EEG Microstate Imbalance in Anti-LGI1 Encephalitis: A Correlation with Inflammation and Cognitive Dysfunction

This study investigates changes in electroencephalogram (EEG) microstates in patients with anti-leucine-rich glioma-inactivated protein 1 (anti-LGI1) encephalitis and explores their correlation with inflammatory markers and cognitive function. Thirty patients with LGI1 encephalitis were compared to a control group of thirty healthy individuals, analyzing demographics, blood/cerebrospinal fluid (CSF) tests, and cognitive assessments. Each participant underwent at least 10 minutes of resting-state EEG recording. Microstate analysis and functional connectivity were performed using MATLAB's EEGLAB toolbox, while standardized low-resolution brain electromagnetic tomography (sLORETA) was employed for microstate source reconstruction. Patients with anti-LGI1 encephalitis exhibited prolonged durations of microstates A, B, and C, reduced occurrence of microstate D, and increased transitions from C to A, with no significant changes in coverage. Microstate A demonstrated decreased activity in the anterior cingulate and lingual gyri. Functional connectivity analysis revealed enhanced slow-wave connectivity and diminished fast-wave connectivity in the frontal-parietal lobes. Correlation analyses showed that microstate A positively correlated with inflammatory indices such as the neutrophil-to-lymphocyte ratio (NLR), systemic inflammation index (SII), and systemic inflammatory response index (SIRI). In contrast, microstate D correlated with the derived neutrophil-to-lymphocyte ratio (dNLR). Microstates B and C inversely correlated with NLR and SII. Furthermore, the duration and coverage of microstate A, along with the transition probability from A to D, inversely correlated with Mini-Mental State Examination (MMSE) scores. Similarly, the AD/BC ratio in occurrence, duration, and coverage also negatively correlated with MMSE scores. These findings revealed alterations in EEG microstates in patients with LGI1 encephalitis, highlighting an imbalance in the AD/BC ratio associated with inflammatory processes and cognitive impairments.