The main symptoms of this condition are a drooping (on one side only) of the corner of the mouth, the lower eyelid and, to a lesser extent, the facial muscles. It can occur quite suddenly, when the facial nerve is compressed, causing the loss of movement in one side of the face.
The facial nerve is large and important, running in a narrow bony canal across the top of the middle ear. It controls the muscles of facial expression and taste. If the membranes lining the middle ear swell, the lining of the nerve canal may also become swollen, preventing impulses from running down to the face.
In many instances the condition, most commonly brought on by a draught or a bad cold, is temporary. As soon as the cold clears up and the associated swelling goes down, the nerve function is restored. However, if the drainage from the lymph nodes is very poor the swelling will remain and the patient will be left with a permanent weakness in the facial muscles on one side.
As it is difficult to get to the site of the actual trouble in the canal, electrical treatment is almost always needed. This is particularly important, as the time element is so crucial: the longer the nerve is compressed the more likely it is to become permanently damaged.
About nine months to a year after an attack, the nerve can start to die from the pressure exerted on it. Although it is still possible to relieve the pressure, you can never restore a dead nerve associated with the brain. As long as treatment is given in time, the problem can usually be reversed.