An EMG assess the electrical activity of a nerve root and is sometimes recommended for patients with back pain. After three weeks of pressure on a nerve root, the muscle the nerve goes to will begin to spontaneously contract. Compression of a nerve will also slow electrical conduction along that nerve. EMG’s are also sometimes useful to distinguish nerve degeneration (neuropathy) from nerve root compression (radiculopathy).
The test involves placing small needles into the muscles, so there is some discomfort for the patient. There are no major risks, although the tests are not highly reliable in determining which nerve is compressed.