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Symptoms and Diagnosis of CIS


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The symptoms associated with a clinically isolated syndrome (CIS) depend on where the damage to the myelin occurs in the central nervous system (CNS):

  • Spinal cord (partial or transverse myelitis): The onset may be sudden, developing over one to two hours, or more gradual, developing over one to two weeks. The specific symptoms experienced depend on which area of the spinal cord is affected and can include muscle weakness, abnormal sensations in the arms and legs, bladder and bowel problems or L’hermitte’s symptom, described as an electric shock sensation on movement of the neck.
  • Optic nerve (optic neuritis): Onset may be sudden or develop over a period of hours to days; symptoms include blurred vision vision loss (usually in only one eye), pain behind the eye, decreased color vision or blind spots.
  • Brainstem: Symptoms can include nausea, vomiting, double vision, dizziness, hearing loss and unsteady walking.

It is important to contact a neurologist if you are experiencing the symptoms listed above. The neurologist will want to determine if the cause of your symptoms is a condition that should be treated immediately. If it is determined that you do have CIS, your neurologist will be able to help you understand the probability of your condition progressing to MS.


In diagnosing CIS, it is important to rule out other potential causes as some may require immediate intervention. The process of diagnosis includes:

  • A complete medical history, including information about the specific symptoms and duration of the current episode
  • Neurological examinations
  • Magnetic resonance imaging (MRI) is used to look for signs of inflammation and demyelination (lesions) in the CNS
  • Blood tests are done to identify or rule out other potential causes for the symptoms
  • A lumbar puncture (spinal tap) may be performed to examine the fluid that surrounds the brain and spinal cord (CSF) for oligoclonal bands. The 2017 McDonald criteria for diagnosing MS allow for the presence of oligoclonal bands in a person's cerebrospinal fluid to help speed the diagnosis. 


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