Electroencephalography (EEG) is a test that measures your brain wave activity. It is used to assess your brain function. Brain cells (or neurons) communicate by producing electrical signals. These signals are measured by the EEG and any abnormalities are detected.
The EEG is safe and painless.
What is EEG used for?
Your doctor may order this test to check for seizures or other brain problems. For this test, several small metal disks (electrodes) are attached to the scalp with adhesives, or with water-based gel or paste. During the test, wavy lines (waveforms) appear on a screen or on paper. They will be studied to assess your brain function. In some people who are prone to seizures, parts of this test may slightly increase their chance of having a seizure. Sometimes it is necessary to repeat an EEG with sleep deprivation. EEG may be performed in a doctor’s office or a hospital lab. The test typically takes less than an hour, although much of the time is spent attaching the electrodes.
Sometimes, the electrodes are left on for several hours or days so that the EEG test can record brain waves for a longer periods of time. In these cases, you may need to stay in the hospital or can go home with a portable EEG recorder.
Before your test
Prepare for your test as instructed. Wash and dry your hair. But, don’t use any hairstyling products. Your scalp and hair should be clean and free of excess oil. Take your routine medications, unless told not to. You may be asked to sleep during the EEG. To help you do this, you may be told to stay up all or part of the night before the test. Or, you may be given medication to help you sleep during the test. If so, someone will need to drive you home after the test. Your test will take about 60 minutes. Arrive with enough time to check in.
For your safety and for the success of your test, tell the technologist about:
– Any medications or herbs you take
– Any seizures you may have had in the past
EMG and NCS Tests
Electromyography (EMG) and nerve conduction studies (NCS) are tests that measure muscle and nerve function. In most cases, both tests are performed. NCS is most often done first. You will be asked to lie on an exam table with a blanket over you. You may have one or more of the following.
Nerve conduction study (NCS)
During NCS, mild electrical currents are used to test how fast impulses move along your nerves. Small metal disks (electrodes) will be attached to your skin on the area of your body being tested. This will be done using water-based gel or paste. A doctor or technologist will apply mild electrical currents to your skin. Your muscles will twitch, but the test won’t harm you. Currents are usually applied to the same area several times. Usually the intensity of the electrical stimulation is increased on each body part. Despite some increasing discomfort that varies from person to person, the electrical shock is not dangerous. The test may continue on other parts of your body unless the reason for doing the test is limited to a small part of the body.
Most of the electrodes will be removed for EMG. The doctor will clean the area being tested with alcohol. A very fine needle will be inserted into the muscles in this region. When the needle is inserted, you may feel as if your skin is being pinched. Try to relax and do as instructed, since you will be asked to relax and contract the muscle being tested. Following instructions will allow your doctor to interpret the test results. During each test, wavy lines (waveforms) appear on a screen or on paper. These lines show how well your nerves and muscles work. These waveforms help to determine your test results.
Before the test
Prepare for your test as instructed. Shower or bathe, but don’t use powder, oil, or lotion. Your skin should be clean and free of excess oil. Wear loose clothes. But know that you may be asked to change into a hospital gown. The entire test will take about 60 minutes. Be sure to allow extra time to check in.
Let the technologist know
For your safety and for the success of your test/ tell the technologist if you:
– Have any bleeding problems.
– Take blood thinners (anticoagulants) or other medicines/ including aspirin.
– Have any immune system problems.
– Have had neck or back surgery.
You may also be asked questions about your overall health.
After the test
Before you leave/ all electrodes will be removed. You can then get right back to your normal routine. If you feel tired or have some discomfort/ take it easy. If you were told to stop taking any medications for your test/ ask when you can start taking them again. Your doctor will let you know when your test results are ready.