Bell’s Palsy

Synonyms

1

Overview

Bell‘s palsy is a form of facial paralysis resulting from a dysfunction of the cranial nerve VII causing an inability to control facial muscles on the affected side. If no specific cause (i.e. brain tumor, stroke, maysthenia gravis, Lyme disease) is found, the condition is known as Bell‘s palsy. 

Bell‘s palsy is the most common accute mononeuropathy. It is the most common cause of acute facial nerve paralysis.  

Symptoms

The hallmark of this condition is a rapid onset of partial or complete paralysis that often occurs overnight. In rare cases (<1%), it can occur bilaterally, resulting in total facial paralysis. 

Bell‘s palsy may present with hyperacusis or loss of taste sensation in the anterior 2/3 of the tongue. 

Patient may complain of other symptoms such as facial tingling, moderate or severe headache/neck pain, memory problems, balance problems, ipsilateral limb parasthesias, ipsilateral limb weakness, and sense of clumsiness. 

Causes

It is thought that an inflammatory condition leads to swelling of the facial nerve. The nerve travels through the skill in a narrow bone canal beneath the ear. Nerve swelling and compression in the narrow bone canal are thought to lead to never inhibition, damage, or death. 

Some viruses are thought to establish a persistent (or latent) infection without symptoms (varicella-zoster virus, epstein-barr virus). Reactivation of an existing (dormant) viral infection has been suggested as a cause of acute Bell‘s palsy. Studies suggest that this new activation could be preceded by trauma, environmental factors, and metabolic or emotional disorders, thus suggesting that stress-emotional stress, enviromental stress (ie cold), physical stress (ie truama)- in short, a host of different conditions, may trigger reactivation. 

Diagnosis

Bell‘s palsy is a diagnosis of exclusion. No specific cause can be ascertained. Bell‘s palsy is commonly referred to as idiopathic or cryptogenic, meaning that it is due to unknown causes. 

Prognosis

Corticosteroids have been found to improve outcomes, when used early. Most people recover spontaneously and achieve near-normal to normal function. Many show signs of improvement in as early as 10 days after onset, even without treatment. 

Treatment

There is no cure or standard course of treatment for Bell's palsy. The most important factor in treatment is to eliminate the source of the nerve damage. Some cases are mild and do not require treatment since the symptoms usually subside on their own within 2 weeks. For others, treatment may include medications such as acyclovir -- used to fight viral infections -- combined with an anti-inflammatory drug such as the steroid prednisone -- used to reduce inflammation and swelling.