ID 65 – Magnetoencephalography (MEG) and diffusion tensor magnetic resonance imaging (DTI) of functional and effective brain connectivity in traumatic brain injury (TBI)

Abstract

The present study used an integrated multimodal neuroimaging approach involving MEG and DTI to assess their utility in functional and effective connectivity evaluation in TBI. The study population consisted of TBI patients (25) and a group of healthy subjects (25). All patients in the sample have been examined twice (before and after rehabilitation). All study patients completed a neurorehabilitation program adapted to each individual’s requirements. Patients and controls underwent a neuropsychological assessment, in order to establish their cognitive status in multiple cognitive functions. Traumatic white matter injury has been measured with diffusion tensor imaging (DTI), impaired cortical activation has been detected with MEG. Brain networks connectivity analysis showed: TBI patients exhibit functional connectivity alteration as compared to the control subjects; overall significant reduction of MEG connectivity activity in TBI patients compared with control subjects. Extent of functional disconnection was associated with injury severity. Reduction of MEG connectivity originates from gray matter neurons that experience de-afferentation due to axonal injury to the underlying white matter fiber tracts, which was manifested on diffusion tensor imaging (DTI) as reduced fractional anisotropy. Neuronal reorganization, as measured by brain connectivity, due to comprehensive rehabilitation process correlated with cognitive recovery as indicated by neuropsychological assessment.