What is Multiple Sclerosis?
Before diving into progression, it’s helpful to understand what happens in the body during MS. Multiple Sclerosis is an autoimmune disease where the body’s immune system mistakenly attacks the central nervous system (the brain, spinal cord, and optic nerves). Specifically, it targets myelin, the protective sheath that covers nerve fibers.
When myelin is damaged, it disrupts the electrical signals traveling between the brain and the rest of the body. This disruption causes the wide range of symptoms associated with MS, from numbness and tingling to difficulty walking and vision problems. The way this damage occurs and accumulates over time is what neurologists refer to as “progression.”
The Four Main Types of MS Progression
Neurology teams classify MS into four main types based on how the disease behaves over time. The most common initial diagnosis is Relapsing-Remitting MS, which is what the ad refers to when it says how MS “usually” progresses.
1. Clinically Isolated Syndrome (CIS)
This is not technically a type of MS, but it’s often the very first sign. CIS refers to the first episode of neurologic symptoms caused by inflammation and demyelination in the central nervous system. The episode must last for at least 24 hours.
What it looks like: A person might experience a sudden bout of optic neuritis (vision problems), numbness in a limb, or severe balance issues.
Progression: Having a CIS episode does not automatically mean a person will develop MS. A neurologist will use MRI scans to look for lesions (areas of damage) in the brain or spinal cord. If the MRI shows lesions typical of MS, the person has a high risk of experiencing another episode and being diagnosed with MS. If the MRI is clear, the risk is lower.
2. Relapsing-Remitting MS (RRMS)
This is the most common form of the disease. According to the National MS Society, about 85% of people with MS are initially diagnosed with RRMS. This is the typical starting point for the MS journey.
What it looks like: People with RRMS experience clearly defined attacks of new or increasing neurologic symptoms. These attacks are also called relapses, flare-ups, or exacerbations.
Progression: Following a relapse, there is a period of partial or complete recovery, known as remission. During remission, all symptoms may disappear, or some may continue and become permanent. However, in the remitting phase of RRMS, the disease does not seem to worsen. The progression happens in these steps of attack and recovery.
3. Secondary Progressive MS (SPMS)
Many people who start with an RRMS diagnosis will eventually transition to SPMS. In this stage, the disease progression changes.
What it looks like: The defining feature of SPMS is a steady, gradual worsening of neurologic function and an accumulation of disability over time. The “ups and downs” of relapses and remissions become less apparent or stop completely.
Progression: Instead of distinct attacks, the person may find that their mobility, for example, slowly declines over months and years. Some people with SPMS may still experience occasional relapses, but the underlying trend is a consistent worsening of the condition. Historically, before the development of modern treatments, a majority of people with RRMS would transition to SPMS within 10 to 25 years. Today, Disease-Modifying Therapies (DMTs) are believed to significantly delay or even prevent this transition for many patients.
4. Primary Progressive MS (PPMS)
This type is less common, affecting about 15% of people with MS. It is characterized by a different pattern from the very beginning.
What it looks like: From the onset of the disease, people with PPMS experience a nearly continuous worsening of their symptoms.
Progression: There are no early relapses or remissions. The progression is steady, although the rate of progression can vary. Some people may have periods of stability, and some may experience minor, temporary improvements, but the overall trend is a decline in function. PPMS often presents with mobility and walking challenges as primary symptoms.
How Neurology Teams Monitor Progression
To understand and manage a patient’s MS, neurology teams rely on a set of key tools and assessments. This allows them to track the disease, make treatment decisions, and provide the best possible care.
Neurological Exam: A hands-on assessment where the neurologist tests reflexes, strength, coordination, balance, vision, and sensation. This exam provides a baseline and helps track changes over time.
MRI Scans: Magnetic Resonance Imaging is crucial for visualizing MS. Neurologists use MRIs to see new lesions, active inflammation (often by using a contrast agent called gadolinium), or brain volume loss (atrophy). Regular MRIs help determine if a treatment is working effectively to suppress new disease activity.
The Expanded Disability Status Scale (EDSS): This is a common scale used by neurologists to quantify disability. The scale runs from 0 (normal neurological exam) to 10 (death due to MS). It is heavily weighted towards walking ability. For example, a score of 6.0 indicates the need for a cane or other walking aid. Tracking the EDSS score over years gives a clear picture of disease progression.
By combining these tools, a neurology team can build a comprehensive picture of how a person’s MS is progressing and tailor their management plan accordingly. The goal of modern MS treatment is to slow progression as much as possible, primarily by using DMTs to reduce the frequency and severity of relapses and delay the accumulation of disability.
Frequently Asked Questions
Can MS progression be stopped? Currently, there is no cure for MS that can completely stop or reverse the damage. However, modern Disease-Modifying Therapies (DMTs) are very effective at slowing down the progression of the disease, especially in relapsing forms of MS. They work by reducing the number of relapses and limiting the formation of new lesions in the brain and spinal cord.
Does everyone with RRMS eventually develop SPMS? No, not everyone. Before effective treatments were available, the transition was much more common. With today’s advanced DMTs, many people can manage their RRMS for decades without transitioning to SPMS. Starting treatment early is considered key to delaying this progression.
Is MS a fatal disease? In the vast majority of cases, MS is not a fatal disease. Most people with MS have a near-normal life expectancy. However, severe MS can lead to complications, such as chest or bladder infections, that can be serious. Effective management of the disease and its symptoms is crucial for long-term health.