Your doctor will review your symptoms and your medical history and conduct a physical examination. Your doctor might use several tests, including:
Your doctor may check your neurological health by testing:
- Muscle strength
- Muscle tone
- Senses of touch and sight
Tests to help confirm a diagnosis of myasthenia gravis might include:
Injection of the chemical edrophonium chloride that results in a sudden, temporary improvement in muscle strength might indicate that you have myasthenia gravis.
Edrophonium chloride blocks an enzyme that breaks down acetylcholine, the chemical that transmits signals from your nerve endings to your muscle receptor sites.
Ice pack test
If you have a droopy eyelid, your doctor might place a bag filled with ice on your eyelid. After two minutes, your doctor removes the bag and analyzes your droopy eyelid for signs of improvement.
A blood test might reveal the presence of abnormal antibodies that disrupt the receptor sites where nerve impulses signal your muscles to move.
Repetitive nerve stimulation
In this nerve conduction study, doctors attach electrodes to your skin over the muscles to be tested. Doctors send small pulses of electricity through the electrodes to measure the nerve’s ability to send a signal to your muscle.
To diagnose myasthenia gravis, doctors will test the nerve repeatedly to see if its ability to send signals worsens with fatigue.
Single-fiber electromyography (EMG)
This test measures the electrical activity traveling between your brain and your muscle. It involves inserting a fine wire electrode through your skin and into a muscle to test a single muscle fiber.
Your doctor might order a CT scan or an MRI to check if there’s a tumor or other abnormality in your thymus.
Pulmonary function tests
These tests evaluate whether your condition is affecting your breathing.