Methodical Approach to fMRI Assessment of Motor Connectome in Patients After Severe Traumatic Brain Injury

Abstract

The aim of the study. To identify alterations of motor connectome in patients with varying degrees of hemi-paresis after severe traumatic brain injury (TBI) versus healthy volunteers.Material and methods. The study included 29 patients with TBI aged 18 to 35 years and 23 healthy volunteers aged 20 to 32 years. Participants underwent a comprehensive clinical and neuroimaging study. Motor impairment was evaluated via muscle strength assessment using a five-score scale. The fMRI data were processed using a dedicated CONN software package. Anatomical 3-D connection masks of the whole brain motor functional system in the predetermined regions of interest (ROIs) were used for the assessment. Then the group indicators of functional connectivity (statistical significance of the connection) were computed.Results. It was established that the structure of connections in healthy individuals performing active movement with the right (leading) hand is determined by formation of focus in the cortical and subcortical ROIs in the contralateral hemisphere. With passive movement of the right hand the pale ball becomes functionally active in addition to the activated areas. The striopallidar system structures became active on both sides, and connectivity with the additional motor cortex and the motor cortex of the ipsilateral hemisphere emerged as the paresis increased during active movement. The focus of motor activity during passive movement was determined in the motor cortex and putamen, which makes it possible to use a passive test in patients with gross motor disorders or unconsciousness for a full assessment of the entire structural and functional brain connectome.Conclusion. As hemiparesis increased in patients after severe traumatic brain injury, a decrease in the total number of connection appeared; simultaneous engagement of ancient primordial structures, such as bilateral activation of pale globes, demonstrated neuroplasticity.

Keywords

• traumatic brain injury
• chronic critical illness
• pathogenesis of motor connectome impairment
• neuroplasticity