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, including:

• 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, or twitching of the muscles of the face.
• Facial droop on the affected side, with drooping of the eyebrow and corner of the mouth.
• Problems smiling, talking, or making facial expressions; the mouth may be drawn toward the unaffected side when smiling.
• Drooling from one side of the mouth due to lack of control over the muscles of the face.
• Difficulty eating and drinking; food may fall out from one side of the mouth.
• Altered sense of taste.
• Dry mouth (xerostomia).
• Inability to close or blink the 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 of or behind the ear on the affected side.
• Intolerance to loud noise (hyperacusis).
• Ringing in the ears (tinnitus).

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

• Viral hypothesis: Researchers have long believed that the following viruses 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, reproducing and traveling along the nerve. The virus infects the cells surrounding the nerve. The immune system responds to the damaged cells, causing inflammation of the nerve and subsequent weakness or paralysis of the face.
• Vascular ischaemia: This theory posits that inflammation and swelling of the facial nerve in reaction to any infection or other factors cause compression within the bony canal encasing the facial nerve, leading to restricted blood and oxygen supply to the nerve cells. This, in turn, impacts the function of the nerve, resulting in facial paralysis.
• 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 manner that is not yet clear.

Most scientists believe that something can trigger the reactivation of a dormant viral infection, leading to Bell’s palsy. Potential triggers include factors that impair immunity, such as:

• Stress
• Sleep deprivation
• Physical trauma
• Minor illness

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

• 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 or injury to the brain

A diagnosis of Bell's palsy is usually made based on the following criteria:

• Current symptoms of acute facial nerve weakness on one side of the face with onset in less than 72 hours.
• 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 the 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:

• Blood tests:
  • To rule out other potential causes such as Lyme disease and Ramsay Hunt syndrome.
  • To determine fasting glucose or HbA1c to assess diabetes mellitus as a risk factor.
  • If herpes simplex virus-1 (HSV-1) or varicella zoster virus (VZV) are suspected, serology can be sent for confirmation.
• Hearing and balance tests to assess any involvement of the inner ear.
• Salivary flow test to evaluate changes in salivation.
• Tear test to measure the eye’s ability to produce tears.
• Magnetic Resonance Imaging (MRI) and Computerized Tomography (CT scan) to rule out stroke and other structural causes of pressure on the facial nerve, such as tumors or bone fractures.
• Electromyography (EMG) to assess the facial nerve activity and extent of its damage. It may also help to predict the time and course of recovery.

Currently, there is no known way to prevent or avoid Bell’s palsy. However, potential triggers such as:

• Stress
• Sleep deprivation
• Exposure to extreme cold

can be avoided. The risk from factors like:

• Diabetes
• Hypertension
• Upper respiratory infections
• 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 function properly. In contrast, a stroke occurs due to a 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 conditions share many overlapping symptoms. Since a stroke is a medical emergency, it is advised to seek medical attention as soon as possible.

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 and 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 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 administered in addition to corticosteroids, but evidence suggests that they provide limited benefit.

2. Reduce Discomfort and Complications

• Pain management: Pain medications such as aspirin, paracetamol, or ibuprofen may relieve pain associated with Bell's palsy. A warm, wet cloth applied to the face can also help alleviate pain. Individuals taking prescription medicines should always consult their doctors before taking any over-the-counter drugs due to possible drug interactions.

3. People with Long-Term Bell's Palsy

• Botox injections: Botulinum toxin injections can help people with long-term Bell's palsy in several ways. However, the effects of these injections are temporary, and they need to be repeated every few months. They can:
  • Relax tight facial muscles and reduce 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 due to misdirected nerve regrowth.
• Laser therapy: Laser therapy 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: Acupuncture may help improve facial nerve function and alleviate pain; however, it requires more scientific backing.
• Surgical facial nerve decompression: This surgical intervention is controversial for the 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. Due to 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 significant benefit if they are able to smile again; however, this does not cure the underlying nerve problem.

1. Eye care: Patients with Bell’s palsy have difficulty keeping their eye closed or blinking due to weakened muscles. This can lead to dry eyes, which can be painful and cause blurred vision. It is essential to keep the eyes moist. Methods to assist in this include:
   • Using artificial tear eye drops, gels, and ointments to maintain eye lubrication.
   • Manually closing the eye with a clean finger, using the back of the finger to avoid injury.
   • Using an eye patch to protect the eye.
   • Wearing protective glasses to 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 strengthen muscles and expedite nerve function recovery. However, they may not be suitable for all individuals with Bell's palsy.
3. Mime therapy: This physical therapy involves teaching patients a series of exercises that strengthen facial muscles, resulting in improved coordination and a wider range of movement.
4. Oral care: Due to decreased sensation in the mouth and weakened oral muscles, food can pool in the mouth, leading to dental decay or gum disease. Regular brushing and flossing can help prevent these issues.
5. Care while eating: Weak oral muscles can cause lip and inner cheek abrasions during chewing, potentially leading to oral ulcers. Strategic eating may mitigate this impact. It is advisable to chew food thoroughly and eat slowly. Choosing soft foods can also be beneficial. The inability to lower and evert the lower lip may restrict certain foods. Temporary dental spacers adhered to the lateral aspect of the molar teeth can prevent biting the inner surfaces of cheeks and lips.
6. Care while drinking: Drinking from a glass can be challenging with a droopy mouth. To minimize the risk of dribbling liquids down the chin, it is recommended to use a straw.

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 unable to blink easily and the eyelids cannot completely close. This may render the protective and lubricating tear film of the eye ineffective, resulting in dry eyes and blurred vision. The risk of dryness is higher if Bell’s palsy has also caused a reduction in tear production. The cornea, being particularly sensitive to dryness, can flake off if it remains dry for extended periods, leading to corneal ulceration, which can be painful and may result in infection or scarring, ultimately causing loss of vision.
• Muscle contracture: Contraction and permanent tightness of the facial muscles can lead to a more pronounced appearance of facial asymmetry, especially when one eye appears smaller or a cheek appears larger. Swelling in the muscles may also occur due to loss of nerve function.
• Involuntary muscle movements: As the facial nerve heals, new nerve fibers may regrow in an irregular pattern. For instance, nerve fibers that should connect the brain to the muscles of the mouth may instead connect to the muscles of the eyelid, causing the patient to unintentionally close one eye while trying to smile, known as eye-mouth synkinesis. Conversely, contraction of facial muscles may cause twitching of the corner of the mouth or dimpling of the chin during blinking, referred to as reversed jaw winking.
• Crying while eating: Due to misdirected regrowth of nerve fibers, those connecting the brain to the salivary gland may reconnect to the lacrimal gland, leading to tears being shed while eating. This phenomenon is known as Borgorad's syndrome, crocodile tears syndrome, or gusto-lacrimal reflex.
• Difficulties with speech: If the muscles affecting mouth movement are impacted, slurred speech may occur.
• Loss or altered sense of taste: If the branches of the facial nerve connecting the brain to the tongue do not repair properly, the sense of taste can be permanently altered. In severe cases, this may lead to ageusia, which is a 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 serious side effects are associated with long-term use rather than the short-term use required for treatment. 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 steroid medication course to help prevent withdrawal symptoms such as vomiting or tiredness.

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

However, facial expression is essential to an individual’s sense of well-being and ability to socialize. Marked facial asymmetry can lead to social distress and isolation, impairing interpersonal relationships and potentially leading to depression and anxiety. Thus, mental health is of utmost importance.

If the patient is feeling down about their appearance, they should consider discussing their feelings with a trusted friend or seeking help from a counselor or therapist. These actions may not cure Bell's palsy symptoms, but they can contribute to improved emotional well-being.