Bell's palsy is a neurological disorder that causes paralysis or weakness on one side of the face. One of the nerves that controls muscles in your face becomes injured or stops working properly.Symptoms include: Sudden weakness or paralysis on one side of your face. A drooping eyebrow and mouthDrooling from one side of your mouth. Difficulty closing an eyelid, which causes eye dryness.Most often these symptoms lead to significant facial distortions.Symptoms appear suddenly over a72-hour period a