Subcortical U-Fibers: Signposts to the Diagnosis of White Matter Disease

K.J. Riley, D.P. O’Neill, and S.F. Kralik

View Article on Neurographics Website

Date of Activity Release: Aug. 1, 2018
Date of Activity Expiration: Aug. 1, 2021

Target Audience:
Intended for neuroradiologists and neuroradiology trainees with varying degrees of experience.

Learning Objective:
To recognize how the presence or absence of subcortical U-fiber involvement in white matter disease can help narrow what may otherwise be a very broad differential diagnosis.

White matter diseases can be broadly separated into 3 main categories: diseases that affect myelin metabolism, diseases that result in direct damage to myelin and/or oligodendrocytes, and vascular diseases. Disorders of myelin metabolism (dysmyelinating disorders), including many inherited leukodystrophies, will generally spare the subcortical U-fibers, with their relatively slower rate of myelin turnover. However, conditions in which direct damage to previously normal myelin and/or oligodendrocytes predominates (demyelinating disorders), including multiple sclerosis and progressive multifocal leukoencephalopathy, typically demonstrate early U-fiber involvement. The purpose of this article is to demonstrate how recognizing the presence or absence of subcortical U-fiber involvement as a visible manifestation of the underlying pathophysiology in white matter disease can be extremely helpful in more confidently narrowing what may otherwise be a very broad differential diagnosis.

Commercial Support
No commercial support was received for this activity.

Credit Designation Statement

The American Society of Neuroradiology is accredited by the Accreditation Council for Continuing Medical Education (ACCME) to provide continuing medical education for physicians.

The American Society of Neuroradiology designates this journal-based CME activity for a maximum of 1 AMA PRA Category 1 Credit(s)TM. Physicians should claim only the credit commensurate with the extent of their participation in the activity.

Method of Physician Participation:
Each participant will review the corresponding Neurographics article located at Upon completion, each physician will complete and pass a post-test with a score of at least 80% to receive a CME certificate.

All individuals in control of content have disclosed the following relevant financial relationships. All of these relationships were treated as a conflict of interest, and have been resolved (C7 SCS 6.1-6.2, 6.5)

Authors have no relevant financial relationships.





Barton Branstetter 

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Associate Editor

Stockholder, Clinical Imaging

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Associate Editor

Grant, Atherysys, Inc.; Royalties, Thieme Medical Publishers

Scott Faro

Associate Editor

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Tina Young Poussaint

Associate Editor

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Dheeraj Ghandi

Associate Editor

Grant, Arstasis, Axera Inc.; Consultant, Covidien, EV3

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