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Evoked Potentials (EP)

At WakeMed, we use evoked potentials, also called evoked responses, to measure how quickly a nerve responds to sight, sound or sensation. Evoked potentials help with diagnosing neurological disorders, including multiple sclerosis and spinal cord injury.

You can expect the highest level of patient-focused care — we understand how life-changing neurological conditions can be for patients and their families. Our neurologists, nurses, technologists and staff share the common goal of providing personal care customized to the needs of each patient.

When to Expect Evoked Potentials Testing

We perform evoked potentials in both surgical and laboratory settings.

  • In surgery, a patient may need the test while undergoing spinal procedures, so the surgeon can check to see if the neural pathway is affected.
  • In the neurodiagnostic lab, we use the test to check the nerves in patients who are experiencing hearing, vision and/or sensory symptoms that could be related to nerve damage or injury. We can also test nerves in limbs for numbness.

What to Expect from Evoked Potentials

In evoked potentials testing, the specialist places electrodes on the patient’s scalp to record the response of the nerve. The responses are tracked by the time that the stimulation was applied and the speed at which the patient responds. This provides valuable insight into the functionality of the nerve.

In surgery, these tests are done while the patient is under anesthesia. When performed in our cutting-edge neurodiagnostic lab, the specifics of how the evoked potentials are performed is based on the symptoms the patient is experiencing.

  • In hearing loss, patients undergo an auditory brain stem evoked potential using a series of test tones. Patients are fitted with earphones to provide a hearing pathway.
  • In cases where patients have vision loss, a visual evoked potential is done to determine how patients respond to test patterns on a video screen.
  • In situations where there’s an issue in the arms or legs, we perform somatosensory potential by connecting a tiny electrode to a nerve in the arms or legs to check for function. The nerves are then stimulated by the electrical pulse.

These tests can take anywhere from 30 minutes to a couple of hours, depending on the area being tested.

How to Find Us

Our testing is performed in our three WakeMed Neurodiagnostic Labs.

  • Raleigh Campus, which is located on the 1st floor of the Medical Office Building
  • Cary Hospital, 1900 Kildaire Farm Road, Cary, NC 27518, located in the Cardiopulmonary testing area

More Information and Referrals

We welcome new patients. If you’d like to receive more information about Evoked Potentials testing at WakeMed, please call us at 919-350-3734. If you are a physician referring a patient, please call us at 919-350-7000.


  1. At Outpatient Registration, turn right and follow the hall to the first intersection.
  2. Turn right and walk towards Mental Health and Well-Being.
  3. Look to the left for the elevators, and at the end of the elevator hallway, you will locate the “Neurodiagnostics” door sign.


  1. At Outpatient Registration, veer to the left towards Same Day Surgery. Continue left and follow the hall to the first intersection.
  2. Turn right and walk towards the Cardiopulmonary department.
  3. Neurodiagnostics is located in the Cardiopulmonary testing area.