Acute disseminated encephalomyelitis

Editor-In-Chief: Prab R Tumpati, MD
Obesity, Sleep & Internal medicine
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Acute disseminated encephalomyelitis
Synonyms	Post-infectious encephalomyelitis, post-vaccinal encephalomyelitis
Pronounce	N/A
Specialty	N/A
Symptoms	Fever, headache, nausea, vomiting, seizures, confusion, ataxia, vision problems
Complications	Seizures, coma, death
Onset	Rapid, often following an infection or vaccination
Duration	Days to weeks
Types	N/A
Causes	Often follows a viral infection or vaccination
Risks	Recent infection, vaccination, autoimmune disorders
Diagnosis	MRI, lumbar puncture, blood tests
Differential diagnosis	Multiple sclerosis, neuromyelitis optica, viral encephalitis
Prevention	N/A
Treatment	Corticosteroids, plasmapheresis, intravenous immunoglobulin
Medication	N/A
Prognosis	Generally good with treatment, but can vary
Frequency	Rare
Deaths	N/A

Acute hemorrhagic leukoencephalitis in a patient with multiple sclerosis (MRI)

Acute disseminated encephalomyelitis (ADEM) is an autoimmune disease marked by a sudden, widespread attack of inflammation in the brain and spinal cord. It is characterized by a brief but intense episode of inflammation in the central nervous system (CNS), often following a viral infection or vaccination.

Pathophysiology

ADEM is believed to be an autoimmune response where the body's immune system mistakenly attacks its own myelin, the protective covering of nerve fibers in the central nervous system. This results in demyelination, which disrupts the normal transmission of nerve impulses. The exact mechanism is not fully understood, but it is thought to involve molecular mimicry, where the immune system confuses myelin with viral antigens.

Clinical Presentation

Patients with ADEM typically present with a rapid onset of neurological symptoms such as headache, fever, nausea, and vomiting. Neurological deficits may include ataxia, hemiparesis, optic neuritis, and altered mental status. In severe cases, seizures and coma may occur.

Diagnosis

The diagnosis of ADEM is primarily clinical, supported by magnetic resonance imaging (MRI) findings. MRI typically shows multiple lesions in the white matter of the brain and spinal cord. These lesions are often bilateral and asymmetrical. Cerebrospinal fluid (CSF) analysis may show elevated protein levels and pleocytosis.

Treatment

The mainstay of treatment for ADEM is high-dose corticosteroids, such as methylprednisolone, to reduce inflammation and immune system activity. In cases where patients do not respond to steroids, intravenous immunoglobulin (IVIG) or plasmapheresis may be considered. Supportive care is also crucial to manage symptoms and prevent complications.

Prognosis

The prognosis for ADEM is generally favorable, with most patients experiencing significant recovery within weeks to months. However, some individuals may have residual neurological deficits. Recurrence is rare, distinguishing ADEM from multiple sclerosis, which is a chronic condition with recurrent episodes.

See also

• Multiple sclerosis
• Autoimmune disease
• Demyelinating disease
• Central nervous system