Acute disseminated encephalomyelitis (ADEM) and multiple sclerosis (MS) are both inflammatory autoimmune disorders. Our immune system protects us by attacking foreign invaders that enter the body. Sometimes, the immune system mistakenly attacks healthy tissue.

In ADEM and MS, the target of the attack is myelin. Myelin is the protective insulation that covers nerve fibers throughout the central nervous system (CNS).

Damage to myelin makes it difficult for signals from the brain to get through to other parts of the body. This can cause a wide variety of symptoms, depending on the areas that are damaged.

In both ADEM and MS, symptoms include vision loss, muscle weakness, and numbness in the limbs.

Problems with balance and coordination, as well as difficulty walking, are common. In severe cases, paralysis is possible.

Symptoms vary according to the location of the damage within the CNS.

ADEM

Symptoms of ADEM come on suddenly. Unlike MS, they can include:

Most of the time, an episode of ADEM is a single occurrence. Recovery usually begins within days, and the majority of people make a full recovery within six months.

MS

MS lasts a lifetime. In relapsing-remitting forms of MS, symptoms come and go but may lead to accumulation of disability. People with progressive forms of MS experience steady deterioration and permanent disability. Learn more about the different types of MS.

You can develop either condition at any age. However, ADEM is more likely to affect children, while MS is more likely to affect young adults.

ADEM

According to the National Multiple Sclerosis Society, over 80 percent of childhood ADEM cases occur in children younger than 10 years old. Most other cases occur in people between 10 and 20 years old. ADEM is rarely diagnosed in adults.

Experts believe ADEM affects 1 in every 125,000 to 250,000 people in the United States annually.

It’s more common in boys than girls, affecting boys 60 percent of the time. It’s seen in all ethnic groups across the world.

It’s more likely to appear in the winter and springtime than in the summer and fall.

ADEM often develops within months of an infection. In of cases, it may be triggered by an immunization. However, doctors aren’t always able to identify the triggering event.

MS

MS is usually diagnosed between the ages of 20 and 50. Most people receive a diagnosis while in their 20s or 30s.

MS affects women more than men. The most common type of MS, RRMS, affects women at a rate that is two to three times higher than it is for men.

Disease incidence is higher in Caucasians than in people of other ethnic backgrounds. It becomes more prevalent the farther away a person is from the equator.

Experts believe that around 1 million people in the United States have MS.

MS isn’t hereditary, but researchers believe there’s a genetic predisposition toward developing MS. Having a first-degree relative — such as a sibling or parent — with MS slightly increases your risk.

Due to similar symptoms and the appearance of lesions or scars on the brain, it’s easy for ADEM to be initially misdiagnosed as an MS attack.

MRI

ADEM generally consists of a single attack, while MS involves multiple attacks. In this instance, an MRI of the brain can help.

MRIs can differentiate between older and newer lesions. The presence of multiple older lesions on the brain is more consistent with MS. The absence of older lesions could indicate either condition.

Other tests

When trying to differentiate ADEM from MS, doctors may also:

  • ask for your medical history, including a recent history of illnesses and vaccinations
  • ask about your symptoms
  • perform a lumbar puncture (spinal tap) to check for infections in the spinal fluid, such as meningitis and encephalitis
  • perform blood tests to check for other types of infections or conditions that could be confused with ADEM

The bottom line

Several key factors in ADEM distinguish it from MS, including sudden fever, confusion, and possibly even coma. These are rare in people with MS. Similar symptoms in children are more likely to be ADEM.

The cause of ADEM isn’t well-understood. Experts have noticed that, in more than half of all cases, symptoms arise after a bacterial or viral infection. In very rare cases, symptoms develop after a vaccination.

However, in some instances, no causal event is known.

ADEM is probably caused by the immune system overreacting to an infection or vaccine. The immune system becomes confused and identifies and attacks healthy tissues such as myelin.

Most researchers believe that MS is caused by a genetic predisposition to developing the disease combined with a viral or environmental trigger.

Neither condition is contagious.

Drugs such as steroids and other injectables can be used to treat these conditions.

ADEM

The goal of treatment for ADEM is to stop inflammation in the brain.

Intravenous and oral corticosteroids aim to decrease the inflammation and can usually control ADEM. In more difficult cases, intravenous immunoglobulin therapy may be recommended.

Long-term medications aren’t necessary.

MS

Targeted treatments can help people with MS manage individual symptoms and improve their quality of life.

Disease-modifying therapies are used to treat both relapsing-remitting MS (RRMS) and primary progressive MS (PPMS) in the long term.

About 80 percent of children with ADEM will have a single episode of ADEM. Most make a complete recovery within months following the illness. In a small number of cases, a second attack of ADEM occurs within the first few months.

More severe cases that can result in lasting impairment are rare. According to the Genetic and Rare Disease Information Center, “a small proportion” of people diagnosed with ADEM eventually develop MS.

MS worsens over time, and there’s no cure. Treatment may be ongoing.

It’s possible to live a healthy, active life with either of these conditions. If you think you or a loved one may have ADEM or MS, contact a doctor for a proper diagnosis.