Evoked potential tests

Evoked potential tests are a safe and noninvasive way to measure how well your nervous system is working. These tests record electrical activity in your brain and spinal cord after you receive a specific stimulus, like a sound or a light. By tracking these signals, your provider can see how long it takes your brain to receive and respond to messages from your nerves. This evoked response can reveal changes along nerve pathways that may not show up during a standard neurological exam.

With the oldest neurology department in the nation, Penn Medicine has spent decades refining how we monitor the nervous system. Our laboratories have earned five elite accreditations for the highest technical and professional standards in the country. Our neurodiagnostics team performs thousands of evoked potential tests annually for people all over the nation who come to Penn Medicine seeking advanced tools and expertise. This high volume of testing gives us the clinical insight to make an accurate diagnosis with precision.

Evoked potential tests may be recommended if you have signs of nerve damage or unexplained symptoms like dizziness, vision loss, or a reduced sense of touch. While these tests are great at showing that something is wrong, they are typically used alongside other tools, like MRI scans, to confirm a diagnosis.

Sometimes, specialists use these tests during certain surgeries involving the brain, spine, or head and neck. By monitoring nerve signals in real time, surgeons can see how the nervous system is responding during a procedure. For example, during spine surgery, somatosensory evoked potential tests help the surgeon check whether a neural pathway is affected. This immediate feedback allows the surgical team to make adjustments right away, which can help prevent nerve damage.

An evoked potential test is usually done as an outpatient procedure and typically takes about one to two hours. During the test, small electrodes are placed on your scalp and sometimes on other parts of your body. You’ll either sit or lie down comfortably. Depending on the test, you may listen to sounds, watch visual patterns, or feel mild electrical pulses on your skin. These sensations may feel unusual, but they shouldn’t be painful.

The electrodes record how your brain reacts, which helps specialists analyze the timing and strength of the electrical signals. Unlike an EEG test, which records ongoing brain activity, an evoked response only looks at how your brain reacts to a specific stimulus. Once the test is finished, the electrodes are removed, and you can return to your normal activities.

There’s no recovery time needed after evoked potential tests. A neurologist with specialized training reviews the results, often the same day. They prepare a detailed report and share it with your provider, who will then talk with you about the results and what they mean for your care.