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Electromyography (EMG) and Nerve Conduction Velocity (NCV) studies are used in conjunction to help identify injury or disease of muscles and nerves along the spine, the face and extremities.
An EMG-NCV test is an excellent way to assess the condition of physiological or biochemical functions of a nerve, as opposed totests that are designed to capture images of the structure, such as an X-ray or MRI.
Because a nerve is essentially a conduit the body uses for sending messages to and from the brain, regarding the state of muscles in the body, it is important to know how well the communication system is working. These impulses are normally relayed quickly and efficiently, but an injured muscle, nerve, nerve root or peripheral nerve can confuse the signals, resulting in weakness, numbing, tingling or pain in the area.
When a nerve is stimulated, it sends a signal along its route, and, much like a telephone wire, the signal travels from one end of the line to the other. In the EMG-NCV test, electrodes are placed along the nerve and a mild electrical impulseis applied – which makes the muscles in the area contract and release. It feels much like a static electric shock.
The electrodesused in an EMG test are similar to the electrodes used in an EKG, and althoughthey are actually very thin pins inserted into the musclealong nerve route, theyare designed to cause little discomfort. The electrodes record the electrical signal generated by the muscle as it travels up the nerve. A healthy nerve will transmit the signal faster and stronger than a sick nerve, and the electrodes record the strength and efficiency of the signal. If a muscle is injured or diseased, it may not receive adequate signals and the test is designed to locate the abnormality.
The source of many areas of pain, numbness, tingling and weakness can be found using the EMG-NCV study,which can be of great help when diagnosing a patient’s discomfort and is a tool in determiningappropriate treatment.