During the VEP test, electrodes are attached to the scalp as the patient stares at a pattern on a video monitor. One eye is tested at a time, and the procedure is about an hour long. For the SSEE test, electrodes are again placed on the scalp, but also along the spinal cord. Each extremity is tested separately, and this test can take up to three hours, depending on how extensive the testing is. Finally, in the BAEP test, electrodes are attached to both the scalp and ear lobes.
Patients have earphones placed over the ears and are tested by use of varying degrees of clicks.
Generally, this test runs about an hour, and each ear is tested separately. This is because demyelinated nerve fibers have a harder time sending signals. A drawback for these tests is that they do not identify the cause of any lesions. Blood tests can further rule out other disorders that mimic multiple sclerosis. Hopefully, as technology advances and creates more sensitive tools, perhaps there will be a day when a diagnosis of MS can be made with one simple test.