Post mTBI fatigue is associated with abnormal brain functional connectivity.

Love Engström Nordin,Aniko Bartfai,Farouk Hashim,Per Julin,Marika Christina Möller,Tie-Qiang Li

doi:10.1038/srep21183

Abstract

This study set out to investigate the behavioral correlates of changes in resting-state functional connectivity before and after performing a 20 minute continuous psychomotor vigilance task (PVT) for patients with chronic post-concussion syndrome. Ten patients in chronic phase after mild traumatic brain injury (mTBI) with persisting symptoms of fatigue and ten matched healthy controls participated in the study. We assessed the participants’ fatigue levels and conducted resting-state fMRI before and after a sustained PVT. We evaluated the changes in brain functional connectivity indices in relation to the subject’s fatigue behavior using a quantitative data-driven analysis approach. We found that the PVT invoked significant mental fatigue and specific functional connectivity changes in mTBI patients. Furthermore, we found a significant linear correlation between self-reported fatigue and functional connectivity in the thalamus and middle frontal cortex. Our findings indicate that resting-state fMRI measurements may be a useful indicator of performance potential and a marker of fatigue level in the neural attentional system.

Highlights

The annual incidence of hospital-treated mild traumatic brain injury has been estimated to be 100–300 per 100.000 in the industrialized world and over 600 per 100,000 when including those who do not seek emergency medical care[1]
We developed a voxel-based quantitative data-driven analysis (QDA) method for the analysis of resting-state fMRI data, which derives two metrics named as connectivity count index (CCI) and connectivity strength index (CSI) allowing for direct comparison of functional connectivity measurements between different subjects and at different time points[31]
There was no significant difference in self-rated current fatigue (Visual Analogue Scale of fatigue, visual analog scale of fatigue (VAS-f)) between patients and controls before MRI scanning, but directly after the psychomotor vigilance task (PVT) performance the patients scored significantly higher for current fatigue than the controls

Summary

Introduction

The annual incidence of hospital-treated mild traumatic brain injury (mTBI) has been estimated to be 100–300 per 100.000 in the industrialized world and over 600 per 100,000 when including those who do not seek emergency medical care[1]. MRS can selectively measure disturbance of the brain metabolites in mTBI12 These techniques have been quite successful in mTBI studies and provided important new lines of evidence suggesting that a single concussion can result in lifetime impairment for some individuals and the neuropathology may be present long after the concussion[9,10,12,13,14,15,16,17]. The large number of resting-state fMRI studies in the last few years have led to some interesting findings regarding abnormal brain functional connectivity in mTBI patients. Resting-state fMRI studies of mTBI patients with post-concussion syndrome have revealed reduced functional connectivity at the chronic phase in other networks aside from the DMN, including the thalamic network[26], motor-striatal network[15], frontal regions[13], task positive and salience networks[14]. We can attribute this to the following factors:

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Results

Conclusion