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 10 per cent of people diagnosed with MS have primary-progressive MS. 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:
- Most people diagnosed with primary-progressive MS present with walking difficulties, indicating spinal cord disease, whereas those diagnosed with relapsing-remitting often experience visual or sensory symptoms at disease onset. This is demonstrated on MRI scans which show fewer brain lesions and more spinal cord lesions in individuals with primary-progressive as compare with people with relapsing-remitting MS.
- In primary-progressive MS, brain and spinal cord atrophy (shrinkage) can be seen early in the disease.
Progressive-relapsing is the rarest course of MS, occurring in only about 5 per cent of people diagnosed. People with this form of MS experience occasional relapses with steadily worsening disease from the beginning. Because of the inflammatory activity in progressive-relapsing MS, disease modifying therapies may be of some benefit.
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 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.
Even without an approved disease-modifying therapy, people with a diagnosis of secondary-progressive or primary-progressive MS and their health care teams can do a great deal to manage the disease including rehabilitation and symptom management.
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My doctor said there is no test to confirm whether I have progressive MS. How does he/she know I have it?
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.