What's Making This Girl's Mouth Droop?


Two weeks after a viral syndrome, a 9-year-old girl presents to your clinic with a complaint of several days of weakness of her mouth. In addition to the drooping of the left side of her mouth, you note that she is unable to completely shut her left eye. Her smile is asymmetric, but her examination is otherwise normal. Which of the following is the most likely diagnosis?

a.Guillain-Barré syndrome


c.Cerebral vascular accident

d.Brainstem tumor

e.Bell palsy
Answer / Explanation

The answer is e, Bell palsy.

Bell palsy is an acute, unilateral facial nerve palsy that begins about 2 weeks after a viral infection. The exact pathophysiology is unknown, but it is thought to be immune or allergic. On the affected side, the upper and lower face are typically paretic, the mouth droops, and the patient cannot close the eye. Treatment consists of maintaining moisture to the affected eye (especially at night) to prevent keratitis. Complete, spontaneous resolution occurs in about 85% of cases, 10% of cases have mild residual disease, and about 5% of cases do not resolve. Occasionally infants will have a facial nerve palsy at birth; this is usually related to compression from forceps and spontaneously resolves over several weeks. As this is a compression neuropathy, it should not be called congenital Bell palsy.