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tACS Alters EEG Microstates in DoC

NCT07699055 · Status: COMPLETED · Phase: NA · Type: INTERVENTIONAL · Enrollment: 31

Last updated 2026-07-13

No results posted yet for this study

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 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

Interventions

DEVICE

Transcranial Alternating Current Stimulation

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.

Sponsors & Collaborators

  • Istanbul Medipol University Hospital

    lead OTHER

Study Design

Allocation
NA
Purpose
TREATMENT
Masking
NONE
Model
SINGLE_GROUP

Eligibility

Min Age
18 Years
Sex
ALL
Healthy Volunteers
No

Timeline & Regulatory

Start
2020-12-01
Primary Completion
2021-12-12
Completion
2024-09-12

Countries

  • Turkey (Türkiye)

Study Locations

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Read the full study record

This page highlights key information. For complete eligibility criteria, study locations, investigator contacts, and the full protocol, visit the original record on ClinicalTrials.gov.

View NCT07699055 on ClinicalTrials.gov