Relapsing-remitting MS (RRMS) is the most common form of Multiple Sclerosis (approximately 40% of all MS cases). People with relapsing-remitting MS have unpredictable relapses (attacks) or symptoms, but generally return to normal (the state of 'remission') between attacks. During this time, the person will either fully or partially recover from the symptoms experienced during the relapse.
If the health of some people with relapsing-remitting MS does deteriorate after each relapse, but their condition is stable between relapses, this is called ‘worsening relapsing-remitting MS’.
People with Primary-progressive MS have steadily worsening symptoms from the outset of their diagnosis, and do not have distinct relapses. Their disability gradually worsens, and it may level off at some point or continue over months or years.
Primary-progressive MS is a progressive form of the disease and does not display any definitive periods of relapse or remission.
People with Benign MS (see definition, found below) have mild, infrequent, sensory exacerbations with a full recovery. After one or two attacks with complete recovery and without any disability, this form of MS does not worsen with time and there is no permanent disability or disease progression.