Acute Flaccid Myelitis

What is Acute Flaccid Myelitis?

Acute flaccid myelitis (AFM) is a rare condition mostly found in people under 21, and sometimes in adults with weak immune systems. It mainly affects the anterior part of the spinal cord and, to a lesser extent, the gray part of the brainstem. AFM first appeared in California in 2012 and has since been identified globally. It often occurs in certain areas and follows a two-year seasonal pattern.

Although the exact cause of AFM is unclear, it has been associated with specific viruses such as enterovirus D68, enterovirus A71, West Nile virus, and adenovirus.

Typically, AFM is characterized by sudden, unequal paralysis in the lower motor neurons without affecting sensation. There might be unusual involvement of facial weakness, eye muscle dysfunction, or other muscles related to speech or swallowing. Generally, these symptoms come up after 1 to 10 days of an upper respiratory tract infection. Other common symptoms include muscle weakness in the arms and/or legs, loss of muscle control, and loss of reflexes. In severe cases, paralysis of the breathing muscles may require artificial breathing support.

AFM diagnosis includes identifying the unique symptoms and confirming with diagnostic tests. This involves checking the cerebrospinal fluid (fluid found in your brain and spinal cord) for specific characteristics and detecting specific lesions in the spinal cord through imaging. The long-term outlook for AFM is still under research.

For treatment, rehabilitation, physical therapy, and mental support are essential in getting the best recovery results. Properly monitoring and reporting suspect cases can help further our understanding of AFM, guide public health actions, and reduce its impact. Continuing collaboration and knowledge exchange among healthcare professionals and researchers is crucial.

What Causes Acute Flaccid Myelitis?

The exact cause of AFM, a condition that affects the nervous system, is still unknown. However, it has been linked to several viral infections. Most commonly, the disease is connected to non-polio enteroviruses known as D68 and A71, but other viruses such as adenovirus and West Nile virus have also been suggested to play a role.

There is evidence in animal studies that indicates enterovirus D68 could be responsible for AFM. Experiments with mice showed that when the virus was present, the animals lost motor neurons (the nerves that control muscles) in their spinal cord. This was especially evident in affect limbs. Furthermore, when serum containing the virus was injected into healthy mice, they developed paralysis, a key symptom of AFM.

Further tests showed that giving mice serum with enterovirus D68 antibodies from previously infected animals could prevent AFM. Despite these promising findings, more research is needed to strengthen the evidence and address any limitations.

Risk Factors and Frequency for Acute Flaccid Myelitis

Acute Flaccid Myelitis (AFM) commonly affects people who are younger than 21 and is slightly more common in males. It can affect anyone, even those with no pre-existing health conditions, those with weakened immune systems, or even those with asthma. There isn’t any particular environment, travel exposure, or racial or ethnic group that is more prone to getting AFM.

AFM has become more recognized because of outbreaks in 2014, 2016, 2018, and 2020. Interestingly, it seems to follow a pattern of occurring every other year, mainly in the late summer and early fall. The reason for this pattern isn’t entirely clear, but some think it could be due to changes in community-wide immunity and higher vulnerability to viruses.

Signs and Symptoms of Acute Flaccid Myelitis

Acute flaccid myelitis (AFM) usually starts with signs like fever and breathing problems. Some people also experience stomach issues. Generally, these initial symptoms go away before the development of neurological problems like weakness or loss of muscle tone. These neurological signs often come with additional symptoms like stiffness in the neck, headaches, repeated fevers, and pain in the lower back or affected limbs. AFM tends to worsen quickly over a span of hours or days.

The key symptoms of AFM are:

• Muscle weakness, usually significantly more in one limb
• Decrease in muscle tone
• Reduced reflexes
• Problems with eye movement and facial muscles
• Difficulty in breathing, which in sever cases can lead to respiratory failure

Muscle weakness typically affects the upper body more and can differ between limbs. Sometimes, people may also experience neuropathic pain, mild neck stiffness, and motor nerve deficits. Signs such as mental confusion and loss of sensation, however, are not typically associated with AFM.

Testing for Acute Flaccid Myelitis

Acute Flaccid Myelitis (AFM) is usually diagnosed based on a range of factors, including a patient’s symptoms, medical imaging results, and various lab tests. Different levels of certainty about the diagnosis are possible, which are shown in a specific table of diagnostic criteria for AFM.

To start the diagnosis process, medical professionals collect blood, saliva from the throat, fluid from around the brain and spinal cord (CSF), and stool samples as quickly as possible for lab analysis. Testing for particular viruses such as enterovirus D68 and A71 is most useful in the early stages of the disease. Enterovirus D68 is usually found in respiratory samples, while enterovirus A71 is typically detected in stool samples. Patients with AFM usually show changes in their CSF, including an increased number of lymphocytes and a slight increase in protein.

A special type of magnetic resonance imaging (MRI) of the spinal cord with a contrast dye is usually carried out. The scan frequently shows a brightly lit area in the front part of the spinal cord, which usually spans one or more segments of the spine. In most cases, abnormalities can be seen throughout the entire length of the spinal cord. Other changes, such as swelling around this area, could be seen in the early stages of the disease. The results of these tests often resemble those of other neurological conditions that mainly affect either the motor neurons or nerve fibers.

Other symptoms and signs that could point towards a diagnosis other than AFM include mental confusion that can’t be explained by fever, medication, or breathing difficulties; paralysis that mainly affects the legs and is worse in the bottom part; and overly active reflexes. Additional tests should also be carried out to rule out other health conditions such as infections, tumors, blood vessel conditions, metabolic disorders, and conditions that cause damage to the protective covering of the nerve fibers. In some regions, a lab test to look for poliovirus in a stool sample is suggested. Blood tests for specific antibodies are also necessary to identify potentially treatable diseases like MOG Antibody Disease and Neuromyelitis-Optica Spectrum Disorder.

Blood tests for antibodies that attack nerve cells could suggest Guillain-Barré syndrome, even though this test isn’t entirely specific. It’s also worth noting that low levels of these same antibodies could be found in some nerve conditions and in patients with AFM, therefore not entirely ruling out an AFM diagnosis. If there’s any suspicion of a sudden cut-off in the blood supply to the spinal cord, a special type of computed tomography (CT) called spinal angiography should be performed.

Treatment Options for Acute Flaccid Myelitis

The Centers for Disease Control and Prevention provide guidelines for the emergency treatment of Acute Flaccid Myelitis (AFM) as it’s a significant medical issue. Currently, there aren’t any medications approved by the Food and Drug Administration specifically to prevent or treat AFM. Different treatment options such as high-dose steroids, immune-boosting intravenous fluids, plasma exchange, antiviral agents, interferon, fluoxetine, and rituximab have been tried, but unfortunately, none have been effective in treating this condition.

At present, the primary way to manage AFM is through supportive treatments, which help manage the symptoms. These include providing heart-related support, managing issues related to involuntary body functions and bowel disturbances, controlling pain, preventing blood clots and pressure ulcers (sores that develop from prolonged pressure on the skin).

One promising treatment option for those with incomplete recovery from Acute Flaccid Myelitis is nerve transfer surgery, a procedure where surgeons redirect healthy nerves to restore function in affected areas.

What else can Acute Flaccid Myelitis be?

When a person has symptoms similar to Acute Flaccid Myelitis (AFM), it’s important to check for other health conditions that might be causing these symptoms. This helps doctors to understand what’s really going on, so that they can provide the right treatment. This article mentions several possible conditions that might be mistaken for AFM, and some of the ways they can be distinguished.

• Guillain-Barré Syndrome

Guillain-Barré Syndrome is another condition that might be causing AFM-like symptoms. You might know it – this condition usually leads to weakness in the limbs that gets worse over time, and it might affect both sides of the body equally. It can also cause nerve pain, and problems with other nerves in the face and body. Often, people with this syndrome experience symptoms such as infection in the respiratory or gastrointestinal tract before the onset of weakness.

Tests can help diagnose this disease. For example, a test called CSF analysis often shows a specific pattern that indicates Guillain-Barré Syndrome. Other tests that evaluate nerve signals can give additional clues.

• Poliomyelitis

Poliomyelitis might look like AFM too. It’s caused by a virus that’s very contagious and is usually present in the digestive tract. This virus is common in families with young kids.

Symptoms of this disease include high fever, sore throat, nausea, vomiting, muscle ache, as well as headache and stiff neck. Most infections don’t cause serious illness, but in cases of paralyzing poliomyelitis, severe muscle pain and weakness can occur.

• Botulism

Botulism is a rare, but serious condition caused by a bacteria called Clostridium botulinum. It can cause symptoms that overlap with AFM such as generalized weakness, paralysis, and other symptoms involving the nervous system. Botulism can be triggered by eating contaminated food, getting a wound infected, and other means.

• Acute Demyelinating Encephalomyelitis

Acute disseminated encephalomyelitis (ADEM) is another condition that affects the nervous system and can mimic AFM. It usually develops in children, often after an infection or vaccination.

Symptoms of ADEM include sudden onset of changes in mental status and a wide variety of neurological symptoms. An MRI, a type of imaging test, can reveal features of the disease in the brain and other parts of the nervous system.

• Neuromyelitis-optica Spectrum Disorder

Neuromyelitis-optica Spectrum Disorder (NMOSD) often presents with eye and spine symptoms. Relapses can progress over days to weeks. An MRI and a blood test for a specific marker called the anti-aquaporin-4 antibody can help in diagnosis.

• Spontaneous Spinal Cord Infarction

Finally, Spontaneous Spinal Cord Infarction (SCI) can also mimic AFM. It typically manifest quickly and can cause a variety of neurological symptoms, ranging from motor weakness to sensory changes and autonomic dysfunction.

What to expect with Acute Flaccid Myelitis

The future health outcomes for individuals with AFM (Acute flaccid myelitis) can greatly vary. Some people fully recover, while others may face severe and long-lasting nerve issues, and in some cases, it could even be life-threatening.

Although aggressive early rehabilitation can help improve these outcomes, the degree of recovery is often influenced by the extent of initial nerve damage. Besides, various other factors also affect a person’s recovery, including the speed and severity of symptom onset, the specific areas of the spinal cord affected, and the overall health and age of the individual.

Long-term follow-up care is usually needed for individuals with AFM as remaining weaknesses, paralysis, and other complications can continue, necessitating consistent medical and supportive care. Enhancements in understanding and treating AFM can help improve the long-term health outcomes for individuals suffering from this condition.

Possible Complications When Diagnosed with Acute Flaccid Myelitis

Patients with AFM can experience various complications, which can be grouped into neurological, musculoskeletal, and psychological categories. These complications include:

• Neurological consequences: These might include breathing difficulties requiring ventilator assistance, dependence on artificial nutrition and hydration, nerve-related pain, and chronic constipation.
• Musculoskeletal complications: Patients may face muscle wastage, joint stiffness, deformities of the chest, differences in limb length, dislocated or partially dislocated joints, and a sideways curvature of the spine known as scoliosis.
• Psychological complications: Anxiety and depression can also occur in patients with AFM.

Preventing Acute Flaccid Myelitis

Preventing and educating about AFM (Acute Flaccid Myelitis) is crucial in managing it. Teaching patients and caregivers on how to prevent the condition will help reduce the chances of getting infected and developing AFM. Important methods of prevention include regularly washing hands using soap and water, covering the mouth and nose when sneezing or coughing, and steering clear of people with respiratory symptoms. Also, routine cleaning of surfaces that are touched often helps lessen the spread of viruses.

An important point to hammer home is the necessity of keeping vaccinations up-to-date to stop viruses that cause AFM. Parents should also be informed about signs of AFM, like sudden weakness in the arms or legs or drooping of the face, to make sure they reach out for medical help immediately. Quick medical evaluation is critical for early treatment and better chances of recovery.

Providing resources, connections to specialists, and information about support groups can assist families in dealing with AFM. Furthermore, teaching about how to prevent mosquito bites is also important since some AFM cases are linked to mosquito-borne viruses such as the West Nile.