What is Electro diagnostic Testing (EMG/Nerve Conduction Studies)?
This is a test that your physician may order for further evaluation of any numbness, tingling or progressive weakness that you may be experiencing in your extremities. The testing is performed by a COMG physician with specialized training, typically a Physiatrist (Physical Medicine and Rehabilitation) or a Neurologist. The test typically involves two procedures, Nerve Conduction Testing (NCS), and Electromyography (EMG). The testing usually takes between 60-90 minutes to complete depending on the thoroughness and extent of the exam and the problem being evaluated.
Some common reasons that your physician may order electro diagnostic testing for include: pinched nerves in your neck or back, carpal tunnel syndrome, peripheral neuropathy, sciatica, and numbness or weakness of an arm or leg. The testing can provide information on the presence or absence of nerve injury, as well as the extent, location, and duration of the injury. This information can then be used to accurately diagnose a problem and direct proper treatment.
What is a Nerve Conduction Study (NCS)?
A nerve conduction study is a neurological test that evaluates the conduction of electrical impulses down nerves. Because nerves conduct signals at a standard speed and amplitude (size), diseases of the nerves which may alter these impulses can be detected by measurement of these signals.
The nerve conduction study is performed by placing soft gel pads or metal electrodes over the course of specific nerves in the arms and/or legs. The nerves are then stimulated with a brief electric impulse that most patients describe as a mild shock-like sensation. The information is then recorded by the electrodes on your skin and interpreted by the physician.
What is an Electromyogram (EMG)?
An electromyogram (EMG) is a test that evaluates the responses of muscles and the nerves that supply them. It is performed by inserting a very fine needle, that has a specialized recording electrode at the tip into various muscles, and recording the signals that those muscles and corresponding nerves generate. Most patients report minimal, temporary discomfort during the procedure. Disposable needles are used so there is no risk of infection.
The EMG provides the physician with information about the functioning of both the muscle and the nerves that supply that muscle. The different signals that are recorded help the physician detect normal tissue as well as certain types of injury to muscles and nerves.
How Should I Prepare For This Test?
Electro diagnostic testing is extremely safe. A patient may experience some temporary discomfort during or after the exam but there are no permanent after-effects.
There are no activity restrictions before or after the test. Patients can eat before the exam and should take their usual medication. It is best to not apply any lotions or creams to the skin on the day of the exam as this can prevent the electrode from sticking to the skin.
You should notify the physician performing the exam if you are on blood thinners or have a pacemaker or implanted defibrillator, but generally these are fine for electro diagnostic testing.
Electrodiagnostic studies are done assess the function of the nerves and muscular response to electrical impulses. – View Video