Multiple sclerosis, spinal

Multiple sclerosis is a common demyelinating disease affecting the white matter of the brain and spinal cord. Although pathologists have been familiar with the presence of perivenous demyelinating cord lesions in multiple sclerosis, only rarely have such lesions been detected in living patients prior to the advent of MRI.

Intramedullary demyelinated areas may now be directly demonstrated by MRI (image 1) and can present one of the three following appearances:

- segmental fusiform enlargement of the cord of limited extent (1 - 3 segments)

- a focal hyperintense signal area without any morphological changes of the cord

- cord atrophy (end stage disease)

These three appearances may represent the same lesion at three different stages. Enlargement of the cord, seen in the acute stage as an area of high signal intensity, is due to perivenous inflammation, intersitial edema and/or microglial proliferation.

Gadolinium uptake by active plaques is often seen on MR. Delayed contrast enhancement has been discussed and some authors advocate double dose injection to better demonstrate active plaques.

Differential diagnosis between multiple sclerosis and a spinal cord tumor may be difficult as the abnormalities seen in multiple sclerosis are not specific. However, multiple sclerosis plaques are often pencil shaped and occur preferentially in the dorsal and lateral segments of the cord. On follow up MRI, disappearance of the lesions or cord atrophy is commonly seen. The final diagnosis is usually made on the basis of the patient’s neurological course, CSF examination, visual evoked potentials and presence of similar lesions in the white matter of the brain.

Histology

Multiple sclerosis is a demyelinating disease characterized by "plaques", i.e. foci of demyelination.

Stained by the hematoxylin and eosin method, the plaque is hypercellular. Confirmation with special staining for axis cylinders is necessary (image 2).

Cases

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- Multiple sclerosis

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