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What is Clinically Isolated Syndrome?

August 30, 2016

Clinically isolated syndrome (CIS) refers to the first episode of neurologic symptoms that are experienced by a patient, it is often a sign of multiple sclerosis. Usually lasting at least 24 hours, it’s related to an inflammation or demyelination in the central nervous system. 

A multifocal episode of CIS is when a patient experiences more than one sign or symptom due to lesions in more than one location, and a monofocal episode occurs when only one sign or symptom is experienced, caused by a single lesion. The symptoms being referred to may include an attack of optic neuritis accompanied by numbness or tingling in the legs. After experiencing these episodes, patients often experience a full or partial recovery and they are usually unrelated to fever or infection.

CIS can occur to both men and women at any age, but it is twice to three times more likely to occur in women than in men. While clinically isolated syndrome is associated with multiple sclerosis patients, being diagnosed with it does not mean you have MS. Although many of the symptoms are similar such as numbness, blurred vision, muscle spasms and more, it is because both CIS and MS occur when demyelination interferes with the normal function and transportation of nerve impulses from the brain. This is what causes these neurologic symptoms.

The difference is that CIS refers to the first episode of symptoms and a patient with MS experiences more than one episode. MRI scans of CIS patients show damages only in the area that caused the symptoms while MS patients MRI scans show multiple lesions in different parts of the brain.