Neuodiagnostic Testing ElectroneurodiagnosticsElectroneurodiagnostics is the study and recording of electrical activity in the brain and nervous system. The tests are performed by technologists who record information on paper or computer and the results are interpreted by a specially trained physician. This brochure explains some of the most common tests. Evoked Potential (EP) The EP is a recording of electrical activity from the brain, spinal nerves or sensory receptors in response to specific external stimulation. Electrodes are applied to the scalp and other areas of the body, a series of stimuli is introduced and a computer records the neurological responses. Hundreds of responses are received, amplified and averaged by a computer. The final response is plotted on a graph and interpreted by a physician who looks for particular waveforms and the time it takes them to occur. Evoked potentials are helpful in evaluating a number of different neurological problems, including spinal cord injuries, acoustic neuroma and optic neuritis and each type of EP looks at a different neurological pathway. The three most common types are the brainstem auditory evoked response (BAER), the visual evoked response (VER) and the somatosensory evoked response (SSER).
Preparation for Evoked Potential Please have clean hair, free from oils, hairsprays, or excessive hair products. If you have braids, hair pieces, or other hair accessories or styles that may interfere with the technologist applying the electrodes on your scalp, please call the office to speak with a technologist about your options. The number they can be reached at is (989) 907-8959 ext 1. If you are taking any medication, continue to do so unless your doctor tells you not to. It is important for you to be as relaxed as possible during the test. If you move around, it will interfere with the recording. Wear comfortable clothes. A young child may bring a favorite blanket or a small doll. Electroencephalogram (EEG) An EEG records the electrical activity of the brain. Highly sensitive monitoring equipment records the activity through electrodes that are placed at measured intervals on a patient's scalp. For the patient, the test is not painful. The head is measured and the electrodes are placed on the scalp with a paste-like substance. The test itself usually takes about 90 minutes and the principle role of the patient is simply to remain still, relaxed and comfortable. During the test, the patient may be asked to take repeated deep breaths (hyperventilate) and may be shown a strobe light that flashes at different speeds. Both activities can help reveal different brain patterns that are useful for a diagnosis. Sometimes, physicians also want to observe brain patterns that occur during sleep. For sleep test, the patient may be asked to stay a wake most of the night prior to the EEG appointment or in some cases may be given a mild sedative. EEGs assist physicians in the diagnosis of a variety of neurological problems, from headaches and dizziness to seizure disorders, strokes and degenerative brain disease. The EEG is also used to look for organic causes of psychiatric symptoms and disabilities in children and can assist physicians in determining irreversible brain death. 24-72 Hour Ambulatory EEG The ambulatory EEG records brain activity for a period of 24 -72 hours on a portable recording device. This portable carrying device is kept within a protective carrying case that is worn by the patient for the duration of the test. Electrodes are applied to the scalp with a glue-like substance and the patient is sent home with a diary to record activities and any symptoms during the 24-72 hours. Preparation for EEG Please have clean hair, free from oils, hairsprays, or excessive hair products. If you have braids, hair pieces, or other hair accessories or styles that may interfere with the technologist applying the electrodes on your scalp, please call the office to speak with a technologist about your options. The number they can be reached at is (989) 907-8959 ext 1. If you are taking any medication, continue to do so unless your doctor tells you not to. It is important for you to be as relaxed as possible during the test. If you move around, it will interfere with the recording. Wear comfortable clothes. A young child may bring a favorite blanket or a small doll. Electromyography (EMG) EMG is a diagnostic medical examination and is not a treatment for any illness. EMG is a test used to detect and diagnose disorders of muscles, nerves and the spinal cord. It is a sensitive and precise test that can detect pinched nerves or nerve damage due to injury, ruptured disc or other causes. EMG records the electrical activity of muscles. This activity is shown on a screen and can actually be heard during the test; it sounds much like static. A tiny needle (called an electrode) is inserted in the various muscles being tested. You may have some temporary, mild discomfort. You will be asked to lie down and relax during the test, since normal and abnormal findings are easier to locate in relaxed muscles. You may talk and ask questions during the examination. Areas to be tested will be cleansed with rubbing alcohol. The physician who performs the test will check muscles and nerves that are affected. Frequently the normal side may have to be checked for comparison. The test usually takes about 45-60 minutes. There are no after effects and you may resume all of your usual activities. Nerve Conduction Study (NCS) The NCS records electrical signals from the nerves and muscles. This is done by placing an electrode on the skin and giving the nerve a weak electrical stimulation. You will have a slight, temporary prickling feeling. The test is helpful in diagnosing various nerve disorders such as carpal tunnel and diabetic neuropathy at various sites on the arms, legs or back. Preparation for EMG and Nerve Conduction Study. No special preparation is necessary. You may take your normal medications, including pain medication. If you are on a blood thinner or have a cardiac pacemaker, please mention this to the physician prior to the test. Electroneurodiagnostic Monitoring in the Operating Room Evoked potentials can provide a means of monitoring the spinal cord, brainstem, optic nerves, and cerebral cortex function during surgeries placing those neural structures at risk. Cranial nerve function can also be monitored with spontaneous electromyographic activity and direct cranial nerve stimulation during surgeries involving the skull base, trigeminal neuralgia and acoustic neuromas. The main function of intraoperative evoked potentials is to identify new neurologic impairment early enough to allow prompt correction of the cause. Impairment may be caused by such correctable factors as excessive retraction of nervous system structures, circulatory or systemic impairment resulting in ischemia or anoxia, or mechanical stretching of the spinal cord or cortex. Some of the most commonly performed surgeries utilizing evoked potentials are cervical spine fusions and laminectomies, spinal cord and brain tumors, cerebral aneurysms and thoracolumbar spine stabilizations. |
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800 South Washington Avenue · Saginaw, MI 48601-2524
(989)907-8000 · 1-800-STMARYS |
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