The term progressive MS includes secondary progressive, primary progressive and progressive relapsing MS. Secondary progressive MS follows a diagnosis of relapsing-remitting, where over time, distinct relapses and remissions become less apparent and the disease begins to progress steadily, sometimes with plateaus. Approximately half of the people with RRMS will develop SPMS within 10-20 years of diagnosis. Many people who continue to experience relapses will remain on treatment with one of the disease-modifying therapies.
Primary progressive is characterized by a slow accumulation of disability, without defined relapses. Approximately 15 per cent of people diagnosed with MS have primary progressive MS. About five per cent of people diagnosed with PPMS experience occasional relapses with steadily worsening disease from the beginning. Because of the inflammatory activity, disease modifying therapies may be of some benefit. Primary progressive is generally diagnosed after age 40 and affects both sexes equally, unlike relapsing MS that affects women up to three times more than men. There are several other clinical features that differentiate primary progressive and relapsing MS, including the following:
Although major advances have been made in delaying or preventing progression for relapsing forms of MS — and these forms of MS are relatively well controlled by existing disease-modifying therapies (DMT)— people with progressive MS generally do not benefit from these therapies because they target the inflammatory process, the primary component of relapsing forms of MS. The progressive forms of MS appear to primarily involve neuronal atrophy — a loss of neurons that may or may not result from an inflammatory process (also referred to as neurodegeneration) and that does not appear to respond as well to current anti-inflammatory therapies. There may be options for people living with early primary progressive MS (PPMS) and active secondary progressive MS.
There is currently one DMT, ocrelizumab (Ocrevus), approved for early primary progressive MS in Canada (PPMS). Early PPMS will be defined by duration of disease and level of disability (measured using Expanded Disability Status Scale, EDSS). Ocrelizumab acts as an immunomodulatory drug by targeting and removing potentially harmful B cells (a type of white blood cell) in people living with MS. For more information on how ocrelizumab works, visit the Ocrevus page.
Health Canada has also approved siponimod (Mayzent®) for the treatment of adults with active secondary progressive multiple sclerosis (SPMS) evidenced by relapses or imaging features characteristic of multiple sclerosis inflammatory activity, to delay the progression of physical disability. Please see the Mayzent page for more information. In addition to siponimod, some of the interferon formulations carry a Health Canada indication for active SPMS, these include interferon beta 1a (Avonex, Rebif) and interferon beta 1b (Extavia and Betaseron).
There is no test to confirm progressive MS. Instead, this diagnosis is based on monitoring how your MS progresses. This is done by recording a description of how your symptoms have evolved over time together with measuring changes on your neurological exam (your exam is graded according to the EDSS score). Perhaps surprisingly, other tests such as MRI scans or spinal fluid exams do not indicate the phase of your MS. It is important that you let your doctor know if you’ve noticed changes in your level of functioning. Whether or not such changes represent progression of your illness, discussing them with your doctor will help you to develop the best health care strategy possible.