Medical Edge Newspaper Column

A Connection Between Bell's Palsy and MS?

August 19, 2007
Dear Mayo Clinic:
One of my siblings has Bell's palsy, and three other siblings have MS. Is there any relation between Bell's palsy and MS? -- Austin, Minn.

Answer:
There is no known connection between them, and the fact that three siblings in your family have multiple sclerosis (MS) likely has no bearing on a fourth sibling's Bell's palsy. As MS is a disease of the central nervous system (the brain and spinal cord), it can affect virtually any part of the body.

By contrast, Bell's palsy is a disturbance of the peripheral nervous system -- a separate network that controls muscles and sensation outside of the central nervous system. In particular, Bell's palsy affects only the facial nerve on one side of the face.

This nerve causes the face to move and express emotions such as laughing, smiling and frowning. Thus Bell's palsy produces paralysis and characteristic drooping of the face, often with dryness of the eye because of difficulty in closing the eyelid.

MS can also cause some facial weakness, but the patient typically has other symptoms at the same time: numbness on one side of the face and on the other side of the body, double vision, slurring of words, and lack of balance and coordination. Other potential causes of facial weakness (for example, a stroke) would also have other accompanying signs and symptoms.

Because Bell's palsy is limited to one nerve and one side of the face, it's generally easy to diagnose. In addition, it usually improves on its own. About 70 percent of patients with Bell's palsy will return to normal function within weeks or months. Another 15 percent will have residual weakness that's barely noticeable. The remaining 15 percent will have a permanent and obvious facial palsy.

While the cause of MS is unknown, hereditary factors play a role, and more than one member of a family can be affected, as in your own family's case. Bell's palsy often occurs after a viral illness; and the thinking is that herpes viruses may play a role in many cases.

One way to reduce the probability of residual weakness from Bell's palsy is to seek treatment immediately after onset of symptoms. An oral corticosteroid medication such as prednisone, prescribed during the first five to seven days, can reduce inflammation and swelling, making permanent nerve damage less likely. An antiviral drug such as acyclovir, when taken within that same time frame, may also limit the severity of an attack. But if the patient sees the doctor after, say, a month, these medications will do little or no good. Still, the facial nerve will recover in the majority of cases, with or without medicine.

Please note that during the period before recovery is complete, it's important to protect the eye. Because the eyelid cannot readily close, the resulting dryness could damage the cornea. The patient should use artificial tears during the day and a special lubricant for the eye at night, then patch the eye closed when asleep.

Even for patients with significant nerve damage, the face often appears nearly normal at rest. If the paralysis is complete, surgical intervention may be performed by a specialist in nerve surgery.

-- B. Mark Keegan, M.D., F.R.C.P.(C), Neurology, Mayo Clinic, Rochester, Minn.