Myasthenia Gravis Diagnosis: Key Tests and Procedures

Diagnosing myasthenia gravis (MG) typically involves a series of specialized tests that help identify muscle fatigue and neuromuscular dysfunction. One of the simplest and most commonly used diagnostic tools is the muscle fatigue test. During this test, patients are asked to repeatedly open and close their eyes around 30 times. Doctors observe whether the eye opening becomes noticeably smaller, which may indicate muscle fatigue associated with myasthenia gravis.

Edrophonium (Tensilon) Test for Confirmation

Another important diagnostic method is the edrophonium test. In this procedure, a drug called edrophonium chloride is administered intravenously. If there is a noticeable improvement in muscle strength—particularly in the eyelids or other affected muscles—this is considered a positive result. This temporary enhancement of muscle function strongly suggests the presence of myasthenia gravis.

Antibody Testing and Blood Work

Beyond physical tests, blood tests play a crucial role in confirming a diagnosis. Physicians often test for the presence of acetylcholine receptor antibodies. These autoantibodies interfere with the communication between nerves and muscles and are found in approximately 85% of patients with generalized myasthenia gravis. If these antibodies are detected, it significantly supports the diagnosis.

Electromyography (EMG) for Nerve and Muscle Function

In some cases, an electromyogram (EMG) is performed to evaluate the electrical activity in muscles and nerves. During this test, low-frequency repetitive nerve stimulation is used, and a characteristic finding in myasthenia gravis is a decremental response in the muscle action potential. This decline in signal strength with repeated stimulation is highly indicative of MG.

Combining clinical observations, pharmacological testing, antibody analysis, and electrophysiological studies allows for a comprehensive and accurate diagnosis of myasthenia gravis. If you or a loved one is experiencing unexplained muscle weakness or fatigue, consulting a neurologist for proper evaluation is highly recommended.