Myasthenia Gravis Tests
What is Myasthenia Gravis?
Myasthenia gravis (MG) is a chronic autoimmune neuromuscular disorder that causes weakness in the skeletal muscles, which are responsible for breathing and moving parts of the body, including the arms and legs. It causes loss of muscle strength, fatigue, and muscle weakness that worsens after periods of activity and improves after periods of rest.Myasthenia Gravis Tests
Myasthenia gravis tests are performed to check for antibodies that attack the neuromuscular junction, a nerve-muscle junction, or for drugs that improve muscle strength. Other tests used to diagnose myasthenia gravis include blood tests, electromyography, nerve conduction studies, imaging tests, and a single-fiber electromyography.
Myasthenia Gravis Test Preparation
Before any of the MG tests are performed, your doctor will perform a physical exam to check for signs and symptoms of myasthenia gravis. This can include watching your face and checking your eye movements. You may also be asked to perform some simple activities. Depending on the test being performed, you may be asked to stop taking certain medications for a period of time in order to get accurate test results.
Myasthenia Gravis Test Procedure
The most common MG tests include the following:
- Blood Tests: This test looks for antibodies that attack the neuromuscular junction. These antibodies block the transmission of nerve signals to the muscles, causing weakness. This test is often used to diagnose myasthenia gravis and can also be used to monitor the effectiveness of treatment.
- Electromyography (EMG): This test records the electrical activity of muscles at rest and during contraction. An EMG can help diagnose myasthenia gravis, differentiate it from other muscular disorders, and measure the effectiveness of treatment.
- Nerve Conduction Study (NCS): This test looks at the electrical activity of a motor nerve after it has been stimulated. An NCS can help diagnose myasthenia gravis or other neurological conditions that cause muscle weakness.
- Imaging Tests: Imaging tests can help confirm a diagnosis of myasthenia gravis and rule out other conditions. Imaging tests such as magnetic resonance imaging (MRI) and computed tomography (CT) can help look for abnormalities in the spinal cord or brain that may be causing the muscle weakness.
- Single-Fiber Electromyography (SFEMG): This test measures the electrical activity of single muscle fibers. It is a sensitive test for diagnosing myasthenia gravis and can also be used to monitor treatment.
Risks
Myasthenia gravis tests are generally safe and have few risks. Occasionally, there can be some discomfort with certain tests if a strong electrical current is used, such as in an EMG or NCS. Rarely, there can also be bleeding or infection at the test site.
Why and When are Myasthenia Gravis Tests Needed?
Myasthenia gravis tests are used to diagnose myasthenia gravis, a neuromuscular disorder. Your doctor may order these tests if you have signs and symptoms of myasthenia gravis, such as muscle weakness and difficulty swallowing, or if you have a family history of the condition. These tests can also be used to monitor the effectiveness of treatment.
