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More about Evoked Potential Studies:
Purpose Precautions Preparation Aftercare Normal results Abnormal results Resources |
Definition
Evoked potential studies are a group of tests of the nervous system that measure electrical signals along the nerve pathways.
Description
The person performing the test locates and marks specific spots on the patient's head for placement of electrodes. These spots are cleaned, and an adhesive conducting paste is applied. Cup electrodes are attached. For somatosensory EP, spots on the arm or leg are also marked and cleaned; electrodes may be taped in place. The patient sits or reclines in a chair throughout the tests.
For a visual EP, the patient focuses on a TV screen which displays a checkerboard pattern. The eye not being tested is covered with a patch. For children or others whose attention may wander, goggles are used which show the pattern to one eye at a time. Each eye is usually tested twice, and the entire procedure takes approximately 30–45 minutes.
For auditory EP, headphones are used to deliver a series of clicks to one ear at a time. A masking or static sound is played into the other ear. Each ear is usually tested twice, and the entire procedure takes approximately 30–45 minutes.
For somatosensory EP, mild electrical shocks are delivered to the arm or leg. This may cause some twitching and tingling. The stimulus lasts for about two minutes at a time, and the entire procedure takes approximately 30 minutes.
After the tests, the electrodes are removed with acetone and the scalp is cleaned.
— Richard Robinson
