The electroencephalogram (EEG) is a medical test used to measure the electrical activity of the brain, via electrodes applied to your scalp. An EEG can help diagnose a number of conditions, including epilepsy, sleep disorders and brain tumors. Another name for EEG is brain wave test.
Prior to Procedure:
Depending on the reason for your EEG, you may be given some of the following instructions:
- Shampoo your hair and do not use hairspray or gel the day of the test.
- If you are prone to seizures, arrange for a ride to and from the test.
The EMG (electromyogram) is a test that evaluates the electrical activity in nerves and muscles. This test is helpful to determine if abnormalities exist in the way nerves transmit electrical impulses and the effect this has on muscles. The EMG test consists of two parts:
- Nerve Conduction Study (NCS)
NCS – Nerve Conduction Study
Electrodes are placed on the arms and legs over the nerve to be studied. These electrodes act as microphones to pick up any electrical signal that goes by them. A computer is used to record responses as various nerves are tested. This allows the physician to measure and calculate how fast the nerve is sending the impulses to the muscle.
EMG – Electromyogram Test
The muscles are assessed by inserting a pin electrode into the muscle with the computer then recording the muscle potential. The sensation is similar to that of an injection that goes into the muscle as the pin electrode is inserted into the muscle. (That is if sensory awareness is not a problem.) It is important for the patient to stay as calm as possible to reduce discomfort and to achieve accurate readings.
A TCD test uses ultrasound waves to measure the blood flow rate and direction in the main (cerebral) arteries of the brain. It helps detect blockages, narrowing or spasms of the arteries.
The test does not involve the use of needles or injections. TCD is done with either one or two probes placed against the skin. The examiner spreads a clear gel on the areas of the head where the probe will be placed:
- On each side of your head.
- Under your chin.
- Over your closed eyelid.
- At the back of your neck.
In these places, there is the last amount of thick protective bone and the sound waves can penetrate the best. The examiner adjusts the probe position and orientation to direct the sound waves toward the blood vessels of interest. Finding the best approach may take some time. A compression test may be performed during the exam. In this test, the main artery in the neck (carotid artery) is briefly compressed, and changes in blood flow patterns are observed. A full TCD exam may last 30-45 minutes, and often longer in patients with disease.
The gel is washed off with soap and water. No other after care is needed.
Carotid Doppler ultrasound scanning is a painless way to show the amount of blood flow in the carotid arteries on each side of the neck that carries blood to the head. This picture allows your doctor to see if there is narrowing or blockage of your carotid arteries.