Facial paralysis is loss of facial movement because of nerve damage. Your facial muscles droop or become weak. It usually happens on just one side of the face and is typically caused by:
Infection or inflammation of the facial nerve
Head trauma
Head or neck tumor
Stroke

Facial paralysis can come on suddenly (in the case of Bell's palsy, for example) or can happen gradually over a period of months (in the case of a head or neck tumor). Depending on the cause, the paralysis might last a short or extended period of time.

What Are Symptoms of Facial Paralysis?
Facial paralysis has a major impact on a person's quality of life. You may lose confidence and feel embarrassed. In addition, facial paralysis can cause:
Facial pain
Headaches or dizziness
Earaches, ringing in one or both ears, and sensitivity to sound
Difficulty talking
Inability to express emotion
Difficulty eating or drinking
Drooling
Muscle twitching
Tearing of the eye
Dryness of the eye and mouth

Treatment -
Facial paralysis may benefit from surgery to repair or replace damaged nerves or muscles, or to remove tumors. Small weights may also be surgically placed inside the upper eyelid to help it close.
Some patients may experience uncontrolled muscle movements in addition to paralysis. Botox injections that freeze the muscles, as well as physical therapy, can help.
Physiotherapy is important as muscles which are not used shrink and contract. The affected muscles should be massaged to keep them supple until the person recovers.
If the cause of the facial palsy is a tumour pressing on the nerve, surgery is indicated to remove as much of the tumour as possible.