Reduced Diffusion Tensor Fractional Anisotropy in the Left Arcuate Fasciculus of Patients with Aphasia Caused by Acute Cerebral Infarct

Abstract

INTRODUCTIONAphasia is a common symptom in the acute stage following cerebral infarct. 1) Recent neuroimaging studies have revealed many aspects of the neuropathology of aphasia. 2,3) Aphasia is often associated with lesions within language-related cortical regions such as Wernicke's and Broca's areas or within the neural fiber networks connecting these regions. 4,5) However, the contributions of specific tracts remain unclear, in part because white matter tract disruption cannot be detected by classical neuroimaging modalities. In contrast to classical neuroimaging techniques, magnetic resonance diffusion tensor imaging (DTI) enables the assessment of neural fiber integrity in vivo. 6) Consequently, DTI may be a useful tool for identifying the subcortical white matter structures responsible for aphasia.Most recent DTI studies of aphasia caused by cerebral infarct have investigated patients in the chronic stage. [7][8][9][10] However, patients with aphasia show various patterns of recovery during the months and years after stroke, 11,12) partially resulting from compensation and/or neural plasticity among language-related and other brain areas. 13-15) Accordingly, DTI studies of patients in the chronic phase may not be sufficient to fully describe the neuropathology of aphasia. In this study, we examined patients with aphasia caused by cerebral infarct in the acute stage by using DTI. 16) To determine the Background: Magnetic resonance diffusion tensor imaging (DTI) is a new technique that evaluates neural fiber integrity within the brain. We conducted DTI in patients exhibiting aphasia during the acute stage post-infarct and investigated the neural tracts responsible by comparison with DTI data from age-matched controls. Methods: Fractional anisotropy (FA) maps were generated from diffusion tensor brain images obtained from aphasic patients 14−21 days following their first infarct. Tract-based spatial statistics (TBSS) analysis was then applied. In addition, regions of interest (ROIs) were set within the right and left arcuate fasciculus, and mean FA values were extracted from individual TBSS data. The ratios between FA values in the left and right hemispheres were compared with those of the control group. Results: The study examined 10 aphasic patients and 21 age-matched controls. Brain maps from TBSS analysis revealed significantly reduced FA in the left arcuate fasciculus of the patient group compared with that in the control group. Copyright © 2016 The Japanese Association of Rehabilitation Medicine lesions responsible, we applied tract-based spatial statistics (TBSS) 17) in reference to age-matched control subjects.

Applicability of automated tractography during acute care stroke rehabilitation

“…The XTRACT tool in FSL tracks 42 neural tracts within the brain, including projection, association, and commissural fibers. However, for clarity, we limited our investigations to the CST and AF for two reasons: (1) our previous DTI studies, which focused on stroke patients with supratentorial lesions, indicated that the most severely damaged neural tracts were the CST and AF, and (2) the CST is correlated with motor-related symptoms such as hemiparesis, and the AF is associated with cognition-related symptoms such as aphasia 6,7,28) .…”

Brain regions associated with Brunnstrom and functional independence measure scores in patients after a stroke: a tract-based spatial statistics study

“…Recent imaging studies revealed that the functional role of the SLF includes working memory, motor control, language function, and visual recognition [23][24][25][26][27] . Previous neuroimaging studies of stroke patients reported that neural degeneration in the left SLF was associated with aphasia 28,29) while the right SLF was associated with unilateral neglect 30,31) . As far as we know, our study is the first DTI-FA study to use GLM for both motor and cognition domains.…”

Elucidating the mechanisms of post-stroke motor recovery mediated by electroacupuncture using diffusion tensor tractography

“…In addition, the value of AD was significantly less increased in the experimental group than in the control group. AD refers to the magnitude of diffusion parallel to fiber tracts ( 31 ). A decrease in AD may indicate axonal damage in the acute phase after injury, whereas an AD elevation may be attributed to degenerative processes in the chronic phase ( 30 ).…”