Specific and Evolving Resting-State Network Alterations in Post-Concussion Syndrome Following Mild Traumatic Brain Injury

<div><p>Post-concussion syndrome has been related to axonal damage in patients with mild traumatic brain injury, but little is known about the consequences of injury on brain networks. In the present study, our aim was to characterize changes in functional brain networks following mild traumatic brain injury in patients with post-concussion syndrome using resting-state functional magnetic resonance imaging data. We investigated 17 injured patients with persistent post-concussion syndrome (under the DSM-IV criteria) at 6 months post-injury compared with 38 mild traumatic brain injury patients with no post-concussion syndrome and 34 healthy controls. All patients underwent magnetic resonance imaging examinations at the subacute (1–3 weeks) and late (6 months) phases after injury. Group-wise differences in functional brain networks were analyzed using graph theory measures. Patterns of long-range functional networks alterations were found in all mild traumatic brain injury patients. Mild traumatic brain injury patients with post-concussion syndrome had greater alterations than patients without post-concussion syndrome. In patients with post-concussion syndrome, changes specifically affected temporal and thalamic regions predominantly at the subacute stage and frontal regions at the late phase. Our results suggest that the post-concussion syndrome is associated with specific abnormalities in functional brain network that may contribute to explain deficits typically observed in PCS patients.</p></div

Regions with significant graph properties associations with symptom severity (corrected, p<1/N).

<p><u>Abbreviations:</u><i>d_e</i>, edge diversity; <i>E_l</i>, local efficiency; <i>E_n</i>, nodal efficiency; <i>k</i>, degree; L, left; R, right; <i>s</i>, strength. Definition of basic (<i>s</i> and <i>d_e</i>) and topologic (<i>k</i>, <i>E_l</i> and <i>E_n</i>) measures can be found in the subsection “<i>Characteristics of brain network organization using graph theory</i>” of the Materials and Methods section and in the supporting information File S1, respectively.</p

Brain regions with significant group differences in topological graph properties (<i>k</i>, <i>E_l</i>, <i>E_n</i> and <i>bc</i>) between mTBI patients and controls at p<0.05 (uncorrected).

<p>The node size indicates the number of topological properties with significant group differences. The nodal regions are located according to their centroid stereotaxic coordinates. Nodal color code for the average size effect, hot (resp. cold) colors represent increased (resp. decreased) properties.</p

Association of modularity (left) and local efficiency of superior frontal regions (right) with symptom severity in mTBI patients at the late phase.

<p>Association of modularity (left) and local efficiency of superior frontal regions (right) with symptom severity in mTBI patients at the late phase.</p

Brain regions with significant group differences in basic graph properties (<i>s</i> and <i>d_e</i>) between mTBI patients and controls at p<0.05 (uncorrected).

<p>The node size indicates the number of basic properties with significant group differences. The nodal regions are located according to their centroid stereotaxic coordinates. Nodal color code for the average size effect, hot (resp. cold) colors represent increased (resp. decreased) properties.</p

Clinical and overall graph characteristics of all participants.

<p><u>Abbreviations:</u> GCS, Glasgow coma scale; F, female; M, male; MVA, motor vehicle accident; PCS, post-concussion syndrome; SCL, socio-cultural level. Mean and standard deviation (SD) values are given, except for gender. Bold indicates significance at p<0.05.</p