Intranetwork and internetwork functional connectivity abnormalities in pediatric multiple sclerosis

Active motor functional magnetic resonance imaging (fMRI) studies have shown that pediatric multiple sclerosis (MS) patients have a strictly lateralized pattern of activations and a preserved functional connectivity (FC) within the motor system when compared to age-matched healthy controls. However, it is still not clear whether a preserved FC in pediatric MS is present only in the motor system, or involves other relevant functional system. Resting-state (RS) fMRI is a valuable tool for an unbiased investigation of FC abnormalities of multiple networks. This study explored abnormalities of RS FC within and between large-scale neuronal networks from 44 pediatric MS patients and 27 controls and their correlation with clinical, neuropsychological, and conventional MRI measures. Compared to controls, pediatric MS patients had a decreased FC of several regions of the sensorimotor, secondary visual, default-mode (DMN), executive control, and bilateral working memory (WMN) networks. They also experienced an increased FC in the right medial frontal gyrus of the attention network, which was correlated with T2 lesion volume. Cognitively impaired patients had decreased RS FC of the right precuneus of the left WMN. An increased FC between the sensorimotor network and the DMN, and between the L WMN and the attention network as well as a decreased FC between L WMN and the DMN were also found. A distributed pattern of FC abnormalities within large-scale neuronal networks occurs in pediatric MS patients, contributes to their cognitive status, and is partially driven by focal white matter lesions. Internetwork connectivity is relatively preserved in these patients.