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Multimodal imaging of mild traumatic brain injury and persistent postconcussion syndrome.

Dean PJ, Sato JR, Vieira G, McNamara A, Sterr A - Brain Behav (2014)

Bottom Line: It was hypothesized that only those mTBI participants with persistent PCS would show functional changes, and that these changes would be related to reduced structural integrity and altered metabolite concentrations.There were no behavioral differences between the groups, but participants with greater PCS symptoms exhibited greater activation in attention-related areas (anterior cingulate), along with reduced activation in temporal, default mode network, and working memory areas (left prefrontal) as cognitive load was increased from the easiest to the most difficult task.Functional changes in these areas correlated with reduced structural integrity in corpus callosum and anterior white matter, and reduced creatine concentration in right dorsolateral prefrontal cortex.

View Article: PubMed Central - PubMed

Affiliation: School of Psychology, University Of Surrey Guildford, UK.

ABSTRACT

Background: Persistent postconcussion syndrome (PCS) occurs in around 5-10% of individuals after mild traumatic brain injury (mTBI), but research into the underlying biology of these ongoing symptoms is limited and inconsistent. One reason for this could be the heterogeneity inherent to mTBI, with individualized injury mechanisms and psychological factors. A multimodal imaging study may be able to characterize the injury better.

Aim: To look at the relationship between functional (fMRI), structural (diffusion tensor imaging), and metabolic (magnetic resonance spectroscopy) data in the same participants in the long term (>1 year) after injury. It was hypothesized that only those mTBI participants with persistent PCS would show functional changes, and that these changes would be related to reduced structural integrity and altered metabolite concentrations.

Methods: Functional changes associated with persistent PCS after mTBI (>1 year postinjury) were investigated in participants with and without PCS (both n = 8) and non-head injured participants (n = 9) during performance of working memory and attention/processing speed tasks. Correlation analyses were performed to look at the relationship between the functional data and structural and metabolic alterations in the same participants.

Results: There were no behavioral differences between the groups, but participants with greater PCS symptoms exhibited greater activation in attention-related areas (anterior cingulate), along with reduced activation in temporal, default mode network, and working memory areas (left prefrontal) as cognitive load was increased from the easiest to the most difficult task. Functional changes in these areas correlated with reduced structural integrity in corpus callosum and anterior white matter, and reduced creatine concentration in right dorsolateral prefrontal cortex.

Conclusion: These data suggest that the top-down attentional regulation and deactivation of task-irrelevant areas may be compensating for the reduction in working memory capacity and variation in white matter transmission caused by the structural and metabolic changes after injury. This may in turn be contributing to secondary PCS symptoms such as fatigue and headache. Further research is required using multimodal data to investigate the mechanisms of injury after mTBI, but also to aid individualized diagnosis and prognosis.

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Related in: MedlinePlus

Regions of Interest for fMRI (F-ROI, A) and DTI (D-ROI, B).
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fig02: Regions of Interest for fMRI (F-ROI, A) and DTI (D-ROI, B).

Mentions: The fMRI indices consisted of the z-statistic for each individual extracted from three fMRI regions of interest (F-ROI's, see Table 2). These F-ROIs were areas with significant BOLD response difference between groups, or significant association with PCS symptom report, and were chosen to represent changes in prefrontal areas (F-ROI1: Medial and Inferior Frontal Gyrus [MFG/IFG], 1 > 2.5s PVSAT), default mode network areas (F-ROI2: Posterior Cingulate Cortex [PCC] and Precuneus, 1 > 2.5s PVSAT correlation with RPQ) and attention-related areas (F-ROI3: Supplementary Motor Area [SMA] and Anterior Cingulate Cortex [ACC], 3 > 0-Back correlation with RPQ). ROI masks were created from the overlap between the z-statistic image for the contrast (Z > 1.9, group level analysis) and an AAL labeled mask of the main area of the cluster (Fig.2A)


Multimodal imaging of mild traumatic brain injury and persistent postconcussion syndrome.

Dean PJ, Sato JR, Vieira G, McNamara A, Sterr A - Brain Behav (2014)

Regions of Interest for fMRI (F-ROI, A) and DTI (D-ROI, B).
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4321394&req=5

fig02: Regions of Interest for fMRI (F-ROI, A) and DTI (D-ROI, B).
Mentions: The fMRI indices consisted of the z-statistic for each individual extracted from three fMRI regions of interest (F-ROI's, see Table 2). These F-ROIs were areas with significant BOLD response difference between groups, or significant association with PCS symptom report, and were chosen to represent changes in prefrontal areas (F-ROI1: Medial and Inferior Frontal Gyrus [MFG/IFG], 1 > 2.5s PVSAT), default mode network areas (F-ROI2: Posterior Cingulate Cortex [PCC] and Precuneus, 1 > 2.5s PVSAT correlation with RPQ) and attention-related areas (F-ROI3: Supplementary Motor Area [SMA] and Anterior Cingulate Cortex [ACC], 3 > 0-Back correlation with RPQ). ROI masks were created from the overlap between the z-statistic image for the contrast (Z > 1.9, group level analysis) and an AAL labeled mask of the main area of the cluster (Fig.2A)

Bottom Line: It was hypothesized that only those mTBI participants with persistent PCS would show functional changes, and that these changes would be related to reduced structural integrity and altered metabolite concentrations.There were no behavioral differences between the groups, but participants with greater PCS symptoms exhibited greater activation in attention-related areas (anterior cingulate), along with reduced activation in temporal, default mode network, and working memory areas (left prefrontal) as cognitive load was increased from the easiest to the most difficult task.Functional changes in these areas correlated with reduced structural integrity in corpus callosum and anterior white matter, and reduced creatine concentration in right dorsolateral prefrontal cortex.

View Article: PubMed Central - PubMed

Affiliation: School of Psychology, University Of Surrey Guildford, UK.

ABSTRACT

Background: Persistent postconcussion syndrome (PCS) occurs in around 5-10% of individuals after mild traumatic brain injury (mTBI), but research into the underlying biology of these ongoing symptoms is limited and inconsistent. One reason for this could be the heterogeneity inherent to mTBI, with individualized injury mechanisms and psychological factors. A multimodal imaging study may be able to characterize the injury better.

Aim: To look at the relationship between functional (fMRI), structural (diffusion tensor imaging), and metabolic (magnetic resonance spectroscopy) data in the same participants in the long term (>1 year) after injury. It was hypothesized that only those mTBI participants with persistent PCS would show functional changes, and that these changes would be related to reduced structural integrity and altered metabolite concentrations.

Methods: Functional changes associated with persistent PCS after mTBI (>1 year postinjury) were investigated in participants with and without PCS (both n = 8) and non-head injured participants (n = 9) during performance of working memory and attention/processing speed tasks. Correlation analyses were performed to look at the relationship between the functional data and structural and metabolic alterations in the same participants.

Results: There were no behavioral differences between the groups, but participants with greater PCS symptoms exhibited greater activation in attention-related areas (anterior cingulate), along with reduced activation in temporal, default mode network, and working memory areas (left prefrontal) as cognitive load was increased from the easiest to the most difficult task. Functional changes in these areas correlated with reduced structural integrity in corpus callosum and anterior white matter, and reduced creatine concentration in right dorsolateral prefrontal cortex.

Conclusion: These data suggest that the top-down attentional regulation and deactivation of task-irrelevant areas may be compensating for the reduction in working memory capacity and variation in white matter transmission caused by the structural and metabolic changes after injury. This may in turn be contributing to secondary PCS symptoms such as fatigue and headache. Further research is required using multimodal data to investigate the mechanisms of injury after mTBI, but also to aid individualized diagnosis and prognosis.

Show MeSH
Related in: MedlinePlus