Facial Palsy

What is facial nerve palsy?

Facial nerve palsy is a paralysis (paresis) of the facial nerve (nervus facialis). Signals from the brain travel through it to the muscles of the forehead, cheeks, mouth, and neck. It controls all the major muscles of your face, as well as saliva and tear production, the glands of the nasal mucosa, and the sense of taste in the front two-thirds of the tongue. If the facial nerve is damaged, the muscles and glands associated with it no longer function properly.

The damage can occur in the brain, for example, due to a stroke or a brain tumor. Or the nerve itself may be affected, for example, by a bacterial or viral infection. In the latter case, facial nerve palsy is idiopathic in about two-thirds of cases. In other words, no direct cause can be identified. Idiopathic facial palsy, also known as Bell’s palsy after the London physician Charles Bell, affects approximately 7 to 40 out of every 100,000 people each year. It is the most common disorder of the cranial nerves. Both genders are affected with roughly the same frequency. The risk of this increases with age. In addition, women’s risk is three times higher during pregnancy.

If facial paralysis is properly diagnosed and treated, it can be cured in the vast majority of cases. It is rare for a noticeable consequence, such as an asymmetrical face, to persist.

Facial Nerve Palsy: Causes and Risk Factors

Medicine distinguishes between two different forms of facial nerve palsy:

Central facial palsy: The damage affects the brain. Possible causes include:

• Stroke (cerebral infarction, cerebral hemorrhage): The blood supply to the brain is suddenly interrupted, resulting in dysfunction of the central nervous system and, in some cases, paralysis of certain parts of the body.
• Brain Tumor: A tumor can affect the part of the brain that controls the facial nerve.

Peripheral facial nerve palsy: The facial nerve itself is damaged. In 70 percent of cases, facial paralysis resulting from damage to the peripheral facial nerve is idiopathic—that is, it occurs without any clearly identifiable cause. In the remaining approximately 30 percent of cases, facial nerve palsy is the result of an infectious or inflammatory disease that affects the facial nerve in addition to certain organs. Facial paralysis then occurs acutely alongside other typical symptoms. Causes of inflammatory peripheral facial nerve palsy may include:

• Infection with the herpes simplex virus, the herpes zoster virus (shingles), or its variant, zoster oticus, which specifically affects the ear area. In two-thirds of cases, it leads to facial paralysis. An overview of all herpes viruses.
• Lyme disease, caused by the bacterium Borrelia burgdorferi, which is transmitted by ticks.
• Middle ear infection: It sometimes spreads to the branches of the facial nerve, which runs between the tympanic cavity and the mastoid process.
• Meningitis: It can spread to the facial nerve.
• Melkersson-Rosenthal syndrome: An inflammatory disorder of unknown cause with a wide range of symptoms, sometimes including facial paralysis.
• Sarcoidosis: This connective tissue disorder typically affects multiple organs and can cause facial nerve palsy.
• Sjögren’s syndrome: The body’s own immune cells attack the salivary and lacrimal glands. Facial nerve paralysis can be one of the consequences.

A nerve injury—for example, following a skull fracture or a soft-tissue injury— can also lead to peripheral facial nerve palsy.

Risk Factors for Facial Palsy

• High blood pressure and diabetes mellitus are considered risk factors for facial paralysis. If blood sugar levels are not properly controlled, elevated blood sugar often damages the nerves, including, in some cases, the facial nerve.
• Extreme stress can also contribute to facial paralysis. Occasionally, a cold draft is known to be a trigger.
• The risk of facial paralysis is also increased during pregnancy.
• Newborns can develop facial paralysis if the facial nerve is compressed in the birth canal or due to the use of forceps during delivery.

Symptoms: Facial paralysis, usually on one side

Facial nerve palsy usually develops within 24 to 48 hours. It often starts with pain behind the ear. The main symptom is paralysis of the muscles on one side of your face. In most cases, the side where the nerve is damaged is affected. This means you can only smile, speak, whistle, wrinkle your nose, furrow your brow, or squint with some effort. Usually, one corner of the mouth droops, and a small area behind the ear shows impaired sensation.

In addition, the following symptoms may occur:

• Overall asymmetry of the face
• You can no longer close one eye completely.
• If you are unable to close your eyelid completely, the eyeball moves upward (positive Bell’s phenomenon).
• Because the muscles in your cheeks and lips are paralyzed, you have difficulty speaking.
• The skin between the nose and the corners of the mouth, as well as on the forehead, is suddenly wrinkle-free.
• They are hypersensitive to noise.
• Her sense of taste is impaired.
• They produce less tear fluid and saliva.

If central facial palsy (damage to nerve cells in the brain) is the cause of facial paralysis, it primarily affects the facial muscles around the mouth. Then you’ll still be able to move your forehead muscles.

Diagnosis of Facial Nerve Palsy

If one corner of your mouth is drooping and you can’t close one eye completely, these symptoms indicate that you have facial nerve paralysis. If, in addition, you are unable to furrow your brow, purse your lips, or puff out your cheeks, this confirms the suspicion.

To determine the extent of facial paralysis, we can perform various tests. Here, various departments at the USZ work closely together. The examinations include, among other things:

• A taste test will show whether you can distinguish between sweet, sour, salty, and bitter on your tongue. If not, your taste nerve pathways are also affected.
• The Schirmer test determines whether your eye produces enough tears. For the test, we place narrow strips of paper under the lower eyelids of both eyes. By comparing the two, we can determine whether there is a reduced tear flow in one eye.
• Using a special procedure (impedance measurement), we check whether the stapedius reflex—the mechanism that protects your inner ear from excessive volume—is still intact.
• We perform an otoscopy using an otoscope (an ear speculum equipped with a light and magnifying lens). This allows us to determine whether blisters on the eardrum or in the ear canal suggest zoster oticus.
• Using electromyography (EMG)—a method for measuring electrical currents in muscles—we can determine whether a muscle or the nerve supplying it is damaged. If nerve damage is suspected, we may combine this test with a measurement of nerve conduction velocity (electroneurography). Depending on the results, a decision will be made regarding a possible surgical reconstruction of the damaged nerve.
• A blood test can reveal whether an underlying condition may have caused the facial nerve palsy. Based on blood test results, we can identify the following causes, for example:
  • Lyme disease
  • Infection with the herpes simplex virus or varicella zoster virus.
  • Early Summer Meningoencephalitis (ESME)
  • Diabetes mellitus
• An X-ray of your skull will show whether any fractures or bone abnormalities may be affecting nerve function and causing facial paralysis.
• In some cases, it may be necessary to use computed tomography or magnetic resonance imaging to rule out a brain tumor as the cause.
• Sometimes it is also appropriate to test the cerebrospinal fluid (CSF) for pathogens.

Facial Nerve Palsy: Prevention, Early Detection, Prognosis

Since the cause of idiopathic facial paralysis is unknown, there is no way to prevent it. If facial paralysis is a symptom of a condition such as Lyme disease, herpes zoster oticus, or diabetes, it is crucial that you treat the underlying condition early on.

Early Detection of Facial Paralysis

Early diagnosis of facial nerve palsy is difficult because it usually occurs relatively suddenly.

Course and Prognosis

The course of facial paralysis depends on its cause. In the case of the most common form, idiopathic facial nerve palsy, there is a good chance that the condition will have a favorable outcome. In more than 80 percent of cases, the symptoms resolve on their own within six weeks to six months. Facial paralysis resulting from an accident also has a good prognosis.

However, even after receiving optimal treatment, some patients continue to experience involuntary movements of the facial muscles (known as synkinesias). Fewer than 10 percent can expect to experience permanent facial asymmetry, which may affect their appearance.

In addition, the so-called “crocodile tears” phenomenon may occur during the healing process: this involves tears flowing from only one eye while eating. The reason is an abnormal connection between taste fibers and the lacrimal gland during the regeneration of nerve fibers. It occurs when facial paralysis heals improperly. In addition, in about 7 out of 100 cases of idiopathic facial palsy, paralysis of the same or the other side of the face recurs later.

Self-Help Groups

Talking with others who are going through the same thing can be a great source of support when coping with an illness. If you are looking for a suitable self-help group , you can get advice from Selbsthilfe Zürich. Selbsthilfe Zürich and the University Hospital of Zurich are partners in the national project “Health Literacy Through Self-Help-Friendly Hospitals.”

Facial Palsy: Treatment Depends on the Cause

Treatment for facial nerve palsy takes a two-pronged approach: On the one hand, we treat the underlying condition; on the other hand, we address the direct effects of the paralysis.