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About Myasthenia Gravis
Myasthenia Gravis (MG) is a chronic autoimmune neuromuscular disease which affects skeletal muscles that are responsible for eye movements, breathing, and moving parts of the body, resulting in muscle weakness and fatigue.
A muscle contraction occurs when the muscle receptors receive signals from nerve endings. In MG, the immune system mistakenly attacks muscle receptors by producing anti-receptor antibodies that can block or destroy these muscle receptors, preventing the signals from effectively reaching the muscles. Over time, this may lead to symptoms such as limb weakness, drooping eyelids, and double vision, as well as difficulties with chewing, swallowing, speech, and breathing.
While many patients with MG may be managed with current therapies, some patients may 1) fail to respond adequately despite multiple therapies, 2) not tolerate these therapies, and/or 3) have conditions that do not allow the use of these therapies. These patients may continue to experience profound muscle weakness and severe disease symptoms that limit their functions and their quality of life. Research is needed to develop new treatment options for patients with MG.
The main symptom of MG is weakness affecting skeletal muscles. The muscle weakness tends to worsen during physical activity and improves with rest. Symptoms may include:
|Drooping eyelid(s)||Limited facial expressions|
|Double vision||Breathing problems|
|Altered speech (soft or nasally speech)||Weakness in the neck, arms, and legs|
|Difficulty swallowing||Difficulty walking|
|Problems chewing||Extreme or rapid fatigue|
If you believe you are experiencing any of these symptoms, or you have been diagnosed with MG and are experiencing a worsening of your symptoms, please contact your doctor or a healthcare professional for a medical consultation.
Based on your signs and symptoms and a comprehensive neurological exam, your physician will often conduct a series of tests and assessments to confirm a diagnosis of MG. These may include:
These tests look for certain antibodies that are often found in patients with MG.
Acetylcholine receptor (AChR) antibodies:
Present in approximately 85% of people with MG.
Muscle-specific tyrosine kinase (MuSK) antibodies:
Less common, but may be present in approximately 38 – 50% of people who test negative for AChR antibodies.
Low-density lipoprotein receptor-related protein 4 (LRP4) antibodies:
Uncommon, but may be positive in those who test negative for AChR and/or MuSK antibodies.
This type of test measures the electrical activity in the muscle. The most common electrophysiological tests for evaluating whether someone has MG are:
Repetitive nerve stimulation:
An electrode is placed over the motor nerve and the nerve is electrically stimulated repeatedly several times per second. The response to the stimulation is recorded.
This is a highly specialized technique proven to be the most sensitive technique to detect a neuromuscular transmission defect. It requires the use of a special needle electrode for recording single muscle fiber action potentials.
Treatment for MG is highly individualized. Although patients may be managed with current therapies, not everyone responds the same way to treatment. For many with MG, it may take time to find the right medication, dosing level, or combination of treatments to bring about relief from symptoms. Others may need to change medications because of ineffectiveness and/or side effects. It’s important that patients with MG frequently consult with their doctor to review their current treatment plan and make any necessary changes.
There are five basic therapies used to treat myasthenia gravis:
Muscle weakness may be treated symptomatically with cholinesterase inhibitors (also called anticholinesterase medications). Pyridostigmine bromide (Mestinon) is the main cholinesterase inhibitor that is currently in use. Cholinesterase inhibitors do not address the underlying autoimmune attack on the muscle.
Commonly used immunosuppressive drugs in MG are prednisone, azathioprine, cyclosporine, tacrolimus, and mycophenolate mofetil. In some circumstances, particularly in those with refractory MG, other agents such as rituximab, eculizumab, intravenous immune globulin (IVIG), and cyclophosphamide may be considered.
Most patients with MG may require some form of gluococorticoids or other immunosuppressive drugs at some point in their illness, if not indefinitely. Balancing the improvement of MG symptoms with the side effects of the gluococorticoids and immunosuppressive drugs is always a challenge for the physician and the patient.
Plasmapheresis and IVIG may work quickly but have a short duration of action. These are usually reserved for certain situations, such as severe exacerbations or myasthenic crisis, preoperatively before thymectomy, as a "bridge" while initiating slower acting immunosuppressive drugs, or as an adjuvant to other immunotherapy in patients with refractory MG.
Based on a number of factors – such as your age, severity of the condition, response to previous treatment, and other medical conditions – your doctor can help determine the best course of treatment for you.
Communicate closely with your doctor
Finding the right treatment option(s) for MG can take a while. Talk to your doctor regularly if you experience new or worsening symptoms or side effects due to your medication. It may be time for a change in treatment.
Listen to your body
While symptoms can come and go without warning, others may be caused (or relieved) by specific actions. Consider writing down when symptoms appear, how long they occur, when you feel best, and the times and dosages of any medication you are taking. All this information can help your doctor better tailor a treatment plan for you.
Save your energy
Avoiding fatigue is critical to maintaining health and wellbeing. Conquer MG includes a great list of helpful tips and strategies to help you get through the day.
Nap when needed
In addition to getting plenty of sleep, a few naps throughout the day can help restore your energy levels and potentially reduce the appearance, length, and severity of symptoms.
Like most conditions, stress can trigger or worsen MG symptoms. Stress-relieving activities such listening to music, light yoga/exercise (in consultation with your doctor), and breathing exercises may be helpful.
People with MG may find that muscle weakness in their jaws, lips, and throat can affect their ability to chew or swallow. Consider eating tiny, bite-sized meals throughout the day to keep your energy up. In addition, give your medication time to kick in prior to eating any meals. Finally, consider meeting with a dietitian who can help you plan and maintain a healthy, well-balanced diet.
Sanders, D, et al. International consensus guidance for management of myasthenia gravis. Neurology® 2016;87:419–425
Bird, SJ. Clinical manifestations of myasthenia gravis. Shefner JM, Targoff IN, eds. UpToDate Inc. Retrieved November, 2018, from https://www.uptodate.com (Accessed November 2018).
Bird, SJ. Diagnosis of myasthenia gravis. Shefner JM, Targoff IN, eds. UpToDate Inc. Retrieved November, 2018, from https://www.uptodate.com (Accessed November 2018).
Bird, SJ. Treatment of myasthenia gravis. Shefner JM, Targoff IN, eds. UpToDate Inc. Retrieved November, 2018, from https://www.uptodate.com (Accessed November 2018).