Chen Yin Jie, Nabavizadeh Seyed Ali, Vossough Arastoo, Kumar Sunil, Loevner Laurie A, Mohan Suyash
Division of Neuroradiology, Department of Radiology, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, PA.
Department of Radiology, Children's Hospital of Philadelphia, Philadelphia, PA.
J Neuroimaging. 2017 May;27(3):272-280. doi: 10.1111/jon.12404. Epub 2016 Nov 7.
Wallerian degeneration (WD) is defined as progressive anterograde disintegration of axons and accompanying demyelination after an injury to the proximal axon or cell body. Since the 1980s and 1990s, conventional magnetic resonance imaging (MRI) sequences have been shown to be sensitive to changes of WD in the subacute to chronic phases. More recently, advanced MRI techniques, such as diffusion-weighted imaging (DWI) and diffusion tensor imaging (DTI), have demonstrated some of earliest changes attributed to acute WD, typically on the order of days. In addition, there is increasing evidence on the value of advanced MRI techniques in providing important prognostic information related to WD. This article reviews the utility of conventional and advanced MRI techniques for assessing WD, by focusing not only on the corticospinal tract but also other neural tracts less commonly thought of, including corticopontocerebellar tract, dentate-rubro-olivary pathway, posterior column of the spinal cord, corpus callosum, limbic circuit, and optic pathway. The basic anatomy of these neural pathways will be discussed, followed by a comprehensive review of existing literature supported by instructive clinical examples. The goal of this review is for readers to become more familiar with both conventional and advanced MRI findings of WD involving important neural pathways, as well as to illustrate increasing utility of advanced MRI techniques in providing important prognostic information for various pathologies.
沃勒变性（WD）被定义为在近端轴突或细胞体受损后，轴突进行性顺行性崩解及伴随的脱髓鞘。自20世纪80年代和90年代以来，传统磁共振成像（MRI）序列已被证明对亚急性期至慢性期的沃勒变性变化敏感。最近，先进的MRI技术，如扩散加权成像（DWI）和扩散张量成像（DTI），已显示出一些归因于急性沃勒变性的最早变化，通常在数天左右。此外，越来越多的证据表明先进的MRI技术在提供与沃勒变性相关的重要预后信息方面具有价值。本文回顾了传统和先进MRI技术在评估沃勒变性方面的实用性，不仅关注皮质脊髓束，还关注其他较少被提及的神经束，包括皮质脑桥小脑束、齿状红核橄榄通路、脊髓后柱、胼胝体、边缘回路和视通路。将讨论这些神经通路的基本解剖结构，随后结合有指导意义的临床实例对现有文献进行全面综述。本综述的目的是让读者更熟悉涉及重要神经通路的沃勒变性的传统和先进MRI表现，并说明先进MRI技术在为各种病理状况提供重要预后信息方面日益增加的实用性。
