Evoked Potential Studies (EPs)

Evoked Potential Studies (EPs) are a group of non-invasive neurodiagnostic tests that measure the brain’s electrical responses to specific sensory stimuli.

purpose of tests

EPs help doctors evaluate how well certain pathways in the nervous system are working. They can detect delays or blockages in signal transmission caused by:

  • Multiple sclerosis (MS) and other demyelinating diseases

  • Spinal cord injuries

  • Brain injuries or tumors

  • Hearing or vision problems related to nerve function

  • Peripheral nerve disorders

Types of EP tests

  1. Visual Evoked Potentials (VEP):

    • You look at a screen with alternating checkerboard patterns or flashing lights.

    • Used to test the optic nerve and visual pathways.

  2. Brainstem Auditory Evoked Potentials (BAEP or BAER):

    • You listen to clicking sounds or tones through headphones.

    • Measures the response of the auditory nerve and brainstem.

  3. Somatosensory Evoked Potentials (SSEP):

    • Small electrical pulses are applied to the skin, usually on the wrist or ankle.

    • Records signals traveling through the peripheral nerves, spinal cord, and brain.

What happens during the test

  • Electrode placement: Small recording electrodes are attached to your scalp and sometimes other areas (like neck, arms, or legs).

  • Stimulation: The specific sensory stimulus (visual, auditory, or electrical) is applied.

  • Recording: The electrodes capture the brain’s response, displayed as waveforms on a computer.

  • Duration: Each type of EP typically takes 30–60 minutes.

what it feels like

  • VEP/BAEP: Completely painless—you just watch patterns or listen to sounds.

  • SSEP: You may feel a mild tapping or tingling from the small electrical pulses.

  • No needles are used.