Myasthenia Gravis Tests
Myasthenia gravis (MG) tests are used to diagnose a chronic autoimmune disease that causes muscle weakness by blocking the connection between nerves and muscles.
What are myasthenia gravis (MG) tests?
MG is an autoimmune disease where the immune system produces antibodies that interfere with nerve-to-muscle communication. It affects voluntary muscles, leading to weakness that often worsens with activity and improves with rest.
Types of MG
- Ocular MG: Affects muscles controlling the eyelids.
- Generalized MG: Affects eyelids as well as muscles in the neck, arms, legs, or those controlling eye movement and breathing.
Why do I need MG testing?
You may need testing if you experience symptoms such as drooping eyelids, double vision, weakness in limbs, trouble swallowing or talking, or fatigue.
What happens during MG testing?
Because muscle weakness can be a symptom of many disorders, providers may use several tests:
- Neurological exam: Checks reflexes, muscle strength, tone, balance, and coordination.
- Ice pack test: Placing an ice pack on a droopy eyelid for two minutes; improvement may indicate MG.
- Antibody test: A blood test looking for specific antibodies associated with MG.
- Electromyography (EMG): Uses a small needle electrode to record electrical activity in muscles at rest and during contraction.
- Nerve conduction study: Measures how fast electrical signals move along nerves using surface electrodes.
- Imaging tests: CT scans or MRIs to check for an enlarged thymus gland or a thymoma.
- Edrophonium test: An injection of a drug that briefly relieves muscle weakness to help confirm a diagnosis.
- Lung function tests: Measures how well your lungs are working.
What do the results mean?
If diagnosed, your provider will develop a treatment plan. Options include:
- Medicines: To improve muscle strength or suppress immune responses.
- Plasmapheresis and IV immunoglobin: Procedures to remove abnormal antibodies from the blood.
- Surgery: Removal of the thymus gland.