Сhanges in the brain connectome in patients with multiple sclerosis after complex neurorehabilitation: a prospective study

INTRODUCTION: The presence of steadily progressive neurological deficit in patients with multiple sclerosis (MS) is the main indication for complex rehabilitation with the involvement of a multidisciplinary team of specialists. A detailed analysis of changes in brain connectivity may provide a better understanding of which compensatory brain mechanisms contribute to productive rehabilitation. MRI markers of neurorehabilitation, on the other hand, can facilitate the standardization of rehabilitation measures, help ensure an individual approach and objectify the results of the treatment process. It should be noted that the possibility of using functional resting state MRI (rs-fMRI) as a technique for assessing the results of neurorehabilitation has still not been sufficiently studied.

OBJECTIVE: To evaluate early and delayed changes in the brain connectome in patients with multiple sclerosis before and after complex neurorehabilitation by using resting state functional MRI.

MATERIALS AND METHODS: The study involved 15 patients with multiple sclerosis (EDSS 1.5–6). A comprehensive neurological examination was performed before and after comprehensive inpatient neurorehabilitation. Resting state functional MRI was performed at three control points: before admission, within 3–5 days after completion of neurorehabilitation, and within 25–30 days after discharge.

Statistics: Statistical processing and evaluation of fMRI data results was carried out using the CONN v.22 software package (p-FDR<0,05).

RESULTS: A decrease in connectivity between the regions of the default mode network of the brain (DMN), the subcallosal and occipital cortex (T= –8,34, Т= –9,12), and an increase in connectivity between the regions of the DMN and the left superior parietal lobule were revealed (T=11,72). There was also increased connectivity between the left superior parietal lobule and elements of the salience network (Т=8,38). Connectivity between visual network components and the right frontal lobe increased (Т=7,04), while connectivity with the left frontal and temporal lobes decreased (Т= –8,69, T= –17,68).

DISCUSSION: A decrease in connectivity in the elements of the DMN in patients indicates the stabilization of its functioning and the restoration of the connection between it and the subcallosal cortex, which belongs to the limbic system. A decrease in connectivity between the lingual gyrus and the DMN regions and a simultaneous increase in connectivity with elements of the right frontal lobe may indicate an increase in the functioning of the directed action system. The identified increase in connectivity between elements of the salience network and the left superior parietal lobule may indicate an improvement in the functioning of the sensorimotor system, incl. its conscious components. Increased connectivity between elements of the medial visual network and the right frontal lobe may also indicate an increase in the quality of directed sensorimotor actions, incl. in the «vision-hand» system. Reduced connectivity between elements of the right occipital lobe and the right sections of the somatosensory network, responsible for the perception of space, the location of the limbs, as well as with the left frontal visual field, precuneus and left inferior temporal gyrus, more probably associated with a reorganization of the structures of directional eye movement and attention.

CONCLUSION: The identified early and late changes in the functional networks of the brain indicate a decrease in the pathological activity of the network of the default mode of the brain, an increase in the activity of structures involved in sensory processing of space (including visual and auditory), as well as an increase in the activity of the salience network and elements of information processing from analyzers of proprioceptive sensitivity.

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