Bell's Palsy - Prognosis

Prognosis

Even without any treatment, Bell's palsy tends to carry a good prognosis. In a 1982 study, when no treatment was available, of 1,011 patients, 85% showed first signs of recovery within 3 weeks after onset. For the other 15%, recovery occurred 3–6 months later. After a follow-up of at least 1 year or until restoration, complete recovery had occurred in more than two-thirds (71%) of all patients. Recovery was judged moderate in 12% and poor in only 4% of patients. Another study found that incomplete palsies disappear entirely, nearly always in the course of one month. The patients who regain movement within the first two weeks nearly always remit entirely. When remission does not occur until the third week or later, a significantly greater part of the patients develop sequelae. A third study found a better prognosis for young patients, aged below 10 years old, while the patients over 61 years old presented a worse prognosis.

Major complications of the condition are chronic loss of taste (ageusia), chronic facial spasm, facial pain and corneal infections. To prevent the latter, the eyes may be protected by covers, or taped shut during sleep and for rest periods, and tear-like eye drops or eye ointments may be recommended, especially for cases with complete paralysis. Where the eye does not close completely, the blink reflex is also affected, and care must be taken to protect the eye from injury.

Another complication can occur in case of incomplete or erroneous regeneration of the damaged facial nerve. The nerve can be thought of as a bundle of smaller individual nerve connections that branch out to their proper destinations. During regrowth, nerves are generally able to track the original path to the right destination - but some nerves may sidetrack leading to a condition known as synkinesis. For instance, regrowth of nerves controlling muscles attached to the eye may sidetrack and also regrow connections reaching the muscles of the mouth. In this way, movement of one also affects the other. For example, when the person closes the eye, the corner of the mouth lifts involuntarily.

Around 9% of patients have some sort of sequelae after Bell's palsy, typically the synkinesis already discussed, or spasm, contracture, tinnitus and/or hearing loss during facial movement or crocodile tear syndrome. This is also called gustatolacrimal reflex or Bogorad’s Syndrome and involves the sufferer shedding tears while eating. This is thought to be due to faulty regeneration of the facial nerve, a branch of which controls the lacrimal and salivary glands. Gustatorial sweating can also occur.