title: Wallerian Degeneration Beyond the Corticospinal Tracts: Conventional and Advanced MRI Findings.
abstract: 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.
authors.affiliation: Division of Neuroradiology, Department of Radiology, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, PA.
authors.forename: Yin Jie
authors.initials: YJ
authors.lastname: Chen
authors.affiliation: Division of Neuroradiology, Department of Radiology, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, PA.
authors.forename: Seyed Ali
authors.initials: SA
authors.lastname: Nabavizadeh
authors.affiliation: Department of Radiology, Children's Hospital of Philadelphia, Philadelphia, PA.
authors.forename: Arastoo
authors.initials: A
authors.lastname: Vossough
authors.affiliation: Department of Radiodiagnosis, Sanjay Gandhi Postgraduate Institute of Medical Sciences, Lucknow, India.
authors.forename: Sunil
authors.initials: S
authors.lastname: Kumar
authors.affiliation: Division of Neuroradiology, Department of Radiology, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, PA.
authors.forename: Laurie A
authors.initials: LA
authors.lastname: Loevner
authors.affiliation: Division of Neuroradiology, Department of Radiology, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, PA.
authors.forename: Suyash
authors.initials: S
authors.lastname: Mohan
mesh_terms: D003337:Corpus Callosum / Q000000981:diagnostic imaging* / Q000473:pathology; D038524:Diffusion Magnetic Resonance Imaging; D056324:Diffusion Tensor Imaging / Q000379:methods; D006801:Humans; D008279:Magnetic Resonance Imaging / Q000379:methods; D009434:Neural Pathways / Q000000981:diagnostic imaging / Q000473:pathology; D011379:Prognosis; D011712:Pyramidal Tracts / Q000000981:diagnostic imaging* / Q000473:pathology; D014855:Wallerian Degeneration / Q000000981:diagnostic imaging* / Q000473:pathology
keywords: DTI; DWI; Wallerian degeneration; axonal injury