Let's get back to basics. To kick off myasthenia gravis awareness month, we wanted to provide you with a little education on MG; MG 101 so to speak. Read about the physiological process of this disease, symptoms, diagnostic measures, and treatment options for this rare neuromuscular disorder.
What is the process in which myasthenia gravis occurs?
Myasthenia gravis is an autoimmune disorder. An autoimmune disorder occurs when the immune system, which usually protects the body from foreign invaders, mistakenly attacks itself.
Myasthenia gravis is a neuromuscular disorder as well. In a person with myasthenia gravis, there is a miscommunication between the nerve and muscle at the neuromuscular junction, the area in which nerve cells transmit signals to muscles to activate contraction. Messages are communicated through cells called neurotransmitters. These neurotransmitters typically bind to receptors for a muscle to contract, however; in a person with myasthenia, antibodies, which are produced by the body to usually protect it, will mistakenly either block, alter or destroy the receptor sites, preventing the muscle from contracting.
Myasthenia gravis affects what muscles?
Myasthenia gravis affects the skeletal muscles of the body. Skeletal muscles are voluntary muscles, which are muscles that humans choose to move (i.e. raising your arm), whereas involuntary muscles are muscles that move automatically without conscious control (i.e. the heart).
What antibodies are associated with myasthenia gravis?
There are various antibodies found in patients with myasthenia gravis. A healthcare provider such as a neurologist may order a blood test(s) to determine if there are elevated levels of specific antibodies to support an MG diagnosis. The following antibodies have been identified, however researchers suggest there are more antibodies to be discovered:
AChR: acetylcholine receptor antibody. The most common antibody associated with myasthenia gravis.
MuSK: muscle-specific tyrosine kinase. An even rarer subtype of myasthenia gravis.
LRP4: low-density lipoprotein receptor-related protein 4. Patients that test negative for both AChR and MuSk may test positive for LRP4.
Some patients test negative for all antibodies associated with myasthenia gravis, however; they still may present with physical symptoms that align with an MG diagnosis. These patients are said to be “seronegative.”
What other tests can patients undergo to confirm a myasthenia gravis diagnosis?
There are various measures a healthcare provider may take in order to confirm or rule out a myasthenia gravis diagnosis. A healthcare provider will first conduct a physical and neurological examination. During this examination, the physician is assessing a person’s muscle strength as well as coordination and things like muscle tone. Healthcare providers may also conduct a single fiber electromyography, or SFEMG. An SFEMG is a test that stimulates a person’s nerves repeatedly with electricity to measure the muscle response.
Other diagnostic measures include:
CT Scan: HCPs may order this type of imaging to examine the thymus gland. The thymus gland is considered an important part of the immune system that helps fight off infections. In patients with myasthenia gravis, the thymus gland may be enlarged (thymic hyperplasia) or even develop a tumor known as a thymoma.
Ice Pack Test: A HCP will place an ice pack on the patient’s eyelid for a couple of minutes and then remove it to see if eyelid drooping has improved. Patients with MG typically struggle with droopy eyelids. When the muscle cools, weakness in MG patients is temporarily improved.
What are some of the typical symptoms that myasthenia gravis patients have?
In MG, a patient has muscle weakness which tends to worsen after activity and improves after rest. The severity of MG varies from patient to patient, however there are core symptoms that are involved with MG. Some of these symptoms include:
Weakness in the eyes including drooping of one or both eyelids, blurred or double vision, and general weakness
Change in facial expression such as an asymmetric smile
Difficulty chewing and/or swallowing
Trouble speaking; the muscles become impaired that are used in speech
Weakness throughout the voluntary muscles including arms, hands, legs, and neck
Difficulty breathing
How is myasthenia gravis treated?
There are multiple treatment options for patients with MG. What works for one person may not work for the other, therefore it is important to discuss all options with your healthcare provider. The following is a general list of the current treatments for MG. There are many new emerging therapies on the horizon—talk to your physician about upcoming treatment options that are currently in the process of research and development.
Anticholinesterase inhibitors; symptomatic treatment of MG
Corticosteroids and other non-steroid immunosuppressants
Monoclonal antibodies such as eculizumab (Soliris) and rituximab (Rituxan)
Rapid acting immunotherapies including plasmapheresis and intravenous immunoglobulin
Thymectomy; surgical removal of the thymus gland
Newly FDA-approved drugs including Efgartigimod (Vyvgart) and Ravulizumab-cwvz (Ultomiris)
What is the outlook for someone with myasthenia gravis?
Although the words “myasthenia gravis” mean “grave muscle weakness,” the majority of MG patients can improve their symptoms and lead fulfilling lives with the right treatments.
If not treated properly, an MG patient can go into a “myasthenic crisis.” A myasthenic crisis is a medical emergency that occurs when the muscles that control breathing weaken to the point where individuals require a ventilator to help them breathe. It may be triggered by infection, stress, surgery, or an adverse reaction to medication. It is important to maintain an understanding of MG symptoms and to listen to the body when there are signs of a crisis.
Finding the right treatment strategy can take some time, however; many MG patients are able to maintain a stable lifestyle and some even go into remission. The outlook for myasthenia gravis is a positive one.
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