Evoked Potential Testing
Arriving for your appointment
▪ There are volunteers at the main information desks who can direct you.
▪ Your appointment is in the EEG lab, J module/ 2nd floor.
▪ Please stop and register 15 minutes before your scheduled visit. Registration is on the main
floor as you make your way on ‘Main Street’ to the EEG lab in the J module. Follow ‘Main
Street’ towards the H module. Registration will be on your right hand side. After
registration, continue right on ‘Main Street’ through the H elevator lobby to the J lobby.
Please check in at the desk.
What is Evoked Potential Testing
This test measures how well the nerves in your body send messages to your brain. This is done
by stimulating nerves and viewing nerve pathways in action.
Small metal disks will be placed on your scalp on the areas lying over the parts of the brain being
stimulated. These disks will be held in place using special glue, made just for this test. Sound,
light, or sensation is used to excite your nerves. This causes information to be sent along nerve
pathways. Waveforms are measured on a computer from certain spots on the body as the
messages pass by on their way to the brain. How quickly or slowly messages reach different
spots on the body may help your doctor find damaged areas in your nerves.
This test should not be painful.
Types of Evoked Potential Tests
Visual Evoked Potential (VEP)
Five disks will be placed on your scalp. You will have a patch placed over one of your eyes.
There will be a checkerboard screen placed a few feet in front of you. You will be asked to gaze
at the middle of the screen. The checks will reverse back and forth from black to white. A
number of trials will be done on each eye. Please bring any glasses or contacts that you use.
Brainstem Auditory Evoked Potential (BAEP)
Two disks will be placed on your scalp. One disk will be placed behind each ear. You will lie
down on a bed while wearing headphones. In one ear you will hear a clicking sound and in the
other a constant static noise. A number of trials will be done for each ear.
Somatosensory Evoked Potential (SSEP)
Your doctor may order this test for either your arms, legs or both. Disks will be placed on your
scalp, spine, arms, or legs. While you are lying on a bed, the technologist will apply a mild
electrical current to the nerves in your wrists and ankles. You may feel your muscles twitch.
This test will not harm you. A number of trials must be done on each arm or leg.
Before your test
Eat your normal meals.
Take any needed medicine, unless your doctor tells you not to.
Wear loose fitting clothes.
Arrive 15 minutes before your scheduled test time.
During your test
Testing will take about 1 hour to complete. If we are doing all 3 tests, please plan on spending
your whole morning or afternoon with us.
After your test
Your doctor will have the test results of the EEG within 7-10 days.
If you have any questions, or if you need to change the date or time of the test, please call.
EEG lab at (608) 263-8483. If you live out of the area, call 1-800-323-8942. Ask for the EEG
Your health care team may have given you this information as part of your care. If so, please use it and call if you
have any questions. If this information was not given to you as part of your care, please check with your doctor. This
is not medical advice. This is not to be used for diagnosis or treatment of any medical condition. Because each
person’s health needs are different, you should talk with your doctor or others on your health care team when using
this information. If you have an emergency, please call 911. Copyright © 10/2015 University of Wisconsin Hospitals
and Clinics Authority. All rights reserved. Produced by the Department of Nursing. HF#6572