Diagnosis

There's no specific test for Bell's palsy. Your doctor will look at your face and ask you to move your facial muscles by closing your eyes, lifting your brow, showing your teeth and frowning, among other movements.

Other conditions — such as a stroke, infections, Lyme disease and tumors — can cause facial muscle weakness that mimics Bell's palsy. If the cause of your symptoms isn't clear, your doctor may recommend other tests, including:

• Electromyography (EMG). This test can confirm the presence of nerve damage and determine its severity. An EMG measures the electrical activity of a muscle in response to stimulation and the nature and speed of the conduction of electrical impulses along a nerve.
• Imaging scans. Magnetic resonance imaging (MRI) or computerized tomography (CT) may be needed on occasion to rule out other possible sources of pressure on the facial nerve, such as a tumor or skull fracture.