Acute Disseminated Encephalomyelitis

What is Acute Disseminated Encephalomyelitis?

Acute disseminated encephalomyelitis (ADEM), also known as post-infectious encephalomyelitis, is a severe, autoimmune disorder that impacts the central nervous system, which includes our brain and spinal cord. It often arises after an infection or immunization, causing inflammation and damage to the insulation of nerve fibers (demyelination) in the brain and spinal cord, sometimes even affecting the nerve connecting the eye to the brain (the optic nerve). This condition mainly affects children, but it can also occur in adults.

To diagnose ADEM, doctors look for typical signs on a brain MRI, a type of imaging test. The International Pediatric Multiple Sclerosis Study Group has laid out specific criteria to diagnose this condition. According to them, the diagnosis of ADEM includes symptoms affecting the brain (encephalopathy), multiple areas impacted in the central nervous system (polyfocal CNS involvement), and signs of demyelination on a brain MRI.

What Causes Acute Disseminated Encephalomyelitis?

ADEM, which stands for acute disseminated encephalomyelitis, is primarily thought of as a disease that follows an infection or immunization, affecting the brain and spinal cord. Between 50% to 85% of the time, it’s linked to an identifiable infection or vaccination. It has been associated with various viruses and bacteria including cytomegalovirus, Epstein-Barr virus, some types of herpes viruses, influenza, hepatitis A, HIV, and mycoplasma pneumonia. However, in most cases, the exact pathogen causing ADEM is not found. Some bacterial infections linked to ADEM are Leptospira, beta-hemolytic streptococci, and Borrelia burgdorferi.

Before vaccinations were common, ADEM was usually associated with illnesses like measles, rubeola, rubella, mumps, varicella, and smallpox. These days, ADEM is more commonly linked to viral infections of the gut or respiratory system.

ADEM can affect both adults and children, typically appearing 8 to 21 days after they receive a vaccination. The rabies vaccine is the vaccine most often associated with ADEM. Other vaccines, though less frequently linked, include those for measles, whooping cough, tetanus, flu, hepatitis B, diphtheria, rubella, pneumonia, chickenpox, smallpox, human papillomavirus, and polio. The occurrence of ADEM following vaccination has gone down in recent years, probably due to improved vaccine production methods.

Risk Factors and Frequency for Acute Disseminated Encephalomyelitis

ADEM, while considered a rare disease, does affect a small number of children each year. This illness is mostly seen in children aged 5 to 8, but can also occur in younger children and those between 10 and 20 years old. Adults between the ages of 18 to 82 can also be affected. ADEM is more common in males and tends to occur more often during the colder months, such as winter and spring.

A person’s risk of developing ADEM can depend on a few factors. These include their genetic makeup, their exposure to certain infectious organisms, whether they’ve had certain immunizations, and even their skin pigmentation. ADEM can affect all ethnic groups and it occurs globally. In a lot of cases, about 50% to 85%, ADEM is linked to a previous infection or vaccination, usually following a viral or bacterial infection. However, the exact infectious agent causing the disease is not always found.

ADEM affects 0.07 to 0.9 out of 100,000 children annually.
Most cases are found in children between the age of 5 and 8, but it can occur in any age group from children to adults aged 82.
The disease is more common in males and more frequently happens in the colder months.
Genetic traits, exposure to infectious organisms, immunization exposure, and having paler skin can all contribute to the likelihood of developing ADEM.
All ethnic groups are capable of developing ADEM, which is found in every part of the world.
Between 50% and 85% of ADEM cases come after an infection or vaccination, mostly viral or bacterial. However, the exact disease causing ADEM isn’t always known.

Signs and Symptoms of Acute Disseminated Encephalomyelitis

ADEM, or Acute Disseminated Encephalomyelitis, often appears after a sickness or sometimes a vaccination. It typically develops within a few days to 60 days with an average wait of 26 days. However, around a quarter of those affected may not have any noticeable previous event. ADEM’s onset is sudden and quickly gets worse over a few days, leading to various neurological symptoms and often necessitating a hospital stay.

Common symptoms of ADEM include fever, headache, fatigue, discomfort, nausea, and vomiting. Diagnosing ADEM involves identifying a combination of altered mental status and multiple neurological deficits. Altered mental states could involve irritability, confusion, altered perception, sleepiness, or coma. On the other hand, neurological deficits could mean motor or sensory issues, such as weakness in both legs or all four limbs.

Fever
Headache
Fatigue
Discomfort
Nausea and vomiting
Confusion or coma
Motor or sensory issues

Patients may also have problems with brainstem function, such as speech difficulties or eye movement problems. They could have other neurological abnormalities, like seizures, stiff neck, unsteady gait, speech difficulties, involuntary eye movements, inflammation of the optic nerve, inability to urinate, increased pressure in the skull, and unnatural movements. Generally, ADEM patients only experience one event. However, the severity of the condition can fluctuate within three months. If another inflammation event happens after three months, the condition is known as multiphasic ADEM.

Though the ADEM diagnosis criteria primarily focus on children, adults can also get ADEM. Sadly, most studies suggest that the prognosis for adults is often worse. Additionally, some adults may also show signs of peripheral nervous system issues as identified by electrodiagnostic tests. These symptoms may include numbness or a lack of sensation in the limbs and muscle wasting. When an ADEM patient has these peripheral symptoms, it usually results in a worse prognosis and increased risk of recurrence compared to those with only central nervous system involvement.

Testing for Acute Disseminated Encephalomyelitis

If you’re being tested for ADEM, or Acute Disseminated Encephalomyelitis, the best way to do this is through MRI scanning. This type of scan shows bright areas, or ‘hyperintense lesions’, which indicate the presence of ADEM. These areas don’t often show up in all types of MRI scans, but they can be seen on certain ones, like T2-weighted or fluid-attenuated inversion recovery scans.

The scans will typically reveal spots or lesions, which can be single or multiple, in the white and grey matter of the brain. Although ADEM is most commonly seen as multiple, irregular spots throughout the brain, it can also present as spots in the brainstem, cerebellum, and spinal cord.

Scans for ADEM are somewhat unique because the spots typically don’t have distinct borders, making them different from spots seen in conditions like multiple sclerosis. In some cases, the MRI scans may come back normal, even after repeating the scan several times. However, the lesions have been known to show up weeks after symptoms begin, so repeat scanning is often necessary. In fact, the size and positions of the lesions may change over time, even when the patient doesn’t experience any symptoms.

Although MRI scanning is the preferred method, in emergency situations a CT scan might be used to quickly rule out other life-threatening conditions. For ADEM patients, CT scans often come back normal, especially in the early stages of the disease. Later on, the CT scan might show areas of damage in the white matter. Another diagnostic step could include a lumbar puncture to analyze the cerebrospinal fluid (CSF). Patients with ADEM might show abnormalities in 50% to 80% of cases, including an elevated level of a certain protein, signaling the loss of protective nerve covering in the central nervous system. In addition, an electroencephalogram could reveal disturbances in sleep pattern and electrical activity.

Finally, diagnosing ADEM depends on the patient experiencing multiple neurological issues without a history of neurological dysfunction. Anti-MOG antibodies have been identified in a specific subgroup of children with ADEM who tend to have more recurring forms of the disease. ADEM diagnosis in adults has no set criteria but usually includes signs of brain dysfunction and multiple involvement in the central nervous system. In children with ADEM, elevated sedimentation rate, increased C-reactive protein, and mild leukocytosis have been found in 50% of cases.

Treatment Options for Acute Disseminated Encephalomyelitis

When patients arrive with symptoms such as meningeal signs, fever, sudden confusion, and signs of inflammation in the blood or the fluid surrounding the brain and spinal cord, they may be started on supportive care. This often includes administration of acyclovir, an antiviral medication, and antibiotics via an intravenous (IV) line.

The initial treatment for Acute Disseminated Encephalomyelitis (ADEM), a brief but intense attack of inflammation in the brain and spinal cord, is a powerful anti-inflammatory medication called glucocorticoids. A common protocol is administering methylprednisolone at high doses through an IV for 3 to 5 days. This is often followed by a tapered regimen of oral prednisone over 4 to 6 weeks. Cutting this medication regimen short may increase the risk of the illness coming back.

Supportive care, acyclovir, and antibiotics can be started at the same time as the glucocorticoid treatment when a patient first shows symptoms. If the illness doesn’t improve or reacts poorly to the glucocorticoid treatment, then doctors may consider using intravenous immunoglobulin, which is given at a specific dose for 2 to 5 days.

In hard-to-treat cases where other treatments aren’t working, a procedure called plasma exchange is performed 3 to 7 times or a medication called cyclophosphamide may be used.

While diagnosing ADEM (acute disseminated encephalomyelitis), a number of other conditions should be taken into consideration, as they may show similar symptoms:

Aseptic meningitis and acute viral encephalitis: These may present with signs of an underlying infection such as fever, stiff neck, and elevated acute phase reactants like C-reactive protein and erythrocyte sedimentation rate.
The first occurrence of multiple sclerosis: This can show similarities to ADEM in terms of multifocal neurological deficits and MRI appearance, though with subtle differences on MRI. A relapse of multiple sclerosis typically won’t show signs of acute encephalopathy.
Diseases related to myelin oligodendrocyte glycoprotein antibody disease, or MOGAD: It’s part of the evaluation to check the level of the myelin oligodendrocyte glycoprotein (MOG) antibody, especially in children.
Cancer metastases in the brain
Brucellosis, a type of bacterial infection
Cardioembolic stroke, caused by a clot or other particle transported to the brain from the heart
Cauda equina and conus medullaris syndrome, which are types of spinal cord conditions
Cavernous sinus syndromes, conditions affecting the veins in the brain
Neurological complications related to HIV
Cerebral venous thrombosis, blocked blood flow to the brain leading to stroke
Churg-Strauss disease, a rare disorder that causes inflammation of blood vessels

Thorough examination and appropriate tests are required to correctly diagnose these conditions.

What to expect with Acute Disseminated Encephalomyelitis

The outcome of ADEM, a type of brain inflammation, can vary greatly. It largely depends on factors such as the patient’s age, the symptoms, the MRI results, and the presence of a certain type of antibody known as MOG. The most severe forms of ADEM, called acute hemorrhagic encephalitis and acute necrotizing leukoencephalitis, can be life-threatening, with up to a 30% mortality rate.

The type of illness that triggers ADEM also plays a role in the outcome. For instance, if ADEM develops following measles, the prognosis tends to be more severe compared to other infections. In general, however, 50% to 80% of patients make a full recovery after one episode of ADEM.

About a quarter of children who are hospitalized with ADEM need intensive care, and 1% to 3% of these cases can be fatal. Adults tend to have more severe outcomes, with higher rates of intensive care admission, longer hospital stays, less successful recoveries, and higher mortality rates. Long-term brain or nerve damage is rare, as are seizures. However, up to 56% of children may experience cognitive impairment following an episode of ADEM.

Possible Complications When Diagnosed with Acute Disseminated Encephalomyelitis

The extent and specific regions of the Central Nervous System (CNS) involved can largely influence the complications from ADEM (a kind of inflammatory disease of the brain). If the long fiber tracts of the brain’s white matter are involved, it could lead to permanent physical disabilities, including muscle stiffness and varying levels of weakness in the limbs.

Post-ADEM epilepsy is also a fairly common complication among children. Both repeat episodes of ADEM and epilepsy are more frequently seen in children with MOGAD-associated ADEM. Research has proven that impaired mental function could possibly be the most significant long-term complication of ADEM in children. They showed that children between 6 and 15 years old demonstrated mild cognitive deficits with lower intelligence quotient scores, 3.5 to 4 years following ADEM. Those who contracted ADEM at an older age also showed slower verbal processing.

Here’s a breakdown of potential complications from ADEM:

Long-term physical disabilities
Muscle stiffness
Varying degrees of limb weakness
Post-ADEM epilepsy, particularly in children
Repeated episodes of ADEM
Impaired cognitive function
Mild cognitive deficits in children between 6 and 15 years old
Lower intelligence quotient scores in children post-ADEM
Slower verbal processing with onset of ADEM at an older age

Preventing Acute Disseminated Encephalomyelitis

It’s important to know about ADEM (acute disseminated encephalomyelitis). ADEM is a condition where sudden, severe inflammation affects the brain and spinal cord. This often happens after a viral illness, even something as mild as a common cold. Essentially, it’s caused by a faulty response from our body’s defense system, specifically within our brain and spinal cord. This can occur at any age but is more common in children.

If a child starts exhibiting unusual symptoms after getting over a simple viral illness – things like confusion, changed vision, weakness, numbness, or loss of balance – it’s crucial to inform their doctor immediately. Catching ADEM early and starting treatment as soon as possible greatly improves the chances of a good recovery.

Frequently asked questions

Acute disseminated encephalomyelitis (ADEM) is a severe autoimmune disorder that affects the central nervous system, including the brain and spinal cord. It is characterized by inflammation and damage to the insulation of nerve fibers, often occurring after an infection or immunization. ADEM mainly affects children but can also occur in adults.

ADEM affects 0.07 to 0.9 out of 100,000 children annually.

Signs and symptoms of Acute Disseminated Encephalomyelitis (ADEM) include: - Fever - Headache - Fatigue - Discomfort - Nausea and vomiting - Altered mental status (irritability, confusion, altered perception, sleepiness, or coma) - Motor or sensory issues (weakness in both legs or all four limbs) - Problems with brainstem function (speech difficulties or eye movement problems) - Other neurological abnormalities (seizures, stiff neck, unsteady gait, speech difficulties, involuntary eye movements, inflammation of the optic nerve, inability to urinate, increased pressure in the skull, and unnatural movements) - Peripheral nervous system issues in some cases (numbness or lack of sensation in the limbs and muscle wasting) It is important to note that ADEM can have a sudden onset and quickly worsen over a few days, often leading to a hospital stay. While the symptoms primarily focus on children, adults can also be affected by ADEM, with studies suggesting that the prognosis for adults is often worse. ADEM patients may experience one event, but the severity of the condition can fluctuate within three months. If another inflammation event occurs after three months, it is known as multiphasic ADEM.

ADEM can be acquired through infections or vaccinations. It is primarily associated with viral or bacterial infections, such as cytomegalovirus, Epstein-Barr virus, herpes viruses, influenza, hepatitis A, HIV, mycoplasma pneumonia, Leptospira, beta-hemolytic streptococci, and Borrelia burgdorferi. Before vaccinations were common, ADEM was often linked to illnesses like measles, rubeola, rubella, mumps, varicella, and smallpox. Nowadays, ADEM is more commonly associated with viral infections of the gut or respiratory system.

Aseptic meningitis and acute viral encephalitis, the first occurrence of multiple sclerosis, diseases related to myelin oligodendrocyte glycoprotein antibody disease (MOGAD), cancer metastases in the brain, brucellosis, cardioembolic stroke, cauda equina and conus medullaris syndrome, cavernous sinus syndromes, neurological complications related to HIV, cerebral venous thrombosis, and Churg-Strauss disease.

The types of tests that are needed for Acute Disseminated Encephalomyelitis (ADEM) include: 1. MRI scanning: This is the preferred method for diagnosing ADEM. MRI scans can show bright areas or hyperintense lesions in the white and grey matter of the brain, indicating the presence of ADEM. Certain types of MRI scans, such as T2-weighted or fluid-attenuated inversion recovery scans, are more likely to show these lesions. 2. CT scanning: In emergency situations, a CT scan may be used to quickly rule out other life-threatening conditions. CT scans for ADEM patients often come back normal, especially in the early stages of the disease. However, later on, the CT scan might show areas of damage in the white matter. 3. Lumbar puncture: Also known as a spinal tap, a lumbar puncture involves analyzing the cerebrospinal fluid (CSF). Abnormalities in the CSF, such as an elevated level of a certain protein, can indicate ADEM. 4. Electroencephalogram (EEG): An EEG can reveal disturbances in sleep patterns and electrical activity in the brain, which may be indicative of ADEM. It is important to note that the diagnosis of ADEM also depends on the patient experiencing multiple neurological issues without a history of neurological dysfunction. Additionally, the presence of anti-MOG antibodies in a specific subgroup of children with ADEM and certain blood markers, such as an elevated sedimentation rate and increased C-reactive protein, can aid in the diagnosis.

Acute Disseminated Encephalomyelitis (ADEM) is treated with a powerful anti-inflammatory medication called glucocorticoids. The initial treatment involves administering methylprednisolone at high doses through an IV for 3 to 5 days, followed by a tapered regimen of oral prednisone over 4 to 6 weeks. If the illness does not improve or reacts poorly to glucocorticoid treatment, intravenous immunoglobulin may be considered. In hard-to-treat cases, plasma exchange or the use of cyclophosphamide may be necessary.

The potential complications when treating Acute Disseminated Encephalomyelitis (ADEM) include: - Long-term physical disabilities - Muscle stiffness - Varying degrees of limb weakness - Post-ADEM epilepsy, particularly in children - Repeated episodes of ADEM - Impaired cognitive function - Mild cognitive deficits in children between 6 and 15 years old - Lower intelligence quotient scores in children post-ADEM - Slower verbal processing with onset of ADEM at an older age

The prognosis for Acute Disseminated Encephalomyelitis (ADEM) can vary depending on factors such as the patient's age, symptoms, MRI results, and the presence of certain antibodies. The most severe forms of ADEM can be life-threatening, with up to a 30% mortality rate. However, in general, 50% to 80% of patients make a full recovery after one episode of ADEM. Long-term brain or nerve damage is rare, but cognitive impairment may occur in up to 56% of children following an episode of ADEM.

A neurologist.