Behnke Joseph A, Ahluwalia Vishwadeep, Smith Jeremy L, Risk Benjamin B, Lin Jianna, Gore Russell K, Allen Jason W
Department of Radiology and Imaging Sciences, Emory University School of Medicine, Atlanta, GA, United States.
Georgia Institute of Technology, Atlanta, GA, United States.
Imaging Neurosci (Camb). 2024;2. doi: 10.1162/imag_a_00147. Epub 2024 Apr 10.
Vestibular symptoms, such as dizziness and balance impairment, are frequently reported following mild traumatic brain injury (mTBI) and are associated with a protracted recovery, yet the underlying neuroanatomical substrates remain unclear. The present study utilized advanced diffusion MRI (dMRI) techniques including both conventional diffusion tensor imaging (DTI) and neurite orientation dispersion and density imaging (NODDI) to investigate microstructural white matter integrity in individuals with postconcussive vestibular dysfunction (PCVD) within the subacute injury period (median of 35 days from injury; IQR of 23). Study participants included 23 individuals with subacute PCVD and 37 healthy control subjects who underwent imaging and comprehensive clinical vestibular testing. Between-group voxelwise analysis of differences in white matter revealed areas of higher intra-neurite volume fraction (V) and isotropic volume fraction (V) within PCVD subjects compared to controls, which involved overlapping regions within the left hemisphere of the brain. Affected areas of higher V and V included the superior longitudinal fasciculus (SLF) and superior and posterior corona radiata (SCR and PCR, respectively). We examined the relationship between clinical vestibular measures and diffusion metrics including DTI (fractional anisotropy [FA], mean diffusivity [MD], radial diffusivity [RD] and axial diffusivity [AD]) and NODDI (intraneurite volume fraction [V], isotropic volume fraction [V], dispersion anisotropy [DA], orientation dispersion index [ODI]) within 32 regions-of-interest. Clinical vestibular measures included self-reported measures, including the Dizziness Handicap Inventory, Visual Vertigo Analog Scale, and Vestibular/Ocular-Motor Screening, as well as objective vestibular testing using the sensory organization test. Significant correlations were found with clinical measures across all diffusion maps (except DA), within various regions of interest (ROIs), including SLF, SCR, and PCR. These results implicate several important association bundles that may potentiate sensory processing dysfunction related to PCVD. Whether these neuroanatomical differences found within the subacute phase of PCVD are in response to injury or represent preexisting structural variations that increase vulnerability to sensory processing dysfunction is unclear and remains an active area of study.
前庭症状，如头晕和平衡障碍，在轻度创伤性脑损伤（mTBI）后经常被报告，并且与恢复过程延长相关，但潜在的神经解剖学基质仍不清楚。本研究利用先进的扩散磁共振成像（dMRI）技术，包括传统的扩散张量成像（DTI）和神经突方向离散度与密度成像（NODDI），来研究亚急性损伤期（受伤后中位数35天；四分位距23天）患有震荡后前庭功能障碍（PCVD）的个体的微观结构白质完整性。研究参与者包括23名患有亚急性PCVD的个体和37名健康对照者，他们接受了成像和全面的临床前庭测试。对两组之间白质差异的体素分析显示，与对照组相比，PCVD受试者的神经突内体积分数（V）和各向同性体积分数（V）较高的区域，这些区域涉及大脑左半球内的重叠区域。较高V和V的受影响区域包括上纵束（SLF）以及放射冠的上部和后部（分别为SCR和PCR）。我们在32个感兴趣区域内检查了临床前庭测量指标与扩散指标之间的关系，扩散指标包括DTI（分数各向异性[FA]、平均扩散率[MD]、径向扩散率[RD]和轴向扩散率[AD]）和NODDI（神经突内体积分数[V]、各向同性体积分数[V]、离散各向异性[DA]、方向离散指数[ODI]）。临床前庭测量指标包括自我报告的指标，如头晕残障量表、视觉眩晕模拟量表和前庭/眼动筛查，以及使用感觉组织测试的客观前庭测试。在所有扩散图谱（除DA外）上，在包括SLF、SCR和PCR在内의各个感兴趣区域（ROI）内，均发现与临床测量指标有显著相关性。这些结果表明，有几个重要的联合束可能会加剧与PCVD相关的感觉处理功能障碍。在PCVD亚急性期发现的这些神经解剖学差异是对损伤的反应，还是代表预先存在的结构变异，增加了对感觉处理功能障碍的易感性，目前尚不清楚，仍是一个活跃的研究领域。
