*For more information on the following case study see weblinks or click here http://www.fbr.org/swksweb/immunolymeface.html (link to the website please)

 

Case Study

 

Julia awoke with a crooked smile she thought she had a stroke because she could not move the right side of her face no matter how hard she tried. Her eye would not close completely and she could not raise the corner of her mouth. Her grandfather had recently suffered a stroke and Julia worried that she also had a stroke because, in the mirror, her face looked like her grandfather's. However, the doctors could see a subtle difference in the weakness caused by a stroke and weakness caused by ³Bell's Palsy². A stroke is a condition that arises when cerebral neurons are injured by the sudden blockage of blood supply to that part of the brain. These neurons initiate movements of the face by sending signals to neurons in the brainstem. From the brainstem nerve fibers spread out to cover the face (see thefacialnerve and thebrain). 

 

 

Why does the face looks different following a stroke compared to the face following Bell's Palsy (a primary facial nerve injury)?

 

In general, cerebral neurons from the left side of the brain send their signals to brainstem neurons whose nerves innervate muscles on the right side of the face and right sided cerebral neurons go to brainstem neurons that innervate muscles on the left side. However, the facial nerve is somewhat unusual in that the fibers that spread to the upper face (muscles around the eye and the forehead) come from cerebral neurons on BOTH the right and left side of the brain. (see cranial nerves and muscles) The result is a difference on the appearance between facial paralysis resulting from injury to the brain    (stroke) or injury to the facial nerve itself (Bell's Palsy). Look at the faces below:

Question: Why is the woman's face that of someone who had a stroke and the man's face that of someone with Bell's Palsy?

 

 

 

Answer: If you can raise both eyebrows, the facial nerve is intact. Therefore, the woman has had a stroke involving the left side of the brain producing paralysis of the right lower face and the man has a right Bell's Palsy.