Multiple sclerosis (MS) is a progressive neurological disorder characterized by demyelination, which is the loss of the insulating cover around nerve fibers called the myelin sheath. This loss leads to delayed or missing nerve signals. 

MS is classified into four main types by the National MS Society Advisory Committee on Clinical Trials in MS. The types are based on the phase and severity of disease progression. The four types are: clinically isolated syndrome (CIS); relapsing-remitting MS (RRMS); secondary progressive MS (SPMS), and; primary progressive MS (PPMS)

Clinically isolated syndrome (CIS)

In CIS, a patient first experiences MS-like symptoms resulting from nerve inflammation and demyelination lasting more than 24 hours, such as vision problems, difficulty walking, or numbness. Patients with CIS may never have another episode of symptoms, or they could progress into MS at a later date. Patients are considered to have CIS until physicians find more evidence for MS. If MRI imaging shows a lesion in the nervous system, it is likely the symptoms will reoccur and the patient will be diagnosed with MS. The 2017 diagnostic criteria state that a diagnosis of MS requires two nervous system attacks at different locations and at two different times. Sometimes attacks can occur without symptoms and MRI imaging can be used to find other regions of the nervous system that might have been affected.

Relapsing-remitting MS (RRMS)

The most common form of MS is RRMS estimated to account for 80-85 percent of all cases. This form of the disease is characterized by periods of neurodegeneration where new symptoms occur or old symptoms worsen (relapsing), and periods of rest where some or all normal function is restored (remitting). While patients may recover during the remission periods, the disease generally progresses over time and some symptoms are likely to persist even during remission periods.

Secondary progressive MS (SPMS)

RRMS often continues to worsen and eventually may change to SPMS, at which time the disease transitions from relapse and remission phases into a steady progression of symptoms. There still may be periods when the disease is said to be active or not active based on MRI evidence of increasing nervous system damage, and with or without progression based on changes in symptoms. A diagnosis of SPMS usually comes after reviewing the progression of the disease, but there currently are no clear criteria for determining when MS changes from RRMS to SPMS.

Primary progressive MS (PPMS)

In PPMS, the disease starts in the attack phase and there are very few periods of remittance (recovery). However, there sometimes may be periods of stability when symptoms do not worsen. As in the case of SPMS, there are times when the disease can be active or not active, with or without progression. Periods of remission may occur later in the disease. It is estimated that 10-15 percent of patients have PPMS.

Other information

Other terms are sometimes used to describe rare versions of MS progression. 

Malignant MS

Malignant MS is a form of MS similar to PPMS in which the disease does not have periods of relapse and remission, but instead progresses very rapidly. Other names for this form are fulminant/fulminate, Marburg, aggressive, or advanced MS.

Radiologically isolated syndrome (RIS)

In RIS, an MRI taken for other medical reasons reveals evidence of brain lesions that look like MS. In such cases, the patient will not have had symptoms of the disease. Someone with RIS should be monitored and may be diagnosed with MS later if more symptoms appear.

Inactive MS

Another form of MS is inactive or benign MS. This form of the disease shows little or no change over many years, but could change at a later date. Another term sometimes used for inactive MS is “burned-out” MS, in which the disease progression appears to slow after a long period of worsening.


Multiple Sclerosis News Today is strictly a news and information website about the disease. It does not provide medical advice, diagnosis, or treatment. This content is not intended to be a substitute for professional medical advice, diagnosis, or treatment. Always seek the advice of your physician or other qualified health provider with any questions you may have regarding a medical condition. Never disregard professional medical advice or delay in seeking it because of something you have read on this website.

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Özge has a MSc. in Molecular Genetics from the University of Leicester and a PhD in Developmental Biology from Queen Mary University of London. She worked as a Post-doctoral Research Associate at the University of Leicester for six years in the field of Behavioural Neurology before moving into science communication. She worked as the Research Communication Officer at a London based charity for almost two years.


  1. Wife has severe MS. They hit her with a trial. The doctor started her off with Chemotherapy, a drug used for breast cancer called Cytoxan. The idea was to knock out her immune system and rebuild it. She was progressing very very fast all of the sudden. Went from a cane, to a walker, to a wheelchair and diapers within a month after years of taken many MS drugs. The therapy started with 1/2 a gram of Cytoxan for about a month, then the doc decided to up the dose to a gram. That night she had a major seizure. While she has progressed since, it is not as severe and seems to have subsided. While nothing really got better, she has since lost the ability to communicate/speak and has no emotion, it does seem to have helped although she never “Finished” the treatment, and I do not know if it included rebuilding with stem cells which I have read they are now trying. All I can say is I am happy to still have my wife around, if nothing was done, I do not believe she would still be here with us and while I say she has no “feelings” she does seem happy 99% of the time. I do not see any depression or anger which is amazing. I do believe the treatment should be explored more and a gram of Cytoxan for someone who is 4’9″ and 110 lbs is too much …

  2. Jerry W. Shelby says:

    I am 80 have had neuropathy in feet for some time. In past year I have hade headache stiff neck pain in back pain in shoulders. Pain constantly changing. Balance bad. dizziness lightheaded. Haven’t had a good day for over a year. Have been to Doctor but no help

  3. Danielle Boyer says:

    I have complained to medical doctors for over 10 years after my accident which occurred when I was 50 years old. My symptoms of persistent numbness with increasing weakness was negated by the professionals. Finally I asked a neurologist if I had MS, and was sent for blood work and spinal tap. I am awaiting complete results next week but preliminary test are positive with high levels of protein and blood in spinal cord with MRI changes. Please send me information on TRIALS as I need a miracle to help me. My husband has Parkinsons at 61 yrs old and I need to take care of him. Life is full of extraordinary challenges. Please HELP me! Danielle

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