Clinically isolated syndrome (CIS) and multiple sclerosis (MS) may appear the same if the diagnosis is based on clinical symptoms alone.
Clinically isolated syndrome (CIS) is a noncontagious initial presentation of a disease with characteristics of inflammatory demyelination. This has not yet demonstrated dissemination in the time required for the diagnosis of multiple sclerosis (MS).
The episode of CIS lasts for at least 24 hours. It usually has no association with fever or other infections and is followed by a complete or partial recovery.
CIS is a condition with symptoms quite similar to multiple sclerosis. CIS is a single episode (lasting at least 24 hours), whereas MS is a life-long disease.
Symptoms of CIS depend on the location of damage to the myelin in the central nervous system (CNS).
3 parts of the CNS that present with symptoms
- Spinal cord (partial or transverse myelitis)
- The onset may be sudden (developing over one to two hours) or gradual (developing over one to two weeks).
- The specific symptoms experienced depend on the area of the spinal cord affected and may include:
- Muscle weakness, stiffness, or spasticity
- Numbness and tingling
- Abnormal sensations in the arms and legs
- Bladder and bowel problems
- Lhermitte’s sign or barber chair phenomenon (an electric shock sensation on the movement of the neck)
- Optic nerve (optic neuritis)
- Onset may be sudden or develop over hours to days including:
- Blurred vision
- Loss of vision (usually in only one eye)
- Pain behind the eye
- Decreased color vision or blind spots
- Onset may be sudden or develop over hours to days including:
- Brainstem
- Symptoms may include:
- Nausea
- Vomiting
- Double vision
- Dizziness
- Hearing loss
- Unsteady walking
- Difficulty balancing and coordinating
- Symptoms may include:
What is a clinically isolated syndrome?
Clinically isolated syndrome (CIS) refers to the first episode of neurologic symptoms that are caused by inflammation or demyelination (loss of the myelin sheath that covers the nerve cells) in the central nervous system (CNS).
Seventy percent of people diagnosed with CIS are aged 20 to 40 years, but people can develop CIS at older or younger ages too. CIS is two to three times more common in women than men.
CIS can be either be:
- Monofocal episode: A single neurologic sign or symptom is experienced, such as an attack of optic neuritis that is caused by a single lesion.
- Multifocal episode: More than one sign or symptom is experienced, such as an attack of optic neuritis accompanied by numbness or tingling in the legs caused by lesions in more than one place.
How is CIS diagnosed?
To confirm a diagnosis of the clinically isolated syndrome (CIS), the healthcare provider must face two challenges.
- To determine whether the person is experiencing a neurologic episode caused by damage to the central nervous system (CNS)
- To determine the likelihood that a person experiencing this type of demyelinating event is going to go on to develop multiple sclerosis (MS)
It is important to rule out other potential causes that may require immediate medical intervention. The process of diagnosis includes:
- Medical history: Analysis of information about the specific symptoms and duration of the current episode.
- Physical and neurological examinations
- Blood tests: To identify or rule out other potential causes for the symptoms.
- Magnetic resonance imaging (MRI):
- To look for signs of inflammation and demyelination (lesions) in the CNS.
- In CIS, any area of the brain can be damaged, and it may show up on the MRI only in that area of the brain that corresponds to the current symptoms.
- In MS, it may show multiple lesions and evidence of other episodes distinguished by space and time.
- Lumbar puncture (spinal tap): To examine the fluid that surrounds the brain and spinal cord for oligoclonal bands.
Will CIS progress to MS?
Individuals who experience clinically isolated syndrome (CIS) may or may not go on to develop multiple sclerosis (MS).
According to the National Multiple Sclerosis Society, the criteria to categorize people with CIS that may progress to MS include:
- High risk of developing MS: When CIS is accompanied by magnetic resonance imaging (MRI)-detected brain lesions (similar to those seen in MS) the person has a 60 to 80 percent chance of a second neurologic event and diagnosis of MS within several years.
- Low risk of developing MS: When CIS is not accompanied by MRI-detected brain lesions, the person has approximately a 20 percent chance of developing MS over the same period.
According to the 2017 revisions to the McDonald's diagnostic criteria for MS, the diagnosis of MS can be made when CIS is accompanied by MRI findings (old lesions or scars) that confirm that an earlier episode of damage occurred in a different location in the central nervous system (CNS). While the new criteria allow the presence of oligoclonal bands in a person's cerebrospinal fluid to help make the diagnosis.
How is CIS treated?
An accurate diagnosis is important because people with a high risk of developing multiple sclerosis (MS) are encouraged to begin treatment with a disease-modifying therapy (DMT). This delays or prevents a second neurologic episode and the onset of MS if they show extensive MRI changes.
Symptoms of a mild case of the clinically isolated syndrome (CIS), such as optic neuritis, may clear up within a few weeks. The doctor might prescribe high-dose steroid treatment.
Medications that are approved by the U.S. Food and Drug Administration (FDA) for CIS include Avonex, Betaseron, Extavia, and Mayzent. These are prescribed only after a thorough examination and discussion with the patient.
In addition, early treatment may minimize future disability caused by further inflammation and damage to the nerve cells, which could be silent (occurring without any noticeable symptoms).
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How is CIS different from MS?
Clinically isolated syndrome (CIS) and multiple sclerosis (MS) may appear the same if the diagnosis is based on clinical symptoms alone.
In both diseases, damage to the myelin sheath (demyelination) interferes with the way nerve impulses are carried from the brain, resulting in neurologic symptoms.
First or single episode
More than one episode (multiple episodes or flare-ups)
Demonstrate damage only in the area responsible for the current symptoms
Multiple lesions in different areas of the brain
Absence of oligoclonal bands
Presence of oligoclonal bands
Good
Poor
Isolated sensory symptoms
Efferent systems affected
Long interval to the second relapse
A high relapse rate in the first two to five years
No disability
Substantial disability
Normal
Abnormal with a large lesion load