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Worried about finals, Sarah wasn’t sleeping and had become a bit run down. She had noticed a cold sore the week before, but that always occurred around finals. One day, she woke up and her face felt a little numb. The next day, her eye was dry and her smile didn’t quite look right. By the end of the day, her roommate told her she needed to look in the mirror because something was wrong. The side of her face was drooping. Later that summer she still felt tired and had never really recovered from finals. She visited a doctor and when questioned remembered a tick bite in the spring. Sarah had Lyme disease. (Combined patient story.)
Overview
Idiopathic peripheral facial paralysis was described by Persian physicians in the 9th century and by European physicians in the 17th and 18th centuries. “Idiopathic” means without a known cause. In 1821, Scottish neurophysiologist and namesake Charles Bell described the nerves that serve the facial muscles that are affected by the condition.
The 7th facial nerve is most associated with Bell’s palsy This nerve goes through a tight area of bone. Swelling of the muscle around the nerve or the nerve itself may impair function.
The cause of Bell’s palsy remains a mystery. However, it is associated with immune changes and infections like Herpes simplex (the virus that causes cold sores). While a link to stress and Bell’s palsy has not been proven, Herpes simplex is associated with stress. The link between Bell’s palsy and stress may simply be a matter of this connection.
The definition of Bell’s palsy is the that it comes on in less than 72 hours. It usually affects just one side of the face though it can affect both. Bell’s palsy can mimic a stroke, but a physical exam differentiates between the two conditions.
Bell’s palsy is usually associated with self-limiting infections and usually resolves on its own within six months. This has historically been how Bell’s palsy is thought of, and it influences diagnosis and treatment to this day.
Causes
In Lyme-endemic areas, Lyme disease is the most common cause of Bell’s palsy. In those areas, as many as 1 in 4 cases of this condition in both adults and children are due to Lyme disease. Bell’s palsy can also be caused by other Borrelia species, as well as by Rickettsia and Bartonella species infections.
That being said, anything that causes neurological changes can cause Bell’s palsy. Associations have been as varied as sex hormone levels and severe vitamin C deficiency. The most common non-infectious associations are family history, traumatic injury, pregnancy, diabetes, and autoimmune conditions.
In non-Lyme-endemic areas, the most common infections associated with Bell’s palsy are Herpes simplex, Herpes zoster, Epstein-Barr virus, and a variety of respiratory infections. The infection is not always identified, but evidence that respiratory infections play a role comes from the fact that cases of Bell’s palsy went down during COVID-19 isolation measures.
Diagnosis
Bell’s palsy has a lot of causes and in most cases around the world it resolves on its own. Consequently, some treatment recommendations suggest not searching for a cause if there are no other symptoms. Other recommendations note a very small but statistically significant association between Bell’s palsy in children and a cancer diagnosis in the following 60 days, suggesting that a broader workup may be warranted.
Failure to search for a cause when there are other symptoms can miss serious infections such as Lyme disease, as occurred in a case study we discussed here. Researchers in Germany and Australia recommended cerebral spinal fluid analysis and further research into this analysis in cases in Lyme disease-endemic areas.
Bell’s palsy associated with Lyme disease requires prompt diagnosis. Find out more about our Nanotrap Urine Test and early-stage Lyme disease.
There is so much to learn about diagnosing Bell’s palsy. Research is currently fragmented and incomplete. While imaging can be used to diagnose and search for a cause, research on the utility of imaging is incomplete. Exactly what a work-up of Bell’s palsy should include remains poorly defined.
Treatment
Corticosteroids are the most common treatment for Bell’s palsy. However, a retrospective study of outcomes at the Massachusetts Eye and Ear Center, Harvard Medical School, found that corticosteroids were linked with worsened outcomes in people with Lyme disease. They recommended determining if the cause is bacterial or viral before using corticosteroids.
Antiviral medications are commonly used, but their effectiveness is unclear. Surgery to release pressure on facial nerves has been tried but improvement in outcomes does not show up in statistical reviews.
An eye patch may be used to protect the cornea while the eye is dry and/or unable to blink.
While most people recover within six months and never have another incident, some people experience damage to their cornea that can affect their vision due to dry eye and/or lack of blinking. Nerve function loss can be permanent or it can return in a disordered way in which different muscles are triggered than intended (synkinesis).
Physical therapy may be needed to recover from Bell’s palsy, and some people may choose to get plastic surgery if facial droop persists. People with a family history are the most likely to experience repeat events.
Conclusion
Bell’s palsy is a common condition in adults and children that has been recognized for more than 1,000 years. Inquiry into the cause of Bell’s palsy hasn’t been a standard recommendation. However, in certain regions it’s important to identify the cause of Bell’s palsy so that it can be treated swiftly and properly. Recommendations for diagnosis and treatment have not kept up with this development and research is needed.
References
University of Virginia Health System. (2021, February 11). Cold sores: Discovery reveals how stress, illness and even sunburn trigger flareups. ScienceDaily. https://www.sciencedaily.com/releases/2021/02/210211113925.htm
National Institute of Neurological Disorders and Stroke. (2021, November 15). Bell’s palsy fact sheet. https://www.ninds.nih.gov/Disorders/Patient-Caregiver-Education/Fact-Sheets/Bells-Palsy-Fact-Sheet
Greco, A. et al. (2012). Bell’s palsy and autoimmunity. Autoimmunity Reviews, 12(2), 323-328. 10.1016/j.autrev.2012.05.008 https://pubmed.ncbi.nlm.nih.gov/22684016/
Li, X. et al. (2022). Association between COVID-19 vaccination, SARS-CoV-2 infection, and risk of immune mediated neurological events: Population based cohort and self-controlled case series analysis. BMJ, 376, e068373. 10.1136/bmj-2021-068373 https://pubmed.ncbi.nlm.nih.gov/35296468/
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