Pediatric acute flaccid myelitis (AFM)

What is pediatric acute flaccid myelitis (AFM)?

Acute flaccid myelitis (AFM) in children is a rare, serious neurological disease. It affects a part of the spinal cord called gray matter and causes muscles to become weak. It is a type of transverse myelitis.

AFM causes weakness and paralysis in children by damaging the lower motor neurons. These nerve cells stretch from the spinal cord to muscles in the body. When the nerve cells within the spinal cord are damaged, they cause a “flaccid” paralysis (the muscles are loose, not tight). The paralysis can appear very quickly.

Different types of AFM can be distinguished based on what causes them and which parts of the spinal cord are affected. Although the paralysis resembles polio, acute flaccid myelitis in children is usually caused by other viral infections of the spinal cord and not the specific virus that causes polio.

Most recently, enterovirus D68 has been the most common cause of AFM, causing national outbreaks in the summer and fall of 2014, 2016 and 2018. AFM also can be caused by an autoimmune reaction. It affects either just the gray matter in the spinal cord or both the gray and white matter.

What are the signs and symptoms of pediatric acute flaccid myelitis (AFM)?

The signs and symptoms of acute flaccid myelitis in children typically include:

• Unexplained weakness of limbs

• Weakness of facial muscles

• Problems swallowing

How is pediatric acute flaccid myelitis (AFM) diagnosed?

When your child sees the doctor, they will take a detailed medical history and also do a physical exam.

They will do some of these diagnostic tests:

• MRI of the spinal cord, which can determine whether a child has acute flaccid myelitis or another condition.

• Testing of the spinal fluid for levels of white blood cells or other indicators of inflammation

• Testing of a nose (nasopharyngeal) swab, because the virus can be found in the nose and not in spinal fluid.

• Testing of stool specimens or rectal swabs to check for viral infections

• Blood tests to look for certain autoimmune conditions

What causes pediatric acute flaccid myelitis (AFM)?

Acute flaccid myelitis in children may be caused by an enterovirus. Enteroviruses typically cause mild respiratory or gastrointestinal illness, but they can also cause AFM. No one knows why some people with an enterovirus infection develop AFM. In rare cases, AFM can also be caused by an autoimmune reaction.

How is pediatric acute flaccid myelitis (AFM) treated?

In treating AFM at Children’s Health, we first try to limit damage to the spinal cord. We may use high doses of steroids or plasma exchange therapy (PLEX), which replaces the plasma in the blood with other fluids. We also may use intravenous immune globulin (IVIG), which has blood proteins (antibodies) that help fight infections.

We will work with your child to manage their symptoms, which can mean helping manage nerve pain, problems with urinary or bowel function, or other complications.

• Rehabiliation - We will do early rehabilitation that is aggressive and lasts as long as your child needs.

  • Physical therapy (PT), to help your child improve their muscle coordination and strength. We often recommend electrical stimulation (e-stim), which involves putting electrodes over paralyzed muscles that have lost the nerve that controls them. The e-stim keeps the muscles contracting while we are working to help nerves heal and regain function

  • Occupational therapist (OT) also may work with your child on daily activities, such as eating, bathing or putting on their clothes.

• Nerve transfer procedure - Finally, we are one of the few centers in the county where a child can get a nerve transfer procedure, in which a healthy nerve from another part of the body can be moved into a paralyzed hand so that it can move again. This procedure can be useful for select patients.