There is no test that can absolutely show that you have Bell's palsy. Doctors refer to the diagnosis of Bell's palsy as a "diagnosis of exclusion," meaning that Bell's palsy is usually diagnosed after other conditions have been ruled out.
Your doctor will do a complete and careful physical exam. He or she is likely to notice that, upon attempting unsuccessfully to close your eyelid, your eye on the affected side will drift up; this is called the Bell phenomenon. In order to rule out other conditions, your doctor will probably test your hearing and sense of balance and may order other tests, such as skull X-rays, a computed tomography (CT) scan, or magnetic resonance imaging (MRI). Electrical testing may help clarify the diagnosis and may help predict the speed and extent of recovery.
Currently there are no treatments to interrupt Bell's palsy completely. If the condition is thought to be caused by the herpes virus (herpes simplex 1) or by shingles (herpes zoster), you may be given an antiviral medication such as acyclovir. However, these drugs have not been clearly proven to be effective in treating Bell's palsy.
Your doctor may give you a short course of corticosteroids (such as prednisone), aimed at decreasing the inflammation of the facial nerve. This may shorten the course of Bell's palsy. In the meantime, extra care must be taken to protect the eye on the affected side. Because the ability to blink or close the eye is gone, you may be asked to wear a patch over that eye. While some people have excess tearing, others have decreased tearing and must use eye drops to prevent drying in their affected eye. Some doctors suggest that massage of the facial muscles is helpful therapy for Bell's palsy. In very rare instances -- particularly when symptoms of Bell's palsy are greatly prolonged -- surgery to decrease pressure on the facial nerve may be recommended.