Altered microstate dynamics in Functional Neurological Disorder.

Area of Science:

• Neuroscience
• Clinical Neurology
• Brain Network Dynamics

Background:

• Functional Neurological Disorder (FND) presents with disabling symptoms without clear structural brain pathology.
• Investigating disruptions in intrinsic brain network organization is crucial for understanding FND.
• Electroencephalography (EEG) provides high temporal resolution to study brain dynamics.

Purpose of the Study:

• To characterize temporal dynamics of brain activity in FND using EEG microstate analysis.
• To explore the relationship between microstate alterations and FND symptom severity.
• To assess the potential of EEG microstates for discriminating between FND patients and healthy controls.

Main Methods:

• Applied a seven-class microstate decomposition to resting-state EEG data from 39 FND patients and 47 controls.
• Labeled microstates A-G based on established topographies.
• Correlated microstate duration with symptom severity (Simplified-Functional Movement Disorder Rating Scale) and used logistic regression for group discrimination.

Main Results:

• FND patients showed significantly reduced duration of microstate G (sensorimotor integration) compared to controls.
• Reduced microstate G duration negatively correlated with FND symptom severity.
• Distinct microstate transition patterns (A, B, C) suggested altered arousal, visual imagery, and self-referential processing networks in FND.

Conclusions:

• This study provides the first direct evidence of disrupted resting-state microstate organization in a heterogeneous FND cohort.
• EEG microstate analysis offers a valuable tool for understanding the neural underpinnings of FND.
• Findings highlight potential biomarkers for FND diagnosis and severity assessment.