Roughly 20 per every 100,000 people develop myasthenia gravis around the world. It is an equal opportunity disease that affects people of all nationalities. The condition normally first develops between the ages of 40 and 60. Women are more likely to develop the disease at a younger age and men tend to develop it more often past the age of 60. The prevalence is increasing. However, this is likely because of better recognition of the disease and the myasthenia gravis symptoms, as well as a better diagnostic methodology. Still, it is thought to be under-diagnosed.
Oddly, although myasthenia gravis is usually a systemic disorder, it’s the eye doctor that catches it first. This is because myasthenia gravis tends to affect the muscles of the eyes, face and throat first. Read this article to learn what myasthenia gravis is, what causes it, what are the symptoms, and how to treat it.
What Is Myasthenia Gravis?
Myasthenia gravis is an autoimmune disease that occurs when the immune system develops antibodies against acetylcholine receptors. There are several different types of acetylcholine receptors. In the basic sense, these are the receptors responsible for completing the actions of neurotransmitters. Myasthenia gravis varies widely in its severity; some patients experience complete remission while others experience extreme worsening, including respiratory collapse. Even in severe cases though, as long as the disease is properly treated and emergencies are properly addressed, life expectancy is normal.
Since it can be such a serious autoimmune disease and the prevalence is increasing, there are many different studies taking place at the moment attempting to find the best treatments. In fact, the Myasthenia Gravis Foundation of America just announced that it is taking requests for proposals to support “highly focused and innovative” new research projects. They are offering support funds of up to $50,000 per year for projects that meet their criteria.
Symptoms of Myasthenia Gravis
As stated in the introduction, myasthenia gravis often first shows up as ptosis. This is a drooping of one eyelid or both eyelids. Patients may also notice blurring vision or double vision due to the weakening of muscles that control eye focus. An eye doctor may notice that the eye does not track properly when following an object.
Sometimes, myasthenia gravis affects only the eyes. In these cases, we’re talking about ocular myasthenia gravis. However, in most other cases, myasthenia gravis affects the entire body. In this case, it’s called generalized myasthenia gravis.
Generalized Myasthenia Gravis Symptoms
Generalized myasthenia gravis affects the entire body, therefore the symptoms are varied. However, there is a pattern of symptoms that can help practitioners understand disease progression. For the most part, certain muscle groups or all muscles become weaker, especially with repeated activity. In fact, one of the diagnostic tests requires repeatedly stimulating the muscles and checking for an increasingly delayed response via EMG testing. Consequently, myasthenia gravis symptoms increase with exertion and decrease with rest. Patients will notice that their myasthenia gravis symptoms vary greatly according to their daily activity.
The most notable symptoms will involve the head and neck:
- Trouble swallowing; the muscles that coordinate swallowing become to weak to act in unison.
- Difficulty chewing; it’s hard to complete a meal as the mouth muscles easily tire.
- Slurred speech; speech may be ok at first, but prolonged speaking becomes softer and more nasal. This is due to inability to control the muscles that project sound.
- Decreasing facial expressions; the muscles that we use to smile are weakened.
- Waddling type of walk. For the rest of the body, myasthenia gravis often affects arms more than legs. When they do affect legs, you will notice a waddling type of walk.
Known, Possible and Theoretical Causes of Myasthenia Gravis
There are known causes, possible causes and theoretical causes for this disease. We just haven’t learned quite enough about it yet. Research is ongoing and progressing at a very rapid rate; we will probably know a great deal more about what causes this disease in the near future.
Autoimmune antibodies attack the cells of the nervous system and literally destroy our neurotransmitter receptors. Since we have less receptor sites, we experience a delay in nerve signals and weaker response to muscle stimulation.
It is theorized that a protein called tyrosine kinase, which forms the nerve-muscular junction, is blocked by certain antibodies.
The Thymus Gland
It’s postulated that the thymus gland, which is located in your upper chest underneath your breastbone, can induce the production of acetylcholine receptor antibodies because it’s somehow “mis-programmed”. Very often, a patient with myasthenia gravis symptoms will have a tumor in the thymus gland. Whether the tumor is cancerous or not, it is usually removed because it could become malignant. In these cases where a tumor is present, up to 50% of patients will enjoy full remission from the disease.
In some cases, patients have myasthenia gravis symptoms, but they don’t test positive for the known antibodies that cause the disease. The current theory in these cases is that antibodies against lipoprotein-related protein 4 might be involved. This research is uncertain though, as we still have a great deal to learn about the human immune system.
Very rarely, infants are born with congenital myasthenic syndrome. If treated quickly, they can recover in as little as two months. This is why it’s very important to get check ups frequently after birth.
Myasthenia Gravis Treatment
There are several different treatments that can help improve the autoimmune causes of myasthenia gravis symptoms. Most of these are aimed at calming down a hyperactive immune system.
- Corticosteroids. Most often, this treatment involves prescribing prednisone. It’s not without side effects though and can cause weight gain and bloating.
- Prograf and CellCept. These are the same types of drugs intended to prevent rejection of donated organs. Like prednisone, they lessen autoimmune activity.
- Mestinon. These help improve nerve and muscle communication.
- Plasmapheresis. Filtering your plasma can help to remove excess antibodies.
- Rituximab. IV medications such as this can help to eliminate excess white blood cells.
- Removal of thyroid tumors. As stated above, removal of an existing thyroid tumor results in remission about half of the time.
Patients who have myasthenia gravis are more likely to suffer from other autoimmune conditions such as lupus. These extra factors play a large role in overall prognosis of the disorder. For the most part though, this is one of the most treatable autoimmune conditions. It’s important to follow up with your doctor for all necessary testing and treatment. Myasthenia gravis symptoms can become life threatening for a rare few. For the rest, reduction of stress serves an enormous role in lessening symptoms and slowing progression of the disease.
Remember, patients with myasthenia gravis have a normal life expectancy, so you can look forward to a long and fulfilling life despite this diagnosis.