Acute Disseminated Encephalomyelitis

Acute disseminated encephalomyelitis (ADEM) is a neurological disorder characterized by brief but widespread attacks of inflammation (swelling) in the brain and spinal cord that damages myelin. Myelin is the whitish protective coating over nerves that helps with electrical nerve signaling. ADEM often appears following a viral or bacterial infection and sometimes (rarely) following a vaccination. It is sometimes misdiagnosed as the first severe attack of multiple sclerosis, since the symptoms and appearance of damage to the white matter may be similar. ADEM may be an autoimmune condition, in which the body’s immune system mistakenly identifies and attacks healthy cells and tissue.

Acute disseminated encephalomyelitis (ADEM) is sometimes misdiagnosed as an attack of muscular sclerosis (MS), as symptoms may be similar. While those with MS have many episodes over time, ADEM patients have just one episode that may last between a few weeks and a few months.

Neuro-immunological conditions are neurological disorders that are caused by inflammation or autoimmunity. These conditions can affect multiple body systems and cause a range of symptoms, such as weakness, walking problems and difficulty with speaking, swallowing or chewing.

The exact causes of neuro-immunological conditions are not fully understood, but research suggests that they may result from an abnormal immune response that attacks the body’s own tissues and cells, including the nervous system. Factors that may contribute to the development of these conditions include genetic predisposition, viral or bacterial infections, environmental triggers and exposure to toxins.

ADEM often appears following a viral or bacterial infection and sometimes (rarely) following a vaccination. This inflammatory response is triggered by a viral infection or another infectious agent. It is sometimes misdiagnosed as the first severe attack of multiple sclerosis, since the symptoms and appearance of damage to the white matter may be similar. ADEM may be an autoimmune condition, in which the body’s immune system mistakenly identifies and attacks healthy cells and tissue. 

ADEM can occur in people of any age, but it most often occurs in young children. The risk of developing ADEM depends on some factors including an individual’s genetics, exposure to infectious organisms, immunization exposure and lighter skin pigmentation. All ethnic groups are susceptible to developing ADEM, and the condition occurs worldwide.

The primary screening procedure for ADEM is a brain scan (magnetic resonance imaging, or MRI). To determine whether there is an infection in the spinal fluid, your doctor may administer a lumbar puncture, also known as a spinal tap. Types of infections include meningitis or encephalitis. If seizures are a symptom, an electrocardiogram (EEG) is performed. ADEM typically results from a vaccination or viral infection; therefore, no preventive measures are available.

ADEM may be an autoimmune condition, in which the body’s immune system mistakenly identifies and attacks healthy cells and tissue. Symptoms include: 

• Loss of vision in one or both eyes due to inflammation of the optic nerve 
• Weakness that may be severe 
• Difficulty coordinating intended (voluntary) movement such as walking 
• Rapid onset of fever
• Nausea and vomiting
• Confusion and headache
• Numbness or tingling 
• Seizure 
• Some degree of impairment of consciousness, perhaps as severe as coma 

Doctors will first rule out viral infections prior to performing a lumbar puncture (spinal tap) to determine if a patient has ADEM. Following the spinal tap, the neurological team tests the cerebrospinal fluid (CEF) for an excess of white blood cells. Doctors may also perform an MRI to scan for brain damage and to rule out other infections.

Treatment of ADEM is targeted at suppressing the immune system and inflammation in the brain using anti-inflammatory drugs such as corticosteroids. Some individuals may need plasma exchange (plasmapheresis) or immunoglobulin therapy. Most people with ADEM recover within days after treatment, and many will recover completely within six months. In rare instances, ADEM can be fatal.

ADEM is symptomatically similar to multiple sclerosis (MS). ADEM patients experience loss of vision and balance, muscle weakness and numbness. They differ in that ADEM attacks do not repeat, whereas MS involves many attacks over the lifetime. 

ADEM typically involves a one- to two-week hospital stay to reduce inflammation and bring the immune system attack to a stop.

Most people diagnosed with ADEM recover fully over a period of four to six weeks, but symptoms sometimes persist for up to a year. There are some cases of lasting effects, like muscle weakness or damage to vision. 

If you want to develop a deeper understanding of your diagnosis, consider participating in a clinical trial so clinicians and scientists can learn more about you and your disease. Clinical research uses human volunteers to help researchers learn more about a disorder and perhaps find better ways to safely detect, treat or prevent disease.

All types of volunteers are needed—those who are healthy or may have an illness or disease—of all different ages, sexes, races and ethnicities to ensure that study results apply to as many people as possible, and that treatments will be safe and effective for everyone who will use them.

For information about participating in clinical research, visit NIH Clinical Research Trials and You. Learn about clinical trials currently looking for people with ADEM at Clinicaltrials.gov.