Balance impairments are common in people with Multiple Sclerosis (PwMS). However, no studies have examined brain activation while performing balance tasks in PwMS.

The present study aims to investigate hemodynamic response function (HRF) between Healthy Subjects (HS) and PwMS during the execution of balance tasks on a stabilometric platform using functional near-infrared spectroscopy (fNIRS).

We recruited 18 PwMS with mean+standard deviation age of 42.1±10.6 years and Expanded Disability Status Scale (EDSS) of 2.0±1 points, and 18 age- and gender-matched HS aged 37.3±9.7 years. Participants underwent fNIRS recordings while maintaining upright standing on a foam with eyes open (EO) and closed (EC) for 30 seconds. We investigated frontal, occipital, and temporal cortices using the NIRSscoutX system to measure oxy- and deoxyhemoglobin levels for 44 measurement channels. We concurrently measured the Area of the centre of pressure. We used a t-test to compare between-group differences on Area (Platform variable), while we ran a linear mixed model (Area, channel, and group) to fit HRF changes between EO and EC conditions.

We observed statistically significant between-group differences in Area in EO (p=0.04) and EC condition (p=0.02). Group means (standard error) adjusted for Area and multiple comparisons denotes statistically significant differences in 3 active channels (Broadman Area 21): right temporal (Channel 1, HS:1.41(0.23) uM; PwMS:0.41(0.26) uM) and left temporal (Channel 2, HS:1.47(0.23) uM; PwMS:0.30(0.25) uM; Channel 3, HS:1.76(0.23) uM; PwMS:0.98(0.26) uM). We did not observe differences in the other cortical areas.

As expected, balance control is impaired in PwMS on foam with EC. The current study adds to the literature that the increase in HRF observed in EC condition in HS is reduced in PwMS. This reduction occurs explicitly symmetrically in the right and left temporal cortices.

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