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| Acute Disseminated Encephalomyelitis (ADE) |
| Overview |
 | Demyelinating disorder of the CNS that seems to be immune mediated. |
| Pathogenesis is not known. |
| Virus usually is not isolated from the nervous system, an allergic or autoimmune
reaction is most likely. |
| Usually preceded by a viral syndrome or vaccinations. |
| Usually monophasic, but recurrent episodes may occur. |
| Diseases that may trigger the demyelination:
 | measles, rubella, Varicella-zoster, smallpox, mumps, influenza, parainfluenza,
infectious mononucleosis, typhoid, mycoplasma infections, upper respiratory and other
febrile disease |
| vaccination against measles, mumps, rubella, influenza, and rabies. |
|
| Most common overall cause: Nonspecific upper respiratory infections and Varicella
infections. |
|
| Pathology |
| No change occurs in the external appearance of the brain or spinal cord. |
| Loss of myelin, with relative sparing of the axon. |
| Microscopic: perivenular lymphocytic and mononuclear cell infiltration and
demyelination. |
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| Symptoms and Signs |
| Meningeal signs are common early. |
| Subsequent symptoms and signs: related to the portion of the nervous system that is most
severely damaged. |
| Any part of CNS may be affected. |
| Duration of active CNS disease varies from days to weeks. |
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| Clinical testing |
| CSF pressure may be slightly elevated.
| WBC: mild to moderate increase: 15 to 250 cells/mm3 with lymphocytes predominating. |
| Protein: normal or slightly elevated (35 to 150 mg/dl). |
| Glucose: normal |
| Oligoclonal bands are usually negative |
| Myelin basic protein level is usually increased. |
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| EEG: abnormal in most cases, with slow frequency of 4 to 6 Hz and high voltage.
The abnormalities persist for several weeks after apparent clinical recovery. |
| CT head: After several days, the CT scan may show diffuse or scattered low-density
lesions in the white matter, some of which may enhance with contrast. |
| MRI: increased signal intensity on T2 -weighted images. |
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| Treatment |
| Several reports suggest that adrenocorticotropic hormone or corticosteroids reduces the
severity of the neurologic defects. |
| Isolated case reports: plasmapharesis or IVIG used. |
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| Prognosis |
| In patients who survive, the neurologic signs usually improve considerably, with about
90% having complete recovery. |
| The exception is measles, in which sequelae may occur in 20 to 50% of patients. |
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| Further Readings |
| Acute disseminated
encephalitis - Baylor |
| Kanter. DS. Plasmapheresis in fulminant acute disseminated encephalitis. Neurology.
1995;45:824-827 |
| Kepes JJ. Large focal tumor-like demyelinating lesions of the brain: intermediate entity
between multiple sclerosis and acute disseminated encephalomyelitis? A study of 31
patients. Ann Neurol 1993;33:18-27. |
| Kanter DS, Horensky D, Sperling RA, Kaplan JD, Malachowski ME, Churchill WH.
Plasmapheresis in fulminant acute disseminated encephalomyelitis. Neurology
1995;45:824-827. |
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