Acute Disseminated Encephalomyelitis

Question 1

What is acute disseminated encephalomyelitis?

Answer 1

• An acute, uniphasic syndrome caused by an immune-mediated inflammatory demyelination
• Occurs following a viral infection or vaccination, especially in children and young adults
• Involves multiple neurologic symptoms secondary to disease at the brainstem, spinal cord, optic nerves, cerebrum, and/or cerebellum (much like MS)
• Has a quite favorable long-term prognosis

Question 2

Patients have a relatively good long-term prognosis following acute dissemianted encephalomyelitis, however they are at increased risk of developing ___ in the future

Answer 2

Patients have a relatively good long-term prognosis following acute dissemianted encephalomyelitis, however they are at increased risk of developing multiple sclerosis in the future

Question 3

Acute necrotizing hemorrhagic encephalomyelitis (ANHE)

Answer 3

• Hyperacute form of acute disseminated encephalomyelitis (ADEM)
• Similar symptoms and etiology to ADEM, but can rapidly progress to coma and death

Question 4

Of all viruses studied, ADEM occurs most frequently following ___, and usually persents with ___ following this specific infection.

Answer 4

Of all viruses studied, ADEM occurs most frequently following mumps, and usually persents with cerebellar ataxia following this specific infection.

Question 5

Neuropathology of ADEM

Answer 5

• Peri-venous inflammatory myelinopathy
• Engorgement of veins in the white matter of the brain with perivascular edema and significant mononuclear infiltration
• Axons are relatively spared

Question 6

Quick summary of ADEM presentation

Answer 6

Like MS, but all at once

plus encephalopathy

Question 7

The most challenging aspect of diagnosing ADEM is distinguishing it from. . .

Answer 7

. . . the first attack of MS

Clinically, this distinction is usually made by the presence or absence of encephalopathy

Question 8

__ is a laboratory finding typical of MS that is usually absent in ADEM

Answer 8

Oligoclonal bands on CSF is a laboratory finding typical of MS that is usually absent in ADEM

Question 9

MRI features suggestive of ADEM over MS

Answer 9

• Involvement of the thalami
• Peripheral (rather than periventricular) white matter involvement

Question 10

What is the first thing you do when someone presents classically with ADEM?

Answer 10

Start them on empiric acyclovir

HSV encephalitis can look very similar – even more similar than MS given that ADEM and HSV both have encephalitis

You HAVE to rule out viral etiologies before you can assume that this is ADEM

Question 11

Treatment of ADEM

Answer 11

Similar to the treatment of acute MS, ADEM is treated initially with supportive care and IV high dose steroids.

Patients who do not respond to steroids can be given IVIG or plasmapheresis

Question 12

Recurrent ADEM

Answer 12

In a small number of patients who experience ADEM, recurrent ADEM may occur if they experience another infection.

However, this can look a lot like MS!

So, you need to use your clinical judgement very carefully: Is this a second attack that establishes the diagnosis of MS, or a recurrence of ADEM? Encephalopathy and oligoclonal bands are useful for helping to make this distinction.

Question 13

In terms of localization, ADEM lesions have a predilection for. . .

Answer 13

. . . posterior cerebal hemispheric white matter