Causes of Bell's Palsy
The exact causes of Bell's palsy are unknown; however, most research scientists believe that a viral infection such as viral meningitis or the common cold sore virus -- herpes simplex -- causes the condition. In addition, several medical conditions are associated with Bell's palsy, including influenza, headaches, diabetes, and Lyme disease.
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.
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.
There are several medical conditions associated with Bell's palsy. While scientists do not believe these conditions are specific Bell's palsy causes, people with these conditions may be at increased risk for developing the condition. Medical conditions associated with Bell's palsy include: