Bell's palsy

Symptoms Of Bell's Palsy

Symptoms of Bell's palsy vary from patient to patient and range from mild weakness to total paralysis. They tend to appear suddenly and reach peak severity within 48 to 72 hours.

The facial nerve, also called the 7th cranial nerve, travels through a narrow bony shell in the skull, beneath the ear, to the muscles on each side of the face. Each facial nerve directs the muscles on one side of the face, including those that control facial expressions and eye blinking and closing. Additionally, the facial nerve carries signals to the salivary glands, lacrimal or tear glands, and the muscles of a small bone in the middle of the ear called the stapes. The facial nerve also transmits taste sensations from the tongue. 

Generally, Bell's palsy affects only one of the paired facial nerves and one side of the face, however, in rare cases, it can affect both sides.

Because the facial nerve has multiple functions and is so complex, damage to the nerve or a disruption in its function can lead to a range of symptoms mentioned below.

• Often the first symptom of Bell’s palsy is a dull aching pain around the jaw or in or behind the ear. This can occur for a day or two before facial weakness is noticed.

• Weakness/paralysis/twitching of the muscles of the face.

• Facial droop of the affected side of the face, with drooping of the eyebrow and corner of the mouth.

• Problems smiling, talking or making facial expressions. Mouth may be drawn toward the unaffected side on smiling.

• Drooling from one side of the mouth due to lack of control over the muscles of the face.

• Difficulty eating and drinking. Food falls out from one side of the mouth.

• Altered sense of taste. 

• Dry mouth (xerostomia).  

• Inability to close or blink eye.

• Reduced tear production causing dry eyes (xerophthalmia), eye sores or infections.

• Absence of forehead wrinkling.

• On attempted closure, the eye rolls upward (Bell's phenomenon).

• Pain in front or behind the ear on the affected side.

• Intolerance to loud noise (hyperacusis).

• Ringing in the ears (tinnitus).

Causes Of Bell's Palsy

Classically, Bell's palsy has been defined as idiopathic which means that a specific cause for the disease cannot be identified. However, the following causes have been proposed by the researchers.

1. Viral hypothesis: Researchers have long believed that the following virus may play a role in the development of Bell's palsy.

• Herpes simplex type 1, which causes cold sores
• Herpes simplex type 2, which causes genital herpes
• Herpes zoster virus, which causes chickenpox and shingles
• Epstein-Barr virus, which causes mononucleosis
• HIV, which damages the immune system
• Influenza B virus, which causes flu
• Rubella virus, which causes german measles 
• Coxsackie virus, which causes hand-foot-and-mouth disease
• Adenovirus, which causes respiratory illness
• Cytomegalovirus infections
• Paramyxovirus, which causes mumps 

Most scientists believe that reactivation of an existing (dormant) viral infection may cause the disorder. While the actual mechanism in Bell's palsy is unknown, one proposed mechanism is that the patient had a primary viral infection in the past. The virus continues to live in the nerve for months to years and reactivates at a later stage and reproduces and travels along the nerve. The virus infects the cells surrounding the nerve. The immune system responds to the damaged cells, which causes inflammation of the nerve and subsequent weakness or paralysis of the face. 

2. Vascular ischaemia: This theory believes that inflammation and swelling of the facial nerve in reaction to any infection or any other factor, causes compression within the bony canal that encases the facial nerve and leads to restricted blood and oxygen supply to the nerve cells. This in turn impacts the function of the nerve leading to facial paralysis.

3. Autoimmunity: It is also proposed that a viral infection may prompt an autoimmune reaction against a component of the nerve’s myelin covering, leading to the demyelination of the facial nerve, in a way that is not yet clear.

Risk Factors For Bell's Palsy

Most scientists believe that something can trigger reactivation of a dormant viral infection up and triggering Bell’s palsy. The potential triggers can be  those that impair immunity like stress, sleep deprivation, physical trauma, minor illness etc.

Bell's palsy is more often associated with the following risk factors such as: 

• Diabetes
• Hypertension
• Pregnancy especially during the third trimester or after delivery
• Upper respiratory infection
• Ear infections
• Facial anatomy with a narrow facial nerve canal 
• Migraine
• Genetic predisposition
• Exposure to extreme cold weather
• Hypothyroidism
• Sarcoidosis
• Amyloidosis 
• Sjogren’s syndrome
• Tumors of injury to brain 

Diagnosis Of Bell's Palsy

A diagnosis of Bell's palsy is usually made based on current symptoms of acute facial nerve weakness on one side of the face with onset in less than 72 hours and by ruling out other possible causes of facial paralysis. 

A full medical history, including any recent illnesses or viral infections is recorded. The doctor will carry out a comprehensive physical and neurological assessment. 

There is no specific laboratory test to confirm diagnosis of Bell’s Palsy. Routine laboratory or imaging studies are not necessary for most cases, but to assist further with the diagnosis and to rule out other conditions, the doctor may recommend.

Prevention Of Bell's Palsy

Currently there is no known way to prevent or avoid Bell’s palsy.

However, potential triggers like stress, sleep deprivation, exposure to extreme cold etc. can be avoided. Risk from factors like diabetes, hypertension, upper respiratory infection, ear infections & hypothyroidism can be reduced by proper management of the respective diseases.

Bell’s Palsy vs. Stroke

Bell's palsy is the most common cause of facial paralysis. It occurs when the facial nerve that controls the muscles of the face gets injured or fails to work properly. However, Stroke occurs due to lack of oxygen or blood supply to the brain thereby impacting the bodily functions controlled by that specific part of the brain.

Although Bell's palsy is not a stroke, both have many overlapping symptoms. Since stroke is a medical emergency it is advised to seek medical attention at the earliest.
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Specialist To Visit

Bell's palsy is not a life-threatening condition but it can produce symptoms similar to other more serious causes for facial paralysis such as a stroke. Hence, all episodes of facial weakness or paralysis should be immediately examined by a doctor to rule out the possibility of a stroke. Moreover, treatment of Bell's palsy is most effective when administered early, so patients should see their doctor as soon as they experience symptoms of Bell’s palsy.

If you have had a previous episode of Bell's palsy and have another similar episode, you should again be examined to rule out other more serious causes of the facial weakness. The following doctors can be consulted:

• General physician

• Neurologist

• ENT specialist

• Ophthalmologist

Referral to a neurologist should be considered for recurrent or bilateral cases. ENT specialist can be consulted for hearing and balancing issues. If the diagnosis is not straightforward, and a tumor is suspected, the patient should be referred to ENT specialist or a neurologist as appropriate. In case of any eye complications, an ophthalmologist can be consulted.

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Treatment Of Bell's Palsy

Bell's palsy affects each individual differently. Some cases are mild and do not require treatment as the symptoms usually subside on their own within 2 weeks. 

There are no medications specifically approved to treat Bell's palsy. However, certain treatments can help.

1. Improve or fasten recovery

Oral corticosteroids

Oral corticosteroids such as prednisolone have traditionally been prescribed to reduce facial nerve inflammation and swelling in patients with Bell's palsy. Prednisolone is typically prescribed in a 10-day tapering course. It should be started within 72 hours of symptom onset if possible, to increase the probability of recovery. It shows significant treatment benefits in terms of both gain of complete recovery and reduction of long-term sequelae. However, some individuals with co-existing conditions may not respond well to or be able to take steroids. 

Antiviral medication

Since viral infections are attributed as the cause of Bell's palsy, the antiviral drugs acyclovir and valacyclovir have been used to help in recovery. They are usually used in addition to corticosteroids. But evidence suggests that they are of limited benefit.

2. Reduce discomfort and complications

Pain management

Pain medicines such as aspirin, paracetamol, or ibuprofen may relieve pain associated with Bell's palsy. Warm wet cloth applied to the face can also help in alleviating pain. Because of possible drug interactions, individuals taking prescription medicines should always talk to their doctors before taking any over-the-counter drugs.

3. People with long-term Bell's palsy 

Botox injections-

Botulinum toxin injections can help people with long-term Bell's palsy in the following ways. However, the effect of these injections is temporary and they need to be repeated every few months.

• Relax tight facial muscles and reduce any unwanted muscle contractions.

• Relax facial muscles on the unaffected side of the face if they become overactive.

• Improve facial symmetry and appearance.

• Reduce involuntary movements of muscles on the affected side of the face because of misdirected nerve regrowth. 

Laser therapy

It has been shown to improve neural regeneration. A recent small trial using laser therapy on specific points of the face produced promising results, although further research is required.

Acupuncture

It may also help in improving facial nerve function and pain. However, it needs more scientific backing.

Surgical facial nerve decompression

This surgical intervention is controversial for management of Bell's palsy. Some physicians recommend surgical decompression during the first two weeks in patients showing the most severe nerve degeneration. However, the most common complication of this surgery is postoperative hearing loss. Based on the significant potential for harm and the rarity of data supporting benefit, it is  usually not recommended.

Functional facial plastic or reconstructive surgery

These procedures can improve the appearance and symmetry of the face and assist with eyelid closure. Some patients experience enormous benefit if they are able to smile again. However, it does not cure the nerve problem.

Home-care For Bell's Palsy

1. Eye care: Patients with Bell’s palsy have difficulty in keeping their eye closed or blinking because the muscles which close the eye become weak. This can lead to dry eyes which can become quite painful and vision can be blurred. Hence it becomes very important to keep the eyes moist. Methods to help in the same are:

• Using artificial tear eye drops, gels and ointments to keep the eye lubricated

• Manual closure of the eye with a finger to keep it moist -- patients should use the back of their clean finger rather than the tip to insure that the eye is not injured

• Using eye patch to protect the eye

• Protective glasses which can prevent dust from entering the eye

• Taping the eye shut while sleeping (placing the tape over a soft pad)

2. Facial exercises: Facial exercises may help to strengthen muscles and fasten recovery of nerve function. However, they are not suitable for all people with Bell's palsy.

3. Mime therapy: This is a type of physical therapy. The patient is taught a series of exercises which strengthen the facial muscles. This usually results in better coordination and a wider range of movement.

4. Oral care: Due to decrease in sensation in the mouth and strength in oral muscles, it is easy for food to pool in the mouth. This can lead to dental decay or gum diseases. Brushing and flossing can help prevent it.

5. Care while eating: Weak oral muscles can also lead to lip and inner cheek abrasion during chewing food. This can also cause oral ulcers. In such cases, strategic eating may lessen the impact. It is also advised to chew food well and eat slowly. Choosing soft foods can also help. 

The inability to lower and evert the lower lip precludes eating certain foods. Temporary dental ‘spacers’ adhered to the lateral aspect of the molar teeth may be used to prevent biting of the inner surface of cheeks and lips.

6. Care while drinking: Sometimes, it is hard to drink from a glass when the mouth is droopy. To reduce the likelihood of dribbling water or other beverages down the chin, it is advisable to drink from a straw.

Complications Of Bell's Palsy

Most people with a mild case of Bell’s palsy completely recover without any complications. However, recovery from a more severe case involving total paralysis varies. Complications may include: 

Eye complications

If the eyelid muscles are weakened by Bell's palsy, the patient is not able to blink easily and the eyelids cannot completely close. In this way, the protective and lubricating tear film of the eye may become ineffective. This can result in dry eyes and blurred vision. The risk of drying is even higher if Bell’s palsy has also caused a reduction in tear production. 

The cornea (the clear surface at the front of the eye) is particularly sensitive to dryness. If it is dry for long periods of time, the cells of the cornea can flake off and this can lead to formation of ulcers. Corneal ulceration can be painful and result in infection or scarring of the cornea, which can eventually lead to loss of vision.

Muscle contracture

Contraction and permanent tightness of the facial muscles can lead to a greater appearance of facial asymmetry, particularly obvious when one eye appears smaller or a cheek appears larger. Swelling in the muscles is also there due to loss of nerve function.

Involuntary muscle movements

As the facial nerve heals from Bell's palsy, new nerve fibers regrow to replace the old, damaged ones. However, sometimes the nerve fibers regrow in an irregular pattern. For example nerve fibers that should connect the brain to the muscles of the mouth may grow back connecting the brain to the muscles of the eyelid. Hence, a patient may unintentionally close one eye while trying to smile. This is called eye-mouth synkinesis.

The problem can also happen the other way round – contraction of the facial muscles with twitching of the corner of mouth or dimpling of the chin, occurring at the same time while blinking. This is also called reversed jaw winking.

Crying while eating 

Sometimes due to misdirected re-growth of nerve fibers, the ones that usually connect the brain to the salivary gland regrow to connect to the lacrimal gland that produces tears. Thereby, while eating the patient might start shedding tears. This is also called as Borgorad's syndrome or crocodile tears syndrome or gusto-lacrimal reflex.

Difficulties with speech 

If the muscles that affect mouth movement are affected, slurred speech can occur.

Loss or altered sense of taste

If the branches of the facial nerve that connect the brain to the tongue do not repair properly, the sense of taste can be permanently altered. In more severe cases, it may even lead to ageusia, which is chronic loss of taste.

Complications associated with treatment with corticosteroids 

Corticosteroids, such as prednisolone, used in the management of bell’s palsy can cause a range of side effects. Most of the more serious side effects associated occur with long-term rather than the short-term use that is required to treat Bell's palsy.

Side effects of prednisolone include:

• Headache

• Dizziness (spinning sensation)

• Nausea

• Tiredness

• Increased sweating

• Abdominal pain and bloating

• Burning in the upper abdomen or chest pain due to irritation of the lining of the stomach or esophagus

• Increased appetite 

• Indigestion 

• Difficulty sleeping 

• Mood changes such as feelings of anxiety 

• Acne

• Dry skin

• Thinning of skin

• Candidiasis (oral thrush)

• Delayed healing

These side effects generally improve within a couple of days of ceasing treatment. Doctors usually reduce the dose gradually towards the end of the course of steroid medication. This helps prevent withdrawal symptoms such as vomiting or tiredness.

Living With Bell's Palsy

In most cases, Bell's palsy has a good prognosis. Gradual improvement can be seen in a few weeks to some months. Prompt treatment along with physical therapy and good home care are promising for quick recovery. 

However, facial expression is essential to an individual’s sense of wellbeing and ability to socialize. Marked facial asymmetry can lead to social agony and isolation, impaired interpersonal relationships leading to depression and anxiety. Thus in such a case, mental health is of utmost importance. If the patient is feeling down about one’s appearance, he/she should talk about their feelings with a trusted friend or seek help from a counselor or a therapist. These won’t cure your Bell’s palsy symptoms, but they might make you feel better.