- No
- Data monitoring committee
- Yes
- FDA-regulated drug
- No
- FDA-regulated device
- No
- Individual data sharing
- Yes: De-identified individual participant data will be available upon reasonable request to the corresponding author for scientifically sound research purposes.
Study at a glance
From the registry record, last updated by the sponsor on 13 Jul 2026. Recruitment status is as the sponsor reported it: confirm with the study team.
- Official title
- Transcranial Alternating Current Stimulation Is Associated With Changes in EEG Microstate Dynamics in Disorders of Consciousness
- ClinicalTrials.gov ID
- NCT07699055
- Acronym / sponsor ID
- 10840098-772.02-47943
- Conditions
- Disorder of Consciousness
- Keywords
- transcranial alternating current stimulation, gamma oscillations, EEG microstate analysis, consciousness biomarker, dorsolateral prefrontal cortex, disorders of consciousness
- Study type
- Interventional
- Recruitment status
- Completed
- Enrolment
- 31 participants (actual)
- Lead sponsor
- Istanbul Medipol University HospitalUniversity, hospital or other
- Study start
- 1 Dec 2020 (actual)
- Primary completion
- 12 Dec 2021 (actual)
- Study completion
- 12 Sep 2024 (actual)
- First posted
- 13 Jul 2026 (actual)
- Results
- Not posted in the source record
Clinical summary
The research question as the sponsor registered it. This describes what the study plans to test, not what it found.
Disorders of consciousness (DoC), including unresponsive wakefulness syndrome (UWS) and minimally conscious state (MCS), remain difficult to diagnose at the bedside. Electroencephalography (EEG) microstate analysis provides a high-temporal-resolution approach for characterizing large-scale resting-state brain dynamics, and its application in neuromodulation studies remains under investigation.
This study is designed to investigate the effects of a single 20-minute session of 40 Hz transcranial alternating current stimulation (tACS) applied over the bilateral dorsolateral prefrontal cortex (DLPFC) on resting-state EEG microstate parameters in patients with DoC. Participants undergo resting-state EEG recordings immediately before and after a 2 mA, 40 Hz bilateral DLPFC tACS session. EEG microstate maps (A-G) are identified by back-fitting to individual recordings, and microstate parameters including mean duration, occurrence, coverage, and global explained variance (GEV) are calculated. Behavioral assessments are performed using the Coma Recovery Scale-Revised (CRS-R) and the Simplified Evaluation of CONsciousness Disorders (SECONDs). The study aims to characterize changes in EEG microstate dynamics following tACS and to examine their associations with behavioral measures of consciousness.
Study design
- Primary purpose
- Treatment
- Allocation
- Not applicable
- Intervention model
- Single group
- Masking
- None (open label)
- Number of arms
- 1
| Arm | Type | Receives |
|---|---|---|
| Disorders of Consciousness and TACS | Experimental | Device: Transcranial Alternating Current StimulationWe evaluated the effect of a single 20-minute session of 40 Hz transcranial alternating current stimulation (tACS) over the bilateral dorsolateral prefrontal cortex (DLPFC) on resting-state EEG microstate parameters in DoC and their relationships with behavioral consciousness scores. |
Who may qualify
- Ages
- 18 years and older
- Sex
- All
- Healthy volunteers
- Not accepted
- Age groups
- Adult, Older adult
Key inclusion criteria (5 listed)
- Adults aged 18 years or older.
- Medically stable at the time of assessment.
- No administration of sedative or hypnotic medication within the previous 24 hours.
- Preserved wakefulness (spontaneous or elicited by stimulation) with reduced or absent awareness, consistent with Unresponsive Wakefulness Syndrome (UWS) or Minimally Conscious State (MCS).
- Diagnosis confirmed by an experienced neurologist using repeated clinical assessments with the Coma Recovery Scale-Revised (CRS-R) and the Simplified Evaluation of CONsciousness Disorders (SECONDs) performed on different days and at different times during periods of wakefulness.
Key exclusion criteria (7 listed)
- Acute phase of brain injury (within the first 28 days after injury).
- Administration of sedative or hypnotic medication within the previous 24 hours.
- Medical instability (e.g., active infection or hemodynamic instability).
- Epileptic seizures uncontrolled despite anticonvulsant therapy.
- Serious systemic illnesses that could affect the level of consciousness (e.g., sepsis or end-stage organ failure).
Eligibility is decided by the study team after screening; this overview does not establish that a patient qualifies. Full inclusion and exclusion criteria.
Interventions
| Intervention | Type | Arms |
|---|---|---|
| Transcranial Alternating Current StimulationAfter completion of the first 20-minute resting-state EEG, tACS was applied using a Neurosoft / Neurostim device. Stimulation was performed at the 40 Hz gamma frequency, with two stimulation electrodes placed bilaterally over the DLPFC. According to the international 10-20 system, this placement corresponded to the F3 (left DLPFC) and F4 (right DLPFC) electrode positions. The stimulation lasted 20 minutes, and a constant current intensity of 2 mA was used throughout. The current was delivered as a sinusoidal waveform without phase shifting or modulation. The electrodes were sponge-based pads measuring 5 × 7 cm each. To improve conductivity and ensure homogeneous skin contact, the sponge electrodes were moistened with 0.9% isotonic sodium chloride (saline). Electrodes were secured to the skin to optimize contact quality and homogenize current distribution. | Device | Disorders of Consciousness and TACS |
Primary outcome
Resting-State EEG Microstate Parameters
Time frame: Baseline and immediately after the 20-minute tACS session.
EEG recordings were obtained in different settings according to the patient's physical condition. From every individual, a total of 20 minutes of resting-state EEG was obtained. EEG recordings were performed using a Neurosoft NEURON-SPECTRUM-4 device and Neuron-Spectrum.NET software. Recordings were obtained from 19 electrode channels positioned according to the international 10-20 system: Fp1, Fp2, F7, F3, Fz, F4, F8, T7, C3, Cz, C4, T8, P7, P3, Pz, P4, P8, O1, O2. Data were digitized at a sampling rate of 500 Hz. Resting-state electroencephalography (EEG) microstate parameters, including mean duration, occurrence, coverage, and global explained variance (GEV) of microstate classes A-G, derived from 19-channel scalp EEG recordings using microstate analysis.
Coma Recovery Scale-Revised (CRS-R)
Time frame: Baseline and immediately after the 20-minute tACS session.
The CRS-R is a standardized clinical assessment tool used to evaluate the level of consciousness in patients with disorders of consciousness. It consists of six subscales: auditory, visual, motor, oromotor/verbal, communication, and arousal. The total score ranges from 0 to 23, with higher scores indicating a higher level of consciousness. Diagnostic interpretation is based not only on the total score but also on the highest behavioral responses observed within each subscale.
Simplified Evaluation of CONsciousness Disorders (SECONDs)
Time frame: Baseline and immediately after the 20-minute tACS session.
The SECONDs is a brief bedside assessment designed for the rapid evaluation of patients with disorders of consciousness. It assesses arousal and behavioral responses to simple commands and environmental stimuli. The total score ranges from 0 to 8, with higher scores indicating a better level of consciousness. It is a practical tool for screening and longitudinal clinical monitoring.
Results and safety
The study is completed, but results are not available in the source record. That does not mean the treatment did or did not work.
Research links
- Official record on ClinicalTrials.govLast updated by the sponsor 13 Jul 2026.
- Individual participant dataSharing planned: Yes. De-identified individual participant data will be available upon reasonable request to the corresponding author for scientifically sound research purposes.
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Referral and contact
AzTrials does not enrol participants or take referrals. Contact the study team or a site listed below; they decide who can take part. This study is not recruiting at the moment.
The record lists no contact. Use the official record to reach the sponsor.
1 site in 1 country: see every site and its status.
Questions about this trial
What is this clinical trial studying?
A study testing Transcranial Alternating Current Stimulation in people with Disorder of Consciousness, run by Istanbul Medipol University Hospital at 1 site in Turkey (Türkiye).
The full registered description is in the About this study section and the official record.
Who may be eligible to take part?
The sponsor lists 5 inclusion and 7 exclusion criteria. Eligibility is decided by the study team after screening, so read the full criteria and contact a listed site.
Is this clinical trial currently recruiting?
The record says: finished, as of the sponsor's last update on 13 Jul 2026. Status can change between updates, so confirm with the study contact before making plans.
Where is the study taking place?
The record lists 1 site in Turkey (Türkiye). Whether a site is taking part right now should be confirmed with that site. See every site.
What are the possible benefits and risks?
They depend on the study and the treatment, and no study can promise a benefit. The study team explains the known risks during informed consent, before anyone joins; the record itself does not list them.
Are results available for this study?
The study is completed, but results are not available in the source record. That does not mean the treatment did or did not work.
How can a doctor refer a patient or contact the research team?
The record lists no contact. The official record names the sponsor, who can be asked directly. AzTrials does not enrol participants or take referrals.
What does the primary outcome measure?
Resting-State EEG Microstate Parameters (time frame: Baseline and immediately after the 20-minute tACS session.). The study lists 3 primary outcomes in all. It is what the study was designed to measure, not a finding.
Where can I read the original study information?
Does a listing mean the treatment is approved or proven to work?
No. A listing means the study is registered. It does not show that the treatment is safe, works, or is approved by a regulator.
How often is this information updated?
AzTrials copies changed records from ClinicalTrials.gov every night and reloads the whole registry every week. The sponsor last updated this record on 13 Jul 2026.