High-density EEG microstates for functional evaluation of visual pathway in multiple sclerosis: a correlation study...

Visual pathway dysfunction is common in multiple sclerosis (MS). While visual evoked potentials (VEPs) remain the gold standard for assessing functional integrity, high-density EEG (hdEEG) microstate analysis offers insight into resting-state neural dynamics. This exploratory study aimed to evaluate visual pathway alterations in patients with relapsing-remitting MS (RRMS) through microstate analysis - particularly the visual processing microstate, Map-B - and to compare these findings with VEP parameters.

Twenty-two RRMS patients underwent hdEEG recording. Segmentation analysis identified dominant microstates, and temporal parameters (mean duration, frequency, time coverage, and global explained variance- GEV) were computed. All subjects also underwent full-field pattern-reversal VEPs, measuring N75, P100, and N145 latencies, N75-N145 dispersion, and amplitude.

VEP N75-N145 dispersion negatively correlated with Map-B GEV and frequency. In patients with normal N75-N145 dispersion, Map-B expression positively correlated with P100 and N145 latencies.

Altered temporal dynamics of Map-B microstates reflect visual pathway dysfunction in RRMS. Reduced Map-B representation may indicate decreased visual cortical activity, whereas increased expression may represent compensatory mechanisms.

hdEEG microstate analysis provides a promising, non-invasive tool for assessing resting-state visual cortical function in MS, complementing conventional VEP evaluation.