Acute disseminated encephalomyelitis

Case contributed by A.Prof Frank Gaillard

Presentation

Newly diagnosed multiple myeloma presented initially with cervical myelopathy - MRI revealed no compressive lesion but a small area of what looked like demyelination in the C-spine. He went on to have MRI Brain which was normal (not shown), we commenced him on methylprednisolone pulse of 3g and IVIG (CSF- ruled out infection) but after a few days he developed a progressive delirium/encephalopathy with seizures.

Patient Data

Age: 68
Gender: Male

Extensive, but fairly subtle, bilateral supratentorial white matter high T2 signal intensity without enhancement or restricted diffusion. 

MRI

2 weeks later - plasma exchange

Two weeks later there has been dramatic white matter T2 hyperintensity with incomplete FLAIR suppression centrally, in regions of low T1 signal. Since the previous scan numerous small areas of restricted diffusion have developed as well as many small regions of signal loss on gradient echo imaging, consistent with small haemorrhages. Bilateral occipital cortical involvement has developed. 

MRA is unremarkable. 

MRI

2 weeks later still

Two week later still, there has been significant diminution of the FLAIR signal abnormality, with little if any abnormal restricted diffusion. During this time however, striking further haemorrhagic changes have developed, not only in the cerebral hemispheres but also involving the cerebellum. 

MRA continues to be normal in appearance, with no beading or stenoses evident. 

Pathology

MICROSCOPIC DESCRIPTION:

1&2. The sections show unremarkable dura mater and pia arachnoid. No specific diagnostic abnormality is seen in either specimen. In particular, there is no inflammatory cell infiltration and no evidence of tumour is seen.

3. The sections show two cores of cerebral white matter. These show several foci of rarefaction of myelin in perivascular white matter. Mononuclear inflammatory cells are noted within perivascular spaces. These are predominantly CD3+ T lymphocytes. The surrounding white matter shows reactive gliosis and there is microglial activation. CD68+ monocyte-macrophages are also noted within perivascular spaces as well as the T lymphocytes. Immunostaining for SV40/BK virus is negative. The features are strongly suggestive of acute disseminated encephalomyelitis (ADEM). No evidence of tumour is seen.

4. The sections show cerebral cortex with overlying leptomeninges. Cortical laminar architecture is preserved. No dysplastic features or evidence of malformation of cortical development are seen. Immunostaining for A beta protein is negative. The leptomeninges are unremarkable with no inflammatory cell infiltration seen.

DIAGNOSIS:

  1. Dural biopsy: Unremarkable dura.
  2. Arachnoid: Unremarkable pia arachnoid.
  3. Left frontal white matter: Features strongly suggestive of acute disseminated encephalomyelitis (ADEM).
  4. Cortical surface: Unremarkable cerebral cortex and leptomeninges.

Case Discussion

Commenced him on treatment for myeloma- cyclopshophamide and dexamethsone as his serum paraprotein has risen to 10g/L over the last few weeks.

Syphilis serology was found to be positive and he was treated with benzylpenicillin, CSF syphilis was negative.

Histology suggested ADEM. 

Acute disseminated encephalomyelitis (ADEM) as the name would suggest, is featured by a monophasic acute inflammation and demyelination of white matter typically following a recent (1-2 weeks prior) viral infection or vaccination.

Imaging appearances vary from small punctate lesions to tumefactive regions, which have less mass effect than one would expect for their size, distributed in the supratentorial or infratentorial white matter. Compared to multiple sclerosis, involvement of the callososeptal interface is unusual. Lesions are usually bilateral but asymmetrical. Involvement of cerebral cortex, subcortical grey matter, especially the thalami, and the brainstem is not very common, but if present are helpful in distinguishing from multiple sclerosis.

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Case information

rID: 37704
Case created: 19th Jun 2015
Last edited: 31st Aug 2015
Inclusion in quiz mode: Included

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