What Is Acute Disseminated Encephalomyelitis?
Acute disseminated encephalomyelitis is an autoimmune disease, meaning it is caused by the immune system attacking part of the body (in this case, brain tissue) as if it resembles a virus or foreign invader due to a recent trigger . The damage causes symptoms, usually affecting the spinal cord, which is responsible for conducting the neural impulses and reflexes of the body.
Symptoms of the preceding illness may be severe, such as a headache, fever, nausea, vomiting, and altered mental status (confusion, aggression or sleepiness). The acute disseminated encephalomyelitis-specific symptoms that follow include difficulty moving the limbs or eyes, trouble swallowing or speaking, vision loss, new or spastic movements, an inability to urinate, as well as seizures that may be lethal. Bleeding in the brain and symptoms of psychiatric illness, such as depression or psychosis, are also possible.
Treatment mainly involves steroids, immune globulin, or plasma exchange to regulate the immune system’s response.
Any neurologic changes should immediately send someone to the hospital, where imaging the brain will reveal damage to your nerves and rule out other possible causes. Treatment involves anti-virals or antibiotics in case of a possible infection, but oppositely, immune-suppressive drugs would be started if it really is your own immune system doing the damage.
How common is Acute Disseminated Encephalomyelitis?
Symptoms that always occur with Acute Disseminated Encephalomyelitis:
- Being severely ill
Acute Disseminated Encephalomyelitis is also known as
- Post Infectious Encephalomyelitis
Acute Disseminated Encephalomyelitis Symptoms
The following sections will cover symptoms specific to this condition as well as the preceding illness.
In the case of acute disseminated encephalomyelitis, there often must be a recent exposure to a viral illness, symptoms of a viral illness, or a vaccine prior to the development of other symptoms (between six and 45 days prior). The illness is often described as severe, though this seems to have no relationship to the development of the symptoms of acute disseminated encephalomyelitis. Non-specific signs of this prior illness include [1,2]:
- Nausea and vomiting
- Altered mental status: Such as confusion, aggression, or sleepiness
There are a host of neurological complaints that can be attributed to acute disseminated encephalomyelitis. Any part of the body supplied by the spinal cord can be affected by acute disseminated encephalomyelitis. Specifics are detailed below :
- ”Motor deficits”: Motor deficits are commonly seen, and include paraparesis (e.g. a lack of ability to move the lower limbs fully) or tetraparesis (e.g. the inability to move all four limbs sufficiently).
- Difficulty in moving the eyes willfully
- Inability to speak or slurring of speech
- Difficulty swallowing
- Inability to read
- Loss of vision
- New spastic or shaking movements
- Inability to urinate
- Seizures: Accompanied by increased pressure within the skull which can result in death.
Bleeding within the brain
A rarer form of acute disseminated encephalomyelitis may cause bleeding within the brain that will be visible on radiological examination of the brain. Bleeding can be focal (e.g. located in one spot) or present in small amounts throughout the brain. Usually, this is a finding that necessitates urgent treatment with an agent that can decrease the activity of the autoimmune system, likely a steroid. However, viral illnesses can also trigger similar bleeds within the brain. Determining which is occurring will require a seasoned medical practitioner.
Symptoms of psychiatric illness
It is less common, but some individuals may present with psychosis or depression following this illness. This is more common if there is a relapse, and in some cases, a relapse can appear as new depression or new psychosis. The treatment is the same, primarily involving steroids. However, treatment can be supplemented with appropriate psychiatric drugs if changes are believed to be durable by your care team.
Acute Disseminated Encephalomyelitis Causes
Acute disseminated encephalomyelitis is caused by a mixture of environmental exposures and genetic factors. To occur, the immune system must be predisposed to over-react when confronted with viral or bacterial particles and then actually be exposed to these triggering particles. The excitability of the immune system is largely genetic and the exposure to different viral particles is largely behavioral or dictated by an individual’s environment.
When the body is exposed to a viral particle, it builds a defense against subsequent attacks; however, in people with acute disseminated encephalomyelitis, it builds a response against some component of the central nervous system — affecting the brain and spinal cord. Myelin, a protein that helps nerve signals move faster, is often specifically targeted by the immune system. Therefore, the symptoms of acute disseminated encephalomyelitis are often defined by the brain’s difficulty communicating or slow communication with other parts of the body.
Acute disseminated encephalomyelitis is believed to occur more frequently in children, particularly between 5 to 8 years old . It has been related to many different viral illnesses, however, none of them have been conclusively linked.
Viral infections (not vaccinations) are more common causes of acute disseminated encephalomyelitis. However, because acute disseminated encephalomyelitis is triggered by an overactive immune system interacting with a viral particle, vaccines also have a chance of causing acute disseminated encephalomyelitis . Acute disseminated encephalomyelitis occurred in some cases after administration of an older version of the rabies vaccines (Semple), however, this risk has largely been eliminated for this vaccine and others . Mycoplasma pneumoniae is one type of bacteria that has been linked to acute disseminated encephalomyelitis to a limited extent.
Treatment Options and Prevention
Once you are in the care of medical professionals and the diagnosis has been determined, the primary treatment of this disorder involves the use of steroids. Steroids can decrease the activity of the immune system and prevent further damage to the spinal cord or brain. Usually, a large dose of steroids is given followed by a decreasing dosage for up to six weeks if you improve. Steroids are not always given to children but there is evidence of their efficacy for this condition .
Intravenous immune globulin
Immune globulin is naturally produced in your body to respond to infections. It attaches to the foreign particle and inhibits its functionality or labels it for destruction. Additional immune globulin can be created or collected and then given via IV to hamper your body’s ability to interact with the particles causing the autoimmune response. Administrations have been found effective in individuals who have a limited response to steroids.
There is less data on the effectiveness of plasma exchanges, but this data shows that multiple plasma exchanges can slow the progression of acute disseminated encephalomyelitis. Multiple plasma exchanges involve giving you new plasma without high concentrations of autoimmune cells and signals that can trigger acute disseminated encephalomyelitis.
While most children respond well to this illness and can make a full recovery, adults have a harder time. The majority of adults show some recovery but many are left with some residual loss of function, which differs by case . Acute disseminated encephalomyelitis is considered a monophasic illness, meaning it is a one-time episode; however, it can also be recurrent or multiphasic (and worsening) .
When to Seek Further Consultation
Because acute disseminated encephalomyelitis can affect vision, limb movement, urination and breathing, it is often a medical emergency. Damage is cumulative and grows over time so early treatment is necessary.
Questions Your Doctor May Ask to Diagnose
To diagnose this condition, your doctor would likely ask about the following symptoms and risk factors.
- Are you sick enough to consider going to the emergency room right now?
- How long has your current headache been going on?
- Have you been feeling more tired than usual, lethargic or fatigued despite sleeping a normal amount?
- Have you experienced any nausea?
- How severe is your headache?
The above questions are also covered by our A.I. Health Assistant.
- Acute Disseminated Encephalomyelitis (ADEM). Myelitis.org. Myelitis.org Link
- Acute Disseminated Encephalomyelitis. National Organization for Rare Disorders. NORD Link
- Chen Y, Ma F, Xu Y, Chu X, Zhang J. Vaccines and the risk of acute disseminated encephalomyelitis. Vaccine. 2018;36(26):3733-3739. PubMed Link
- Acute Disseminated Encephalomyelitis. Boston Children’s Hospital. Boston Children’s Hospital Link
- Acute Disseminated Encephalomyelitis. United Leukodystrophy Foundation. ULF Link