Clinically Isolated Syndrome (CIS)

What is Clinically Isolated Syndrome (CIS)?

Clinically Isolated Syndrome (CIS) is a neurological condition characterized by the first clinical manifestation of demyelination within the central nervous system. It is the initial presentation of an underlying cause such as multiple sclerosis (MS). CIS is usually caused by a single inflammatory or demyelinating event in the white matter of the central nervous system.

CIS is often marked by the appearance of symptoms that can’t be explained by any other condition. Common symptons of CIS can include vision changes, tingling and numbness, balance problems, muscle weakness, and bladder control problems. Without further supportive evidence, however, these symptoms may be difficult to distinguish from other conditions or may be considered non-specific.

Diagnosing CIS

CIS is most often diagnosed using MRI imaging, which can reveal changes in the white matter in a person’s brain that are associated with demyelination. Other testing such as lumbar puncture and evoked potential studies can also be used to confirm the diagnosis. A physician may also perform a complete medical history and physical examination to look for any other contributory factors.

In some cases, a person may experience symptoms of CIS but have an MRI results that are seen as inconclusive. In this case, the diagnosis of CIS is considered an exclusion diagnosis, which means that other causes have been ruled out and the most likely cause of the symptoms is CIS.

The Outlook for People with CIS

Although some people with CIS eventually develop MS, the majority don't. Up to 90% of people with CIS may remain free of a definitive diagnosis of MS up to 10 years after the first CIS episode. As such, CIS is considered to be a self-limiting illness. This means that about 90% of people with CIS will experience spontaneous remission, with no progression.

For those who eventually develop MS, the disease generally follows a typical course. Common MS treatments, such as medications, physical therapy, and lifestyle modifications, can help people manage their individual symptoms and improve their quality of life.