Leyden Kelly M, Kucukboyaci N Erkut, Puckett Olivia K, Lee Davis, Loi Richard Q, Paul Brianna, McDonald Carrie R
1 Multimodal Imaging Laboratory, University of California, San Diego, CA, USA ; 2 San Diego State University/University of California, San Diego Joint Doctoral Program in Clinical Psychology, San Diego, CA, USA ; 3 Department of Cognitive Science, 4 Department of Biology, University of California, San Diego, CA, USA ; 5 Comprehensive Epilepsy Center, Department of Neurology, University of California, San Francisco, CA, USA ; 6 Department of Psychiatry, University of California, San Diego, CA, USA.
Quant Imaging Med Surg. 2015 Apr;5(2):247-63. doi: 10.3978/j.issn.2223-4292.2015.02.01.
Diffusion tensor imaging (DTI) has provided considerable insight into our understanding of epilepsy as a network disorder, revealing subtle alterations in white matter microstructure both proximal and distal to the epileptic focus. These white matter changes have been shown to assist with lateralizing the seizure focus, as well as delineating the location/anatomy of key white matter tracts (i.e., optic radiations) for surgical planning. However, only recently have studies emerged describing the utility of DTI for probing cognitive networks in patients with epilepsy and for examining the structural plasticity within these networks both before and after epilepsy surgery. Here, we review the current literature describing the use of DTI for understanding language and memory networks in patients with temporal lobe epilepsy (TLE), as well as the extant literature on networks associated with executive functioning and global intelligence. Studies of memory and language reveal a complex network of frontotemporal fibers that contribute to naming and fluency performance in TLE, and demonstrate that these networks appear to undergo adaptive changes in response to surgical intervention. Although studies of executive functioning and global intelligence have been less conclusive, there is accumulating evidence that aberrant communication between frontoparietal and medial temporal networks may underlie working memory impairment in TLE. More recently, multimodal imaging studies have provided evidence that disruptions within these white matter networks co-localize with functional changes observed on functional MRI. However, structure-function associations are not entirely coherent and may breakdown in patients with TLE, especially those with a left-sided seizure focus. Although the reasons for discordant findings are unclear, small sample sizes, heterogeneity within patient populations and limitations of the current tensor model may account for contradictory and null findings. Improvements in imaging hardware and higher field strengths have now paved the way for the implementation of advanced diffusion techniques, and these advanced models show great promise for improving our understanding of how network dysfunction contributes to cognitive morbidity in TLE.
扩散张量成像（DTI）为我们将癫痫理解为一种网络疾病提供了相当多的见解，揭示了癫痫灶近端和远端白质微结构的细微改变。这些白质变化已被证明有助于确定癫痫发作灶的位置，以及勾勒关键白质束（即视辐射）的位置/解剖结构以用于手术规划。然而，直到最近才有研究出现，描述了DTI在探测癫痫患者认知网络以及检查癫痫手术前后这些网络内结构可塑性方面的效用。在此，我们回顾当前描述使用DTI来理解颞叶癫痫（TLE）患者语言和记忆网络的文献，以及关于与执行功能和整体智力相关网络的现有文献。对记忆和语言的研究揭示了一个复杂的额颞纤维网络，其有助于TLE患者的命名和流畅性表现，并表明这些网络似乎会因手术干预而发生适应性变化。尽管对执行功能和整体智力的研究结论性较差，但越来越多的证据表明，额顶叶和内侧颞叶网络之间的异常通信可能是TLE患者工作记忆受损的基础。最近，多模态成像研究提供了证据，表明这些白质网络内的破坏与功能磁共振成像上观察到的功能变化共定位。然而，结构 - 功能关联并不完全一致，在TLE患者中可能会失效，尤其是那些左侧有癫痫发作灶的患者。尽管不一致结果的原因尚不清楚，但小样本量、患者群体的异质性以及当前张量模型的局限性可能解释了相互矛盾和无结果的发现。成像硬件的改进和更高的场强现在为先进扩散技术的应用铺平了道路，这些先进模型有望改善我们对网络功能障碍如何导致TLE患者认知发病的理解。
