Explore Neuromuscular MedicineMyasthenia Gravis
What Is Myasthenia Gravis?
Myasthenia Gravis (MG) is a chronic autoimmune condition that effects neuromuscular transmissions, effectively causing the communication between nerves and muscles to break down, causing muscle weakness and rapid fatigue. MG usually affects the muscles that help you move, such as those in your eyes, face, neck, arms, and legs. It can affect your ability to:
- Move your eyes or blink.
- Keep your eyes open.
- Have single vision.
- Make facial expressions.
- Chew, swallow, and talk.
- Raise your arms up and lift objects.
- Walk upstairs or get up from a chair.
MG symptoms usually appear quickly, and muscle weakness worsens after physical activity and improves after rest.
Diagnosing MG
MG is an autoimmune disease, meaning it is caused by the body generating unique antibodies (proteins that our immune system normally creates) that result in it attacking itself. It isn’t always clear why self-reactive antibodies in MG develop, but their production has been linked to abnormalities in the thymus, an organ that is involved in the immune system.
It is not clear what triggers the autoimmune response, but it has been associated with tumors of a gland called the thymus in the chest, as well as certain medications. Your doctor may order a chest CT to determine whether you have an enlarged thymus or a thymus tumor (thymoma). If so, an operation to remove it may improve control of MG.
With MG, the immune system produces antibodies that bind to receptors on the muscles, preventing signals from activating them. These self-reactive antibodies can be detected in the majority of patients diagnosed with MG.
Electromyography (EMG) and nerve conduction testing (NCS) can also help diagnose MG by showing decreased muscle responses with repetitive stimulation. A special technique called single-fiber EMG is a sensitive test for assessing the presence of MG and is sometimes used to diagnose it.
The exact cause of MG is unknown, and there is no known way to prevent or cure it. However, treatment can help manage symptoms.
Symptoms
MG symptoms may come and go. They usually get better when the weak muscle is rested, but worsen again when used. Most patients start by experiencing visual symptoms, namely drooping eyelids and double vision, and roughly 50% of those patients go on to develop more generalized weakness as reflected in the examples below. Symptoms often progress and may be at their worst one or two years after the disease begins.
Common symptoms of muscle weakness with MG include:
Eye Muscles
- Drooping of one or both eyelids, called ptosis.
- Double vision, called diplopia, may affect horizontal or vertical vision. It may improve or stop when one eye is closed.
Face & Throat Muscles
- Your speech might sound soft or nasal, depending on which muscles are affected.
- You may choke easily, making it difficult to eat, drink, or take pills. When you swallow liquid, it may come out of your nose.
- The chewing muscles might tire halfway through a meal, especially if you've been eating something hard to chew, such as steak.
- You might have trouble fully raising your eyebrows or holding a smile because the muscles tire quickly. Your facial expression may not fully reflect what you are feeling.
Neck & Limb Muscles
- Weakness in the neck, arms, and legs may develop as the condition progresses, affecting your walking, and weak neck muscles can make it difficult to hold your head up.
Shortness of Breath
- MG can be life-threatening if it weakens the respiratory muscles. You should inform your neurologist if you develop shortness of breath. If symptoms are mild, pulmonary function tests may help monitor your breathing. If you suddenly become severely short of breath, call 911 to be taken to a hospital, as a ventilator may be necessary to assist with breathing while specialized treatments are administered.
Risk Factors
While MG can affect anyone at any age, the condition is most common among women around age 40 and among men after age 60. You may be at higher risk if you have:
- A history of other autoimmune conditions, including rheumatoid arthritis and lupus.
- Thyroid disease.
Complications
Weakness and fatigue from MG can keep you from participating in activities you enjoy. This may lead to stress and depression. However, studies also show that most people with myasthenia gravis can tolerate light activities and exercises on a routine basis.
Up to 1 in 5 people with MG experience a myasthenic crisis or severe respiratory muscle weakness. You may need a respirator or other treatments to help you breathe. This is a life-threatening medical emergency. An estimated 20% of people with MG experience at least one myasthenic crisis in their lifetime.
Diagnosis
To diagnose MG, your healthcare provider will perform a physical exam and ask detailed questions to learn more about your symptoms and medical history. Testing confirms a diagnosis. It may include:
- Blood antibody tests: About 85% of people with myasthenia gravis have unusually high levels of acetylcholine receptor antibodies in their blood. Approximately 7% of people diagnosed with MG have antibodies to muscle-specific kinase (MuSK).
- Imaging scans: An MRI or CT scan can check for thymus gland problems like tumors.
- Electromyography (EMG): An EMG measures the electrical activity of muscles and nerves. This test detects communication problems between nerves and muscles.
Treatment
At UConn Health, our Myasthenia Gravis program offers the latest diagnostic testing and treatments. It provides our patients access to the following resources:
- Comprehensive patient care, including dedicated nursing staff.
- Access to newer and dedicated treatment strategies.
- Support groups led by a social worker and provider team.
- Clinical trial platform providing opportunities for novel treatment interventions.
- Patient educational conferences and programming.
Medications have been used for long-term control of MG. These often include a steroid (prednisone) and an acetylcholinesterase inhibitor (pyridostigmine). The goal in treating MG is to limit the burden of symptoms and minimize steroid use as much as possible. Given this, other immunosuppressing medicines, either oral, injected, or infused, can be used on their own or sometimes together to calm self-reactive immune system activity. We work with our patients to find the medication best suited for their disease.