What is Facial Nerve Palsy?
The facial nerve controls all of the muscles that blink the eyes and move the face to form facial expressions. The facial nerve can be injured by skull fractures, lacerations, infections, tumors, or surgery and radiation used to treat tumors. These cases typically affect one side of the face. Other patients are born with a condition called Moebius (Möbius) syndrome where the facial nerve and muscles that move the face do not form on one or both sides of the face. These conditions result in a face that does not move normally. Depending on the areas of the face affected and the severity of the conditions, patients may have difficulty closing their eyes with increased eye irritation and tearing. Patient may have difficulty closing their mouth and have a “mask-like” face without the ability to smile.
What Causes Facial Nerve Palsy?
Interestingly, the cause of Moebius (Möbius) syndrome has been a mystery since it was described over 130 years ago. Researchers just recently discovered genes that may be responsible for causing this condition. Facial palsy may develop later in life in children and adults for many reasons. Some patient’s develop idiopathic facial palsy, a condition called Bell’s palsy, for no apparent reason. These cases of Bell’s palsy often improve on their own but should be evaluated by an ENT specialist to make sure something else is not causing the facial nerve weakness and to determine the likelihood that the condition will improve on its own. Other causes of facial nerve palsy include viral infection, lacerations, fractures of the skull, brain tumors or tumors of the salivary glands, surgery used to treat tumors, radiation used in the treatment of tumors, and stroke. A thorough evaluation by your doctor or referral to a specialist may be needed to determine the cause of this condition.
How is Facial Palsy Evaluated?
Patients who develop a facial nerve palsy may require testing to determine its cause and to determine if the condition will improve on its own. These tests may include a CT scan or MRI. In some cases an electrodiagnostic test (electroneurography) may help to determine the likelihood of recovery. Your primary doctor or ENT specialist will help to determine what testing is needed. Patients with facial palsy that affects their eyelids may also need an evaluation by an eye doctor (ophthalmologist) to determine if their eye shows signs of injury resulting from the inability to close the eye regularly. Patients with Moebius (Möbius) syndrome typically do not need additional testing to look for a cause of their condition, but an evaluation by a geneticist may be helpful.
How is Facial Palsy Treated?
The treatment of facial palsy is determined by the cause and what portions of the face are affected. Patients with Bell’s palsy typically improve without treatment. While waiting for the condition to improve, procedures are sometimes necessary to protect the eye on the affected side of the face.
Patients with Bell’s palsy that does not improve after a prolonged period of time, patients with Moebius (Möbius) syndrome, and patients with facial nerve palsy that resulted from an injury or tumor may be candidates for facial nerve reconstructive surgery. The exact details of your case will determine the best operation to treat your specific condition.
Operations that are available to treat facial palsy conditions include:
Gold Weight Insertion
Patients with significant weakness of the muscles that close the eye are unable to blink normally and close the eyes. This can result in drying of the eye, irritation, and injury to the cornea that can lead to blindness if not treated or prevented. Patients with Bell’s palsy often can tape the eye shut or wet the eye with ointment or eye drops until the condition improves. When facial palsy is longer lasting, implantation of a gold weight in the upper eyelid may help it to close and help it to moisten and protect the eye. The gold weight can be removed if the facial weakness improves.
Facial Nerve Repair/Grafting
If a facial nerve is cut it may be possible to repair the ends and allow the nerve to regenerate. Alternatively, if a section of the nerve is removed as the result of an injury or surgery to treat a tumor, the nerve may need to be replaced with a nerve graft. Repairing the nerve with either technique does not result in immediate return of nerve function. The nerve ends must regrow from the site where the nerve is repaired. Patients do not see improvement until at least 3-6 months after their reconstructive surgery.
Cross Face Nerve Grafting
In some cases the facial nerve on the affected side cannot be repaired after an injury or tumor surgery. In selected cases, a nerve graft from the normal, unaffected side, to the injured side may return function to the face.
Functional Muscle Transfer (free flap reconstruction)
Functional muscle transfer uses a muscle from the leg, the gracilis muscle, to replace the muscles needed to smile. Many muscles perform the same function as the gracilis and patients may walk and run normally after its removal. This operation improves the drooping of the paralyzed face and allows the patient to elevate the corner of the mouth in a smile.
The gracilis muscle is transferred to the face as a free flap and a microsurgical procedure is carried out to connect it to an artery and vein in the neck. Patients are closely monitored for 3-5 days after surgery to make sure the vascular connections feeding the muscle are working. The gracilis muscle is connected to a nerve to a muscle involved in chewing, the masseter muscle. After three to six months, the patient is able to smile on the affected side by clenching their teeth. With time and practice, they learn to use this as their emotional smile. This is the operation recommended for patients with Moebius (Möbius) syndrome.