What Is the Difference Between Clinically Isolated Syndrome and Multiple Sclerosis?

Medically Reviewed on 6/1/2022
clinically isolated syndrome
Not all individuals with a clinically isolated syndrome (CIS) develop multiple sclerosis (MS).

Clinically isolated syndrome (CIS) is often considered as a phenotype or phase of multiple sclerosis (MS).

The clinical symptoms of both CIS and MS look identical. Both are the conditions where the myelin sheath around the neuron is damaged (demyelination) and interferes with the transmission of nerve impulses from the brain. This results in various neurological symptoms.

But the differences between CIS and MS include:

Number of episodes of neurological symptoms

  • CIS is the first episode of symptoms caused by inflammation and demyelination in the central nervous system, whereas MS is characterized by several episodes and flare-up symptoms caused by demyelination.
  • CIS occurs as an isolated episode, and there is no certainty whether you may have another episode. However, MS is a lifelong condition. Once you are diagnosed with MS, you may have several episodes at any point in life, but these flare-ups are manageable with treatment.

Radiological changes

  • An MRI with CIS may show damage just in the area responsible for the current symptoms; an MRI with MS may show several lesions in different parts of the brain.

Diagnosis criteria

  • According to the 2017 modifications to the diagnostic criteria, the diagnosis of MS can be made only when there is an occurrence of another episode following CIS, and there should be MRI evidence of the second episode.
  • If oligoclonal bands are detected in the cerebrospinal fluid, it points toward the diagnosis of MS.

Can you assess the risk of early MS in patients with CIS?

The earliest presentation of multiple sclerosis (MS) is a clinically isolated condition. However, not all individuals with a clinically isolated syndrome (CIS) develop MS. A single faulty brain magnetic resonance imaging (MRI) identifies people who are at a higher risk of developing MS early; however, existing criteria are restricted by either inadequate specificity (T2 lesions) or sensitivity (contrast-enhancing lesions).

Studies conducted on serial images of MRIs of many patients with CIS increased positive predictive value, sensitivity, and specificity for the development of early MS. This also helped in identifying individuals who are at a lower risk of developing early MS.

Are there any common features between CIS and MS?

Both clinically isolated syndrome (CIS) and multiple sclerosis (MS) destroy the covering of the neurons (myelin sheath) in your brain and spinal cord. This disrupts the usual flow of neuronal messages in your body.

As a result, CIS and MS may exhibit similar symptoms, such as:

  • Numbness
  • Tingling
  • Vision difficulties
  • Difficulty walking and balancing
  • Dizziness
  • Bladder difficulties

CIS symptoms, such as an MS flare-up, last for at least 24 hours. Both disorders are more common in women, and they often manifest in individuals under the age of 50 years.


What Is Multiple Sclerosis? MS Symptoms, Causes, Diagnosis See Slideshow

What are the disorders associated with CIS?

Clinically isolated syndrome is connected with the following disorders and symptoms:

  1. Optic neuritis
  2. Transverse myelitis
    • The spinal cord is damaged in this disorder. Muscle weakness, numbness, and tingling, and bladder and bowel problems are also possible symptoms.
  3. Lhermitte’s sign
    • This sensation, also known as the barber chair phenomenon, is produced by a lesion on the top section of your spinal cord. You will experience an electric shock-like sensation from the back of your neck through your spinal column. This usually happens when you bow your neck downward.

How does treatment differ for CIS and MS?

The treatment depends on your condition and symptoms. When you are diagnosed to have multiple sclerosis (MS), you will be started on treatment immediately.

This is not the case with the clinically isolated syndrome. The symptoms may go away on their own, or you may be prescribed a steroid to help alleviate them. You may be wondering how to proceed with the treatment in long run.

If your assessment indicates higher chances of developing MS, then you will be advised by your doctor to start treatment for MS immediately. This is known as a disease-modifying treatment. Some studies reported that precautionary treatment may postpone the onset of MS and help avoid significant disability.

Medically Reviewed on 6/1/2022
Image Source: iStock image

Clinically Isolated Syndrome (CIS): https://www.nationalmssociety.org/What-is-MS/Types-of-MS/Clinically-Isolated-Syndrome-(CIS)

Clinically Isolated Syndrome: https://www.cedars-sinai.org/health-library/diseases-and-conditions/c/clinically-isolated-syndrome.html