Multiple Sclerosis (MS) is a chronic, unpredictable disease of the central nervous system, involving the brain, spinal cord, and optic nerves. It occurs when the immune system mistakenly attacks the protective myelin sheath covering nerve fibers, causing inflammation and damage. Historically, MS was viewed as relentlessly progressive, but modern therapeutic strategies often allow individuals to achieve long periods of disease stability, effectively halting measurable progression.
Understanding Different MS Trajectories
The course of multiple sclerosis varies widely, making the potential for stopping progression highly dependent on the disease type. The most common form is Relapsing-Remitting MS (RRMS), affecting approximately 85% of people diagnosed initially. RRMS is characterized by clearly defined attacks (relapses) of new or worsening neurological symptoms, followed by periods of partial or complete recovery (remission).
Relapsing forms of MS, including RRMS, are primarily driven by inflammatory activity, making them the most responsive to current immune-modulating treatments. Primary Progressive MS (PPMS) affects 10 to 15% of people and is defined by a gradual, steady worsening of neurological function from the onset without early relapses or remissions. The pathology in PPMS involves more neurodegeneration and less inflammation, posing greater challenges for halting progression.
The third major trajectory is Secondary Progressive MS (SPMS), which follows an initial period of RRMS. In SPMS, disability begins to accumulate progressively, with or without occasional relapses. The shift from RRMS to SPMS often signifies a transition from a disease dominated by inflammation to one involving more chronic neurodegeneration, which can make achieving stability more difficult than in the earlier relapsing phase.
Defining Stability
In clinical practice, the medical definition of “stopping progression” is captured by a composite measure known as No Evidence of Disease Activity (NEDA). Achieving NEDA has become the primary goal of modern MS management, moving beyond simply reducing the frequency of relapses. This concept recognizes that inflammation and damage can occur silently within the central nervous system, even without a patient experiencing new symptoms.
The most common criteria for NEDA, referred to as NEDA-3, encompasses three distinct measures of disease activity over a specified period, typically one year or more. The first component is the absence of clinical relapses (no new or recurrent neurological symptoms lasting more than 24 hours). The second measure requires no sustained worsening of physical disability, tracked using the Expanded Disability Status Scale (EDSS).
The third component of NEDA is the absence of new disease activity visible on Magnetic Resonance Imaging (MRI) scans. This means there should be no new or enlarging lesions, which represent areas of active inflammation or damage in the brain and spinal cord. Achieving this triad of clinical and radiological stability is considered the best available evidence that the disease has been successfully halted.
The Role of Treatment in Halting Progression
Disease-Modifying Therapies (DMTs) are the most important factor to stop MS progression. DMTs alter the immune system’s function to suppress the inflammatory attack on the central nervous system. These treatments target the underlying disease process to reduce relapses, limit new lesions, and slow disability accumulation.
The consensus among neurologists is that aggressive and early treatment provides the best chance for long-term stability. This strategy, sometimes called “treating to target,” aims to achieve NEDA as quickly as possible to prevent irreversible damage to the nerves. Early initiation of a highly effective DMT can significantly reduce the risk of future disability and delay the conversion from RRMS to SPMS.
DMTs are administered through various routes, including injections, oral medications, and intravenous infusions. For the relapsing forms of MS, these therapies are highly effective at controlling the inflammatory stage of the disease. Even for progressive forms, specific DMTs have demonstrated an ability to slow the rate of disability progression.
Factors Influencing Long-Term Disease Stability
While DMTs form the backbone of treatment, several patient-specific and environmental factors influence long-term stability. Receiving an early diagnosis is associated with better outcomes because it allows for prompt treatment initiation before permanent neurological damage occurs. The prognosis is generally more favorable for individuals who are younger when symptoms first appear.
A patient’s adherence to their prescribed treatment regimen is another powerful predictor of stability. Studies have shown that consistent use of DMTs over a long period is associated with better clinical outcomes, including a lower risk of disease progression and delayed conversion to SPMS. Lifestyle choices also play a supportive role in overall health and disease management.
Managing comorbidities, such as hypertension or obesity, is important as these conditions can contribute to inflammation and potentially worsen neurological outcomes. Non-pharmacological interventions, including regular physical exercise and adopting a healthy diet, can improve overall quality of life and support the effectiveness of medical treatments. Stress mitigation strategies may also help reduce the risk of relapses.