It also may be associated with thyrotoxicosis , rheumatoid arthritis , systemic lupus erythematosus , and other immune system disorders. In many cases, no other disorder is identified. Myasthenia gravis affects about 3 out of 10,000 people. Symptoms may worsen with pregnancy or menstrual periods. Reflexes and sensation are normal.
Facial involvement is usually early.
Eyelids may droop. EMG results vary. Acetylcholine receptor antibodies may be present in the blood. A Tensilon test is positive in most cases. A baseline muscle strength evaluation is performed.