Acute flaccid myelitis
Acute flaccid myelitis (AFM) is a serious condition of the spinal cord. Symptoms include rapid onset of arm or leg weakness and decreased reflexes. Difficulty moving the eyes, speaking, or swallowing may also occur. Occasionally, numbness or pain may be present. Complications can include trouble breathing.
| Acute flaccid myelitis | |
|---|---|
| Other names | Acute flaccid paralysis with anterior myelitis, polio-like syndrome |
| Magnetic resonance imaging of the spinal cord in a case of AFM showing cord swelling in (d) which has resolved three weeks later in (e). | |
| Specialty | Neurology |
| Symptoms | Weakness, decreased reflexes, trouble swallowing or speaking |
| Complications | Trouble breathing, urinary retention |
| Usual onset | Rapid |
| Causes | Generally unknown; thought to be caused by viral infection |
| Diagnostic method | Medical imaging, nerve conduction studies, cerebral spinal fluid testing |
| Differential diagnosis | Transverse myelitis, Guillain–Barré syndrome, acute disseminated encephalomyelitis |
| Treatment | Supportive care, physical therapy, mechanical ventilation |
| Prognosis | Variable |
| Frequency | Rare |
The cause of most cases is unclear as of 2018. More than 90% of recent cases have followed a mild viral infection such as from enteroviruses. While polio can cause AFM, since 2014, it has not been involved in cases in the United States. The underlying mechanism involves damage to the spinal cord's grey matter. Diagnosis may be supported by medical imaging of the spine, nerve conduction studies, and cerebrospinal fluid testing.
Treatment involves supportive care. Physical therapy may be recommended. Occasionally, mechanical ventilation is required to support breathing. Outcomes are variable. The condition is rare and occurs most commonly in children. Fewer than one in 500,000 children is affected per year in the United States. Although the illness is not new, an increase in cases has been seen since 2014 in the United States. In 2018, 233 cases were confirmed in the United States.