Clinically Isolated Syndrome


Clinically isolated syndrome (CIS) is a possible diagnosis for patients who experience an episode that may represent the onset of  multiple sclerosis (MS), a disease of the central nervous system, or may represent an isolated episode that does not require ongoing treatment.

The episode may only affect one area of the central nervous system (monofocal), or multiple areas (multifocal). An experienced medical team, such as the one at Cedars-Sinai Multiple Sclerosis Center, will determine if the episode of symptoms is an indication of multiple sclerosis, and whether the patient is at a high or low risk of developing the disease.


Symptoms of CIS are similar to those of an MS relapse. The main difference between the two conditions is patients with CIS experience only one episode, while MS patients experience multiple episodes.

Symptoms of CIS include:

  • Numbness or tingling
  • Vision problems, such as double vision
  • Spasticity or stiffness of the muscles
  • Difficulty controlling the bladder or bowels
  • Difficulty with walking and coordination
  • Muscle weakness
  • Paralysis
  • Dizziness
  • Shakiness
  • Sexual dysfunction

Causes and Risk Factors

Patients with CIS tend to be diagnosed between the ages of 20 and 40, but the condition can occur at any age.

Since the risk of MS is significantly higher when a parent has been diagnosed with the disease, genetic factors may play a role. The unusual relationship between a person's geographic location during childhood and the risk of MS later in life suggests there may be environmental factors at work in the the risk of CIS or MS.


Diagnosis of CIS begins with the physician taking a detailed medical history and performing a neurological examination. Because CIS can have similar symptoms of other nervous system disorders, diagnostic tests will help rule out other causes and confirm a diagnosis. These tests may include a magnetic resonance imaging (MRI) scan of the brain and spinal cord.

The patient's medical team may order a lumbar puncture, also known as a spinal tap, along with cerebrospinal fluid analysis and nerve function tests. Blood tests may be performed to rule out other conditions that have similar symptoms.

Patients diagnosed with CIS will have routine checkups to determine if their condition is progressing toward MS.


There is no cure for CIS. The FDA has approved medications to manage the symptoms of certain types of MS and patients diagnosed with high-risk CIS may be prescribed one or more of these to delay the onset of MS and manage symptoms. These medications may be used to reduce the frequency and severity of episodes a patient experiences.

Choosing the right medication requires careful consideration of the risks and benefits, along with close collaboration with an experienced neurologist with experience in treating the disease, such as those at the Cedars-Sinai Department of Neurology.

© 2000-2022 The StayWell Company, LLC. All rights reserved. This information is not intended as a substitute for professional medical care. Always follow your healthcare professional's instructions.
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