ADEM

Acute disseminated encephalomyelitis
From Wikipedia, the free encyclopedia

Classification and external resources
ICD-10 G04.0
ICD-9 323.61, 323.81
DiseasesDB 158
eMedicine neuro/500
MeSH D004673


Acute disseminated encephalomyelitis (ADEM) is an immune mediated disease of the brain.[1][2][3] It usually occurs following a viral infection but may appear following vaccination, bacterial or parasitic infection, or even appear spontaneously. As it involves autoimmune demyelination, it is similar to multiple sclerosis, and is considered part of the Multiple sclerosis borderline[4][5] diseases. The incidence rate is about 8 per 1,000,000 people per year.[6] Although it occurs in all ages, most reported cases are in children and adolescents, with the average age around 5 to 8 years old.[7][8][9] The mortality rate may be as high as 5%, full recovery is seen in 50 to 75% of cases, while up to 70 to 90% recover with some minor residual disability.[10] The average time to recover is one to six months.

ADEM produces multiple inflammatory lesions in the brain and spinal cord, particularly in the white matter. Usually these are found in the subcortical and central white matter and cortical gray-white junction of both cerebral hemispheres, cerebellum, brainstem, and spinal cord,[11] but periventricular white matter and gray matter of the cortex, thalami and basal ganglia may also be involved.

When the patient suffers more than one demyelinating episode, it is called Recurrent disseminated encephalomyelitis[12] or Multiphasic disseminated encephalomyelitis[13](MDEM).Contents [hide]
1 Causes and antecedent history
2 Acute hemorrhagic leukoencephalitis
3 Experimental allergic encephalomyelitis
4 See also
5 References
6 External links

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Causes and antecedent history

Viral infections thought to induce ADEM include influenza virus, enterovirus, measles, mumps, rubella, varicella zoster, Epstein Barr virus, cytomegalovirus, herpes simplex virus, hepatitis A, and coxsackievirus; while the bacterial infections include Mycoplasma pneumoniae, Borrelia burgdorferi, Leptospira, and beta-hemolytic Streptococci.[14] The only vaccine proven to induce ADEM is the Semple form of the rabies vaccine, but hepatitis B, pertussis, diphtheria, measles, mumps, rubella, pneumococcus, varicella, influenza, Japanese encephalitis, and polio vaccines have all been implicated.[6][15][16][17][18][19][20][21][22][23][24] In rare cases, ADEM seems to follow from organ transplantation.[18] The risk of ADEM from measles vaccination is about 1 to 2 per million,[17]
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Acute hemorrhagic leukoencephalitis

Acute hemorrhagic leukoencephalitis (AHL, or AHLE), also known as acute necrotizing encephalopathy (ANE), acute hemorrhagic encephalomyelitis (AHEM), acute necrotizing hemorrhagic leukoencephalitis (ANHLE), Weston-Hurst syndrome, or Hurst's disease, is a hyperacute and frequently fatal form of ADEM. AHL is relatively rare (less than 100 cases have been reported in the medical literature as of 2006),[25] it is seen in about 2% of ADEM cases,[18] and is characterized by necrotizing vasculitis of venules and hemorrhage, and edema.[26] Death is common in the first week[27] and overall mortality is about 70%,[25] but increasing evidence points to favorable outcomes after aggressive treatment with corticosteroids, immunoglobulins, cyclophosphamide, and plasma exchange.[14] About 70% of survivors show residual neurological deficits,[26] but some survivors have shown surprisingly little deficit considering the magnitude of the white matter affected.[27] This disease has been occasionally associated with ulcerative colitis and Crohn's disease, septicemia associated with immune complex deposition, methanol poisoning, and other underlying conditions.
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Experimental allergic encephalomyelitis
Main article: Experimental autoimmune encephalomyelitis

Experimental allergic encephalomyelitis (EAE) is an animal model of CNS inflammation and demyelination frequently used to investigate potential MS treatments.[28] An acute monophasic illness, EAE is far more similar to ADEM than MS.[29]