Multiple sclerosis (MS) manifests in different patterns, depending on early symptoms and how the disease progresses. Each course represents a different type of MS, an autoimmune disease that affects the central nervous system (CNS). It’s common to be diagnosed with one type and then later, if the course of disease progression changes, get a new diagnosis.

Magnetic resonance imaging (MRI) scans help doctors detect and diagnose MS. MRI scans show lesions (also called plaques or scars) on the brain and spinal cord resulting from demyelination (loss of myelin, the fatty substance that insulates nerves in the brain and spinal cord). These lesions may point to a certain type of MS. In addition, doctors consider scores on the Expanded Disability Status Scale (EDSS) to measure disease progression.

There’s some controversy among doctors and researchers about how to classify different forms of MS. Read on to learn about the various types of MS, including related conditions and rarer forms.

1. Clinically Isolated Syndrome

Clinically isolated syndrome (CIS) is not a type of MS but a condition that may or may not progress into MS. Many people who go on to develop MS are initially diagnosed with CIS.

Clinically isolated syndrome is not a type of multiple sclerosis but a condition that may or may not progress into MS.

CIS means that a person has had one episode of neurological symptoms lasting at least 24 hours and caused by demyelination. The episode may be monofocal, with one sign or symptom caused by a single lesion, or multifocal, with several signs or symptoms caused by multiple lesions.

When an MRI reveals older lesions in someone with CIS, doctors may diagnose MS without waiting for additional episodes. Some people with CIS never have another episode of symptoms or develop new lesions, remaining diagnosed with CIS.

When diagnosing CIS, the doctor will assess the risk of developing MS. People with CIS who have lesions similar to those seen in people with MS are at higher risk of developing MS within the next few years than people without MS-like lesions. People with lower risk may be treated temporarily with corticosteroids, and those at higher risk may be advised to begin a disease-modifying therapy (DMT) to prevent new clinical episodes and new lesions in the CNS.

Read more about symptoms of clinically isolated syndrome.

A related term is “radiologically isolated syndrome (RIS).” In a person with RIS, a lesion is found during an unrelated MRI scan, but there are no MS-like symptoms. As with CIS, a person with RIS isn’t diagnosed with MS but may be at risk of developing it at some point.

2. Relapsing-Remitting Multiple Sclerosis

Relapsing-remitting MS (RRMS) is the most common form of MS. About 85 percent of people with MS have this type, and they’re usually diagnosed in their 20s or 30s. Women are two to three times more likely to have RRMS than men, according to the National Multiple Sclerosis Society. RRMS tends to cause more brain lesions than spinal cord lesions, resulting in increased cognitive (thinking and memory) and visual symptoms.

About 85 percent of people with multiple sclerosis are diagnosed with relapsing-remitting MS.

People with RRMS have a clear pattern of relapses (also called flare-ups or exacerbations) and remissions. During relapses, disease activity flares, causing new or more intense symptoms. New lesions may appear. During remission, people with RRMS may recover fully or partially, and symptoms of MS may lessen, disappear, or remain permanent. The disease doesn’t appear to progress during remission.

RRMS may be further described as being “active” or “not active” based on MRI scans and “worsening” or “not worsening” based on disability testing. These descriptions help doctors decide whether treatment is effective and whether to recommend a more aggressive approach.

People diagnosed with RRMS are encouraged to immediately begin long-term maintenance treatment with a DMT to reduce the frequency and severity of flares and delay disease progression.

Some people with RRMS eventually transition to secondary progressive MS (SPMS) many years after the initial diagnosis.

Read more about relapsing-remitting MS symptoms.

3. Primary Progressive Multiple Sclerosis

About 15 percent of people with MS have primary progressive MS (PPMS), which is most often diagnosed in adults in their 40s and 50s.

In people with PPMS, the condition generally progresses without clear relapses or periods of remission. Neurological function and disability get worse over time. PPMS tends to cause more lesions in the spinal cord than in the brain, resulting in increased motor symptoms such as difficulty walking. Over time, PPMS may be further described as being “active” or “not active” based on MRI scans and “with progression” or “without progression” based on disability testing.

In progressive forms of MS, the condition generally progresses without clear relapses or periods of remission, and disability gradually gets worse.

Currently, ocrelizumab (Ocrevus) is the only medication approved by the U.S. Food and Drug Administration (FDA) to treat PPMS.

Progressive-relapsing MS (PRMS) has been viewed as a subset of PPMS, characterized by clear periods of acute relapse, but the disease progresses between relapses without remission.

Read more about primary progressive MS.

4. Secondary Progressive Multiple Sclerosis

People who are first diagnosed with RRMS and later experience a consistent worsening of neurologic function and greater disability might be rediagnosed with SPMS. Individuals with SPMS may continue to have fewer flares associated with demyelination, like in RRMS, or flare-ups may give way to a more steadily progressive course.

Like PPMS, SPMS may be further described as “active” or “not active” based on MRI scans and “with progression” or “without progression” based on disability testing. If SPMS is active and progressing, doctors may recommend more aggressive treatment.

DMTs that are FDA-approved to treat SPMS include cladribine (Mavenclad), siponimod (Mayzent), and mitoxantrone.

5. Benign Multiple Sclerosis

The idea of benign MS is debated by doctors and researchers. Some people with MS have mild symptoms and little or no disability, but their condition must be tracked for 10 to 15 years before it can be called benign based on EDSS scores. Benign MS isn’t given as the initial diagnosis but, rather, after many years of assessing the disease pattern.

Benign MS appears to be linked with a milder disease course for those with RRMS. Doctors’ opinions differ regarding the value of a benign MS diagnosis. Some may believe that it’s safe to stop treatment with DMTs after a certain number of years without progression, but others feel that treatment decisions shouldn’t be based on a benign MS diagnosis.

6. Rare Forms of Multiple Sclerosis

Tumefactive MS is a rare form of the disease, with signs and symptoms similar to those caused by brain tumors. Tumefactive MS is often misdiagnosed as a type of brain tumor called an astrocytoma. People who experience an episode of tumefactive MS often go on to develop RRMS. People with tumefactive MS can be treated with some DMTs.

Pediatric MS (diagnosed in people under 18) is extremely rare, accounting for 3 percent to 5 percent of MS diagnoses. The disease course in pediatric MS is similar to that of RRMS in adults. On average, children with MS experience relapses two to three times more frequently than adults with early-stage RRMS. Children with MS are treated with DMTs.

Two other rare types of MS, Marburg variant MS (also known as “fulminant MS” or “malignant MS”) and Baló’s concentric syndrome, are characterized by rapid progression and poor outcome. Some doctors don’t consider these conditions to be types of MS but, rather, distinct diseases.

Talk With Others Who Understand

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