Myasthenia Gravis: What You Should Know: Causes, Symptoms And Treatment

What Is Myasthenia Gravis?

Myasthenia gravis (MG) is an autoimmune musculoskeletal disorder (a disorder that causes the immune system to attack the healthy body’s cells) of voluntary muscles (muscles under your control).
These include facial, throat, and diaphragm muscles, arms, and legs. They connect to bones and are essential for breathing, swallowing, facial movements and other body movements.
body’s.¹

What Are The Causes of Myasthenia Gravis?

MG affects both men and women in all kinds of populations. It most commonly affects young adult women (under 40) and older men (over 60), but it can occur at any age, including childhood.
MG is not inherited or contagious, but the disease may occur in more than one member of the same family.²

The exact causes of MG are not fully understood, however there can be following reasons of developing the disorders.

Symptoms of Myasthenia Gravis

Common symptoms may include:

• Weakness of the eye muscles
• Drooping of one or both eyelids
• Blurred or double vision
• Changes in facial expressions
• Difficulty swallowing
• Shortness of breath
• Impaired speech
• Weakness in the arms, hands, fingers, legs, and neck

What Is Myasthenia Gravis Treatment?

The treatment of MG mainly aims to control the symptoms and improve the quality of life. However, in some cases, the drugs may required for a a longer duration.
Occasionally some people may have to go to the emergency room in case of an emergency.

Drugs For Treating MG

Commonly used drugs to treat MG include the following:³

• Pyridostigmine
• Steroids
• Immunosuppressants

Anticholinesterase medications

Anticholinesterase medications helps the transmission of electrical signals between the nerves and muscles. It can reduce muscle weakness, but the effect only lasts a few hours.

These may include mestinon or pyridostigmine. You may need to take repeating doses of the medicine. It is the only medicine required to control the symptoms for some people.
Possible side effects of pyridostigmine may include stomach cramps, diarrhoea, muscle twitching and feeling sick. Tell your healthcare provider if you get any of these, as they may be able to prescribe other medicines to help with side effects.

Steroids

Steroid tablets such as prednisolone work by reducing the activity of the immune system. It is to stop it from attacking the communication system between the nerves and muscles.
Prednisolone is usually started in the hospital if you have problems with swallowing or breathing or other symptoms getting worse and you need treatment quickly.
Long-term treatment with steroids can cause unpleasant side effects, such as weight gain, mood swings and an increased risk of getting infections.

Immunosuppressants

Immunosuppressants are used when steroids are not controlling the symptoms. Commonly used immunosuppressants are azathioprine or mycophenolate, mycophenolate mofetil, and tacrolimus. 
These drugs work to improve muscle strength by suppressing the production of abnormal antibodies
It may take at least three months for azathioprine and around six months for mycophenolate before you start feeling the medicine’s benefits.
Side effects can include an increased risk of getting infections, feeling or getting sick, loss of appetite and tiredness. You’ll also need regular blood tests to check the amount of medicine in your body.
If these medicines keep your symptoms under control for a long time (usually years), it may be possible to eventually stop taking them.

Eculizumab

The U.S. Food and Drug Administration (FDA) has approved using Eculizumab to treat generalized myasthenia gravis in adults who test positive for the anti-acetylcholine receptor (AchR) antibody. Eculizumab is an effective inhibitor of a key complement protein known to contribute to neuromuscular junction damage in myasthenia gravis.⁴

Plasmapheresis and intravenous immunoglobulin

These therapies are used in severe cases of MG to remove damaging antibodies that attack the neuromuscular junction. They are usually only effective for a few weeks or months.

• Plasmapheresis uses a machine to remove harmful antibodies in plasma.
• Intravenous immunoglobulin is a highly concentrated injection of antibodies recieved from healthy donors. It promotes the reduction of autoantibodies that interfere with nerve-to-muscle communication. 

Thymectomy: A Surgery For Myasthenia Gravis

Thymectomy is a surgery to remove the thymus gland. It can help reduce symptoms, possibly by rebalancing the immune system.

In people with myasthenia gravis due to thymoma and those with no visible thymoma, the surgery can reduce muscle weakness and the need for immunosuppressive drugs. ⁵

What Is Myasthenia crisis?

Myasthenia crisis is an emergency that needs immediate medical attention. It is caused by worsening of the MG symptoms and requires respiratory support. It requires intensive medical care, boosted immunosuppressive treatments and constant monitoring.
⁶MG and its associated crises are not common ED presentations, but it is critical to recognize them, as the person can otherwise go into respiratory failure. 

References:

1. NIH. National Institute of Neurological Disorders and Stroke. https://www.ninds.nih.gov/health-information/disorders/myasthenia-gravisMyasthenia Gravis. ↩︎
2. Jayam Trouth, A., Dabi, A., Solieman, N., Kurukumbi, M., & Kalyanam, J. (2012). Myasthenia gravis: a review. Autoimmune diseases, 2012, 874680. https://doi.org/10.1155/2012/874680 ↩︎
3. NHS: Myasthenia gravis treatment. ↩︎
4. (2021). United States : Pfizer And Biontech Receive First U.S. Fda Emergency Use Authorization Of A Covid-19 Vaccine In Children Ages 5 Through 11 Years. MENA Report, . ↩︎
5. NIH. National Institute of Neurological Disorders and Stroke. https://www.ninds.nih.gov/health-information/disorders/myasthenia-gravisMyasthenia Gravis. ↩︎
6. Hogan C, Lee J, Sleigh BC, Banerjee PR, Ganti L. Acute Myasthenia Crisis: A Critical Emergency Department Differential. Cureus. 2020 Aug 15;12(8):e9760. doi: 10.7759/cureus.9760. PMID: 32944474; PMCID: PMC7489768. ↩︎