Browsing by keyword "White Matter"
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Connectivity in Autism: A Review of MRI Connectivity StudiesAutism spectrum disorder (ASD) affects 1 in 50 children between the ages of 6 and 17 years. The etiology of ASD is not precisely known. ASD is an umbrella term, which includes both low- (IQ < 70) and high-functioning (IQ > 70) individuals. A better understanding of the disorder and how it manifests in individual subjects can lead to more effective intervention plans to fulfill the individual's treatment needs.Magnetic resonance imaging (MRI) is a non-invasive investigational tool that can be used to study the ways in which the brain develops or deviates from the typical developmental trajectory. MRI offers insights into the structure, function, and metabolism of the brain. In this article, we review published studies on brain connectivity changes in ASD using either resting state functional MRI or diffusion tensor imaging.The general findings of decreases in white matter integrity and in long-range neural coherence are well known in the ASD literature. Nevertheless, the detailed localization of these findings remains uncertain, and few studies link these changes in connectivity with the behavioral phenotype of the disorder. With the help of data sharing and large-scale analytic efforts, however, the field is advancing toward several convergent themes, including the reduced functional coherence of long-range intra-hemispheric cortico-cortical default mode circuitry, impaired inter-hemispheric regulation, and an associated, perhaps compensatory, increase in local and short-range cortico-subcortical coherence.
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Severe leukoaraiosis portends a poor outcome after traumatic brain injuryBACKGROUND AND PURPOSE: It is now well accepted that traumatic white matter injury constitutes a critical determinant of post-traumatic functional impairment. However, the contribution of preexisting white matter rarefaction on outcome following traumatic brain injury (TBI) is unknown. Hence, we sought to determine whether the burden of preexisting leukoaraiosis of presumed ischemic origin is independently associated with outcome after TBI. METHODS: We retrospectively analyzed consecutive, prospectively enrolled patients of > /=50 years (n = 136) who were admitted to a single neurological/trauma intensive care unit. Supratentorial white matter hypoattenuation on head CT was graded on a 5-point scale (range 0-4) reflecting increasing severity of leukoaraiosis. Outcome was ascertained according to the modified Rankin Scale (mRS) and Glasgow outcome scale (GOS) at 3 and 12 months, respectively. RESULTS: After adjustment for other factors, leukoaraiosis severity was significantly associated with a poor outcome at 3 and 12 months defined as mRS 3-6 and GOS 1-3, respectively. The independent association between leukoaraiosis and poor outcome remained when the analysis was restricted to patients who survived up to 3 months, had moderate-to-severe TBI [enrollment Glasgow Coma Scale (GCS) < /=12; p = 0.001], or had mild TBI (GCS 13-15; p = 0.002), respectively. CONCLUSION: We provide first evidence that preexisting cerebral small vessel disease independently predicts a poor functional outcome after closed head TBI. This association is independent of other established outcome predictors such as age, comorbid state as well as intensive care unit complications and interventions. This knowledge may help improve prognostic accuracy, clinical management, and resource utilization.