What are Evoked Potential Studies
Evoked potential studies (EP studies) are used to check for abnormal delays in the brain’s response when a stimulus is applied to a specific part of the body. Various types of stimuli may be used in these studies depending on the part of the body being tested.
EP studies can be done to check for problems with the sensory pathway involved in sight, hearing, or touch. These studies are done for people who may have a disease or injury that affects the sensory pathway that transmits messages to the brain from the area of the body being tested.
EP studies are also helpful in determining if a problem is coming directly from a brain or nerve issue versus a psychiatric issue. The following are some examples of why an EP study may be done:
- An EP study of the eyes may be done to help diagnose multiple sclerosis, Parkinson disease, blindness, or lesions on the optic nerve.
- An EP study of the ears may be done to help diagnose hearing disorders, brain tumors, or brain stem lesions.
- An EP study of the legs or arms may be done to help diagnose spinal cord injuries, head injuries, or multiple sclerosis.
In an EP study, electrical activity in your brain is monitored by attaching electrodes to the outside of your skull. The steps of the procedure vary depending on the part of the body being tested.
Tell a health care provider about:
- Any allergies you have.
- All medicines you are taking, including vitamins, herbs, eye drops, creams, and over-the-counter medicines.
- Any problems you or family members have had with anesthetic medicines.
- Any blood disorders you have.
- Any surgeries you have had.
- Any medical conditions you have.
- Any illegal drug use.
What are the risks?
There are no risks or complications associated with this procedure.
What happens before the procedure?
- You may be instructed to wash your hair with shampoo the morning before the procedure.
What happens during the procedure?
- Gel will be put on parts of your scalp.
- Electrodes will be attached to your scalp in the areas where the gel was applied. These electrodes will also be attached to devices that will monitor the electrical activity in your brain.
- A
stimulus will be applied. The stimulus will vary depending on the area of
the body being tested:
- Eyes. You will be asked to look at a strobe light or a moving checkerboard pattern. A patch may be placed over one eye while the other is tested.
- Ears. You will be asked to wear earphones and listen to clicking noises or bursts of sound.
- Arms or legs. An electrical current will be applied to nerves in your wrist or knee.
- While the stimulus is being applied, the electrical activity in the appropriate area of your brain will be monitored to see how the brain responds.
What happens after the procedure?
- You may return to your normal activities unless your health care provider tells you otherwise.
- It is your responsibility to obtain your test results. Ask the lab or department performing the test when and how you will get your results.
