What Is An Evoked Potential?

An evoked potential is the electrical response of the central nervous system created by an external stimulus. An evoked potential test ascertains the time it takes for the nerves to react to an external stimulation. These signals are recorded from the cerebral cortex, the spinal cord, the brainstem and the peripheral nerves.

The types of responses made by the nerves are as under:
• Visual evoked potential or response- This is done when the eyes are stimulated by observing a test pattern. This is a regularly used inducing potential test used to diagnose multiple sclerosis.
• Auditory evoked potential or response- This is related to the auditory nerves which are stimulated by listening to a test tone.
• Somatosensory evoked potential or response- This is done when the nerves of the legs and arms are aroused by an electrical pulse.

The responses are recorded from the brain with the help of electrodes fitted onto the scalp. The location of the electrodes applied on the scalp region depends on what kind of potential response the doctor wants to elicit.