Bell’s Palsy (Idiopathic Facial Paralysis)

Bell’s Palsy
Body Parts: Head
Medical Subjects: Nervous System

What Is Bell's Palsy?

If you have such an experience:

There was nothing wrong with your face before going to bed the night before, but you were shocked when you got up the next day and looked in the mirror. Your mouth was crooked, leaking air, and leaking water when brushing teeth. When you eat, food residues always remain between your teeth and cheeks.  And, you can't blink or close your eyes. 

You feel very scared. In fact, this is likely to be bell's palsy.

Bell's palsy is a disease with sudden onset, unclear etiology and unilateral facial expression muscle disorder. This may be due to inflammation and edema of the "facial nerve" caused by infection or ischemia of multiple viruses.  It is called "Bell's palsy" because Charles Bell, an English anatomist in the 19th century, first discovered and described it.

Although Bell's palsy can cause symptoms which is seems to  terrible, most patients can be cured. Oral glucocorticoid treatment in time within 3 days after the onset of the disease is helpful to the rapid recovery of the disease and reduce the risk of sequelae. However, a small number of patients will leave sequelae such as hemifacial spasm.

What is facial nerve? What does it do?

There are 12 pairs of cranial nerves in human body, and the facial nerve, one of them, is the seventh pair of cranial nerves. Many people think that the facial nerve only has the function of controlling the movement of the facial muscles, but it is not so.

Facial nerve is a mixed nerve, and its main functions include:

  • Dominate facial muscle movement and make various expressions.
  • Dominate lacrimal gland, submandibular gland and sublingual gland, secrete tears and saliva.
  • Pass the taste from the front 2/3 of the tongue to the brain, and let us taste it.
  • Transfer the feelings from the external auditory canal and auricle to the brain.

Therefore, after facial nerve injury, not only the facial paralysis mentioned above will appear, but also the symptoms such as taste loss, auditory allergy, abnormal secretion of tears and saliva, etc. Facial nerve injury in different positions may show different symptoms.


What Is The Cause Of Bell's Palsy?

  • Could be related to viral activation. The most common virus is herpes simplex virus (HSV), followed by varicella zoster virus, and other viruses include cytomegalovirus, Epstein-Barr virus, adenovirus, rubella virus, mumps virus, influenza B virus, coxsackievirus, and others. The virus may induce the immune response of the body, leading to inflammation, demyelination and paralysis of the facial nerve.
  • It may also be related to facial nerve ischemia. For example, diabetes leads to microangiopathy, causing facial nerve ischemia, inflammation and swelling.
  • Bell's palsy in pregnant women during late pregnancy or postpartum may be related to facial nerve compression or edema caused by fluid retention during pregnancy. It may also be related to the fact that the hypercoagulable state during pregnancy caused thrombosis of the nourishing vessels of the facial nerve, leading to ischemic edema of the facial nerve.

Where is the damaged part of facial nerve of Bell's palsy patients?

The damaged part of the facial nerve is in the facial nerve canal.

Under normal circumstances, the facial nerve only accounts for 25% ~ 50% of the pipe diameter, and the "living space" is very spacious. When Bell paralysis, the facial nerve is edema due to inflammation, ischemia and other reasons, and the pressure in the facial nerve tube suddenly increases, which makes the facial nerve compressed and the blood supply limited, resulting in dysfunction.

The symptoms of different Bell's palsy patients are not exactly the same. This is because:

  • Different patients have different damaged parts of facial nerve in facial nerve canal, so the symptoms of lacrimal gland secretion, saliva secretion, abnormal hearing and abnormal taste are different.
  • Different patients have different severity of facial nerve damage, so the degree of facial paralysis will be different.

Which people does Bell's palsy easily occur in?

  • Generally speaking, Bell's palsy is more common in adults, diabetics, people with weakened immunity, and pregnant women (especially in the third trimester).
  • Children under 10 years of age are less common.
  • The incidence is the same in men and women.
  • Cold and cool breeze stimulation, recent upper respiratory tract infection, etc. can induce Bell's palsy.

Why does Bell's palsy occur easily among diabetic patients?

The risk of Bell's palsy in diabetic patients is 29% higher than that in non-diabetic patients, because high blood sugar can damage the capillaries that supply nerves, which can lead to ischemia and swelling of the facial nerve. Nocturnal ischemia will worsen, so Bell's palsy often occurs at night. Many patients wake up and find that they have facial paralysis.

In addition, diabetic patients are more difficult to recover from facial paralysis and have a higher recurrence rate than non-diabetic patients.

If a patient with Bell's palsy who comes to the hospital is screened for blood sugar, it is very likely that diabetes that has not been discovered before is detected. It is important to detect and actively control blood sugar as early as possible.


What Are The Symptoms And Manifestations Caused By Bell's Palsy?

Facial paralysis caused by Bell's palsy is mostly unilateral.

Symptoms that are sure to occur are:

  • On the side of the lesion, forehead wrinkles and nasolabial folds become shallow.
  • When the eyebrows are lifted hard, the forehead wrinkles on the side of the lesion are not obvious.
  • When closing the eyes forcefully, the diseased side is not as tight as the normal side, and even the eyes cannot be closed completely, exposing the whites of the eyes.
  • When smiling, the face is asymmetrical, and the corner of the mouth is tilted toward the side with normal facial nerve function.
  • When doing puffing movements, the corners of the mouth on one side of the disease will leak.

It can be simply judged as follows: The side with shallow forehead lines, shallow nasolabial folds, and tight eyes closed is the facial neuropathy side, and the side with the corner of the mouth tilted when smiling is the normal side of the facial nerve.

Symptoms that may appear are:

Earache, decreased tear production, tearing, eye pain, blurred vision, hyperacusis, decreased taste, and decreased salivation.

Why does Bell's palsy cause earache?

Some patients always feel a dull pain behind the ear, and it hurts even when pressed. What is going on?

What are the branches of the facial nerve outside the skull?

The facial nerve is divided into five terminal branches outside the skull, which innervate the facial expression muscle movement from top to bottom. From top to bottom, they are: temporal branch, zygomatic branch, buccal branch, mandibular branch, and cervical branch.

  • Temporal branch: Dominate quota head muscle, orbicularis oculi muscle, corrugator muscle, cone muscle. Can make movements such as frowning forehead, closing eyes, and frowning nose.
  • Zygomatic branch: innervate the zygomatic major muscle, zygomatic minor muscle, canine muscle, levator alar muscle, levator lip muscle, depressor septum muscle, nasal muscle, and nostril muscle. Can make movements such as showing teeth, flap the nose, lift the nose, zoom the nostril.
  • Buccal branch: innervating the upper part of buccal muscle and orbicularis oris muscle. You can whistle, suck, pout, drum your cheeks and keep your mouth shut.
  • Mandibular branch: it innervates the lower part of the laughing muscle, lower lip quadratus muscle, deltoid muscle, chin muscle and orbicularis oris muscle. You can smile, pull down your lower lip, and make your chin appear chin-nest and keep your mouth closed.
  • Cervical branch: innervating platysma. It can pull down the spat, and make facial expressions of fear or nausea in cooperation with other muscles.

How To Check For Bell's Palsy?

What are the signs of Bell's palsy?

Most patients seek medical attention because they find that they have a crooked mouth.

If the corners of the mouth are normal, you can also do some small tests to help determine whether there is facial paralysis, such as closing your eyes, bulging your cheeks, or blowing a whistle in the mirror. If these actions cannot be completed, or the two sides are obviously asymmetrical, Then it is likely to have facial paralysis symptoms.

If these abnormal manifestations occur suddenly, accompanied by symptoms such as loss of taste, abnormal sensitivity to sound stimulation, and pain behind the ears, the possibility of Bell's palsy needs to be considered and prompt medical treatment is required.

What kind of examinations will the doctor perform for patients with suspected Bell's palsy?

Bell's palsy is a common disease. Experienced doctors can make a diagnosis by asking the medical history, observing the patient's performance, and performing a neurological examination.

But sometimes, in order to rule out facial paralysis caused by brain problems, the doctor may also recommend head CT or magnetic resonance examination. In order to avoid missed diagnosis and cause adverse consequences.

In addition, neuroelectrophysiological examinations can be performed to assess the severity of facial nerve damage, which is helpful for doctors to judge whether the condition of the disease is optimistic.

What is the significance of neuroelectrophysiological examination of Bell's palsy?

Electroneurophysiological examinations include: facial nerve electrogram (ENoG) and facial electromyography (EMG).

"ENoG" method principle

Electrically stimulate the facial nerve trunk in front of the ear, record the depolarization potential of the facial muscle with skin electrodes, and compare the wave amplitude of the diseased side with the healthy side.

If the amplitude of the affected side is higher than 10% of the healthy side, the possibility of complete recovery is high. If the amplitude of the affected side is less than 10% of the healthy side, the possibility of complete recovery is low, but it is not impossible to achieve complete recovery.

"EMG" method principle

The relaxation state and the depolarization potential of the facial muscles during spontaneous contraction were recorded by needle electrodes. For patients who do not respond to electrical stimulation of the facial nerve, or patients whose facial muscle contraction is too weak, "EMG" can be used as a supplement to "ENoG" to better detect the remaining axons.

Do all patients with Bell's palsy need a neurophysiological examination?


Patients with mild facial paralysis usually recover well and do not need to undergo "ENoG" or "EMG".

Patients with severe facial paralysis can objectively judge the severity of facial nerve damage through "ENoG" or "EMG" examination, predict the possibility of complete facial nerve function recovery, and whether it is necessary to perform facial nerve decompression.

14-21 days after the onset of facial paralysis, the reliability of neuroelectrophysiological examinations will decrease. Therefore, neuroelectrophysiological examinations are generally performed 7 to 14 days after the onset of disease.

In addition to Bell's palsy, what diseases will manifest as unilateral paralysis?

  • Infectious diseases: such as varicella-zoster virus infection, Lyme disease, syphilis, HIV infection, mycoplasma infection, otitis media, and otitis externa.
  • Microvascular disease: such as diabetes, hypertension, etc.
  • Trauma: such as temporal bone fracture damage to the facial nerve.
  • Tumors: include tumors of the facial nerve (such as schwannomas) or tumors adjacent to the facial nerve. Slow-onset facial paralysis usually needs to be suspected of being caused by the tumor, although 20%-27% of tumor patients also present with acute-onset facial paralysis.
  • Iatrogenic injuries: such as neck and face cosmetic surgery, parotid surgery, acoustic neuroma resection, resection of other tumors in the facial nerve pathway, etc. Sometimes the tumor has invaded the facial nerve and is difficult to separate. In order to achieve the effect of completely removing the lesion, the function of the facial nerve has to be sacrificed.

What is the difference between facial paralysis caused by varicella-zoster virus and Bell's palsy?

Facial paralysis and a series of other symptoms caused by varicella-zoster virus infection of the facial nerve are called "Ramsay Hunt syndrome". In addition to the manifestations of facial paralysis, it is also accompanied by skin herpes, dizziness, hearing loss, Severe earache.

When an experienced doctor accepts patients with facial paralysis, he will carefully check whether there are herpes in the external auditory canal, auricle and ear circumference, and ask the patients whether there is dizziness, vomiting, deafness and the degree of earache, so as to distinguish whether it is Bell paralysis or "Ramsay Hunt syndrome".

Compared with Bell's palsy, the facial paralysis of "Ramsay Hunt syndrome" recovers more slowly, earaches are more persistent and severe, and the risk of hearing loss is greater. Treatment requires glucocorticoids combined with antiviral drugs.

Clinically, some patients who are infected with varicella-zoster virus but do not develop ear herpes may be misdiagnosed as Bell's palsy.

Is it possible for Bell's palsy to have facial paralysis on both sides at the same time?

Bilateral simultaneous facial paralysis is not very common and is often not Bell's palsy. Possible causes: Guillain-Barre syndrome, sarcoidosis, Lyme disease, meningitis (cancerous or infectious), bilateral neurofibromas (neurofibromatosis type II), etc.


Can Bell's Palsy Be Prevented?

The exact cause of the disease is unknown, and it may be related to viral infection or inflammatory reactions. Therefore, there is no very effective prevention method. The only way to prevent the disease is to eat healthily and exercise as much as possible to reduce the chance of viral infection.


What Are The Treatments For Bell's Palsy?


It is the main treatment drug for Bell's palsy. Early medication can shorten the course of the disease and reduce the risk of sequelae. Oral glucocorticoid therapy should be started within 72 hours of onset.

Anti-viral drug

Patients with severe facial paralysis can be given oral antiviral drugs in addition to oral glucocorticoids.

Eye care

Some patients will have incomplete closed eyes and/or insufficient tear secretion, which leads to excessive dryness of the cornea, reduced ability to remove foreign bodies, and in severe cases, corneal ulcers and necrosis, leading to blindness. Therefore, eye care is required to keep the corneal surface moist.

operation treatment

Because the mechanism of Bell's palsy is that the facial nerve is inflamed and swollen and is compressed by the facial nerve canal, theoretically, facial nerve decompression can be performed to reduce facial nerve compression to relieve symptoms. But not all patients are suitable for surgical treatment.

Are there any side effects in patients with Bell's palsy if oral glucocorticoids are used for treatment?

Short-term oral glucocorticoids usually do not have serious side effects. Some patients may experience night insomnia and excitement, but these adverse reactions usually disappear by themselves after stopping the drug.

Long-term use of glucocorticoids can lead to side effects such as increased blood sugar, central obesity, induction or aggravation of infections, osteoporosis, gastric ulcers, and hypokalemia.

Patients with Bell's palsy should not refuse to use glucocorticoids for fear of side effects, so as not to delay treatment.

How to treat Bell's palsy with antiviral drugs?

It is not recommended to use antiviral drugs alone instead of glucocorticoids. Studies have shown that this therapy is not beneficial for Bell's palsy.

For patients with severe facial paralysis, oral antiviral drugs can be added on the basis of oral glucocorticoids.

Antiviral drugs can choose acyclovir or valaciclovir.

How should patients with Bell's palsy receive eye care?

For patients with incomplete eye closure, the following eye care methods are recommended to avoid corneal dryness:

  • Artificial tear drops: Commonly used, but need to be used frequently.
  • Eye ointment: more commonly used, but it is easy to blur vision, you can use it at night before going to bed.
  • Moisturizing eye mask: A special eye mask made of polyethylene that can maintain a certain humidity can be purchased online.
  • Ordinary eye mask: Be careful not to directly touch the cornea, otherwise it will damage the cornea and the effect will be counterproductive.

If you experience eye pain, eye itching, photophobia and other symptoms during the treatment, you need to go to the ophthalmology department immediately, do not delay!

Under what circumstances do patients with Bell's palsy need surgery?

Most patients with Bell's palsy, if they can receive medication in time, can recover very well even without surgery.

Only those patients with severe facial paralysis, facial nerve electrogram (ENoG) showing facial nerve degeneration more than 90%, and facial electromyography (EMG) showing no motor unit potential, suggesting that the prognosis may be poor, should be considered for surgical treatment. Perhaps benefit from facial nerve decompression surgery.

The possible complications of facial nerve decompression include hearing loss, further damage to the facial nerve, and cerebrospinal fluid leakage.

Can patients with Bell's palsy be cured?

Most patients with Bell's palsy can be cured. Most patients begin to recover 2 to 4 weeks after the onset of the disease, and fully recover after 3 to 4 months. Even without any treatment, 70% of patients can recover completely 6 months after the onset of illness.

A small number of patients may have sequelae of hemifacial weakness and hemifacial spasm.

What sequelae may be caused by Bell's palsy?

About 9% of Bell's palsy patients will have sequelae, mainly including:

  • Facial spasm: It is an involuntary spasm or twitch that occurs on one facial expression muscle.
  • Facial muscle contracture: It is manifested as a contracture of different degrees of facial expression muscles on one side, such as narrowing of the eye cleft and deep nasolabial fold.
  • Joint movement: When the damaged facial nerve regenerates, some nerve fibers erroneously grow into the adjacent nerve sheath. For example, if the fiber that innervates the orbicularis oculi muscle is incorrectly connected to the fiber that innervates the depressor orbitalis muscle, the oral-eye movement will appear (involuntarily pouting or crooked mouth during blinking). Or the fibers controlling the secretion of the salivary glands are mistakenly connected with the fibers controlling the secretion of the lacrimal glands, which can cause tears on the affected side when eating and chewing.

What are the factors influencing the unsatisfactory recovery of patients with Bell's palsy?

If you have the following conditions, it may be more difficult and slow to recover:

  • Age older than 60 years: The probability of incomplete recovery for patients younger than 30 years old is only 10% to 15%, and the probability of incomplete recovery for patients older than 60 years is 60%.
  • Severe facial paralysis
  • At the time of onset, the affected side had decreased taste and decreased salivation.

Will Bell's palsy recur?

About 4% to 14% of patients will relapse, and the recurrence side can be on the same side or the contralateral side of the initial onset. For recurrences, attention should be paid, and it is necessary to perform high-resolution MRI or CT examination to determine whether there are tumors, infections or other lesions.


What Should Patients With Bell's Palsy Pay Attention To In Life?

In the acute phase, you should rest appropriately and pay attention to keeping your face warm. Wear a mask when you go out, do not wash your face with cold water, and avoid blowing cold wind directly.

Most patients have a sudden onset of illness, which inevitably leads to nervousness, anxiety, fear, and irritability. Worrying about facial changes and being made fun of, or worrying about the poor treatment effect and leaving sequelae, so we must correctly understand the disease and face it optimistically.

Can patients with Bell's palsy undergo self-rehabilitation exercises?

Yes, you can do the following exercises:

  • Passive facial muscle massage exercise: Massage the paralyzed facial muscles for 5 to 10 minutes each time, 2 to 3 times a day, with moderate force and softness.
  • Active expression muscle exercises: face the mirror to raise eyebrows, close eyes, lift nose, show teeth, pout, and bulge cheeks. 2 to 3 times a day, each exercise training 10 to 20 times.

Related Articles