Most individuals with myasthenia can lead a normal or nearly normal life if treatment is started on time.
Myasthenia gravis or grave muscle weakness is a neuromuscular disorder that causes gradual progressive weakness in the muscles that allow the body to move (skeletal muscles). This condition is more common in women aged younger than 40 years and men aged over 60 years. Although very few patients may have complete remission of the symptoms after thymus surgery, others may need life-long therapy to manage symptoms. Most people with this condition can enjoy a good quality of life even with mild to moderate symptoms and have normal life expectancy. Treatment for myasthenia gravis significantly improves muscle weakness, and a person with this condition leads to a relatively normal life. Patients usually may take part in all daily activities, including work, and their life expectancy is near normal. However, patients may experience a minor reduction in their physical capacity and quality of life.
To summarize, life expectancy is not lessened by the disorder, but the quality of life may be affected. Some people may experience a temporary or permanent period where there are no symptoms, and treatment may be stopped. Permanent remissions occur in about one-third of all people who undergo surgery to remove the thymus gland.
What are the causes of myasthenia gravis?
Myasthenia gravis is an autoimmune condition that affects the nerves and muscles. Autoimmune conditions are caused by the body's immune system mistakenly attacking its own body or tissue. In myasthenia gravis, the immune system produces antibodies (proteins) that block or damage muscle receptor cells. This prevents messages from being passed from the nerve endings to the muscles, which results in the muscles not contracting (tightening) and becoming weak. It is thought that the thymus gland, part of the immune system located in the upper chest, may be linked to the production of these antibodies. Approximately, 10% of people with myasthenia gravis have a benign tumor of the thymus gland. Myasthenia gravis can also be triggered in some people by particular viruses or medicines. It is also thought that some people’s genes (maybe also inherited) make them more likely to develop autoimmune diseases.
What are the common symptoms of myasthenia gravis?
Symptoms may sometimes be missed or diagnosed only after a period of time. For most people with myasthenia gravis, symptoms are mild at first but get steadily worse over several months, reaching their most severe within the two years. Myasthenia gravis becomes worse when the affected muscle/s is used and improves when it is rested; symptoms often get worse as the day goes on but may get better with rest or a good night’s sleep. The most common symptoms include:
- Tiring easily just from the act of chewing, especially chewy food such as meat
- Weak or droopy eyelids
- The weakness of the facial muscles causing a “snarling” smile
- Blurred or double vision
- Slurred or nasal speech
- Difficulty breathing, particularly when exercising or lying flat
- Difficulty with neck leading to difficulty in holding up the head
- Difficulty walking
- Difficulty balancing and lifting
- Difficulty swallowing food and/or drinks
When muscle weakness can cause severe swallowing or breathing problems (known as a myasthenic crisis), it requires urgent medical attention.
What are the treatment options for myasthenia gravis?
In initial and mild cases, patients may need plenty of rest and avoid stressors in life. Treatment options include:
- Pyridostigmine or Neostigmine: These may be prescribed for myasthenia gravis. They prevent the breakdown of acetylcholine, an important chemical that helps the muscles contract (tighten). They can improve muscle contractions and strengthen the affected muscles. They are often used as the first line of treatment for myasthenia gravis if the initial symptoms are not too severe. Side effects include stomach cramps, muscle twitching, diarrhea, and nausea.
- Steroid: Prednisolone is usually prescribed if symptoms are worsening despite using Pyridostigmine.
- Immunosuppressants: Azathioprine, Methotrexate, or Mycophenolate may be prescribed to suppress the immune receptors that may cause myasthenia gravis.
- Thymectomy: In a few cases, the doctor may recommend surgery to remove the thymus gland. It is thought that the immune system resets itself after the thymus gland is removed. However, the improvement may take some time to occur. It is usually seen within the first year, although in some cases, it can take up to three years. It is usually recommended for people aged under 60 years.
Intravenous immunoglobulin therapy: In this treatment, patients may be injected with normal antibodies from donated blood that temporarily change the way the immune system operates.