Myasthenia gravis (pronounced `my˖ĕs˖`thēēn˖ē˖ă `grăv˖ĭs), also known simply as MG, is a rare neuromuscular disorder. When the first case of MG was documented in 1672 by Thomas Willis, an Oxford physician, not much was known or understood about it. Today, we know there are multiple causes for MG as well as treatment options. The most common form of MG is a chronic autoimmune neuromuscular disorder that is characterized by fluctuating weakness of the voluntary muscle groups.
While there is no known cure for myasthenia gravis (MG), there are several effective treatments. Spontaneous improvement and even remission, although uncommon, may occur without any specific therapy. However, as every case of MG is unique, you and your doctor will decide on a treatment plan for your specific needs.
In preparation for your doctor's visit, you can review and bring a copy of the MG treatment guidelines with you. The MG treatment guidelines are the result of a multi-year effort to develop agreement among an international group of MG experts on the use of various treatments for people with MG. These guidelines were developed and updated with leadership from our Medical Advisory Committee members and was re-published in the December 4, 2020 issue of Neurology, titled the "International Consensus Guidance for Management of Myasthenia Gravis Update 2020." This paper is a significant new resource for physicians caring for MG patients. You can VIEW the LATEST GUIDANCE. To view the webinar on previous 2016 MG Treatment Guidelines, please click here.
With treatment, you may expect to see modest to significant improvement in your strength, helping you lead a full life. New treatments continue to give hope to people with MG, their family and their caregivers. Information on available treatments is below.
Surgical removal of the thymus gland is highly effective in MG patients
This is the surgical removal of the thymus gland. The thymus gland is located in the middle of your upper chest and lies over your heart. This gland plays a role in the production of antibodies. While it is most active in early childhood, the thymus gland usually shrinks over time and by early adulthood is believed to no longer function. But sometimes, the thymus gland remains large and continues to be active in antibody production. Effectiveness of this surgical procedure varies with each patient. It is removed in an effort to improve the weakness caused by MG, and to remove a thymoma, a tumor (usually benign or in some cases malignant) on the thymus that presents itself in only 10% of patients. Every person diagnosed with MG should have a CT scan of the chest to check for a tumor. The neurological goals of a thymectomy are significant improvement in the patient’s weakness, reduction in the medications being employed, and ideally a permanent remission (complete elimination of all weakness and off all medications). A thymectomy is usually not used to treat active disease but rather it is believed to improve long-term outcome. Results may not be seen for one to two years or more after the thymectomy.
Mestinon® (pyridiostigmine bromide)– allows acetylcholine to remain at the neuromuscular junction for a longer period, which in turn allows activation of more receptor sites, resulting in increased conductivity and muscle engagement. Mestinon® comes in two forms, fast-acting 60 mg tablets and long-lasting slow-release 180 mg capsules known as Timespan®, which delivers pyridiostigmine bromide over a 12-hour period.
Neonatal Fc receptor (FcRn) blockers
The U.S. Food and Drug Administration (FDA) has approved argenx's VYVGART® (efgartigimod alfa-fcab) for the treatment of generalized myasthenia gravis (gMG) in adult patients who are anti-acetylcholine receptor (AChR) antibody positive. These patients represent approximately 85% of the total gMG population. VYVGART is a prescription medication and the first FDA-approved treatment that uses a fragment of an IgG antibody to treat adults with anti-AChR antibody positive generalized myasthenia Gravis. It is given in treatment cycles with a break between each cycle. A treatment cycle consists of a 1-hour infusion each week for 4 weeks (4 infusions total). The treatment is specifically designed to attach to and block the neonatal Fc receptor (FcRn), resulting in the reduction of IgG antibodies, including the harmful AChR antibodies that cause gMG symptoms. Receptors called “FcRn” extend the life of IgG antibodies. In gMG, this allows harmful AChR antibodies to continue causing gMG symptoms. But IgG antibodies, including harmful AChR antibodies, that cannot attach to an FcRn are removed by the body. When harmful AChR antibodies that cause gMG symptoms are removed, they can no longer disrupt nerve-muscle communication. This treatment is offered by argenx and you can learn more by visiting the following: https://vyvgart.com/
C5 Protein Inhibitors
AstraZeneca, and its Alexion rare disease group, announced that the United States Food & Drug Administration (FDA) has officially approved the Ultomiris® (ravulizumab-cwvz) treatment for adult patients with generalized myasthenia gravis (gMG) who are anti-acetylcholine receptor (AChR) antibody-positive, which represents 80% of people living with the disease.This FDA action marks the first and only approval for a long-acting C5 complement inhibitor for the treatment of gMG. According to Alexion, the medication works by inhibiting the C5 protein in the terminal complement cascade, a part of the body’s immune system. When activated in an uncontrolled manner, the complement cascade over-responds, leading the body to attack its own healthy cells. Ultomiris is administered intravenously every eight weeks in adult patients, following a loading dose. Ultomiris showed early effect and lasting improvement in activities of daily living and has potential to reduce treatment burden with dosing every 8 weeks. You can read more about this treatment at the following website. https://www.astrazeneca.com/media-centre/press-releases/2022/ultomiris-approved-in-the-us-for-adults-with-generalised-myasthenia-gravis.html
Corticosteroids and immunosuppressant agents
Corticosteroids, such as Prednisone or an immunosuppressant agent such as Imuran®, Cellcept®, or Cyclosporin® , may be prescribed by your doctor as a stand-alone medication or in combination. These medications suppress your body’s production of antibodies that may be blocking or binding onto your body’s acetylcholine receptors. This blocking or binding of the acetylcholine receptors causes weakness.
Complement Inhibitors including Soliris
Soliris® or its generic name eculizumab, is the newest classification of infusible drugs to be FDA-approved for the treatment of gMG in adult patients who are anti-acetylcholine receptor antibody positive. This drug works to reduce immune system attacks that may contribute to gMG symptoms. You and your doctor will decide if this approach is best for you.
Intravenous immune globulins (IVIg)
Your doctor may prescribe IVIG as part of your treatment regimen. During IVIG, a line is placed into a vein to receive delivery of immune globulins (IgG). A typical IVIG infusion may take from 4- 8 hours and is typically in a hospital setting. This influx of IgG is thought to override your own antibody production (which may be causing your weakness) while providing you protection from possible infections. Results are often temporary, so repeated treatments are required.
IgG Sub-cue Hizentra
A new, less invasive method of delivering immune globulins (IgG) is being reviewed for MG use. This method is known as IgG sub-cue, which means subcutaneous or “under the skin”. In this method of IgG delivery, a series of 4-6 short needles are placed into the subcutaneous layer of skin across your abdomen. These needles are connected in a spider web fashion to the pump. A typical sub-cue infusion may only take from 1-3 hours and can be done at home.
Therapeutic Plasma Exchange
Therapeutic Plasma Exchange, or Plasmapheresis – Also known as Plasma exchange or PLEX. This is a filtration procedure whereby abnormal antibodies are removed from blood plasma. This procedure requires two intravenous (IV) lines or a port placed before undergoing PLEX. Your doctor may decide you need this treatment to quickly improve strength prior to surgery. As your body continually produces antibodies, repeated PLEX treatments may be required.
Certain medications may cause worsening of MG symptoms. Remember to tell your doctors and dentists about your MG diagnosis and the medications you are currently taking. It is important to check with your doctor before starting any new medication, including over the counter medications or preparations. To review the list of cautionary drugs, please VISIT the MGFA Cautionary Drugs page.