Definition and Overview

Bell’s palsy is characterised by the temporary weakness or paralysis of one side of the face. It occurs when the nerve that controls facial muscles becomes inflamed or swollen.

Bell’s palsy is not a symptom of stroke. In fact, it is rarely serious nor life-threatening. The majority of patients are able to make a full recovery within a year. Treatments to relieve inflammation of the facial nerve and its symptoms are available.

According to statistics, Bell’s palsy affects one in every 5,000 people. It can occur in both men and women. It is more common in people between the ages of 15 and 60.

Causes of Condition

Bell’s palsy occurs due to trauma to the nerve that controls facial muscles. This nerve, which is also known as the seventh cranial nerve, passes through a narrow area within the skull. When inflamed, it presses against the cheekbone. This can cause damage to the nerve’s protective cover. When this happens, the signals from the brain are not properly transmitted to the muscles in the face, causing them to weaken temporarily.

Doctors are not sure what causes the facial nerve to become inflamed. However, they have long suspected that the following viral infections play a role:

  • Cytomegalovirus infections

  • Epstein-Barr, which causes mononucleosis

  • Herpes simplex, the common cause of cold sores and genital herpes

  • Herpes zoster, which causes chickenpox and shingles

  • Influenza B, the common cause of flu

  • Mumps (mumps virus)

  • Respiratory illnesses (adenovirus)

  • Rubella, which causes German measles

People who seem to have an increased risk of Bell’s palsy are pregnant women and those who have recently given birth. Those with upper respiratory diseases and diabetes also have an increased risk of the disorder.

Key Symptoms

Symptoms of Bell’s palsy tend to develop all of a sudden. Very few people report ever noticing warning signs before the condition develops. In the majority of cases, patients go to sleep and wake up in the morning unable to move one side of their face. They also often experience the following on the affected side of the face:

  • Difficulty closing and opening the mouth and eye

  • Drooling

  • Drooping

  • Headache

  • Pain around the jaw

  • Pain behind the ear

  • Sudden muscle weakness, which can be mild (partial paralysis) or severe (no movement at all)

  • Reduced in the amount of tears produced

If left untreated, the disorder can lead to a number of complications. Some of which can become a cause for concern. An example is serious infection to the eye because of the patient’s inability to close it even when sleeping. This can lead to corneal drying, which in its severe form, can lead to severe vision loss.

Who to See and Types of Treatments Available

Bell’s palsy is diagnosed and treated by neurologists. Neurologists specialise in disorders that affect the brain, spinal cord, and nerves. The disorder is diagnosed in what doctors call “process of elimination.” With this method, they rule out other medical conditions that cause the same symptoms, such as stroke, tumours, and Lyme disease.

Doctors usually start with a physical examination. They often try to close the eyelid on the affected side of the face. In patients with Bell’s palsy, the eyelid will not stay closed unless a surgical tape is used. This is often followed by a test that detects nerve damage and its severity (electromyography). It uses electrodes to measure the speed and strength of signals traveling along a specific nerve.

Imaging scans, such as computed tomography (CT) and magnetic resonance imaging (MRI), can also be used to rule out brain tumours and skull fracture.


Bell’s palsy is treated with anti-inflammatory drugs (corticosteroids) that reduce the swelling of the facial nerve. Antiviral drugs are also provided if the patient has a viral infection.

Other treatments focus on treating or reversing the complications of the condition. These include:

  • Eye drops - Bell’s palsy patients are unable to blink on the affected side of the face. They cannot also close the affected eye when they go to sleep. This causes them to produce only a small amount of tears, which increases the risk of eye infection and damage. To prevent this, patients are given eye drops and ointment. They are also advised to use surgical tape to keep their affected eye closed when and as needed.

  • Physical therapy (PT) - This is used to strengthen facial muscles.

  • Botox injections - Used to relax tight facial muscles and reduce muscle contractions.


The long-term outlook for patients with Bell’s palsy is generally good. Many are able to fully recover especially if they are diagnosed and treated early. However, a small number of patients suffer from mild symptoms even after a year of developing the condition. In some patients, these symptoms can be permanent.


  • Facial nerve palsy. The Merck Manual Professional Edition.

  • Berg, T., Bylund, N., Marsk, E., Jonsson, L., Kanerva, M., Hultcrantz, M., & Engström, M. (2012, May). The effect of prednisolone on sequelae in Bell’s palsy. Arch Otolaryngol Head Neck Surg, 138(5), 445-449. Retrieved from

  • Peng, K.-P., Chen, Y.-T., Fuh, J.-L., Tang, C.-H., & Wang, S.-J. (2014, December 17). Increased risk of Bell palsy in patients with migraine [Abstract]. Neurology, 84(2), 116-124. Retrieved from

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