Primary progressive multiple sclerosis causes brain and nerve function to worsen without notable periods of remission and relapse. This is one of several forms that multiple sclerosis can take.

Multiple sclerosis (MS) is an autoimmune disease. It occurs when the immune system, which usually defends the body against infection and disease, targets the protective myelin coating that covers the nerves.

Around 10–15% of people with MS have primary progressive MS (PPMS).

In this article, we describe PPMS, its treatment, outlook, and additional strategies for managing symptoms.

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PPMS causes the function of the brain and central nervous system (CNS) to worsen progressively. This occurs without episodes of remission and relapse.

Some people with PPMS may experience periods when the disease is stable.

For this reason, doctors add modifiers to more specifically describe MS progression. The goal is to help a person receive the most effective treatment.

Below are these modifiers and their definitions:

  • Active: A brain MRI shows inflammatory or new lesions and wider disease activity.
  • Not active: Symptoms continue, but the disease is not causing further lesions.
  • With progression: Levels of disability are increasing, and a person’s symptoms are worsening.
  • Without progression: The disease is not causing further disability, and a person’s symptoms are steady.

In people with relapsing-remitting MS or secondary progressive MS, symptoms episodically develop or worsen and ease or resolve. In a person with PPMS, the disease effects gradually grow more severe, or new symptoms develop without remission periods.

In addition, people with PPMS usually develop symptoms about 10 years later than those with relapsing types of MS.

All types of MS typically involve only the CNS. But PPMS causes a distinct type of damage. It tends to cause fewer lesions on the brain and more lesions on the spinal cord than other MS forms.

PPMS lesions also tend to contain fewer inflammatory cells. The combination of these factors can mean that the condition is more difficult to diagnose and treat than types that remit and relapse.

Unlike relapsing-remitting MS, which affects more females than males, PPMS typically affects both equally.

PPMS symptoms can affect a person’s everyday life and their ability to complete regular tasks. Problems with mobility are characteristic of PPMS, usually due to spinal cord damage.

A person with PPMS may experience many of the same symptoms as a person with relapsing-remitting MS. A study from 2014 notes these can include:

Any type of MS can lead to many of these symptoms. Distinguishing PPMS from other types requires time and repeated diagnostic tests.

A person must experience symptoms that consistently worsen over the course of 1 year for a doctor to diagnose PPMS. In addition to having progressive symptoms, a person must exhibit at least two of the following criteria:

  • MS-related lesions in the brain that show on an MRI scan
  • two or more MS-related lesions on the spinal cord
  • elevated levels of immunoglobulin G antibodies or certain immune proteins in the spinal fluid

Disease-modifying therapies (DMTs) are a core part of MS treatment, but these medications can be less effective in people with PPMS.

Trials have shown ocrelizumab and siponimod to be moderately effective in treating PPMS and secondary progressive MS.

Guidelines from 2018 described ocrelizumab as “the only DMT shown to alter disease progression in individuals with primary progressive MS (PPMS) who are ambulatory.”

Other measures

A range of therapies and strategies can help a person with PPMS to manage their symptoms.

Examples include:

  • Other medications: These can help reduce effects of the disease, such as symptoms of depression, muscle spasms, and bladder problems.
  • Therapies: Physical, occupational, speech, and psychological therapies can help enhance strength, mood, and mobility.
  • Lifestyle adjustments: These should support physical and mental health. Examples include eating a healthful diet, exercising, meditating, and participating in counseling or group therapy.

It is also important for a person with any type of MS to avoid exposure to extreme temperatures. Being overheated can worsen symptoms.

To gauge a person’s outlook, and the extent of disability from MS, a doctor may use the Kurtzke Expanded Disability Status Scale. The scores range from 0.0, demonstrating that a person has no symptoms, to 10.0, indicating that the presentation of MS may be fatal.

Some of the key functional differences on the scale include:

  • 4.0: A person is able to walk without an assistive aid, such as a cane. They are able to stand or walk around for at least 12 hours a day without overly reduced function.
  • 5.0: A person is able to walk without an aid for about 200 meters (m). The level of disability is severe enough to limit some daily activities, such as full-time work.
  • 6.0: A person needs occasional or daily assistance and uses a cane, crutch, or brace to walk distances of 100 m or more.
  • 7.0: A person is unable to walk for 5 m with an aid and usually uses a wheelchair.
  • 8.0: A person generally cannot move from a bed or chair and may use a motorized wheelchair. At this phase, a person’s arms are usually unaffected.

The transition between a score of 4.0 and 5.0 usually represents a change in a person’s ability to walk, which is a primary symptom of PPMS.

The authors of a 2015 study reported that the average time that it takes for a person with a diagnosis of PPMS to reach a score of 4.0 is 8.1 years.

The authors also found that the time it takes to reach 8.0 can vary, but on average, this takes about 20.7 years. Symptom progression is faster in people with PPMS than in those with a relapsing type of MS.

MS itself is rarely fatal. But complications due to the disease can impact a person’s life expectancy. The average life expectancy of a person with MS is 5–10 years fewer than the global average.

Those with more advanced forms of MS are also at a greater risk for life-threatening complications. This can lead to a shorter life expectancy.

A study published in 2017 reported that the average life expectancy for people with PPMS was 71.4 years. In contrast, the average life expectancy for people with relapsing-remitting MS was 77.8 years.

The age at which a person first experiences MS symptoms may also have an impact on their life expectancy. The above study found that, on average, people with PPMS lived for 25.5 years after onset. People with relapsing-remitting MS lived for an average of 42.8 years after onset.

The progression of PPMS can be unpredictable.

The severity of symptoms and the rate at which they progress varies from person to person. People with PPMS typically experience a faster rate of disease progression than those with other relapsing forms of MS.

People with PPMS typically experience more difficulty with their overall mobility. They may also require more assistance with everyday activities than those with other forms of MS.

PPMS is incurable, but DMTs and lifestyle modifications may help a person live with the disease.