Cookies help us deliver our services. By using our services, you agree to our use of cookies. Learn more

Myasthenia Gravis

What is Myasthenia Gravis?

Myasthenia Gravis is an autoimmune disease causing muscle weakness and muscle fatigue in specific muscles, such as eye muscles, or in multiple muscle groups, also known as the generalized form. In the majority of cases, eye muscles are affected first, leading to dropping eyelids or double vision, and gradually develops into the generalized form, affecting multiple muscles. Myasthenia Gravis occurs when antibodies, one of the body's natural immune defenses, mistakenly targets and damages certain molecules on muscle cells that are responsible for receiving the nervous signal to contract. Myasthenia Gravis is more likely to affect adults; childhood cases are also possible. Occasionally some affected individuals can have issues with the muscles involved in breathing.

 

Synonyms

  • Myasthenia Gravis

Myasthenia Gravis is an autoimmune disease causing muscle weakness and muscle fatigue in specific muscles, such as eye muscles, or in multiple muscle groups, also known as the generalized form. In the majority of cases, eye muscles are affected first, leading to dropping eyelids or double vision, and gradually develops into the generalized form, affecting multiple muscles. Myasthenia Gravis occurs when antibodies, one of the body's natural immune defenses, mistakenly targets and damages certain molecules on muscle cells that are responsible for receiving the nervous signal to contract. Myasthenia Gravis is more likely to affect adults; childhood cases are also possible. Occasionally some affected individuals can have issues with the muscles involved in breathing.

Acknowledgement of Myasthenia Gravis has not been added yet.

The prevalence of myasthenia gravis is between 15 and 179 per million individuals. Approximately, 1 and 30 individuals per million are diagnosed each year. The majority of affected individuals are adults with a small number of children and adolescents affected. Childhood cases are more commonly observed in Asian countries. Age and sex affect the prevalence of myasthenia gravis. Between about 40 and 50 years of age and during puberty, males and females are equally affected. Myasthenia Gravis is more prevalent in women under 40 years of age and men over 50 years of age.

Name Abbreviation
Myasthenia Gravis MG

Muscles contract when they receive a signal from a nerve cell. The site of communication between a muscle cell and a nerve cell is called a neuromuscular junction. A nervous signal travels in a nerve cell until it reaches the nerve’s terminal at the neuromuscular junction. Then, the nerve cells release chemicals called neurotransmitters which travel a short distance from the nerve cell to the muscle cell. There are receptors on the muscle cell that detect the presence of these neurotransmitters. When these receptors bind and detect the neurotransmitter, they initiate a cascade of events that lead to the contraction of the muscle cell. In myasthenia gravis, the immune system mistakenly produces antibodies that block or damage acetylcholine receptors. Antibodies are proteins made by the immune system that identify and attack foreign particles. In autoimmune disorders, the antibodies mistakenly identify self-molecules as foreign and attack itself. The neurotransmitter at the neuromuscular junction is called acetylcholine. The majority of affected individuals have antibodies that block or damage acetylcholine receptors (AChR) on muscle cells. These are known as anti-AChR antibodies. In a smaller number of affected individuals, the antibodies attack other proteins, specifically, lipoprotein-related protein 4 (LRP4) and muscle-specific kinase (MuSK). Regardless of the type of proteins the antibodies attack, the consequence inhibits the proper transmission of a signal from the nerve cell to the muscle cell. In a small percentage of affected individuals, none of the three antibodies can be detected. It is possible that there are other antibodies involved that have not been identified.

Myasthenia gravis is not an inherited disease. However, during pregnancy, mothers can pass on the defective antibodies to the fetus through the placenta. This is known as transient neonatal myasthenia gravis. When infants are born, they experience muscle weakness and fatigue. If treated properly, the symptoms disappear within a couple of months. 

The thymus gland is involved in the development and regulation of immune activity, which  is believed to be associated with myasthenia gravis. Normally, the thymus shrinks in size after puberty. Myasthenia gravis affected individuals often show abnormalities related to the thymus. In about three-quarters of cases, the thymus is larger than normal (hyperplasia). In some cases, a thymoma or thymus tumor can develop. Thymomas are typically harmless, but can develop into cancer in rare cases. Thymus abnormalities are more common in individuals with AChR antibodies than those with LRP4 antibodies. They are usually not observed with cases with MuSK antibodies. It is possible that the thymus in affected individuals is not functioning normally and cannot remove the immune cells that produce antibodies that attack the healthy body tissue. Most cases of myasthenia gravis occur for unknown reasons. However, a small percentage of affected individuals may have family members with myasthenia gravis or other autoimmune conditions. There is also evidence for a slight genetic predisposition in individuals with certain Human Leukocyte Antigens (HLAs). HLAs are proteins involved in the regulation of the immune system.

In very rare cases, congenital myasthenia gravis might be present. Unlike the other forms, this is not an autoimmune condition and is caused by defective changes in genes responsible for encoding proteins involved in neuromuscular transmission.

Myasthenia Gravis causes muscle weakness and muscle fatigue, which worsens with activity and improves with rest. This condition can affect specific localized muscles, such as eye muscles in ocular myasthenia gravis, or affect a range of muscle groups in generalized myasthenia gravis. Myasthenia Gravis can affect any muscle group, but certain muscle groups are more common. 

 

The majority of affected individuals first develop symptoms in the eye and eyelid muscles. This can lead to drooping of eyelids and blurry or double vision. In others, symptoms may begin in the jaw, face, and throat muscles. In such cases, symptoms can include impaired speech, weak or hoarse voice, difficulty chewing or swallowing, change in facial expression, or shortness of breath. In more generalized cases, the muscles of the arms, legs, and neck may be affected, making moving or holding one’s head up difficult. 

 

Some affected individuals may experience myasthenic crisis. Myasthenic crisis is when the muscles involved in breathing become affected and makes it very difficult to breathe. Myasthenic crisis may be triggered by stress, infection, surgery, childbirth, certain medications, or no clear cause. 

 

Soon after the onset of symptoms, individuals may experience periods of exacerbation followed by periods of symptom improvement. However, the symptoms tend to gradually worsen in the first few years after onset. Symptoms may temporarily worsen after strenuous physical activity, infection, childbirth, or menstruation.

 

In transient neonatal myasthenia gravis, infants may have difficulty sucking, swallowing, or breathing, have limited mobility, or have a weak cry. When treated, these symptoms disappear within a couple of months. 

 

Congenital myasthenia gravis is usually observed in newborns but it can also present in adulthood. Signs and symptoms are similar to other forms. However, there may be sudden and transient episodes when breathing subsides or lower than normal weight gain and growth in children.

Diagnosis of myasthenia gravis is based on the clinical history and a number of neurological, immunological, and other specialized tests. Myasthenia gravis is suspected when muscle weakness and fatigue are present without any other neurological impairments. Neurological examination includes checking muscle strength, sense of touch, sensitivity to cold and heat, reflexes, balance, muscle coordination, and eye movement. Other tests are performed to identify anti-AChR, anti-MuSK, and anti-LRP4 antibodies in the blood. Respiratory abilities are also checked to evaluate the risk of myasthenic crisis. The presence of a thymoma can also aid in the diagnosis of this condition. 

One of the commonly used diagnostic tests is called a Tensilon test. During this test, a substance (edrophonium) that inhibits the breakdown of acetylcholine is used, which increases the amount of acetylcholine present at the neuromuscular junction to interact with the receptors. When injected with this substance, an individual affected by myasthenia gravis is expected to experience a temporary increase in muscle strength. This occurs because there is an increased acetylcholine-receptor interaction which increases the transmission of the signal from the nerve to the muscle cell. This leads to an increased ability to contract muscles. This test is usually used to check if edrophonium reduces the amount of eyelid drooping in the individual.

Edrophonium has side effects such as abdominal cramping, nausea, vomiting, and in rare cases, increased heart rate, and difficulty breathing. Therefore, it is not suitable for everyone. Alternatively, an ice pack test is used instead. A cold pack is applied on the drooping eyelid for a few minutes. Similar to edrophonium, the cold reduces the breakdown of acetylcholine. Therefore, a temporary improvement in the drooping of the eyelid is expected after the ice pack test.

In most affected individuals, one of the anti-AChR, anti-MuSK, or anti-LRP4 antibodies is above normal levels. A blood test can be performed to identify the presence of these antibodies. In rare cases, these antibodies are not detected and other tests are required to confirm the diagnosis.

Two tests can be used to assess the electrical activity of the body and its interaction with muscles. The first test is called repetitive nerve stimulation. In this test, electrodes are used to send repeated impulses to a particular muscle to cause muscle fatigue. The nerves are also tested constantly to see if signal transmission worsens as the muscle fatigues. Muscle fatigue is stronger in individuals with myasthenia gravis than in healthy individuals. The second test is called single-fiber electromyography (EMG). In this test, electrodes are used to send signals to a single muscle cell which allows the evaluation of the neuromuscular transmission at that cell. A chest computed tomography (CT) scan or magnetic resonance imaging (MRI) can  be used to check for the presence of a thymoma. 

Initial treatment of myasthenia gravis is with cholinesterase inhibitors, which inhibit the breakdown of acetylcholine and increase the amount of acetylcholine available to improve signal transmission at the neuromuscular junction. This improves muscle contraction and strength. These agents are also used in infants with transient neonatal myasthenia gravis for days to weeks and in some cases of congenital myasthenia. 

In many cases, cholinesterase inhibitors are used with immunosuppressive drugs. These drugs reduce the activity of the immune system and reduce the amount of defective antibodies produced. 

In individuals with thymoma, a surgical procedure called thymectomy removes the thymus. In cases where a thymoma is not present, this procedure may still be beneficial, depending on the affected region and the type of antibodies present. Thymectomy is recommended for individuals without thymoma when it is generalized but not recommended for those with the localized, ocular type. In addition, thymectomy is recommended for individuals with anti-AChR antibodies and those with no detectable antibodies. However, it is not recommended for individuals with anti-MuSK antibodies. This procedure is also not effective in individuals with congenital myasthenia gravis.

Myasthenia gravis may lead to a medical emergency known myasthenic crisis. In these cases, treatment includes respiratory assistance using mechanical ventilators, administration of antibiotics, and possibly plasmapheresis or intravenous immunoglobulin. Plasmapheresis and intravenous immunoglobulin administration are two short-term treatments that can be used in sudden and severe exacerbations of symptoms in myasthenia gravis. Plasmapheresis is a procedure in which blood enters a specialized machine that can remove abnormal antibodies and blood enters back into the body without those abnormal antibodies. Intravenous immunoglobulins are injections of high concentrations of antibodies that modulate the way the immune system functions and reduces the severity of symptoms temporarily. 

Physical therapy and lifestyle modifications help with maintaining muscle strength.

With the advancement of treatment, individuals affected by myasthenia gravis can have a normal life expectancy. However, depending on the severity of symptoms, quality of life can be affected due to reduced physical ability and the risk of further complications, such as myasthenic crisis. In addition, many individuals who undergo thymectomy can experience complete and permanent remission of symptoms. 

Tips or Suggestions of Myasthenia Gravis has not been added yet.

Gilhus NE, Owe JF, Hoff JM, Romi F, Skeie GO, Aarli JA. Myasthenia gravis: a review of available treatment approaches. Autoimmune Diseases. 2011;2011:847393. doi:10.4061/2011/847393

 

Jayam Trouth A, Dabi A, Solieman N, Kurukumbi M, Kalyanam J. Myasthenia gravis: a review. Autoimmune Diseases. 2012;2012:874680. doi:10.1155/2012/874680

 

Jordan A, Freimer M. Recent advances in understanding and managing myasthenia gravis. F1000Research. 2018;7:F1000 Faculty Rev-1727. doi:10.12688/f1000research.15973.1

 

Mayoclinic. Myasthenia gravis. 2019. Available from https://www.mayoclinic.org/diseases-conditions/myasthenia-gravis/symptoms-causes/syc-20352036

 

Melzer N, Ruck T, Fuhr P, et al. Clinical features, pathogenesis, and treatment of myasthenia gravis: a supplement to the Guidelines of the German Neurological Society. Journal of Neurology. 2016;263(8):1473–1494. doi:10.1007/s00415-016-8045-z

 

National Institute for Neurological Disorders and Stroke. Myasthenia Gravis Fact Sheet What is myasthenia gravis? 2017. Available from https://www.ninds.nih.gov/disorders/patient-caregiver-education/fact-sheets/Myasthenia-gravis-fact-sheet

 

National Organization for Rare Disorders. Myasthenia Gravis. 2017.  Available from https://rarediseases.org/rare-diseases/myasthenia-gravis/

 

Phillips WD, Vincent A. Pathogenesis of myasthenia gravis: update on disease types, models, and mechanisms. F1000Research. 2016;5:F1000 Faculty Rev-1513. Published 2016 Jun 27. doi:10.12688/f1000research.8206.1

 

Statland JM, Ciafaloni E. Myasthenia gravis: Five new things. Neurology Clinical Practice. 2013;3(2):126–133. doi:10.1212/CPJ.0b013e31828d9fec

Community Details Update Created by RareshareTeam
Last updated 20 Nov 2019, 02:36 AM

Posted by RareshareTeam
20 Nov 2019, 02:36 AM

Hi everyone,

The myasthenia gravis community details have been updated. We added more information about the cause, prevalence, symptoms, diagnosis, and treatment. Hopefully, you find it helpful. 

remission??? Created by silcyc
Last updated 28 Feb 2011, 11:02 PM

Posted by silcyc
28 Feb 2011, 11:02 PM

I was diagnosed with ocular myasthenia gravis in 2006 but have had it quite a few years longer. My vision would double many times in a week and a few weeks ago I realized it hasn't happened in many months. I know there's no cure but I'm really hoping that this will be a LONG remission. I also have sarcoidosis and that's enough to deal with. Any of you others in remission?

Community External News Link
Title Date Link
Community Resources
Title Description Date Link
Myasthenia Gravis Foundation of America (MGFA)

The Myasthenia Gravis Foundation of America (MGFA) is the only national volunteer health agency dedicated solely to the fight against myasthenia gravis.

03/20/2017

Clinical Trials


Cords registry

CoRDS, or the Coordination of Rare Diseases at Sanford, is based at Sanford Research in Sioux Falls, South Dakota. It provides researchers with a centralized, international patient registry for all rare diseases. This program allows patients and researchers to connect as easily as possible to help advance treatments and cures for rare diseases. The CoRDS team works with patient advocacy groups, individuals and researchers to help in the advancement of research in over 7,000 rare diseases. The registry is free for patients to enroll and researchers to access.

Enrolling is easy.

  1. Complete the screening form.
  2. Review the informed consent.
  3. Answer the permission and data sharing questions.

After these steps, the enrollment process is complete. All other questions are voluntary. However, these questions are important to patients and their families to create awareness as well as to researchers to study rare diseases. This is why we ask our participants to update their information annually or anytime changes to their information occur.

Researchers can contact CoRDS to determine if the registry contains participants with the rare disease they are researching. If the researcher determines there is a sufficient number of participants or data on the rare disease of interest within the registry, the researcher can apply for access. Upon approval from the CoRDS Scientific Advisory Board, CoRDS staff will reach out to participants on behalf of the researcher. It is then up to the participant to determine if they would like to join the study.

Visit sanfordresearch.org/CoRDS to enroll.

Community Leaders

 

Expert Questions

Ask a question

Community User List

I have myasthenia gravis .....
My medical conditions: Dysa...
Diagnosed with Myasthenia G...
I have been diagnosed with ...

Start a Community


Don't See Your Condition On Rareshare?

Start your own! With a worldwide network of 8,000 users, you won't be the only member of your community for long.

FAQ


Have questions about rareshare?

Visit our Frequently Asked Questions page to find the answers to some of the most commonly asked questions.

Discussion Forum

Community Details Update

Created by RareshareTeam | Last updated 20 Nov 2019, 02:36 AM

remission???

Created by silcyc | Last updated 28 Feb 2011, 11:02 PM


Communities

Our Communities

Join Rareshare to meet other people that have been touched by rare diseases. Learn, engage, and grow with our communities.

FIND YOUR COMMUNITY
Physicians

Our Resources

Our rare disease resources include e-books and podcasts

VIEW OUR EBOOKS

LISTEN TO OUR PODCASTS

VIEW OUR GUIDES

Leaders

Our Community Leaders

Community leaders are active users that have been touched by the rare disease that they are a part of. Not only are they there to help facilitate conversations and provide new information that is relevant for the group, but they are there for you and to let you know you have a support system on Rareshare.