Approximately 10 out of every 100,000 people have the neuromuscular disease known as myasthenia gravis, or MG. This is a chronic, autoimmune disease that causes muscle weakening that exacerbates, or gets worse, with activity. This disease is lessened with frequent periods of rest. Occurring in mostly women under the age of 40 and men over the age of 60, it can, however, strike anyone including children.
Due to an abnormal thymus gland, myasthenia gravis makes antibodies that work against themselves and block the substance acetylcholine, from binding to the muscle. Myasthenia gravis will have the most effect on the muscles that control chewing, talking, eye movements, swallowing, the extremities, and facial movements.
Blood tests for the condition include antibody laboratory testing. These blood tests will recognize abnormal antibodies in higher than normal levels due to an overactive immune system. It will show an abnormal nerve-to-muscle pathway. The abnormal antibodies shown are the acetylcholine receptor antibodies, which indicate myasthenia gravis. The acetylcholine receptor testing is measured in nanomoles per liter. The normal range for this particular test is 0-.03 nM/liter.
Ten to twenty percent of patients with myasthenia gravis will have normal testing results. A person who only exhibits signs and symptoms of ocular myasthenia gravis will test normal 50 percent of the time. In a mild case of myasthenia gravis only one person out of every five people will test negative.
An additional antibody can also be found, as sometimes a myasthenia gravis patient will test negative for the acetylcholine receptor antibody. This other antibody is the MuSK antibody. Other confirming testing is done as well, such as a standard electromyogram, known as an EMG. This is done with repetitive stimulations and will show abnormal responses in a myasthenia gravis patient. This can also show as negative in a myasthenia gravis patient.
During a edrophonium test, the chemical is injected into a patient intravenously and will block the acetylcholine allowing a patient with MG to have an increased level of strength in the muscles. The ultimate diagnostic testing source for people with myasthenia gravis is a single-fiber EMG. This test will be the determining factor in the diagnosis of myasthenia gravis.
If it is determined that a person has myasthenia gravis medications are usually the general form of treatment. These medications give symptomatic relief, but a cure for myasthenia gravis has not been found. Consulting with your physician along with regular check-ups can keep your myasthenia gravis in control. People with this condition can lead productive lives and daily activity with proper rest, nutrition and treatment of their symptoms. Close monitoring and consultation with your physician throughout your disease is necessary in order to achieve optimal health and a good quality of life.
RESOURCES
National Institute of Neurological Disorders and Stroke: Myasthenia Gravis Fact Sheet
MayoClinic: Myasthenia Gravis
Myasthenia Gravis Foundation of America: Test and Diagnostic Methods
Boston Children\’s Hospital: Myasthenia Gravis
The University of Chicago Medicine: Myasthenia Gravis