Evoked potentials (EP) (a.k.a. evoked response testing) are tests that record the speed it takes for a nerve signal to completely reach the brain. EP tests can identify the type of study that is recorded by taking the average of EEG activity after the patient is presented with a stimulus. EP tests can be carried out using somatosensory, auditory, or visual stimulation of nerves of the legs or arms.

EP tests are specifically useful because they can locate damage along the neural pathways that may not be detected during a regular neurological examination. EP tests are one of several types of examination used to diagnose a neurologic condition.

There are 3 primary types of evoked potential tests, which are as follows:

Brainstem Auditory Evoked Response (BAER): A BAER test measures the electrical signals that the auditory pathway in your brain creates when certain sounds are heard. This test aids in the diagnosis of neurologic abnormalities of the brainstem, auditory pathway, and auditory nerve and brainstem.

Visual evoked potential (VEP): A VEP test measures the electrical signals that the visual cortex creates in response to visual stimuli. This test aids in diagnosing Multiple Sclerosis (MS), as well as diagnosing issues with the visual pathway, specifically the optic nerve.

Somatosensory evoked potential (SEP): A SEP test can identify damage within the brain and spinal cord. This test measures the brain’s response to mild electrical shocks in various locations on the body. This test is used to determine the amount of time it takes for a nerve signal to travel from the peripheral nerves, through the spinal cord, to the brain.

The primary difference is that an EEG gauges and records the brain’s electrical signals as they normally occur, whereas an evoked potential test measures how quickly the nerves respond to stimulation.