Facial Nerve Disorders: Bell's Palsy

What is Bell’s Palsy?

Bell’s Palsy is unilateral idiopathic facial paralysis. This means that it affects one side of the face, and other potential causes have been excluded (see Diagnosis, below). It is the most common cause of facial paralysis. Note that Bell’s Palsy specifically refers to acute facial paralysisafterthe exclusion of other diagnoses.  It is incorrect to refer to all cases of facial paralysis as “Bell’s Palsy.”


How is Bell’s Palsy Diagnosed?

The diagnosis of Bell’s Palsy is usually a clinical diagnosis. This means a physician will make the diagnosis after a history and physical exam are performed in order to excludeother possible causes of facial paralysis, such as stroke or trauma.  Blood tests or imaging (such as an MRI) may be required in certain cases in order to exclude other potential causes of acute facial paralysis.  Typically, Bell’s palsy has a rapid onset, with facial paralysis on one side of the face developing over 48-72 hours or less.


What causes Bell’s Palsy?

Bell’s palsy is likely due to viral inflammation around the facial nerve as it travels within the base of the skull.  


How is it treated?

Treatment of Bell’s Palsy involves taking a brief course of oral steroids and may include an oral antiviral medication as well. Typically, patients who are promptly treated for Bell’s palsy recover full facial movement.  Prognosis for recovery in Bell’s Palsy is generally quite good, as 70% of untreated patients recover to normal or near-normal function.  With the addition of medical therapy, recovery appears to improve to 90-95% of appropriately treated patients.  

After recovery from Bell’s Palsy, typically 6 months or more after initial diagnosis, some patients may notice unwanted facial movement or muscle spasms, or facial discomfort. These may be signs of synkinesis and can be improved through treatment.