This leads to disruption in the communication between a person's brain and their nerves.
Eventually, damage also affects the nerve fibers known as axons. Multiple sclerosis (MS) can affect a person's movements and vision.
MS can develop in four different ways:
- relapsing-remitting MS (RRMS)
- secondary progressive MS (SPMS)
- progressive-relapsing MS (PRMS)
- primary progressive MS (PPMS)
For each type, symptoms progress in a different way.
What is primary progressive MS?
A person with PPMS may eventually need help to get around.
Doctors characterize PPMS as a form of MS where neurological function gets consistently worse, without episodes of relapse or remission.
However, some people with PPMS may experience temporary plateaus and sometimes minor reductions in symptoms.
PPMS is less common than other types of MS. Reports vary, but estimates suggest that only about 10 percent of all people with MS go on to develop PPMS.
With RRMS and SPMS, the relapsing types of MS, the symptoms come and go. In contrast, a person with PPMS will experience a continued worsening of symptoms without any remission.
Typically, all types of MS cause damage to the central nervous system. But PPMS causes a different type of damage than the relapsing types do. For example, people with PPMS tend to develop fewer brain lesions called plaques, but they often have more lesions on the spinal cord.
According to the National MS Society, PPMS is more difficult to diagnose and treat than the relapsing forms.
People with PPMS usually develop their symptoms about 10 years later than those with relapsing types. According to Johns Hopkins Medicine, doctors typically diagnose a person with PPMS when they are between the ages of 35 and 39.
Another key difference is that the relapsing types of MS affect two to three times more women than men, where PPMS affects both sexes in equal number.
PPMS can affect everyday life and a person's ability to complete daily tasks. A key symptom associated with PPMS is difficulty walking. This may result from the damage to the spinal cord that occurs with PPMS.
MRI scans may be used to track the progression of MS.
Additional symptoms that a person with PPMS may experience include:
- changes in mood
- muscle weakness
- problems thinking clearly
- problems with bowel and bladder control
- sexual dysfunction
- trouble maintaining balance
- trouble seeing
Many of these symptoms can occur with all types of MS, and distinguishing PPMS from other types can take time and repeated diagnostic tests. To have a diagnosis of PPMS, a person must experience worsening symptoms over the course of a year.
In addition to progressive symptoms, a person must meet at least two of the following criteria:
- MS-related lesions in the brain that an MRI scan can detect
- two or more MS-related lesions on the spinal cord
- elevated IgG antibodies or specific immune system proteins in the spinal fluid
A doctor will likely recommend regular MRI scans to track the progression of MS.
Only one drug appears to affect disease progression in people with PPMS, and this is the disease modifying therapy (DMT), ocrelizumab (OCR), with the brand name Ocrevus.
In February 2016, the United States Food and Drug Administration (FDA) granted OCR "Breakthrough Therapy Designation" for PPMS.
Guidelines published in 2018 describe OCR as "the only DMT shown to alter disease progression in individuals with primary progressive multiple sclerosis (PPMS) who are ambulatory."
The guidelines recommend prescribing OCR to people who are likely to benefit from it, unless there are risks to the individual that outweigh the benefits.
However, there is no evidence that OCR can help people who are no longer mobile.
In addition, there are steps a person can take to manage symptoms and enhance their quality of life.
- Medications to relieve symptoms: These can reduce specific symptoms, including depression, muscle spasms, and bladder problems.
- Rehabilitation: Therapy can enhance strength, improve mobility, and promote independence whenever possible.
- Healthy living steps: These can promote physical and mental wellness. Examples include eating a healthful diet, exercising, and participating in counseling or group therapy.
In addition to these treatments, it is important for a person with any type of MS to avoid exposure to excessive heat temperatures. Overheating can cause the symptoms to worsen.
MS, and particularly PPMS, is an unpredictable disease with a very unpredictable course.
Progression can be severe, and some people with PPMS may experience difficulty walking, mood changes, balance problems, visual disturbances, bladder and bowel difficulties, and fatigue. The rate at which this progression occurs can vary from person to person.
According to an article published in the Journal of Neurology, Neurosurgery, and Psychiatry, the progression may depend on the types of symptoms a person has and the age at which they receive their diagnosis.
To gauge disability related to MS, a doctor may use the Kurtzke Expanded Disability Status Scale or EDSS. The numbers range from 0.0 (no symptoms) to 10.0 (death due to MS).
Some of the key functional differences on the scale include:
Currently, there is no medication available to treat PPMS, but there are steps a person may take to enhance the quality of their life.
- 4.0: Able to walk without using an assistive aid, such as a cane or walker. A person is able to be up and about for at least 12 hours a day without overly reduced function.
- 5.0: Able to walk without an aid for about 200 meters. However, a person's disability is severe enough to limit full daily activities, such as working full time.
- 6.0: Needs occasional or everyday help, walking with a cane, crutch, or brace for distances of 100 meters or more.
- 7.0: Unable to walk 5 meters even with an aid. Usually needs a wheelchair.
- 8.0: Usually restricted to bed or chair or may need a motorized wheelchair. A person at this phase will generally have effective use of their arms.
The transition from phase 4.0 to 5.0 usually represents a change in a person's ability to walk. This is one of the major symptoms a person with PPMS experiences.
According to an article published in the Journal of Neurology, Neurosurgery, and Psychiatry, the average time it takes for a person with a diagnosis of PPMS to reach EDSS 4 is 8.1 years.
The time scale before a person with PPMS reaches EDSS 8.0 may vary, but on average it takes about 20.7 years. The speed at which symptoms progress is faster in PPMS than in the relapsing types of MS.
As scientific advances lead to new medications, there is hope that the outlook for PPMS will improve in the future.