ROCHESTER, Minn. - Bell's palsy - which causes sudden weakness or paralysis on one half of the face - is not associated with stroke, and most people recover completely. But according to the July issue of Mayo Clinic Health Letter, it's still advisable to seek emergency care to confirm a diagnosis and start treatment, which can up the odds of full recovery.

The disorder is often related to a viral infection. The nerve that controls facial muscles passes through a narrow corridor of bone on its way to the face. If the nerve becomes inflamed or swollen, typically due to a viral infection, it can become compressed, irritated and injured in this narrow pathway. The result is Bell's palsy.

Symptoms include:

Abrupt weakness or limpness on one side of the face (Most people don't experience total paralysis.)

A dry, irritated eye with tears dripping from the corner

Pain around the ear or jaw, ringing in the ears, sensitivity to noise

Headache

Loss of taste or a decrease in saliva production

Bell's palsy can affect anyone, at any age. The risk rises until about age 40 and then begins to decrease. The condition is most likely to occur in people who have certain viral infections, such as cold sores or upper respiratory infections, and in those who have Lyme disease or diabetes.

Treatment increases the likelihood of full recovery and may help shorten the recovery time. A doctor may prescribe a course of oral corticosteroids to help reduce inflammation around the facial nerve.

Researchers have studied antiviral drugs as a way to speed recovery.

There's some controversy on their effectiveness. Mayo Clinic doctors say there may be benefit if the drugs are given within the 72 hours of symptom onset.

For most people, symptoms begin to improve within a few weeks. Complete recovery may take three to six months or even longer in severe cases.

About 85 percent of those with Bell's palsy recover completely.