Update: Due to new guidelines defining the courses of MS published in 2014, Progressive-relapsing MS is no longer recognized as a separate course of MS due to overlap with other phenotypes.
Progressive-relapsing MS (PRMS) is the rarest of the MS disease courses, only affecting about 5% of people diagnosed with MS. It is similar to primary-progressive MS (PPMS) because both types of MS are steadily progressive from disease onset. With PPMS, there is steadily worsening of neurologic function from the very beginning, although the rate of progression may vary over time with the patient experiencing occasional plateaus or minor temporary improvements. PRMS also has a steady worsening of neurologic function (disease progression) from the beginning, but with occasional relapses (attacks)
Because MS tends to progress at differing rates and with fluctuating symptoms within each patient, it may not be clear at the beginning of disease onset that a patient has PRMS. A physician may initially diagnose a patient with PPMS until a relapse or exacerbation occurs, then change the diagnosis to PRMS.
How is PRMS different from SPMS?
Secondary-progressive MS (SPMS) differs from PRMS in that it is not steadily progressive from disease onset. SPMS occurs as asecondary phase of MS following relapsing-remitting MS (RRMS), the most common form of MS.
Unlike PRMS, which is progressive from the start, SPMS marks the point at which MS transitions from RRMS and enters a more steadily progressive disease course. During SPMS, the patient may or may not continue to experience relapses or attacks as the disease worsens. In PRMS, the patient continues to experience relapses or attacks with a worsening of neurologic function over time.
How is PRMS diagnosed?
PRMS is diagnosed when a patient with MS who has experienced progressive decline in neurologic function from the disease onset experiences an attack (relapse, exacerbation, or flare-up) marked by a temporary worsening of symptoms or increased disability.
A physician may initially diagnose a patient with primary-progressive MS (PPMS) and then change the diagnosis to PRMS after a relapse occurs.
A physician will use the patient’s medical history, laboratory tests including magnetic resonance imaging (MRI) and a careful neurologic exam to make the diagnosis of PRMS.