An electromyography, or EMG, test can detect various neuromuscular diseases, motor issues, nerve damage and degenerative conditions such as amyotrophic lateral sclerosis, carpal tunnel syndrome and cervical spondylosis, according to Brigham and Women’s Hospital. It can also detect Guillain-Barre syndrome, Lambert-Eaton syndrome and muscular dystrophy.
Doctors typically use an EMG to diagnose myasthenia gravis, peripheral neuropathy, polymyositis and radial nerve dysfunction, states Brigham and Women’s Hospital. The test is often accompanied by a nerve conduction velocity test to determine whether a person has a nerve disorder or a muscle disorder.
An EMG test measures muscle electrical activity to identify the presence of neuromuscular problems, explains Brigham and Women’s Hospital. It involves inserting a thin needle called an electrode into the muscle. The electrode measures electrical activity as an individual contracts muscles or stays relaxed. A monitor known as an oscilloscope displays the results.
To prepare for an EMG, a person should not use any cream or lotion before the test, states Brigham and Women’s Hospital. Smoking and consuming caffeinated drinks should be avoided around two to three hours prior to the test. Individuals should inform their doctors if they use a pacemaker and what medications or supplements they currently take. Physicians also recommend wearing loose clothing that allows quick access to the body part involved in the diagnostic test.