What is Clinical Isolated Syndrome?  Clinical Isolated Syndrome (CIS) is a collection of symptoms and findings that sometimes leads to the illness Multiple Sclerosis (MS).  To be diagnosed with CIS you must have an “attack” of symptoms, such as poor vision in one eye, numbness, weakness, or clumsiness, lasting 24 hours or longer, and it must be caused by demyelination.

Often the diagnosis of CIS is determined in conjunction with MRI testing. Demyelination can be found with this test. Normally the area of the body tested is the brain or the spinal cord.  When a person has more than 2 lesions that are similar to those found in MS (such as contrast enhancing and T2 / FLAIR lesions) there is a good chance that MS will be diagnosed in the next several years.  When the MRI studies show only 1 or no lesions, there is a lower chance that MS will be diagnosed.

A good example of a condition similar to CIS is optic neuritis.  We have a good understanding of the chances of developing MS after an attack of optic neuritis, based on the MRI findings. Patients with CIS who are at risk of developing MS are sometimes instructed to consider using medication to prevent future symptoms.  These medications are usually disease-modifying therapy like the kind that is used to treat MS.