What is Bell’s palsy?
Named after an early 19th century Scottish anatomist (Sir Charles Bell), Bell’s palsy describes a dysfunction of the seventh cranial nerve (ie, facial nerve). An inflammatory condition affecting the nerve results in paralysis of the muscles of facial expression. The result is usually a one-sided facial droop that is most often temporary. The term “Bell’s palsy” is misused often to described any instance of facial paralysis.
Why does Bell’s palsy occur?
Bell’s palsy is an acquired condition and occurs in approximately 1 in 5000 people, and its incidence increases with age. It is considered a diagnosis of exclusion, meaning that other known causes of facial nerve dysfunction must be ruled out. It is the result of inflammation within the nerve, a term called mononeuritis. It most notably follows a systemic viral infection such as the common cold, herpes, varicella-zoster virus, Lyme disease, and others. Other theories entertain the possibility of an autoimmune disease process as the source of facial nerve dysfunction. In addition, the condition seems to occur more often in pregnant individuals and diabetics. Most instances of true Bell’s palsy last several days to months, but can sometimes result in permanent paralysis.
What are some problems associated with Bell’s palsy?
Loss of facial nerve function in Bell’s palsy produces similar problems as facial paralysis from other causes. Aside from the obvious facial droop, patients can have problems with eye closure. This can lead to drying of the eyes, tearing, and in the worst case, scarring of the cornea. In addition, inability to move the corner of the mouth can result in speech difficulties and drooling. Smiling is distorted as are other facial expressions. The facial asymmetries are magnified with animation.
Although Bell’s palsy affects motor nerves of the face, unusual tingling sensations have been reported of the overlying skin. In addition, abnormal twitching can develop as the nerve recovers. This is called synkinesis, and it describes a phenomenon whereby the re-innervation of the facial muscles results in “mis-wiring.” This manifests in a variety of abnormal twitching patterns. For example, the eye will blink when smiling or vice versa. In one unusual manifestation of abnormal nerve regeneration, patients can produce tears when eating (gustatolacrimal reflex). The reason for this is that nerve branches supplying these functions are also derived from the facial nerve. Taste itself can be affected.
Can Bell’s palsy be passed on?
In recent years, there have been reports of clusters of families affected with Bell’s palsy. It is difficult to understand why this could occur, but it is believed that an underlying hereditary autoimmune disorder may be the culprit. Otherwise, Bell’s palsy resolves within 3 months in more than 80 percent of patients and does not get passed on.
How is Bell’s palsy treated?
As mentioned previously, most cases of Bell’s palsy resolve spontaneously within 3 months. Others may require antiviral medication and steroids to settle inflammation related to a viral infection. In the case of synkinesis, treatment can prove challenging. Botulinum toxin injections in specific locations can help interfere with abnormal nerve conduction, while facial therapy can be helpful for strengthening natural nerve pathways.
In the event of permanent paralysis, defined as lasting 18 months or longer, surgical intervention may be necessary. Various areas will be targeted for reanimation, including the mouth, eyes, and forehead. Both dynamic and static options are used to balance the face and restore better symmetry.
It is important to have a doctor skilled in facial paralysis management follow along to make sure that recovery is happening in steady fashion. Depending on the rate of recovery, the decision to proceed to surgery and which surgical procedure to choose is then considered. There are opportunities to re-establish nerve function and prevent irreversible paralysis, if it is determined early enough that facial nerve regeneration is not occurring as expected. However, in the setting of longstanding Bell’s palsy (greater than 12-18 months), the surgical decision becomes more obvious, and the type of surgery necessary will be different.
What is the recovery like from Bell’s palsy or its treatment?
Most cases of Bell’s palsy will require no intervention. With time (3-6 months), the paralysis will resolve on its own in most cases. A short course of steroids and/or antiviral therapy is sometimes given. The key to management is to make sure there is some evidence of steady improvement during the first several months. A doctor with a specialty in facial paralysis will need to follow along to make sure that recovery is proceeding as expected.
Synkinesis (described above) can develop over the intervening weeks during recovery or after surgery. This can be sometimes quite stubborn and will recover additional treatment using botulinum toxin or other surgical approach to disrupt the mis-wired muscles.
In the event that surgery is required to re-establish facial movement, the recovery will depend on the option chosen. In general, all available options will require 2-4 weeks of limited activity and avoidance of exercise, heavy lifting, rough play, or contact sports. Several months are required for nerve regeneration, but patients are allowed to gradually increase their activity level back to normal. Dr. Panossian will discuss the expected postoperative recovery from each of the potential surgical options at the time of your consultation.
What are the risks and complications of surgery to correct Bell’s palsy?
The risks associated with medical therapy are relatively minor. However, surgery for longstanding Bell’s palsy carries certain risks. As with any surgery, there is a small chance of bleeding, infection, or anesthesia problems. Usually, the greatest risk is that the surgery simply doesn’t work. There are a host of reasons for why this might happen, including failed nerve regeneration, postoperative trauma or infection, or prolonged time to recovery of movement (a function of slow nerve regeneration and a long distance to the target muscles). Thankfully, this is rare. More commonly, certain asymmetries can persist in the relaxed state or with animation. These can be minor or more substantial. Sometimes, waiting some time will improve facial asymmetry.
Complications of surgery can include hematoma in the first few days, requiring drainage in the operating room. Infection of the cheek can require a brief hospitalization for intravenous antibiotics and/or surgical drainage. Revisions may be required to correct bad scarring (keloids or hypertrophic scars) or significant asymmetries.