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Myasthenia Gravis

Myasthenia Gravis vs. Bell’s Palsy: What Is the Difference?

Doctor consulting with patient about myasthenia gravis and Bell's palsy

Myasthenia gravis (MG) and Bell’s palsy are neurological conditions that cause muscle weakness but have different underlying causes, symptoms, disease onsets, diagnoses, and treatment procedures. 

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This article discusses the major differences between myasthenia gravis and Bell’s palsy disorders to educate patients or caregivers on when to seek immediate medical care. 

Myasthenia Gravis vs. Bell’s Palsy: Overview

Myasthenia gravis, or MG, is an autoimmune neuromuscular disorder that causes skeletal muscle weakness and severe fatigue. MG mainly affects the voluntary muscles, especially those surrounding the eyes, mouth, throat, and limbs. However, in rare cases, MG can lead to acute respiratory paralysis if not diagnosed early. 

On the other hand, Bell’s palsy is a condition that causes temporary facial paralysis on one side of the face (either left or right). The muscles on one side of the face do not work properly due to damage to the facial nerve, which makes half of the face appear to droop. 

Causes

Myasthenia gravis is an autoimmune disorder, which means the immune system produces autoantibodies that block or destroy the receptor sites of acetylcholine (a chemical produced by nerves and acts as a signal to tell muscles to contract). When the receptor sites are blocked or destroyed, the muscles receive fewer nerve signals, which leads to muscle weakness. 

On the other hand, Bell’s palsy is caused or triggered by a viral infection (e.g., herpes simplex virus). When the immune system reacts against the virus, it also affects the facial nerve. As a result, the facial nerve becomes inflamed (swollen), leading to failure of nerve signal transmission to the surrounding facial muscles.

Signs and Symptoms

Myasthenia gravis and Bell’s palsy share one or two similar symptoms, which can sometimes lead to misdiagnosis. For example, most patients with MG experience drooping eyelids and trouble swallowing, which also fall into the symptom categories of Bell’s palsy disorder. 

However, both conditions have different major signs and symptoms, which are as follows:

Symptoms Myasthenia GravisBell’s Palsy
Muscle weaknessGeneralized and affects both sides of the faceLocalized to only one side of the face (either left or right)
Facial involvementDifficulty with facial expression (e.g., smiling or frowning) but not limited to one sideFacial expression is limited to one side (asymmetry)
Drooping of mouth
Drooling and excessive tearing
Eye symptomsDrooping of one or both eyes (ptosis)Double visionDrooping of one eye or difficulty closing one eyelid, which leads to eye dryness or irritation
Facial painDifficulty chewing, swallowing, or speakingPain around the jaw or behind the ear of the affected side

Myasthenia Gravis vs. Bell’s Palsy: Prevalence

MG can affect people of any age, but it is more prevalent in young women in their 20s or 30s and older men in their 60s or 70s. 

Unlike MG, Bell’s palsy affects men and women equally, usually between the ages of 15 and 60 years old.

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Myasthenia Gravis vs. Bell’s Palsy: Diagnosis

Doctor preparing to draw blood for a blood test

The doctor follows a series of tests for the diagnosis of MG, which include:

  • Physical evaluation: To check medical history and symptoms
  • Blood test: To check the presence of anti-acetylcholine receptor antibodies (AChR) or anti-muscle-specific kinase antibodies in the blood
  • Electromyography (EMG): To check communication problems between muscles and nerves
  • Imaging studies like MRI and a chest CT: To check if there are any other disease associations such as thymus gland abnormalities or tumor

Bell’s Palsy is easier to diagnose, and the doctor performs a physical exam to check if a patient has trouble moving facial muscles. The doctor also conducts electromyography to confirm the diagnosis or assess nerve damage. 

Treatment Procedure

MG is a long-term disease and has no cure yet. However, several treatment procedures or medications can help manage this condition and reduce disease-associated symptoms, which include:

Conversely, Bell’s palsy is a temporary condition that recovers easily with rest, medication, and physical therapy. Doctors typically prescribe corticosteroids or antiviral medication to reduce nerve inflammation. In most cases, lubricating eye drops are also prescribed if patients have trouble fully closing their eyes.

Summary

Let’s quickly review the main differences between myasthenia gravis and Bell’s palsy disorders.

Summary Table: Myasthenia Gravis vs. Bell’s Palsy

Key DifferencesMyasthenia GravisBell’s Palsy
Type of disorderAutoimmune disorderViral infection-associated neurological disorder
Affected areasVoluntary muscles throughout the bodyFacial muscles on one side of the face
Onset and durationDevelops more gradually and fluctuates throughout the dayDevelops suddenly and can get worse over 48 hours 
PrevalenceYoung women and older menBoth men and women are equally affected
Progression and recoveryLong-term chronic condition and requires ongoing managementTemporary and good chance of recovery
Treatment approachLong-term immunotherapyShort-term steroids and supportive care

REFERENCES:

  1. Bell’s Palsy. National Institute of Neurological Disorders and Stroke. https://www.ninds.nih.gov/health-information/disorders/bells-palsy
  2. Myasthenia gravis. National Institute of Neurological Disorders and Stroke. https://www.ninds.nih.gov/health-information/disorders/myasthenia-gravis
  3. Elnazeir, M., Narayanan, S., Badugu, P., Hussain, A., Tareen, T., Hernandez, A. R., Liu, W., Palade, A. E., & Brown, M. E. (2020). Myasthenia Gravis Masquerading as an Idiopathic Unilateral Facial Paralysis (Bell’s Palsy)—A Very Rare and Unique Clinical Find. Frontiers in Neurology, 11, 517879. https://doi.org/10.3389/fneur.2020.00709
  4. Trouth, A. J., Dabi, A., Solieman, N., Kurukumbi, M., & Kalyanam, J. (2012). Myasthenia Gravis: A Review. Autoimmune Diseases, 2012(1), 874680. https://doi.org/10.1155/2012/874680
  5. Balakrishnan, A. Bell’s Palsy: Causes, symptoms, diagnosis and treatment – ProQuest. https://www.proquest.com/openview/fde94ebbdecd7cda8f5cbfbfecb5f288/1?pq-origsite=gscholar&cbl=54977
  6. Abbott, S. A. (2010). CASE STUDY: Diagnostic challenge: Myasthenia gravis in the emergency department. Journal of the American Academy of Nurse Practitioners, 22(9), 468–473. https://doi.org/10.1111/j.1745-7599.2010.00541.x
This information is not a substitute for medical advice or treatment. Talk to your doctor or healthcare provider about your medical condition prior to starting any new treatment. AmeriPharma™ Specialty Care assumes no liability whatsoever for the information provided or for any diagnosis or treatment made as a result, nor is it responsible for the reliability of the content. AmeriPharma™ Specialty Care does not operate all the websites/organizations listed here, nor is it responsible for the availability or reliability of their content. These listings do not imply or constitute an endorsement, sponsorship, or recommendation by AmeriPharma™ Specialty Care. This webpage may contain references to brand-name prescription drugs that are trademarks or registered trademarks of pharmaceutical manufacturers not affiliated with AmeriPharma™ Specialty Care.
MEDICALLY REVIEWED BY Dr. Christine Leduc, PharmD

Dr. Christine Leduc, PharmD, was born and raised in Irvine, CA. She attended college at Midwestern University, where she graduated cum laude. The most rewarding part of her job is suggesting lifestyle changes, educating patients on how their medication works, and precepting future pharmacists. Her areas of expertise are customer service and knowledge of specialty medication. Having worked in the service industry in the past, she has gained the customer service skills necessary to understand the needs of her patients. Dr. Leduc is currently precepting students from Marshall B. Ketchum University, University of Kansas, and Midwestern University. In her free time, she enjoys traveling, baking, and gardening. See Author Biography

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