Acute flaccid myelitis

Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]; Associate Editor(s)-in-Chief: Syed Hassan A. Kazmi BSc, MD [2]

Historical Perspective

• In 2014, physicians in California and Colorado (USA) noted an increase in the number of patients presenting with the acute onset of flaccid paralysis and MRI findings consistent with lesions in the gray matter of the spinal cord.
• In 2014, a total of 120 cases were identified in the US and 22 were identified in 2015
• In 2016, 145 cases of AFM were diagnosed across the USA.

Causes

Acute flaccid myelitis (AFM) may be caused by viral infections or environmental toxins. The following viruses are known to be associated with AFM:

• West Nile Virus
• Coxsackievirus
• Adenovirus
• Poliovirus
• Enterovirus 71 (EV 71) and Entervirus D68 (EV 68)

Diagnosis

Diagnostic Criteria

Diagnosis	Criteria
Confirmed	Acute onset of flaccid limb weakness AND An MRI showing a spinal cord lesion largely restricted to gray matter and spanning one or more spinal segments
Probable	Acute onset of flaccid limb weakness AND Cerebrospinal fluid (CSF) with pleocytosis (white blood cell count 9 5 cells/mm3

Symptoms

The following are the symptoms of acute flaccid myelitis:

• Acute onset of flaccid limb paralysis (asymmetric)
• Fever
• Pain in the paralytic limb
• Eyelid drooping

• Difficulty with swallowing or slurred speech

• Cranial nerve abnormalities
• Headache
• Neck pain
• Bowel/bladder changes