Evoked Potential Test
What is it?
An evoked potential test measures the
electrical signals sent by the brain when nerves
are stimulated. These are called evoked responses.
The most common types of evoked potential tests
are visual, auditory (hearing), and somatosensory,
which refers to the pathway of nerve impulses
between the limbs and the brain.
Who needs this procedure?
Evoked potential tests can be used to diagnose
diseases of the nervous system, such as multiple
sclerosis, that affect the patient’s response time
because of damage to the nerves. They are also
used to diagnose hearing loss, vision loss caused
by optic nerve damage, and to test brain response
in infants and abnormal electrical discharges in
people with epilepsy.
How do I prepare for this procedure?
Your hair should be clean and dry, and free of
any styling products, barrettes, or hairpins. Your
physician will advise you if there are any
medications you shouldn’t take the day of the
test.
How is this procedure performed?
To perform an evoked potential test, the
healthcare professional will place wires, called
leads or electrodes, on the skin in the areas
where the nerves will be tested. The wires are
attached to clean skin with a paste that conducts
the signal or may be taped in place. Then, the
healthcare provider will use a stimulus to test
the brain’s response. For example, a visual evoked
potential test may use flashes of light or
patterns; an auditory test would use sounds pumped
through headphones; and a somatosensory test would
use a mild electrical shock that feels like a
small tingle. A computer measures the brain’s
response to the stimuli, and analyzes and
pinpoints the location of any nerve damage. The
test takes about 30 minutes.
What can I expect after the procedure?
An evoked potential test has no lasting effects
and will not have an impact on any of your regular
activities. Your doctor will advise you of the
test results after they have been read and
analyzed.
Self-care tips
Follow your doctor’s recommendations for any
necessary treatment.
This information has been designed as a comprehensive and quick reference
guide written by our health care reviewers. The health information written
by our authors is intended to be a supplement to the care provided by your
physician. It is not intended nor implied to be a substitute for
professional medical advice.
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