The criteria for diagnosing relapsing-remitting MS require evidence of at least two separate areas of damage (“dissemination in space”) to the myelin in the central nervous system (CNS) that have occurred at different points in time (“dissemination in time”). In addition, the doctor must be able to rule out any other diseases that might be responsible for the person’s symptoms. Recent changes to these criteria allow the presence of oligoclonal bands in a person's cerebrospinal fluid to substitue for "dissemination in time," thereby speeding up the diagnostic process for many people.
When evidence of dissemination in time and space is clear from a person’s medical history and neurologic exam, the diagnosis may be made very quickly. Tests that may be used to help the physician confirm the presence of damage in the CNS include magnetic resonance imaging
(MRI), visual evoked potential
(VEP) testing, and analysis of the cerebrospinal fluid
that surrounds the spinal cord. People who have experienced only one episode of neurologic damage — known as a clinically-isolated syndrome
— may need to wait some time for a confirmed diagnosis of MS.