What are the causes of facial palsy? What are the manifestations? These are the two main questions that many friends are concerned about. Patients with facial palsy often suddenly find that one cheek does not move well and the mouth is crooked when washing the face or rinsing the mouth in the early morning. If the facial expression muscle is completely paralyzed, the forehead wrinkles disappear, the eye fissures are enlarged, the nasolabial folds are flattened, the corners of the mouth droop, and the corners of the mouth are skewed to the healthy side when the teeth are exposed. The patient’s side cannot make movements such as forehead wrinkles, frowning, eye closure, puffing and pouting. When puffing the cheeks and whistling, the affected side of the mouth leaks air because the lips cannot be closed. When eating, food residue is often left in the gap between the teeth and cheeks on the affected side, and saliva often flows down from that side. Because the tear dots are turned inward with the lower lid, the tears do not drain normally and spill out.