Last updated Sept. 27, 2021, by Marisa Wexler, MS
✅ Fact-checked by Inês Martins, PhD
Approximately 15% of people with multiple sclerosis (MS) are diagnosed with the primary progressive form of the disease, commonly known as PPMS.
The disease is called “primary progressive” because it progresses from the onset of the first symptoms. In contrast to relapsing-remitting MS (RRMS), in which periods of worsening symptoms (relapses) are followed by periods of little or no symptoms (remissions), PPMS symptoms steadily worsen over time without periods of remission.
PPMS can be classified as “active” or “not active” based on whether or not the patient experiences occasional relapses or has evidence of new disease activity on MRI scans. PPMS also can be classified as with or without progression, based on whether the person experiences worsening disability over time.
While all forms of MS are caused by inflammation in the nervous system, people with PPMS tend to have less inflammation than those with relapsing forms of MS. These patients also tend to have fewer lesions in the brain, but more in the spinal cord, relative to other MS types.
People with PPMS can experience many of the same symptoms as those with relapsing forms of MS, but weakness in leg muscles and difficulty walking tend to be more common in PPMS. Patients also tend to require more assistance with their daily activities and to struggle more at work.
Whereas RRMS is substantially more common in women than men, PPMS affects both genders equally. Additionally, PPMS usually develops later in life than RRMS, by about a decade, on average. Most people with PPMS are diagnosed between the ages of 40 and 60, though earlier diagnoses do occur.
How is PPMS diagnosed?
To be diagnosed with PPMS, a person must experience one year of continual disease progression — that is, a year of continuously worsening symptoms, without periods of remission when symptoms ease.
The diagnosis also requires clinical testing to confirm that symptoms are a result of the immune system attacking the nervous system. For a formal diagnosis of PPMS, at least two of the following must be present:
- At least one MS-like inflammatory lesion in the brain
- At least two MS-like inflammatory lesions in the spinal cord
- High levels of immune proteins (specifically an elevated immunoglobulin G index or an oligoclonal band) in the fluid that surrounds the brain and spinal cord.
A PPMS diagnosis can take a long time, especially in cases when neurologic symptoms have just begun. Research suggests that, on average, diagnosis takes two to three years longer for PPMS than for RRMS.
How is PPMS treated?
On March 28, 2017, Ocrevus (ocrelizumab) became the first treatment approved by the U.S. Food and Drug Administration to treat PPMS. In clinical trials, Ocrevus was found to slow disability progression in people with PPMS, especially when treatment was started early in the course of disease.
To date, Ocrevus remains the only therapy approved to treat PPMS. Other therapies are in development, and clinical trials are ongoing to test new treatments.
Patients can use other means to manage PPMS, beyond medication. Appropriate exercise and healthy eating habits are important for people with MS, and physical and occupational therapy can help minimize muscle weakness and restore movement.
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