Causes of Facial Paralysis
Bell's Palsy
Sir Charles Bell
The most common cause of facial weakness which comes on suddenly is referred to as "Bell's palsy." This disorder is probably due to the body's response to a virus: in reaction to the virus the facial nerve within the ear (temporal) bone swells, and this pressure on the nerve in the bony canal damages it.In order to be sure that this is the cause of the facial weakness, and not something else, a special set of questions will be asked. After an examination of the head, neck, and ears, a series of tests may be performed. The most common tests are:
- Hearing Test: Determines if the cause of damage to the nerve has involved the hearing nerve, inner ear, or delicate hearing mechanism.
- Balance Test: Evaluates balance nerve involvement.
- Tear Test: Measures the eye's ability to produce tears. Eye drops may be necessary to prevent drying of the surface of the eye cornea).
- Imaging: CT (computerized tomography) or MRI (magnetic resonance imaging) determine if there is infection, tumor, bone fracture, or other abnormality in the area of the facial nerve.
- Electrical Test: Stimulates the facial nerve to assess how badly the nerve is damaged. This test may have to be repeated at frequent intervals to see if the disease is progressing.
Incidence and Prevalence Bell's palsy affects about 40,000 people in the United States every year. It affects approximately 1 person in 65 during a lifetime. It is more commonly seen in young adults, and persons of Japanese descent have a slightly higher incidence of the condition. Bell's palsy is the most common cause of facial paralysis worldwide and one of the most common neurological disorders involving a cranial nerve.
Risk Factors
Conditions that compromise the immune system, such as HIV, increase the risk for Bell's palsy. Stress, pregnancy, and diabetes are also risk factors. Diabetics are more than 4 times as likely to develop the disorder compared to the general population.
Other risk factors include the following:
- Bacterial infections such as Lyme disease or typhoid fever
- Neurological disorders such as Guillain-Barre syndrome, multiple sclerosis, and myasthenia gravis
- Traumatic injury to the head or face
- Tumor causing nerve compression
- Viruses such as influenza, the common cold, or infectious mononucleosis
Diagnosis, Prognosis, and Treatment of Bell's Palsy
The three questions most often asked by the patient are: What is the cause (diagnosis)? When can I expect recovery (prognosis)?, and What can be done to bring about the best recovery at the earliest possible moment (treatment)? In order to answer these questions, your doctor must perform an extensive evaluation to determine the cause and which area of the facial nerve is involved, so that the best treatment can be prescribed.
Treatment
The results of diagnostic testing will determine treatment.
- If infection is the cause, then an antibiotic to fight bacteria (as in middle ear infections) or antiviral agents (to fight syndromes caused by viruses like Ramsay Hunt) may be used.
- If simple swelling is believed to be responsible for the facial nerve disorder, then steroids are often prescribed.
- In certain circumstances, surgical removal of the bone around the nerve (decompression) may be appropriate.
Help Your Recovery
When the facial nerve is paralyzed, considerable attention must be given to maintaining a healthy eye, which requires a constant flow of tears. These tears are spread out over the eye by blinking, but blinking is diminished or eliminated in facial nerve paralysis. Diminished blinking and the absence of tearing together can reduce or eliminate the flow of tears across the eyeball, resulting in drying, erosion, and ulcer formation on the cornea and possible loss of the eye.
Closing the eye with a finger is an effective way of keeping the eye moist. Use the back of the finger to ensure that the eye is not injured with the finger tip. Protective glasses or clear eye patches are often used to keep the eye moist, and to keep foreign materials from entering the eye.
If the eye is dry, you may be advised to use artificial tears to keep it moist. The drops should be used as directed by your doctor. You may have to put one or two drops in the affected eye every hour while you are awake, and place ointment in your eye at bedtime.
1 American Academy of Otolaryngology-Head & Neck Surgery
Frequently asked questions about bell’s palsy
- When do you need to be treated with steroids? patients really need to be treated in first 72 hours with high dose steroids and antiviral medications
- What other treatments is absolutely needed when this occurs? immediate eye protection
- What factors may have poor impact on recovery? patients with complete or no recovery in 3 weeks, age over 60, diabetics, recurrent paralysis, pregnant women, poor ENoG scores
- What percent of individuals have complete recovery? 3 groups of patients
- Group 1 regains complete recovery of facial motor function without sequelae.
- Group 2 experiences incomplete recovery of facial motor function, but no cosmetic defects are apparent to the untrained eye.
- Group 3 experiences permanent neurologic sequelae that are cosmetically and clinically apparent.
- 85% achieve good recovery; 10% have some asymmetry; 5% experience severe sequelae.
- `EMG/ENoG are key for prognostic indication
- What is the most common cause of bell’s palsy? Most experts now believe HSV-1 causes the facial nerve to “unravel” resulting in facial paralysis.
- What is the rate of Familial facial nerve paralysis? The incidence of familial bell’s palsy is 2.4-28.6%.
- What is the chance the bell’s palsy can occur a second time? The recurrent rate for bell’s palsy is 2-15% (more likely if first episode in childhood) with recovery generally worse with multiple palsies.
