Symptoms of acute flaccid myelitis include the sudden onset of: Arm or leg weakness. Loss of muscle tone. Loss of reflexes (areflexia). Loss of coordination and balance. These symptoms develop over a few hours or days. Other symptoms include: Difficulty moving your eyes or drooping eyelids. Facial droopiness or muscle weakness. Difficulty with swallowing (dysphagia). Slurred speech. Pain in your arms, legs, neck or back. Bladder and bowel dysfunction. AFM can affect any or all of your limbs, but it most commonly affects your upper limbs. Sometimes, AFM can affect the muscles you need to breathe. This can lead to respiratory failure, which is life-threatening and requires immediate treatment. Signs of respiratory failure include: Rapid and shallow breathing. Extreme fatigue and sleepiness. Restlessness. If you or your child develop any symptoms of AFM, seek medical care right away.