Department of Brain and Cognitive Sciences, Massachusetts Institute of Technology, Cambridge, Massachusetts, USA.
Epilepsia. 2012 Jun;53(6):1024-32. doi: 10.1111/j.1528-1167.2012.03466.x. Epub 2012 Apr 23.
Periventricular nodular heterotopia (PNH) is a malformation of cortical development associated with epilepsy and dyslexia. Evidence suggests that heterotopic gray matter can be functional in brain malformations and that connectivity abnormalities may be important in these disorders. We hypothesized that nodular heterotopia develop abnormal connections and systematically investigated the structural and functional connectivity of heterotopia in patients with PNH.
Eleven patients were studied using diffusion tensor tractography and resting-state functional connectivity MRI with bold oxygenation level-dependent (BOLD) imaging. Fiber tracks with a terminus within heterotopic nodules were visualized to determine structural connectivity, and brain regions demonstrating resting-state functional correlations to heterotopic nodules were analyzed. Relationships between these connectivity results and measures of clinical epilepsy and cognitive disability were examined.
A majority of heterotopia (69%) showed structural connectivity to discrete regions of overlying cortex, and almost all (96%) showed functional connectivity to these regions (mean peak correlation coefficient 0.61). Heterotopia also demonstrated connectivity to regions of contralateral cortex, other heterotopic nodules, ipsilateral but nonoverlying cortex, and deep gray matter structures or the cerebellum. Patients with the longest durations of epilepsy had a higher degree of abnormal functional connectivity (p = 0.036).
Most heterotopic nodules in PNH are structurally and functionally connected to overlying cortex, and the strength of abnormal connectivity is higher among patients with the longest duration of epilepsy. Along with prior evidence that cortico-cortical tract defects underlie dyslexia in this disorder, the current findings suggest that altered connectivity is likely a critical substrate for neurologic dysfunction in brain malformations.
室周结节性异位（PNH）是一种与癫痫和诵读困难相关的皮质发育畸形。有证据表明，异位灰质在脑畸形中可能具有功能性，连接异常可能在这些疾病中很重要。我们假设结节性异位会形成异常连接，并系统地研究了 PNH 患者异位结节的结构和功能连接。
使用扩散张量纤维束追踪和静息态血氧水平依赖功能磁共振成像（BOLD）对 11 名患者进行研究。可视化纤维束末端位于异位结节内，以确定结构连接，分析与异位结节有静息态功能相关性的脑区。检查这些连接结果与临床癫痫和认知障碍测量值之间的关系。
大多数异位结节（69%）与上覆皮质的离散区域具有结构连接，几乎所有（96%）都与这些区域具有功能连接（平均峰值相关系数 0.61）。异位结节还与对侧皮质、其他异位结节、同侧但不重叠的皮质以及深部灰质结构或小脑的区域具有连接。癫痫持续时间最长的患者具有更高程度的异常功能连接（p = 0.036）。
PNH 中的大多数异位结节在结构上和功能上与上覆皮质相连，癫痫持续时间最长的患者异常连接的强度更高。结合先前关于皮质-皮质束缺陷是该疾病诵读困难的基础的证据，目前的发现表明，连接改变可能是脑畸形神经功能障碍的关键基础。
