Bell’s Palsy (One-Sided Facial Paralysis)

Definition

Bell’s palsy is a condition where there is a sudden weakness of the muscles on one side of the face leading to drooping and the inability to close one eye properly. It can affect people of any age group. Swelling and inflammation of the facial nerve supplying the facial muscles is the reason behind the facial muscle paralysis. A characteristic feature in Bell’s palsy is its rapid onset and progression of paralysis on the one side of the face. Rarely Bell’s palsy may affect muscles of both the sides.

In most of the cases the condition resolves on its own within weeks to months. In small number of cases some of symptoms of Bell’s palsy persist for life. Corticosteroids are known to improve the outcome. Sometimes antiviral drugs are also prescribed as a viral infection is thought to be one of the causes leading to inflammation of the facial nerves.

Symptoms

The symptoms of Bell’s palsy usually occur suddenly and progresses rapidly, often overnight. Presenting symptoms include:

• Mild weakness to complete paralysis of facial muscles on one side leading to drooping of the mouth and inability to close the eye on the affected side of the face.
• Pain in the jaw or around the ear region.
• Increased sensitivity to sound.
• Headache.
• Reduced taste inability to taste food via the anterior two-third of the tongue.
• Alteration in the amount of saliva or tear production.

Although in most cases, the symptoms of Bell’s palsy usually disappear completely without any residual damage within 6 months. However, in a handful cases of complications may arise. These complications include permanent damage to the facial nerve, re-growth of the facial nerve fibers in the wrong direction leading to unintentional contraction of certain muscles, and loss of vision either partially or completely due to corneal damage from excessive dryness and eye injury since the eyelid cannot close completely.

Causes

The facial nerve supplying the muscles of the face may become inflamed (swollen) along its course from the brain. The exact cause of this nerve inflammation is not always known. Since the facial nerve travels from the brain to the face by passing through a narrow bony canal, it can easily become compressed and result in Bell’s palsy.

The facial nerve is the 7th cranial nerve that runs from the brain to supply the muscles of the face.

Other than the facial paralysis, the production of tears and saliva, sense of taste and sound perception are also affected. Swelling (inflammation) of the facial nerves occur mostly due to viral infection. Common viruses responsible for Bell’s palsy include:

• Herpes virus both herpes simplex and herpes zoster
• Cytomegalovirus (CMV)
• Epstein –Barr virus (EBV)
• Adenovirus
• Rubella (German measles) virus
• Influenza viruses
• Coxsackievirus

Common risk factors for suffering from Bell’s palsy are pregnancy especially during last trimester or during first week after giving birth, recent history of suffering from a cold or the flu, previously having Bell’s palsy or having a family history of the condition which indicates a genetic predisposition.

Treatment

Bell’s palsy often resolves spontaneously. This means that the symptoms disappear completely even without treatment in the majority of cases. However, it is advisable to see a medical professional to assess the condition and minimise the chances of complications developing later on. Treatment options for Bell’s palsy include:

• Corticosteroids to reduce the inflammation.
• Antiviral drugs to destroy the viruses responsible for the infection.
• Physiotherapy to strengthen the affected muscles.