Electro Diagnostic
EMG (electromyography) and Nerve Conduction Tests evaluate nerve and muscle functions. These tests can establish if a nerve is pinched, give a numeric value to how severely it is pinched, and often where it is pinched. The test can last anywhere from half an hour to an hour. The quality of the results is particularly dependent on the skill of the person administering the test. During the Nerve Conduction portion of the test, electrodes, much like EKG patches, are placed along the known course of the nerve. The nerve is stimulated with a tiny electrical current at one point. The nerve must then transmit the signal along its course, and an electrode placed further down the arm or leg captures the signal as it passes it. A healthy nerve will transmit the signal faster and stronger than a sick nerve. The EMG portion of the test measures the electrical activity in muscles. Muscles normally receive constant electrical signals from healthy nerves, and in return “broadcast” their own healthy electrical signals. During the EMG portion of the test, the doctor places acupuncture-like needles into the muscles to record the electrical signal from the various muscles in the arm or leg. If a muscle doesn’t receive adequate signals from a sick nerve, it broadcasts signals, which show the muscle is confused. From the Nerve Conduction Test and the EMG’s, the doctor can correlate which nerves are pinched and the seriousness of the condition. This information can then be used to help formulate further treatment plans.
ELECTROENCEPHALOGRAMS (EEG) are often necessary to rule out seizure activity and to look for focal slowing of the brain that would indicate injury of the brain.
Evoked Potentials (EP) are sometimes ordered to assess the speed of electrical conduction across the spinal cord. If the spinal cord is significantly pinched, the electrical signals will travel slower than usual. SSEP’s may also be used to monitor spinal cord function during surgical procedures, although since the spinal cord ends before the lumbar spine, this is usually of limited value during lumbar spinal surgery and it is used more often in cervical (neck) or thoracic (chest) spine surgery.
