Myasthenia Gravis

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Myasthenia Gravis Diagnosis & Tests

Examination may be normal or may show muscle weakness that progressively worsens as the muscle is used. In many patients the eye muscles are affected first. Reflexes and sensation are normal. Weakness may affect the arms, legs, breathing or swallowing muscles and any other muscle group.

• Standard EMG results are usually normal. Repetitive stimulation (type of nerve conduction studies) are more sensitive.
• Single-fiber EMG is even more sensitive.
• Acetylcholine receptor antibodies may be present in the blood.
• A Tensilon test is positive in some cases but must be interpreted carefully by a doctor experienced at this. Baseline muscle strength is evaluated. After Tensilon (edrophonium, a medication that blocks the action of the enzyme that breaks down the transmitter acetylcholine) is given, muscle function may improve.