Facial paralysis is the loss of facial muscle movement due to a weakened or damaged facial nerve, usually occurring on one side of a patient’s face. Causes of facial paralysis or facial weakness include trauma to the face or skull, a tumor in the head and neck or a stroke. Facial paralysis may also be congenital. Cases of facial paralysis that are due to tumor removal may be effectively treated by surgery. Facial paralysis is a complex disorder and is treated via a multidisciplinary team at Keck Medicine of USC.