A pilonidal cyst, sometimes called pilonidal disease, is a fluid-filled sac that usually occurs on the tailbone at the top of the buttocks. It usually starts as an infection of a hair follicle in the ...

3% to 2% of all cases. Unilateral facial nerve paralysis causes an uneven appearance of the face. It looks like one side of the face is droopy, with a flattened nasolabial fold. This fold is the deep ...