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Clinically isolated syndromes suggestive of multiple sclerosis

Michael J Olek, DO
Section Editor
Francisco González-Scarano, MD
Deputy Editor
John F Dashe, MD, PhD


A clinically isolated syndrome (CIS) is a first symptomatic episode compatible with demyelination or multiple sclerosis. In a radiologically isolated syndrome (RIS) an individual presents without overt clinical symptoms but with MRI findings highly suggestive of multiple sclerosis [1]. CIS and RIS can create diagnostic and therapeutic dilemmas, since a substantial percentage of patients with CIS and MRI lesions go on to develop multiple sclerosis.

This topic will discuss the clinical features, evaluation, and management of CIS and of RIS suggestive of multiple sclerosis.

Other aspects of multiple sclerosis are discussed separately. (See "Diagnosis of multiple sclerosis in adults" and "Clinical features of multiple sclerosis in adults" and "Disease-modifying treatment of relapsing-remitting multiple sclerosis in adults" and "Treatment of progressive multiple sclerosis in adults" and "Symptom management of multiple sclerosis in adults" and "Optic neuritis: Pathophysiology, clinical features, and diagnosis" and "Optic neuritis: Prognosis and treatment".)


A clinically isolated syndrome (CIS) is defined as the first clinical episode that is suggestive demyelination or of multiple sclerosis, lasts at least 24 hours, and occurs in the absence of fever, infection, or encephalopathy [2]. The typical patient with a CIS is a young adult with a single episode of central nervous system dysfunction followed by at least partial resolution. Symptoms usually develop over the course of hours to days and then gradually remit over the ensuing weeks to months, though remission may not be complete.

In contrast, a radiologically isolated syndrome (RIS) is defined by incidental brain or spinal cord MRI findings that are highly suggestive of multiple sclerosis, based upon location and morphology within the central nervous system, in an asymptomatic patient lacking any history, symptoms, or signs of multiple sclerosis [1]. Typically the MRI has been obtained for a completely unrelated condition such as headaches or an episode of trauma.

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Literature review current through: Dec 2017. | This topic last updated: Jul 27, 2017.
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