Diagnosis
There are a lot of ways through which a person with Myasthenia Gravis is diagnosed. The first and foremost is a good history that helps determine the nature and course of the disease. This also gives clues about the list of differentials and what other problems could be associated with this disease.
After asking all relevant questions, proper evaluation and examination of the affected muscles are then completed. The power and the tone of the muscles are assessed along with a complete motor and sensory exam. Short commands are given to the patient to help diagnose the condition and the extent of severity.
There are a few diagnostic tests that are also done to help evaluate. They are mentioned as follows:
- Edrophonium Chloride test: this test is done as the initial test to help diagnose the condition. Edrophonium Chloride is a short-acting acetylcholinesterase inhibitor. This chemical acts by prolonging the action of the duration of Acetylcholine at the neuromuscular junction. It is injected in the patients who complain of weakness and betterment in the strength and functioning of the muscles gives clues that it is indeed a pathology concerning the neuromuscular junction and the release of Acetylcholine.
- Ice pack test: Individuals who have ptosis are usually tested using the ice pack. This non-pharmacological technique is used as the edrophonium test poses a lot of problems for such individuals and is hence contraindicated. It is simply done by placing an ice pack on the affected eye for a good five minutes, and betterment in ptosis is then observed.
- Blood tests: Blood tests are also carried out to check for antibodies circulating in the body. The ones specific for Myasthenia Gravis are Acetylcholine receptor antibodies that give clues to this disease.
- Genetic tests: These tests are also carried out in order to check if there is a defect in the genetic machinery of the patient and if it can be passed along to other generations.
- Repetitive nerve stimulation Test: This test is done when the nerve is repetitively stimulated to check for a decrement, a 10% decrement is seen in patients with Myasthenia Gravis.
- Electromyography: Single fiber electromyography is the test that specifically tests for this disease and is known to be the most accurate test to get to the diagnosis.
- Chest X-Ray: A chest X-ray is carried out in all patients of Myasthenia Gravis to check for respiratory involvement and to exclude any respiratory problem that could be the cause of breathlessness.
- MRI: An MRI is done in order to exclude any thymoma that could mimic the symptoms of Myasthenia Gravis.
All these tests help differentiate Myasthenia Gravis from any other muscular disorders that could be the cause of muscle weakness. These diseases include; Lambert Eaton syndrome, the intoxication of organophosphate, disorders involving the mitochondria, ischemia of the brainstem, as well as motor neuronal disease.
