Multiple sclerosis (MS) does not affect everyone in the same way, particularly because there are several types of the condition. Whereas some people may be diagnosed with the clinically isolated syndrome (CIS), others might have relapsing-remitting MS (RRMS), secondary progressive MS (SPMS), or primary progressive MS (PPMS). This article focuses primarily on PPMS and discusses its prognosis and life expectancy.
MS is a chronic autoimmune disease in which the immune system attacks components of the central nervous system (CNS), including the brain, spinal cord, and optic nerves. A common feature of MS is the destruction of the protective myelin sheath that covers nerve cells. This destruction is mediated by cells in the immune system that have mounted an autoimmune attack against the body. This ultimately affects how nerve cells function and communicate with each other and can have an impact on their ability to relay sensory, motor, and cognitive information. The damage caused by the immune system will eventually lead to the formation of lesions in the brain and spinal cord that are detectable using magnetic resonance imaging (MRI).
One of the defining factors for PPMS involves where the damage to the CNS has occurred. People with PPMS tend to have more lesions located on the spine than in the brain. This condition usually causes people with PPMS to have more motor function issues than individuals with other forms of MS. PPMS is also defined by its gradually worsening symptoms, rather than a pattern of relapse and remission as occurs in relapsing forms of MS.
PPMS is relatively rare and only affects about 10 percent of individuals diagnosed with MS. Although women are three times more likely to develop a relapsing form of MS, PPMS is diagnosed equally between men and women. PPMS can be more difficult to initially diagnose than other forms of MS, and treatment can also be more challenging.
Living with PPMS can present many challenges. Symptoms and progression of the disease can differ greatly between individuals. Some symptoms of PPMS include:
Unfortunately, people living with PPMS tend to have a poorer prognosis compared to individuals living with other forms of MS. This may be related to the fact that PPMS does not involve periods of remission. Therefore, CNS damage and subsequent disability often accumulate more quickly.
The first symptoms to arise and a person's age at onset may influence the prognosis of PPMS. Individuals who exhibit more symptoms simultaneously at onset may develop the disease more rapidly. Additionally, individuals diagnosed with PPMS at a younger age tend to have slower disease progression.
PPMS usually affects people later in life, with the average age at onset being 10 years later than those with relapsing forms of MS. This can be a positive thing for people with PPMS because it means they were able to live with more disease-free years. Because the lesions are more prevalent in the spine than the brain with PPMS, those affected usually exhibit more symptoms related to motor function — such as difficulty walking. People with PPMS tend to exhibit fewer symptoms related to thinking, memory, and cognition when compared to individuals with relapsing MS.
People living with PPMS may need to rely on assistive technologies as their disease progresses. These aids include the use of a walking cane, walker, or wheelchair. The average amount of time it takes for someone with PPMS to progress to wheelchair use is 12.1 years.
Do disease-modifying therapies exist for PPMS? The U.S. Food and Drug Administration (FDA) has only approved one medication for the treatment of PPMS. Ocrevus (ocrelizumab) is a monoclonal antibody therapy that works by depleting a specific immune cell type, known as B cells. B cells can contribute to PPMS by secreting destructive autoantibodies or activating other immune cells to attack the CNS. Depleting these cells with Ocrevus has been shown to reduce the progression of clinical disability in individuals with PPMS. People receiving Ocrevus were able to delay their progression to a wheelchair by seven years (average of 19.2 years without a wheelchair).
In addition to treating the disease itself, a doctor may also prescribe medications to help with the symptoms of PPMS, such as depression, pain, fatigue, bladder control, and sleep. Lifestyle changes, including a healthy diet and regular exercise, may also improve prognosis. Finally, other physical, recreational, occupational, and speech therapy approaches may be beneficial for disease outcomes related to PPMS.
Although there is no cure for PPMS, the condition is not considered to be fatal. Most individuals with PPMS pass away from common causes, such as cancer or heart disease.
People living with any form of MS on average have a seven-year reduction in life span. Some studies have shown that life expectancy can be slightly more reduced in people with PPMS. As mentioned previously, the relapsing forms of MS affect women more than men, but this gender bias is not observed with PPMS. However, women diagnosed with PPMS exhibit poorer survival when compared to men with PPMS.
Fortunately, the world of medicine is constantly advancing and evolving. As researchers learn more about the immune system, the CNS, and PPMS, more treatments for this condition may be developed.
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