Bell's Palsy: Managing to Save Face

What could be more central to our sense of self than our faces? So imagine what it would be like to watch powerlessly while half your face progressively droops like melted wax. That's what happens in Bell's palsy.

Bell's palsy is a condition causing weakness or even total paralysis of the muscles on one side of the face, typically developing over 3-72 hours. It can occur at any age and affects the genders about equally. People with diabetes and depressed immune systems are at increased risk of having this condition, as are women in the third trimester of pregnancy. Bell's palsy affects about 11 out of 1000 people sometime during their lives.

The problem lies within the facial nerve, also known as the seventh cranial nerve. The nerve is like a telephone-cable and contains thousands of individual nerve-fibers. There are two facial nerves, one for each side of the face, and by far the most common pattern is that one side of the face is affected and not the other.

The facial nerve ultimately connects the brainstem (junction between the upper brain and spinal cord located at the base of the skull) to the muscles of the face. Along the way it travels through a narrow canal in the skull bone. After exiting this canal near the bottom of the ear it divides into thousands of tiny branches before reaching the facial muscles.

In Bell's palsy the portion of the nerve within the skull's bony canal becomes inflamed for unclear reasons, though an infection with herpes simplex virus (the same virus that causes cold sores) is suspected in most cases. The condition is not contagious.

Because the bony canal is rigid and narrow, the swollen nerve-bundle has little room to expand, and compression of the nerve-fibers can further injure them and cause more loss of muscle function. MRI scans of the head can detect the inflammation, but only if gadolinium (the MRI-equivalent of x-ray dye) is infused into a vein prior to scanning.

The weakness in the lower facial muscles produces a lop-sided smile. Patients sometimes mis-identify the side of their face that is affected: they focus on the side of the face that is "drawn" rather than on the side that lacks the ability to draw. Weakness in the lower face also interferes with talking, eating and drinking, and beverages can dribble from the corner of the mouth. Weakness of the upper face causes flattening of forehead-wrinkles and inability to raise an eyebrow.

But the most significant problem is weakness in the muscles that close the eye, including those involved in blinking. Blinking