What Causes Bell’s Palsy?

April 11, 2022

Bell’s palsy is a sudden weakening of the facial muscles, causing half the face to look sunken, lop-sided, or droopy. Bell’s palsy only occurs on one half of the face and can resemble a stroke. However, these similarities are only on the surface. The possible long-term effects of Bell’s palsy are distinct from those of a stroke.

You may have heard of Bell’s palsy but aren’t exactly sure what it is, why it happens, or what the symptoms are. This article will give you a basic overview of what Bell’s palsy is and how it may affect your life.

Potential Causes

Generally, Bell’s palsy occurs without much warning, and the causes are not well understood. It may be a reaction to a viral infection or a result of nerve-sheath swelling in the nerves on one side of the face. The viruses correlated with Bell’s palsy include cold sores, chickenpox, respiratory or virus that affect the upper lungs, the mumps, the flu, among other viruses. Ironically, much of the damage to the nerves comes not from the virus, but from your own immune system which aggressively attacks the virus, and causes collateral damage to the nerve. That is why steroids are so useful to avoid the long-term negative side effects of Bell’s palsy, if they are given quickly and in the correct dose.

Symptoms and Those Most at Risk

Symptoms of Bell’s palsy include a rapid onset of weakness or complete paralysis to one side of your face. This can occur within a few hours but may take about a day to completely show itself. There may be a drooping appearance to the face, making it difficult to express yourself or close your eyes. Drooling and loss of taste are also associated with the onset of Bell’s palsy.

There may also be pain around the jaw or behind the ear on the affected side, which may come with headaches and increased sound sensitivity.

Women in the third trimester of pregnancy experience many changes in weight and fluid balances and are more at risk for Bell’s palsy than other individuals. Those who have infections in their upper respiratory system, are genetically predisposed, or have diabetes are also more at risk. However, you are unlikely to get Bell’s palsy more than once in a lifetime.

Long Term Complications

Most cases of Bell’s palsy go away within a month or so, but in 5-8% of cases, symptoms may persist for a person’s entire lifetime. You may have permanent damage to some facial nerves and will never regain movement in that place, or you may have involuntary muscle movement that makes your face twitch or your eyes close. At worst, if not cared for, patients can even go blind in the affected eye if the surface becomes too dry and the cornea gets overly irritated. Some of the side effects of long-term Bell’s palsy, called synkinesis, can be treated with neuromodulator injections (botulinum toxin) or even surgery. If you have some of these symptoms, you should speak to your physician or see UCSF Facial Plastic Surgery for evaluation.

Concluding Thoughts

Understanding Bell’s palsy can help you see the warning signs as they develop. If you feel any of the paralysis symptoms described here, be sure to contact a doctor. While Bell’s palsy is not a stroke, it may feel like a stroke or be an expression of an underlying illness. Most Bell’s palsy symptoms go away, but addressing the causes is essential to preserving your good health. It is therefore extremely important to seek immediate medical care if you or someone else begins to experience symptoms of Bell’s palsy.