Bell's palsy is a weakness (partial or total) of the facial nerve. The facial nerve is the nerve that controls expression on each side of the face, tearing, taste, and even hearing to some extent.
In Bell's palsy, facial weakness develops suddenly or over a period of 48 hours. Often it is first noticed by a patient's family member as a crooked smile or slurred speech. Patients have repeatedly reported that it was noticed on first getting up in the morning. Other common symptoms include a sensation of facial numbness or tingling, a sensation of pulling of the face or mouth to one side, sensitivity to loud sounds, excessive tearing or dry eye, difficulty eating, headache, pain behind the ear, a change in taste.
About 1 in 5000 people in the United States experience Bell's palsy each year. The problem can occur at any age. Bell's palsy occurs more often in pregnant women, people with diabetes, influenza, a cold or another respiratory illness than in other people.
The cause of Bell's palsy is unknown. However, a prevalent and well supported theory states that the paralysis is a result of a viral infection. According to this theory, a virus, such as HSV-1 that is normally latent (or sleeping) within the nerve cells, is activated. The virus begins actively replicating and producing injurious agents. As a result, the nerve becomes swollen and electrical activity is impaired.
Most patients with sudden facial weakness on one side have Bell's palsy. However, this diagnosis should be made by a physician, such as an ENT doctor. There are many other causes of facial paralysis. Your doctor will ask you how quickly the facial weakness developed, what other symptoms were present -- such as fever, headache, hearing loss, dizziness, weakness or numbness in the arms and legs, difficulty swallowing, and hoarseness. Your doctor will also need to know about any past medical problems, medications, and your family's medical history. A complete physical exam is absolutely necessary.
Other causes of facial paralysis include ear infections, trauma, Lyme disease, birth trauma, genetic disorders, tumors of the ear or brain, and stroke, among others.
If you have a slowly progressive facial weakness, a facial weakness that has not recovered within 3-6 months, a facial weakness with other concerning symptoms, persistent headaches, or a recurrent facial weakness, you may not have Bell's Palsy. You should have a complete evaluation by a physician.
Patients with Bell's palsy should look forward to a complete recovery. If the weakness was incomplete (some movement was present), the prognosis for 100 percent recovery is extremely good. In this case, 95 precent of patients will have the return of perfectly normal function. A few patients may have mild persistent symptoms such as a mild smile weakness or twitch.
More than 80 perent of patients with total paralysis will recover satisfactorily. The great majority of patients will recover to completely normal function. About 17 percent of patients have mild dysfunction. This may include a slight weakness of the face or an occasional twitch of the lip or eye, all barely perceptible to anyone but the patient him/herself. A small percentage of patients (4 percent) may have more significant dysfunction, such as persistent weakness or spasms.
For most patients, recovery begins within 3 weeks. The sooner the onset of recovery, the better the final outcome. If paralysis persists without recovery for more than 3 months, persistent problems are more likely. If there is no recovery within 6 months, a re-evaluation by a physician is necessary.
Your doctor will perform a complete history and physical. Often a hearing test will be ordered. Your doctor may order a test for facial nerve function such as an ENoG and EMG and/or a radiographic study. Follow-up visits will be schedule to monitor your symptoms. If the weakness does not improve, a more extensive work-up will be required.
Eighty percent of patients with Bell's palsy have normal or near-normal recovery without any treatment. It is a minority of patients at risk for moderate to poor recovery that we are trying to help with treatment. It is widely believed that the use of steroids, such as prednisone or methylprednisolone, to reduce inflammation within the nerve may hasten and improve facial nerve recovery. Some doctors also use antiviral agents.
If the eyelid becomes paralyzed, eye care is very important. Blinking is the mechanism that protects the eye from external debris and spreads tears over the cornea. Under normal circumstances we blink every 5-7 seconds. With every blink the eyelid spreads moisture over the cornea. With facial paralysis the ability to blink may be disrupted. Eyelid closure can be weak or the eye can be stuck wide open. The eye may also be dry, because of a reduction in tear production. In this situation the eye is susceptible to corneal abrasions. This can be very serious.
Good eye care includes:
How to tape the eye:
Surgery may be recommended to relieve pressure on the facial nerve if the paralysis is complete and electrical testing indicates that it is necessary. This involves removal of bone around the nerve in order to decompress the facial nerve. This surgery requires a short hospitalization. Facial nerve decompression may improve the eventual recovery of nerve function.
If the paralysis does not improve, there are many surgical options for improving the function and appearance of the face. This is highly individualized and may include eyelid surgery, facial nerve grafts, suspension techniques, or brow/face lifts.
Eye closure may improve by implanting the upper eyelid with a gold weight. This helps to prevent dryness and irritation of the eye and helps to improve the appearance. Shortening of the lower lid may be performed during the same operation to reduce drooping of the lower lid and the associated constant tearing. Complications of these procedures are rare and include bleeding, infection, droopy eyelid, extrusion of the implant and visual loss.
Hypoglossal-Facial Nerve Anastomosis
A graft between the tongue nerve and the facial nerve may be performed to supply motor function to the face. This may improve tone at rest as well as with smiling. Some degree of tongue weakness may occur and may affect speech or swallowing.
Temporalis Muscle Transposition or Static Suspension
Transferring one of the jaw muscles or attaching a sling made of synthetic material to the corner of the mouth can provide improvement of facial symmetry. If muscle is used, smiling can be relearned by attempting to bite at the same time. Unlike hypoglossal-facial nerve anastomosis, no tongue weakness is expected and chewing problems are rare. The surgeon always attempts to overcorrect the pull at the corner of the mouth. This over-correction and the significant face swelling usually resolve in 4-6 weeks. Rarely, a very thick muscle may result in a bulge.
While facial reanimation surgery cannot provide a return to normal facial function, the improvement in eye protection and appearance is usually gratifying. Not infrequently, a secondary procedures or revisions may be required to obtain the best results or modify results because of the passage of time.