Causes of Bell's Palsy: An Introduction
Bell's palsy occurs when the nerve that controls the facial muscles is swollen, inflamed, or compressed, resulting in facial weakness or paralysis. Exactly what causes this damage, however, is unknown.
Causes of Bell's Palsy: Possible Viral Infection
Most research scientists believe that a viral infection such as
viral meningitis or the
common cold sore virus -- herpes simplex -- causes Bell's palsy. They believe that the facial nerve swells and becomes inflamed in reaction to the infection, causing pressure within the fallopian canal and leading to an infarction (the death of nerve cells due to insufficient blood and oxygen supply).
In some mild cases (where recovery is rapid), there is damage only to the myelin sheath of the nerve. The myelin sheath is the fatty covering, which acts as an insulator, on nerve fibers in the brain.
Other Possible Causes of Bell's Palsy
There are several medical conditions associated with Bell's palsy. While scientists do not believe these conditions are specific causes of Bell's palsy, people with these conditions may be at increased risk for developing the condition. Medical conditions associated with Bell's palsy include: