Bell’s Palsy
Bell’s Palsy is a form of facial paralysis that results from some type of damage caused to the facial nerves. The paralysis is temporary and usually will resolve on its own. For more severe cases, there are medications and other therapeutic treatments that can help.
The facial nerve affected is known as the 7th cranial nerve. This nerve travels beneath the ear, through the skull to each side of the face and controls the facial muscles. These muscles are those that control
eye blinking and closing. They also control facial expressions such as smiling and frowning. The 7th cranial nerve transmits impulses from the tear ducts, taste buds, saliva glands and the stapes (a small bone in the middle ear).
When a patient is inflicted with Bell’s Palsy the nerve function is disrupted causing incomplete messages to get through to the brain. With the message not getting through the result is a facial droop, weakness or paralysis.
Bell’s Palsy is the most common cause of facial paralysis and is not related to a stroke. Generally only one of the nerves is affected resulting in a droop on one side of the face. In rare cases it can affect both.
Bell’s Palsy is named for Sir Charles Bell, a Scottish surgeon in the late 19th century who discovered the connection between the 7th cranial nerve and the disorder.
Signs and Symptoms
With the functions of the facial nerve being so complex, as you can imagine the patient may present with an array of symptoms. The symptoms the patient experiences depends of the severity of the damage to the nerve and can range from mild weakness to total paralysis. Symptoms may include:
- weakness or paralysis on one or both sides of the face.
- twitching
- drooping of the eyelid
- drooping of the corner of the mouth
- drooling
- dryness of the eye or mouth
- impaired taste
- excessive watering of one eye
- pain or discomfort around the jaw and behind the ear
- ringing in one or both ears
- headache
- loss of taste
- hypersensitivity to sound
- dizziness
- impaired speech
- difficulty eating and drinking
- headache
Pathophysiology
Bell’s Palsy occurs when there is trauma to the facial nerve. The facial nerve is enclosed in narrow, bony canal known as the Fallopian canal. For most of its path it is protected, so how the damage occurs is unknown.
Most scientists and physicians agree that a viral infection is most likely the cause. The belief is that the facial nerve becomes inflamed in reaction to the infection. This swelling causes compression of the nerve inside of the Fallopian canal. The pressure leads to ischemia, a starvation of blood and oxygen to the cells.
This disorder has been associated with:
- Viral meningitis
- influenza
- the common cold
- hypertension
- diabetes
- Lyme disease
- trauma such as skull fracture
Diagnosis
Diagnosis is made upon the patients clinical presentation. There is no specific lab test for the disorder. A test called electromyography (EMG) can confirm nerve damage. Blood test may identify a concurrent viral infection as a possible cause for the Bells Palsy. Magnetic Resonance Imaging (MRI) or computerized Tomography (CT) can be used to rule out other possible causes.
Examination
You will need to differentiate between an upper and lower motor neuron lesion of the facial nerve. A lower motor neuron lesion occurs with Bell’s palsy, whereas an upper motor neuron lesion is associated with a cerebrovascular accident. A lower motor neuron lesion causes weakness of all the muscles of facial expression. The angle of the mouth falls. Weakness of frontalis occurs, and eye closure is weak. With an upper motor neuron lesion frontalis is spared, normal furrowing of the brow is preserved, and eye closure and blinking are not affected.
Check that no other cranial nerves are involved. Bell’s palsy is seventh nerve palsy in isolation. Look also for a painful rash over the ear, which indicates Ramsay Hunt syndrome caused by herpes zoster virus. Look for pointers to a more serious underlying cause that might require urgent referral of the patient: bilateral Bell’s palsy; recurrent Bell’s palsy; association with a rash elsewhere or with feeling generally unwell (which may indicate sarcoid or Lyme disease); or a previous episode that could have been the effect of demyelination. Although it is rare, always bear in mind the possibility of a seventh nerve palsy caused by a space occupying lesion.
Treatment
Bell’s Palsy typically has a rapid onset of symptoms that usually only last for 1-2 weeks. Symptoms frequently resolve on their own with no need for treatment. However in more severe cases the patient may need medication or therapy to keep them comfortable and assist in recovery.
Corticosteroids such as prednisone or solucortef have proven to be effective in decreasing inflammation of the facial nerve, thereby decreasing pressure on the nerve and reducing injury. Antivirals may be effective in treating the virus that may have led to the inflammation. Pain medication, either prescription or over the counter, may be needed to keep the patient comfortable. Benzodiazapine’s may be effective in reducing patients anxiety level. Stress plays a significant role in the body’s ability to fight a viral infection such as herpes simplex.
Treatment for the eye is important and should not be overlooked. Protection and lubrication are needed especially at night. The natural blinking ability is interrupted and the eye may not close at night while sleeping. Lubricating ointments are longer lasting then artificial tears and an eye patch is often worn for two reasons; one is to protect the eye from debris the second is to help with balance issues. With some patients, the stapes in the middle ear can be affected. The middle ear is the region of the body responsible for balance. Covering one eye makes the patient more steady and less dizzy.
Acute Treatment
The mainstay of pharmacologic therapy for acute idiopathic facial nerve palsy (Bell’s palsy) or facial nerve palsy of suspected viral etiology is early short-term oral glucocorticoid treatment. In severe acute cases, combining antiviral therapy with glucocorticoids may improve outcomes. Eye care is important for patients with incomplete eye closure as mentioned above.
Glucocorticoid and antiviral therapy — Early treatment with oral glucocorticoids for all patients with idiopathic facial nerve palsy (Bell’s palsy) or facial nerve palsy of suspected viral etiology. Treatment should preferably begin within three days of symptom onset. The suggested regimen is prednisone (60 to 80 mg/day) for one week.
Surgical intervention is rarely used because people with Bell’s palsy generally recover, but there is a small group who do not. In rare cases cosmetic surgery of the jaw or fallopian canal may be needed to reduce constriction of the nerve caused by deformity.
Some surgeons have thought that an operation to free the nerve could improve recovery. One study was conducted to assess the effects of surgery for Bell’s palsy compared with treatment with medicines, and no treatment at all. To measure the effects of surgery they looked at recovery of paralysis at 12 months. The first study compared surgery with a steroid medicine and the second study compared surgery with no treatment. In the first study the surgery and no surgery groups appeared to have similar facial nerve recovery at nine months. The second study found no differences in recovery of the facial paralysis after one year, between the participants who had an operation and those who had no treatment.
Prognosis
Prognosis is very good for patients with Bell’s Palsy. The extent of the nerve damage determines recovery. Improvement is gradual, with or without treatment. Patients usually begin to feel better in 1-2 weeks but may not reach full recovery for 3-6 months.
References:
Bell’s Palsy. Retrieved from https://www.ninds.nih.gov/Disorders/Patient-Caregiver-Education/Fact-She…
Bell’s palsy. Retrieved from https://rarediseases.info.nih.gov/diseases/5906/bells-palsy.
Hyperlink:
http://www.ninds.nih.gov/Disorders/Patient/bellspalsy
Hyperlink:
http://www.rarediseases.info.nih.gov/diseases/590
Hyperlink:
http://www.ninds.nih.gov/disorders/All-Disorders
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