White matter integrity and cognition in chronic traumatic brain injury: a diffusion tensor imaging study
White matter integrity and cognition in chronic traumatic brain injury: a diffusion tensor imaging study
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DOI：
10.1093/brain/awm216
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发表时间：
2007-10-01
期刊：
影响因子：
14.5
通讯作者：
Little, Deborah M.
中科院分区：
文献类型：
--
作者：
Kraus, Marilyn F.;Susmaras, Teresa;Little, Deborah M.
创伤性脑损伤（TBI）是一个严重的公共卫生问题。即使是最常见的轻度损伤，也可能导致持续的神经行为障碍。弥漫性轴索损伤是TBI后的常见发现，并被认为有助于预后，但使用标准神经影像学检查可能并不总是明显的。扩散张量成像（DTI）是一种较新的方法，评估轴突的完整性在体内。当前研究的主要目的是利用DTI在所有严重程度的慢性TBI范围内表征白色物质的完整性。第二个目的是检查白色物质完整性和认知之间的关系。20例轻度、17例中重度TBI和18例对照者进行了DTI和神经心理学测试。根据DTI数据计算各向异性分数、轴向扩散率和径向扩散率。分数各向异性是白色物质完整性的主要量度。感兴趣的区域分析包括前和后放射冠，皮质脊髓束，扣带纤维束，外囊，小钳和大钳，胼胝体，体和压部，额枕下束，上级纵束和矢状层。认知领域的分数计算执行，注意力和记忆力测试。在中度至重度TBI组的所有13个感兴趣区域均发现分数各向异性降低，但轻度TBI组仅在皮质脊髓束、矢状层和上级纵束中发现分数各向异性降低。白色物质负荷（测量FA减少的区域总数）与所有认知领域呈负相关。径向和轴向扩散率值的分析表明，所有严重程度的TBI都可能导致一定程度的轴突损伤，而不可逆的髓鞘损伤仅在中度至重度TBI时明显。目前的数据强调，白色物质的变化存在于光谱，包括轻度TBI。整体白色神经病理学指数（白色物质负荷）与认知功能相关，因此较大的白色病理学预示较大的认知缺陷。从机制上讲，轻度TBI白色物质变化可能主要是由于轴突损伤，而不是髓鞘损伤。更严重的伤害影响两者。DTI提供了一个客观的手段来确定认知缺陷与TBI的关系，即使是在评估前几年受伤的情况下。
Traumatic brain injury (TBI) is a serious public health problem. Even injuries classified as mild, the most common, can result in persistent neurobehavioural impairment. Diffuse axonal injury is a common finding after TBI, and is presumed to contribute to outcomes, but may not always be apparent using standard neuroimaging. Diffusion tensor imaging (DTI) is a more recent method of assessing axonal integrity in vivo. The primary objective of the current investigation was to characterize white matter integrity utilizing DTI across the spectrum of chronic TBI of all severities. A secondary objective was to examine the relationship between white matter integrity and cognition. Twenty mild, 17 moderate to severe TBI and 18 controls underwent DTI and neuropsychological testing. Fractional anisotropy, axial diffusivity and radial diffusivity were calculated from the DTI data. Fractional anisotropy was the primary measure of white matter integrity. Region of interest analysis included anterior and posterior corona radiata, cortico-spinal tracts, cingulum fibre bundles, external capsule, forceps minor and major, genu, body and splenium of the corpus callosum, inferior fronto-occipital fasciculus, superior longitudinal fasciculus and sagittal stratum. Cognitive domain scores were calculated from executive, attention and memory testing. Decreased fractional anisotropy was found in all 13 regions of interest for the moderate to severe TBI group, but only in the cortico-spinal tract, sagittal stratum and superior longitudinal fasciculus for the mild TBI group. White Matter Load (a measure of the total number of regions with reduced FA) was negatively correlated with all cognitive domains. Analysis of radial and axial diffusivity values suggested that all severities of TBI can result in a degree of axonal damage, while irreversible myelin damage was only apparent for moderate to severe TBI. The present data emphasize that white matter changes exist on a spectrum, including mild TBI. An index of global white matter neuropathology (White Matter Load) was related to cognitive function, such that greater white matter pathology predicted greater cognitive deficits. Mechanistically, mild TBI white matter changes may be primarily due to axonal damage as opposed to myelin damage. The more severe injuries impact both. DTI provides an objective means for determining the relationship of cognitive deficits to TBI, even in cases where the injury was sustained years prior to the evaluation.