Most of those diagnosed with AFM report having a respiratory or gastrointestinal illness before the onset of weakness. The predominant presentation is a rapid onset of weakness within hours to a few days that may affect the limbs, face, and the muscles that control breathing and/or swallowing. The weakness may rapidly progress from limb weakness to more severe symptoms, including respiratory failure, so hospitalization for observation is recommended even with mild symptoms. Those with AFM may not be able to breathe, swallow, or move their eyes normally. Weakness varies greatly, ranging from mild to very severe. AFM may result in weakness, partial paralysis, or total paralysis of just one limb or all limbs. The pattern of paralysis and how individuals present are widely variable. Weakness most often occurs in proximal muscles, meaning the muscles closest to the center of the body. Pain in the neck, back, or limb may be an early symptom. Autonomic instability, such as issues with heart rate, blood pressure or temperature regulation, may occur as well. Sensation and bowel and bladder function are generally spared in children with AFM. Some individuals, those more severely affected, may have inflammation in both the white and grey matter of the spinal cord (upper and lower motor neuron) and may experience impaired sensation and/or bowel and bladder dysfunction.