Tuesday, August 2, 2011

Best Post of March 2011 - Dawson Fingers: A Cocktail-Party Term Worth Knowing

The next in our "Best of the Month" series is from March 10, 2011:

Dawson Fingers (in box)
One of the nice things about teaching is that you frequently learn a lot from your students and residents. I had never heard of a radiological finding in multiple sclerosis known as "Dawson Fingers" until I was informed of it by Southern Illinois University second-year medical student Joshua Billington and neurology resident Laxmi Prasad Dhakal. "Dawson Fingers" are a purely radiological finding, which may be why the term is not found in neuropathology textbooks (at least not in the indices of eight different neuropathology textbooks that I consulted). Here's what Adams and Victor's Principles of Neurology (9th edition, page 889) has to say on the subject: "Especially diagnostic are oval or linear regions of demyelination, oriented perpendicularly to the ventricular surface; they correspond to the radially oriented fiber bundles of the white matter and periventricular veins. When viewed in sagittal images, they extend outward from the corpus callosum in a fimbriated pattern and have been termed 'Dawson Fingers'. These areas may extend into the centrum semiovale and may reach the convolutional white matter. Even one highly characteristic lesion is sometimes enough to confirm the diagnosis in the proper clinical circumstances; multiple lesions are more convincing. The presence of such lesions in the corpus callosum is diagnostically useful, as this structure is spared in many other disorders."  See the image above (from Adams and Victor, page 876) depicting Dawson Fingers on sagittal T2-weighted FLAIR MRI. The irony here is that this finding was named after a neuropathologist, James Walker Dawson (1870-1927), despite the fact that many neuropathologists are unfamiliar with the term (well, OK, maybe just me). Thanks to Dr. Dhakal and Pre-Dr. Billington for informing me of this eponymous finding -- one that neuropathologists should probably be able to throw around at any neuroscience cocktail party.

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