2-Minute Neuroscience: Bell's Palsy

Bell’s palsy is a disorder characterized by facial weakness or paralysis, typically on one side of the face. It results from the dysfunction of cranial nerve VII, the facial nerve, but the cause of the facial nerve dysfunction is unknown. In this video, I discuss the symptoms, possible causes, and prognosis for Bell’s palsy. 🧠 Take your learning further with my free, self-paced Introduction to Neuroscience course featuring my videos, articles, and hundreds of quiz questions: https://neuroscientificallychallenged... If you're looking for accessible and entertaining ways to learn more about the brain, check out my books: 📚Your Brain, Explained: What Neuroscience Reveals About Your Brain and its Quirks: https://www.amazon.com/Your-Brain-Exp... 📚Bizarre: The Most Peculiar Cases of Human Behavior and What They Tell Us About How the Brain Works: https://www.amazon.com/Bizarre-Peculi... TRANSCRIPT: Bell’s palsy is a disorder that results from the dysfunction of cranial nerve VII, the facial nerve. It involves weakness or paralysis, typically on one side of the face. The onset of the condition is rapid, usually progressing to maximum severity within 72 hours. While there can be a number of causes of facial weakness or paralysis, the cause of Bell’s palsy is unknown, and diagnosis is made by ruling out other potential causes like Lyme disease, trauma, tumors, etc. In other words, Bell’s palsy is only diagnosed when there is not another identifiable cause of the facial paralysis. The symptoms of Bell’s palsy can vary from case to case in both form and severity, but the most common symptom is rapidly developing weakness on one side of the face. There can be a number of other symptoms that emerge from facial nerve dysfunction, including drooping of the eyelid, drooping of one side of the mouth, drooling, an inability to completely close the eye, excessive tearing and pain in the eye, facial pain, loss of taste, hypersensitivity to sound on the affected side, and other symptoms depending on the case. Although the cause of Bell’s palsy is unclear, there is evidence that many cases may have a viral origin. Reactivation of latent viruses such as the herpes simplex virus has been hypothesized to be an important factor in many cases of Bell’s palsy, but how exactly viruses might damage the facial nerve is still uncertain. Other factors potentially involved in the development of Bell’s palsy include reduced blood supply to the facial nerve and damage to the facial nerve caused by inflammation. Most cases of Bell’s palsy start to improve without any medical intervention within a few weeks, and recover completely within 3 to 4 months. Less commonly, symptoms may last longer, never completely disappear, or fade away and then reoccur. REFERENCES: Baugh RF, Basura GJ, Ishii LE, Schwartz SR, Drumheller CM, Burkholder R, Deckard NA, Dawson C, Driscoll C, Gillespie MB, Gurgel RK, Halperin J, Khalid AN, Kumar KA, Micco A, Munsell D, Rosenbaum S, Vaughan W. Clinical practice guideline: Bell's palsy. Otolaryngol Head Neck Surg. 2013 Nov;149(3 Suppl):S1-27. doi: 10.1177/0194599813505967. PMID: 24189771. The National Institute of Mental Health. Bell’s Palsy Fact Sheet. NIH Publication No. 18-NS-5114. 2018. Retrieved from: https://www.ninds.nih.gov/Disorders/P... Reich SG. Bell's Palsy. Continuum (Minneap Minn). 2017 Apr;23(2, Selected Topics in Outpatient Neurology):447-466. doi: 10.1212/CON.0000000000000447. PMID: 28375913. Zhang W, Xu L, Luo T, Wu F, Zhao B, Li X. The etiology of Bell's palsy: a review. J Neurol. 2020 Jul;267(7):1896-1905. doi: 10.1007/s00415-019-09282-4. Epub 2019 Mar 28. PMID: 30923934; PMCID: PMC7320932.