What is Acute Disseminated Encephalomyelitis?
Acute Disseminated Encephalomyelitis (ADEM) is a neurological disorder in which inflammation affects the brain and spinal cord. The inflammation causes damage to myelin, the fatty coating that surrounds nerve cells. Myelin is vital for nerve cell protection and function.
ADEM often occurs after a viral or bacterial infection, suggesting that it is caused by an inappropriate reaction by the body’s immune system to the infection. In such an autoimmune condition, the body’s immune system attacks and damages healthy cells.
Symptoms of ADEM
In most ADEM cases, inflammation is preceded by a viral or bacterial infection. The infection commonly affects the upper respiratory system and causes symptoms such as a sore throat or cough. ADEM symptoms emerge as soon as a few days after the infection but may take 2-4 weeks to appear. In some cases, there is no infection, and the event that triggers ADEM isn’t identifiable.
Symptoms of ADEM include:
- Lethargy or sleepiness
- Nausea or vomiting
- Problems with coordination or balance
- Vision disturbances
- Difficulty swallowing
- Weakness in the limbs
What Causes Acute Disseminated Encephalomyelitis?
ADEM is likely caused by an immune system response to an infection in which the body misidentifies healthy cells as infectious agents. Infections that have been associated with ADEM include:
- Epstein-Barr virus
- Herpes simplex virus
- Bacterial infections
In rare cases, ADEM may be triggered by a reaction to a vaccine. Vaccinations that have been associated with ADEM include:
- Whooping cough (pertussis)
Is Acute Disseminated Encephalomyelitis Hereditary?
ADEM is not an inherited disorder. No specific genes have been associated with the condition, and there are no known cases in which ADEM appears to run in families. Some people may have an increased risk of developing ADEM, but the higher risk probably comes from a combination of genetic and environmental factors.
How Is Acute Disseminated Encephalomyelitis Detected?
ADEM is sometimes misdiagnosed as multiple sclerosis (MS) because its symptoms are similar to those of early MS. However, the two disorders differ in crucial ways, including:
- ADEM is more common in children. However, MS more often affects adults.
- Unlike MS, ADEM symptoms usually include rapid-onset fever and some form of sleepiness.
- ADEM is usually characterized by a brief, one-time episode of inflammation and cell damage. MS attacks are recurrent.
How Is Acute Disseminated Encephalomyelitis Diagnosed?
A doctor may suspect ADEM when a child shows neurological symptoms, headaches, and/or fever following an infection. The diagnostic process usually includes tests and exams to look for damage caused by ADEM and rule out other possible causes of the symptoms.
Diagnostic steps may include:
- Magnetic resonance imaging (MRI) to look for damage to brain cells characteristic of ADEM
- Examination of the cerebrospinal fluid (CSF) to look for signs of an infection
- Blood tests or other laboratory tests
PLEASE CONSULT A PHYSICIAN FOR MORE INFORMATION.
How Is Acute Disseminated Encephalomyelitis Treated?
Treatment of ADEM focuses on suppressing the immune system and reducing inflammation in the central nervous system. The most common course of treatment is the administration of corticosteroids such as methylprednisolone. However, if ADEM symptoms don’t respond to this type of treatment, other therapies may be administered, including:
- Intravenous immunoglobulin (IVIg). This therapy uses antibodies from healthy donors to counter the effects of the patient’s autoimmune responses.
- Plasmapheresis. This therapy replaces the patient’s blood plasma with healthy donor plasma to remove immune-system cells from the patient’s blood.
How Does Acute Disseminated Encephalomyelitis Progress?
ADEM symptoms usually develop rapidly and quickly decrease in severity with treatment. In some cases, symptoms are mild and begin to resolve on their own. However, symptoms are more severe in some cases, and more significant neurological symptoms sometimes develop.
Neurological symptoms of ADEM vary from case to case but may include:
- Problems with coordination (ataxia)
- Paralysis or numbness on one side of the body
- Vision loss
- Slurred speech
In some cases, ADEM recurs after the initial episode of inflammation has resolved. In these cases, symptoms are usually treated in the same way as the initial episode.
In rare cases, people who have had ADEM develop multiple sclerosis. Scientists do not know how to predict who is at risk of MS, but it seems more common in children who have ADEM without an identifiable triggering cause.
How Is Acute Disseminated Encephalomyelitis Prevented?
The most significant risk factor for ADEM is an infection that triggers the disorder, so the most effective preventive measure is avoiding infections in the first place. Vaccination against the viral infections that often precede the condition should be administered according to doctors’ recommendations. Because cases in which ADEM is triggered by vaccination are rare, avoiding vaccinations is not recommended.
Acute Disseminated Encephalomyelitis Caregiver Tips
- Vaccinate your children. Prevention of the infections commonly associated with ADEM is the only known way to reduce the risk of the disorder. Follow your doctor’s recommended vaccination schedule.
- Get support from others who understand the disorder. ADEM is rare, and it can be confusing for parents and children who have the condition. The National MS Society provides links to resources for education and support for families dealing with ADEM.
Acute Disseminated Encephalomyelitis Brain Science
Scientists don’t yet fully understand how the immune system interacts with the brain and the central nervous system. In many ADEM cases, the patient’s blood contains antibodies that target a compound called myelin oligodendrocyte glycoprotein (MOG). MOG is a protein that scientists believe is vital in creating myelin, the substance surrounding nerve cells and protecting them from damage. If the immune system attacks MOG in brain cells, the result could be damage to myelin in those cells.
Scientists once believed that MOG antibodies might be responsible for the nerve damage in MS, but research has not backed up that theory. Instead, MOG antibodies seem to be more closely associated with ADEM and other related disorders, such as:
- Optic neuritis
- Brainstem encephalitis
Acute Disseminated Encephalomyelitis Research
Title: PEDIATRIC SONICS: Pediatric Study of Neuropsychology and Imaging in CNS Demyelinating Syndromes. (SONICS)
Contact: Benjamin Greenberg, MD, MHS
University Texas Southwestern
Central Nervous System (CNS) demyelinating conditions include multiple sclerosis (MS), Acute Disseminated Encephalomyelitis (ADEM), Neuromyelitis Optica Spectrum Disorder (NMOSD), and Transverse Myelitis (TM). The symptoms of these conditions are quite variable from patient to patient but can include motor, sensory, visual, gait, and cognitive changes. Conventional MRI can look for new anatomic changes but fails to measure underlying biochemical changes in brain tissue. The purposes of this study are to identify the biologic and anatomic correlations between cognitive profiles and disease activity using MRI imaging techniques.
Pediatric patients (age 12 to 18 inclusive) with a diagnosis of multiple sclerosis, ADEM, anti-MOG mediated demyelinating disease, and healthy controls will be recruited to undergo clinical testing. The study visits will include neuropsychological testing, optical coherence tomography (OCT), and MRI on both the 3T and 7T magnet. Subjects will be asked to undergo two study visits separated by 12 months +/- 2 months. Each study visit will have the same neuropsychological, OCT, and research MRI examinations.
Title: Comparing the Antibody Response to COVID-19 Vaccination in Multiple Sclerosis Patients Treated With Ocrelizumab or Natalizumab (OCR-VAX)
Principal investigator: Joshua Katz, MD
Dragonfly Research, LLC
The primary goal of this study is to determine if subjects currently receiving treatment with ocrelizumab or natalizumab produce antibodies to the SARS-CoV-2 spike protein receptor binding domain following immunization with the COVID-19 vaccine.
The purpose of this study is to see if patients on ocrelizumab (Ocrevus) make antibodies in response to the coronavirus vaccine. Ocrelizumab depletes B-lymphocytes and has the potential to reduce the effectiveness of vaccines. However, the impact of ocrelizumab treatment on coronavirus vaccines is unknown.
Natalizumab (Tysabri) likely has a minimal impact on the efficacy of vaccines. In this study, the investigators will take blood samples in patients being treated with either ocrelizumab or natalizumab before and after vaccination with an FDA-authorized coronavirus (COVID-19) vaccine and compare the antibody response in both groups.
Title: Comprehensive Multimodal Analysis of Neuroimmunological Diseases of the Central Nervous System
Principal investigator: Bibiana Bielekova, MD
National Institutes of Health Clinical Center
Inflammatory or degenerative diseases of the brain and spinal cord, such as multiple sclerosis, may be related to problems with an individual s immune system. However, more information is needed on how the immune system cells interact with the central nervous system (CNS). Therefore, this study will compare tests performed on healthy volunteers and individuals who have signs or symptoms of immune-related damage to their CNS.
This study will include two groups of subjects at least 12 years old. Subjects will either have symptoms of immune-related CNS damage or will be healthy volunteers selected for comparison purposes.
Study participants will visit the NIH Clinical Center on an outpatient basis for an initial evaluation visit. During the visit, patients will provide a comprehensive medical history, undergo a neurological examination, and provide blood samples for research purposes. The healthy volunteers will be asked to schedule a return visit for a magnetic resonance imaging (MRI) procedure and may be asked to undergo other tests requested by the study researchers on an as-needed basis. The group of patients with symptoms of immune-related CNS damage will be asked to undergo a series of tests, including the following:
- MRI procedures, with a minimum of three brain MRIs and one spinal cord MRI taken approximately four weeks apart
- A diagnostic lumbar puncture, performed on an outpatient basis
- Tests of brain and vision activity
- Additional blood and tissue samples
All study participants will return for a follow-up visit one year after the initial evaluation visit. In addition, patients with symptoms of immune-related CNS damage may be offered the opportunity to participate in additional follow-up tests with NIH researchers.