Evoked Potential

What is an Evoked Potential?

An Evoked Potential is a recording of electrical activity from the brain, spinal nerves or sensory receptors in response to specific external stimulation. Electrodes are applied to the scalp and other areas of the body. A series of stimuli is then introduced and a computer records neurological responses to the stimuli. Hundreds of responses are received, amplified and averaged by the computer. The final response is plotted on a graph and interpreted by our neurologists who look for particular waveforms and the time it takes for them to occur. The three most common types of Evoked Potentials are the Brainstem Auditory Evoked Response (BAER), the Visual Evoked Response (VER), and the Somatosensory Evoked Response (SSER).

Why are Evoked Potentials important diagnostic tools?

Evoked Potentials are helpful in evaluating a number of different neurological problems, since each type of EP looks at a different neurological pathway. Evoked Potentials evaluate the functioning of neuroanatomical pathways in the brain, brainstem and spinal cord without using invasive devices or needles.

What happens during an Evoked Potential Test?

Brainstem Auditory Evoked Response (BAER): The BAER assists in evaluating the auditory nerve pathways from the ears through the brainstem. Electrodes are attached to the scalp and earlobes and earphones are placed over the ears. The earphones deliver a series of clicks or tones to each ear separately.

Visual Evoked Response (VER): The VER evaluates the visual nervous system from the eyes to the occipital (visual) cortex of the brain. Electrodes are applied to the scalp. Patients are usually asked to stare at a pattern on a video screen while remaining fully alert. Each eye is tested separately.

Somatosensory Evoked Response (SSER): The SSER assesses pathways from nerves in the arms or legs, through the spinal cord, to the brainstem or cerebral cortex. Electrodes are placed on the scalp and along the spinal cord and a small electrical current is then applied to the skin overlying nerves on the arms or legs. The current creates a tingling sensation, but is not painful. Each leg or arm is tested separately.

How should I prepare for the Evoked Potential Test?

Wash your hair and scalp before the test. Do not use conditioner, hairspray, gels mousse or oils. Wear loose fitting, comfortable clothing (no turtlenecks, please). Allow approximately one hour for each test.

How will I feel after the test?

Our technician will remove the electrodes and cleanse your scalp of the adhesive. You may want to wash your hair again when you get home. Your diet and activities should not be affected. Please ask your doctor or technician if you have any questions.

Which of your locations offer Evoked Potential testing?

Evoked Potential tests are conducted at our Golden Valley and Coon Rapids locations.