Multiple Sclerosis (MS) is usually classified into four types. However, some researchers are starting to measure disease progression in phases, or stages.

MS occurs when your immune system mistakenly targets your central nervous system (CNS).

This damages the myelin sheath in your brain and spinal cord. The myelin sheath protects your nerve fibers and helps send nerve impulses down your spinal cord.

Researchers are still working to understand how MS progresses.

The condition is usually classified into types. However, research suggests MS may also be classified into stages.

Keep reading to learn more about the types and stages of MS, and how your symptoms may progress.

MS is usually classified into four types, partly based on how the condition progresses.

Clinically isolated syndrome (CIS)

CIS involves an isolated episode of neurological symptoms that may or may not recur. If it recurs, it will be a type of MS and no longer isolated.

Relapsing-remitting MS (RRMS)

RRMS involves periods in which symptoms worsen, called flare-ups, and then improve.

Between flare-ups, the changes that cause symptoms don’t appear to progress. However, RRMS may eventually progress to secondary progressive MS.

Over several decades, the course of RRMS will likely change and become more complex.

RRMS affects 70–80% of people with MS.

Secondary progressive MS (SPMS)

Some people with RRMS will go on to develop SPMS, a more aggressive form of MS. This generally happens within 10–25 years of the first diagnosis.

SPMS involves relapses followed by partial recoveries or periods of remission. In SPMS, MS doesn’t disappear between cycles but steadily worsens.

Primary progressive MS (PPMS)

PPMS has a slow and steady progression with no remission periods. There may be occasional plateaus in symptoms and minor improvements in function that tend to be temporary. The progression rate varies over time.

About 10% of people with MS have this type.

MS is complex. It’s difficult to diagnose and hard to pinpoint when it starts and how it will progress before symptoms become visible.

Experts are starting to think about MS in terms of phases.

For example, research suggests that imaging studies have found that background disease activity occurs before symptoms appear. This is called the subclinical phase.

Some experts also propose that there’s enough evidence to describe the following three MS phases:

  • High risk: A person notices early symptoms that may be a sign of MS.
  • Relapsing-remitting phase: Symptoms worsen during a flare-up and then improve or disappear for a while.
  • Progressive phase: Symptoms become progressively more severe.

This shows that the labels for different types of MS are not clear-cut. It might be more useful to describe MS in phases rather than types.

For instance, RRMS may begin long before you notice any symptoms. This means that when you experience CIS, you may already have RRMS.

A 2015 review suggests that 85% of people with MS have a history of CIS. After 15–20 years, around half of people who have experienced CIS go on to develop SPMS.

Early stage or high risk phase

MS results from damage to the nervous system. Symptoms of MS may start to appear once the damage reaches a certain point or affects a specific part of the body or brain.

Common early symptoms may include:

Speak with a healthcare professional if you experience any of these symptoms. They could determine whether you’re at high risk of developing MS based on your medical history and a physical exam.

That said, it’s important to note there’s no definitive test to confirm the presence of MS. Many symptoms also occur with other conditions, so the disease can be hard to diagnose.

Relapsing-remitting phase

For many people with MS, their symptoms will come and go over time.

According to the National Multiple Sclerosis Society (NMSS), an MS flare-up lasts at least 24 hours and occurs at least 30 days after the previous flare-up.

Flare-ups may last weeks or months. These could be followed by periods of remission, where symptoms may not appear for up to several years. During remissions, the disease doesn’t appear to progress.

Even among people with RRMS, the timeline varies widely between individuals.

Progressive phase

In this phase, MS symptoms become progressively worse. You may not experience any improvement or remission. Some people with MS never experience this.

In the past, doctors have talked about RRMS becoming progressive MS, but this may be a stage that some people reach while others don’t.

Children and adolescents may receive a diagnosis of MS, known as pediatric-onset MS (POMS). The NMSS reports that 3–5% of all people with MS noticed symptoms that started before they were 16 years old.

In children, MS tends to progress differently than in adults. It begins more aggressively, and there’s a higher relapse rate early in the disease. Disease progression becomes slower over time, but if your MS began in childhood, it’s more likely to reach the disability milestone at an earlier age than with adult-onset MS.

Children with MS tend to have the relapsing-remitting type rather than progressive MS.

The outlook for MS varies widely among individuals. Symptoms typically worsen over time, but not always. MS doesn’t follow any specific timeline or progression.

According to the NMSS, around 2 in 3 people with MS will retain the ability to walk throughout their lives. However, some people may need assistive devices like a cane or crutches.

If MS progresses to a more advanced stage, it can seriously affect quality of life. For instance, walking, writing, speaking, and thinking can become difficult.

While rarely fatal, MS can shorten life expectancy by up to 7 years. You may need a caregiver to help with everyday tasks.

If you receive a diagnosis of MS, it’s important to remain in touch with your healthcare team. They can monitor your symptoms and change your treatment if MS seems to be worsening. Each person will have their own treatment plan.

Learn about Medicare’s coverage of MS treatment.

What are the 4 stages of MS?

It’s hard to define or predict the stages of MS. In the past, doctors were more likely to refer to types, but some scientists now think it’s more realistic to talk about a subclinical phase — when damage is occurring in the body but with no symptoms — followed by:

  1. A high risk phase, which is when you may start to have symptoms that could indicate MS.
  2. A remitting-relapsing phase, which is when symptoms come and go over time.
  3. A progressive phase, in which you no longer have periods with no symptoms.

What are the 4 different types of MS?

The four different types of MS are clinically isolated syndrome (CIS), relapsing-remitting MS (RRMS), secondary progressive MS (SPMS), and primary progressive MS (PPMS).

What is the life expectancy of someone with MS?

The life expectancy of someone with MS is 7 years shorter than someone without the condition, according to the NMSS. That said, the life expectancy varies for each person. On average, it’s rising due to the development of new treatments.

How quickly does MS progress?

It’s hard to determine the progression of MS because it varies for each person and may depend on the type. A 2016 study found that after 16 years, 18% of people with RRMS progressed to SPMS, and 10.7% now needed a cane to walk 100 meters. However, MS is a lifelong condition that may take years for symptoms to develop.

MS can be difficult to predict, as it affects people differently.

In some cases, symptoms may not worsen over time. For others, however, MS may progress rapidly and affect your ability to function in daily life.

It’s important to work with a doctor who will help you monitor your condition and adjust your treatment as needed over time.