Clinically Isolated Syndromes and the Relationship to Multiple Sclerosis

The most common presentation of multiple sclerosis (MS) is with a clinically isolated syndrome (CIS) affecting the optic nerves, brainstem or spinal cord. Two thirds of patients with CIS will have further episodes of neurological dysfunction and convert to relapsing-remitting MS, while the remaining patients have a monophasic illness, at least clinically. Abnormalities on a baseline MRI scan predict the subsequent development of MS in patients with CIS. In the long term, about 80% of patients with an abnormal MRI convert to MS compared with 20% with a normal MRI. For patients who develop MS the long term prognosis is varied. After 20 years, almost half will have developed secondary progressive MS, while around one third have a benign disease course with little physical disability. Disease-modifying treatments delay conversion to MS in selected CIS patients with abnormal MRI but an effect on long term disability has not been demonstrated. In this review we discuss recent advances in the diagnosis, management and prognostication of patients with CIS.