Acute disseminated encephalomyelitis
| Acute disseminated encephalomyelitis | |
| ICD-10 | G04.0 |
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| ICD-9 | 323.61 |
| DiseasesDB | 158 |
| MeSH | D004673 |
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Acute disseminated encephalomyelitis Microchapters |
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Differentiating Acute disseminated encephalomyelitis from other Diseases |
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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]
Synonyms and keywords: ADEM
Diagnosis
- No one test established the diagnosis of ADEM. Supporting features include an appropriate viral or vaccination history, an appropriate acute neurologic illness, and consistent features on CNS imaging.
Differential Diagnosis
- Acute infectious encephalitis
- Herpes simplex virus
- Most common and treatable form of infectious encephalitis
- Usually due to Human herpesvirus 1 (HSV-1), though HSV-2 accounts for 5%
- One-third occur during primary infection
- Most commonly involves the temporal and frontal lobes; speech disorders, bizarre behaviors, and gustatory and olfactory hallucinations are common
- Fever present in 90%. Altered state of consciousness present in most.
- Associated with scattered hemorrhages, CSF red cells
- Treated with acyclovir 10 mg/kg IV q8h; reduces mortality and morbidity if started early enough. Untreated mortality is 70%.
- Epstein-Barr virus
- Lyme disease
- Arborviruses
- Viruses transmitted by arthropods, mosquitos and tick
- Most common in the summer and fall (in contrast to winter and spring presentations of measles, mumps and VZV).
- Present with:
- Fever
- Headache
- Gastrointestinal symptoms
- Neurologic disease typically presents day 2 or 3
- CSF typically shows elevated protein, a few hundred white blood cells, normal glucose
- No specific treatment
- Eastern equine encephalitis
- Presents with flu-like symptoms, fever, headache, vomiting, seizures, and progressive neurologic disease
- Seen mostly along the east coast of the U.S.
- Mosquito and bird vectors
- Most common in those <15 or >55 years of age
- Most virulent of arborviruses: 70% mortality
- Western equine encephalitis
- Mosquito vector
- Young children
- Often asymptomatic
- Western U.S.
- California encephalitis
- Worldwide
- Most common in school-age children
- Mosquito vector
- Gastrointestinal (GI) symptoms common
- St. Louis encephalitis
- Wild bird reservoir
- Wild bird – mosquito cycle
- Throughout U.S.
- Japanese encephalitis
- Flavivirus endemic in Southeast Asia from India to Japan
- Mosquito transmission
- Vaccine available
- Mycoplasma infection
- Cytomegalovirus infection
- Ehrlichiosis
- Measles
- VZV/chickenpox
- Mumps encephalitis
- CNS features present in ~1% of cases
- Not all patients have parotitis
- Most common in winter and spring
- Most patients recover completely, but some patients left with deafness, seizure, and mental retardation
- Confirmed via culture or serology
- Mycoplasma
- Bacterial meningoencephalitis
- Other infectious encephalitidies
- Herpes simplex virus
- Acute multiple sclerosis (MS)
- MS may not be possible to exclude, and to some extent depends upon the natural history of the patient’s disease; MS is typically a chronic disease with a recurrent or progressive course, and ADEM is usually an acute monophasic disease. Both diseases are characterized by demyelination; it is acute in ADEM, and sustained or progressive in MS. It is sometimes best to refer to the illness as an “acute demyelinating disease”, until the disease course declares itself.
- Simultaneous optic nerve, brain and spinal cord involvement, as well as meningismus, drowsiness, coma and seizures, are features suggestive of ADEM instead of MS.
- Optic nerve involvement is typically bilateral in ADEM, and unilateral in MS. Transverse myelopathy is usually complete in ADEM, and partial in MS.
- CSF protein is usually elevated in ADEM, and is often normal in MS. CSF lymphocyte counts >50, and CSF polys are also uncommon in MS.
- In ADEM in contrast to MS, most MRI lesions enhance with gadolinium, suggestive that all lesions are active, and that the disease is therefore monophasic.
- Hypoxic encephalopathy
- Cerebrovascular disease
- CNS vasculitis
- Lupus cerebritis
- Toxin effect
- Acute toxic hepatoencephalopathy – Reye’s syndrome
- Acute liver and CNS disease in children under 15 years of age, characterized by progressive liver and CNS disease, commonly in association with the use of salicylates.
- Often follows a viral infection, especially chickenpox or influenza.
- Patients often present with vomiting and progressive neurologic disease. Hypoglycemia is common. Jaundice is usually not a prominent feature.
- The liver is enlarged and evidence of liver disease includes elevated transaminases, prothrombin time, and ammonia, hypoglycemia, and metabolic acidosis. Cerebral edema and brain neuronal degeneration occurs.
- Mitochondria dysfunction occurs in the liver, brain and muscle. Liver cells show microvacuolization, as do renal tubules.
- Mortality approaches 50%.
History and Symptoms
Presentation
It has an abrupt onset and a monophasic course. Symptoms usually begin 1-3 weeks after infection or vaccination. Major symptoms include fever, headache, drowsiness, seizures and coma. Although initially the symptoms are usually mild, later in the course of the disease patients may even die, if they are not treated properly. Some patients recover completely, while others have permanent neurological impairments.
- The disease presents with progressive, often abrupt, neurologic deterioration. The clinical course is quite variable, and in some cases, rapid progression occurs over hours to days.
- ADEM classically follows a monophasic course, though there are now discussions in the literature about “multiphasic ADEM”
- Features include:
- Somnolence, confusion, lethargy
- Fever – that had previously resolved if there was a precipitating illness
- Headache
- Meningismus
- Motor features may include ataxia, myoclonic movements, and choreoathetosis
- Seizures
- Decerebrite rigidity may develop in severe cases
- Paraplegia, quadraplegia, absent deep tendon reflexes (DTRs), sensory levels, and bladder or bowel involvement suggest prominent spinal cord involvement
- Coma
- Signs of disseminated neurologic disease are usually present
- Motor findings:
- Hemiparesis
- Quadriparesis
- Extensor plantar responses
- DTR’s may be lost initially, and later become hyperactive
- Sensory findings are commonly present
- Brainstem involvement may be present
- Cerebellar involvement is particularly prominent in ADEM that occurs as a consequence of chickenpox
- Motor findings:
- In post-exantham disease, the rash usually appears 2-4 days before the neurologic manifestations, and is typically fading at the onset of neurologic disease.
- Though most cases demonstrate widespread disease (brain, spinal cord, optic nerves, etc), neurologic features may be limited to spinal cord features (transverse myelitis), cerebellar features, etc.
Laboratory Findings
Electrolyte and Biomarker Studies
- CSF protein is usually modestly elevated (50-150 mg/dl)
- CSF lymphocytic pleocytosis is present, usually <200 cells/ul.
- Serum white count may be normal or elevated
MRI and CT
- Radiographic features:
- MRI
- Extensive gadolinium enhancement of white matter of the brain and spinal cord
- Often extensive and relatively symmetric, often also involving the posterior fossa
- Most lesions enhance with gadolinium, suggestive that all lesions are active, and that the disease is therefore monophasic.
- CT is less sensitive and is sometimes falsely negative
- MRI
Risk Stratification and Prognosis
- Prognosis varies with the severity of the neurologic disease. Some patients will not survive the acute illness, and some will be left with neurologic sequelae. Some remarkably recover completely.
- The disease is characteristically monophasic, but descriptions of multiphasic disease have been reported.
- Affected children will often suffer from persistent seizures and behavioral and learning disorders. Adults are somewhat less likely than children to have neurologic sequelae.
Treatment
- There are case reports of improvement with treatment with plasma exhange and intravenous immunoglobulin in patients who have not responded to steroids.
- The first treatment is usually steroids and intensive care is often required.
Pharmacotherapy
Acute Pharmacotherapies
- Most patients are treated with pulse intravenous methylprednisolone with subsequent taper.
Acknowledgements
The content on this page was first contributed by: ELLISON L. SMITH, M.D.
Related Chapters
External links
- Acute Disseminated Encephalomyelitis (ADEM)Information page-> including pathogenesis/aetiology/treatment/prognosis at adem.org
- Acute Disseminated Encephalomyelitis (ADEM) at myelitis.org
- Murthy J (2002). "Acute disseminated encephalomyelitis". Neurology India. 50 (3): 238–43. PMID 12391446.
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Multiple sclerosis Microchapters |
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Diagnosis |
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Treatment |
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Case Studies |
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Acute disseminated encephalomyelitis On the Web |
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American Roentgen Ray Society Images of Acute disseminated encephalomyelitis |
|
Risk calculators and risk factors for Acute disseminated encephalomyelitis |
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