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Diagnostic Tests – Evoked Potentials

Evoked potential tests measure brain activity.  These tests measure how fast sensory information (such as a pin prick to the hand or a flash of light in the eye) reaches the brain. There are three different evoked potential tests: brainstem auditory (BAEP), somatosensory (SSEP), and visual (VEP). BAEP can detect lesions on the brainstem. SSEP can detect lesions on the brain, brainstem, and spinal cord. VEP can detect lesions on the optic nerve (the nerve that connects the eye to the brain).  These lesions are signs of Multiple Sclerosis. Evoked potentials tests are painless and last about 30 minutes. Electrodes are attached to the patient’s scalp. For a VEP test, the patient is told to look at a picture or a flashing light. For a BAEP test, the patient is given a pair of headphones to wear and clicking sounds are played. For a SSEP test, the electrodes are attached to the patient’s wrists or ankles.  A machine is then used to detect brain activity. Additional resources that provide more information on Evoked Potentials: Evoked Potentials Studies (Medical University of South Carolina) Evoked Potential in Multiple Sclerosis (Cleveland Clinic) Evoked Potentials (National Multiple Sclerosis Society)