Neurology Definitions

Electromyography (EMG)
Generally this test is ordered to assess the function of muscles and nerves; usually in the arms and legs. Common symptoms for which doctors order EMG's include: muscle tingling or numbness, muscle weakness or fatigue (tiredness), etc. If you have any doubts as to why you might be undergoing EMG, please discuss the specific reason with your doctor. The EMG will help your doctor figure out if the muscles and/or nerves in question are functioning properly.

The EMG is usually performed by a Neurologist or a Physiatrist (rehabilitation and physical therapy specialist). EMG is an office procedure and usually does not require hospitalization or special preparation. Most EMG's consist of two parts, and take about one hour to perform. Although certain aspects of the procedure may not sound too enjoyable, the EMG is generally very well tolerated.

The first component of an EMG is called a nerve conduction study. During this portion of the test, brief electrical shocks are delivered to your arm or leg in an effort to determine how well your nerves conduct electrical current. In order to accomplish this, the doctor will attach small recording electrodes to the surface of one part of your limb, and then touch your skin at another point with a pair of electrodes. When this happens, you will feel a brief tingling that may or may not be painful. The amount of current delivered is always kept at a safe level. Generally, the EMG is safe for patients wearing pacemakers or other electrical devices. Note that during the nerve conduction study, the doctor or the technician performing the study will occasionally be pausing to make calculations and measurements.

The second part of the test is the actual EMG. This part of the exam involves placing a fine (thin) needle into muscles just beneath the skin. The needles are designed to minimize discomfort. Once the needle is in place, you will be able to hear the sound of the muscle activity amplified by the EMG machine; it will sound something like radio static, which will change as certain muscles are moved. During the needle exam, no electrical shocks are delivered.

While only a few medications interfere with the EMG test, you should talk to your doctor if you have specific questions as to whether or not you should take prescription or non-prescription medications as the time for your test approaches. Some physicians recommend you take two Aspirins or Tylenols before the test; others may prescribe a drug to take an hour before the test.

The physician performing the test may have a general idea of what the findings are during the test; however, the complete results are usually not available until the following day. Your doctor will discuss the results of your test with you once he or she has the complete results.

Electroencephalography (EEG)
How the test is performed:

The test is performed by an EEG technician in a specially-designed room that may be in the health care provider's office or in the hospital. You will be asked to lie on your back on the table or in a reclining chair. The technician will apply between 16 to 25 flat metal discs (electrodes) in different positions on your scalp. The discs are held in place with a sticky paste. The electrodes are connected by wires to an amplifier and the recording machine. The recording machine converts the electrical signals into a series of wavy lines which are drawn onto a moving piece of graph paper. You will need to lie still with your eyes closed because movement can alter the results. You may be asked to do certain things during the recording, such as breathe deeply and rapidly for several minutes or look at a very bright flickering light.

How to prepare for the test:

You will need to wash your hair the night before the test. No oils, sprays or lotions should be used in your hair. The health care provider may want you to discontinue some medications before the test. You should avoid all foods containing caffeine for 8 hours before the test. Sometimes it is necessary to sleep during the test, so you may be asked to reduce your sleep time the night before.

The results of your EEG are interpreted by a neurologist, a physician trained in the area of the nervous system. The results are then sent to your physician who uses them along with your medical history and other test results to make a diagnosis and determine the treatment you need.


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