People with multiple sclerosis (MS) may have symptoms that relapse, steadily progress over time, or progress from the onset of symptoms.
MS is a disease of the central nervous system (CNS), which connects the brain and spinal cord. Different types of MS can progress in different ways.
This article looks at the stages and types of MS, how each may progress, and the typical outlook.
According to the National Multiple Sclerosis Society, MS has four disease progression types.
The International Advisory Committee on Clinical Trials of MS defined these types in 1996. Although experts are currently proposing a new classification system for MS, the following is the current classification system:
- Clinically isolated syndrome (CIS): CIS refers to the first signs of neurological symptoms and may develop into MS, but not in every case.
- Relapsing-remitting MS (RRMS): Around
70–80% of people with MS have this type when they first develop the condition. RRMS symptoms worsen, get better, and then relapse again. RRMS may progress to secondary progressive MS (SPMS) over time. - SPMS: SPMS follows RRMS, and symptoms progress steadily over time.
- Primary progressive MS (PPMS): PPMS is progressive from the beginning when symptoms first appear.
MS always progresses. However, depending on the type of MS, there may be no progression for long periods. Additionally, progression can be very gradual or more rapid.
CIS may or may not progress to MS. Factors that may increase the risk of CIS developing into MS include:
- being a younger age when the disease begins
- being male
- the number of brain lesions
- oligoclonal bands, which are a type of protein in cerebrospinal fluid
People with RRMS may go for years without any relapses, and disability may not progress in severity. RRMS usually progresses to SPMS, but not always, due to treatment.
The nature of progressive types of MS means the disease progresses at a faster rate, although the timeframe can vary.
The following sections explain how each type of MS progresses.
CIS
CIS may develop into MS, but not always. CIS is the term for initial nervous system symptoms that occur due to inflammation and demyelination of the CNS. Symptoms often include:
- vertigo
- vision problems
- difficulty with coordination, balance, and walking
- loss of sensation in the face
- weakness in the arms and legs, affecting one side of the body more than the other
- difficulty speaking and swallowing
- bladder problems
These symptoms must last at least 24 hours for doctors to classify them as CIS.
Doctors use certain criteria to determine how likely people with CIS will develop MS. The criteria include:
- brain lesions on an MRI scan can indicate a high risk of developing MS
- if no brain lesions are present, there is a low risk of developing MS
If an MRI scan shows old brain lesions that show previous damage, then a doctor will diagnose a person with MS. Only 63% of people with CIS will receive an MS diagnosis.
Experts are uncertain how long CIS may take to develop into MS. Early treatment may also help delay or sometimes prevent MS.
RRMS
RRMS symptoms last
As the disease continues, it becomes more difficult for the body to repair after each relapse. This means the disease can worsen as time goes on, although treatment can help. In many cases, recovery or complete remission is possible after a relapse.
Over time, RRMS usually develops into SPMS, but the time frame can vary. Disease-modifying therapies (DMTs) are helping reduce the number of cases that progress and lengthen the time frame RRMS takes to progress.
Read about medications for MS.
Secondary progressive multiple sclerosis (SPMS)
SPMS can follow RRMS. People with SPMS experience a steady change in their abilities over time, but symptoms can progress differently for each person.
SPMS may be active or not active. Active SPMS causes symptom progression, while inactive SPMS may not. Active SPMS may cause increased disability over time.
Treatments are available to help manage SPMS, such as DMTs and rehabilitation strategies.
Primary progressive multiple sclerosis (PPMS)
Around 10–15% of people with MS have PPMS, which is progressive from the first onset of symptoms. Individuals usually develop PPMS in their 40s.
With PPMS, people experience a gradual worsening of symptoms. PPMS does not include relapses, attacks, or remissions. People may have PPMS that is active, not active, with progression, or without progression.
Treatment can help people manage PPMS symptoms. It may include DMTs and rehabilitation therapy to help improve function.
According to a 2017 population study, having MS may shorten life expectancy by around 7 years in comparison with those without MS.
MS is rarely fatal, but complications can arise, which may become life threatening. However, in many cases, complications are preventable or treatable.
It can be difficult to predict how RRMS may progress or how frequent relapses will be. Disease progression may be faster with typically progressive types of MS, although it is also difficult to predict the timeframe for this.
Depending on the type of MS, symptoms can progress in different ways. People may have relapses and periods of recovery, or changes may be gradual and steady.
The time frame for progression can vary. Treatments, such as DMTs, may help prevent or delay disease progression.