Evoked Response Examinations

About the Examinations

Evoked response examinations measure conduction in the central nervous system by averaging the electrical response in the brain to a specific stimulus. These tests are non-invasive, free of complications, involve minimal discomfort to the patient and provide much useful information to the physician. The evoked responses measured at the Neurology Center office are named for the way in which the stimulus is presented: visual, auditory and somatosensory.

Visual Evoked Response (VER)

The stimulus for this examination is a reversing black and white checkerboard pattern, projected on a screen and watched by the patient. The patient must keep his/her gaze fixed on the center of the screen. This test takes about 45 minutes to complete. Please note: If you wear corrective lenses, either glasses or contact lenses, please wear them or bring them with you to the test.

Auditory Evoked Response (BAER)

In this test the patient listens to a rapid (10/second) clicking sound, presented by headphones to one ear at a time, while lying on an examination table. A blocking noise ("static") will be heard in the ear not being tested. This examination takes about 45 minutes routinely, but may run significantly longer with patients who have hearing problems.

Somatosensory Evoked Response (SER)

In this test a nerve at the wrist, ankle and/or behind the knee is stimulated with a mild electrical pulse. This may cause a pulsing or twitching sensation in the stimulated limb. This is the most time-consuming examination, taking two hours or more to accomplish. Please note: do not apply lotions to your skin on the day of the examination.

Prior to the Examinations:

In all three tests, the patient is connected to the measuring equipment by means of electroencephalographic electrodes. For this reason, hair sprays and treatments should not be used prior to an appointment for an evoked response examination.

In addition, since patient relaxation is essential for successful testing, it is advisable to allow ample time in personal schedules for these tests.