Hi and welcome Sharon,
Technically Progressive Relapsing MS (PRMS) no longer exists as an MS diagnostic category, from around 2014 those previously diagnosed with Progressive Relapsing MS are now suppose to be classified as Primary Progressive: active or not active. I'm not sure if your neurologist has made the label up, combined old and new labelling or if there's been a misunderstanding or whats going on but the closest type of MS i'm aware of would be Primary Progressive - not active....There is still PRMS and PPMS information available on MS specific website and MS societies that might help provide you with information.
Primary progressive MS (PPMS)
"PPMS is characterized by worsening neurologic function (accumulation of disability) from the onset of symptoms, without early relapses or remissions. PPMS can be further characterized at different points in time as either active (with an occasional relapse and/or evidence of new MRI activity) or not active, as well as with progression (evidence of disease worsening on an objective measure of change over time, with or without relapse or new MRI activity) or without progression. Approximately 15 percent of people with MS are diagnosed with PPMS. "
"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) "
I would honestly recommend you be very wary of any neurologist who's diagnosed you with the rarest type of MS without providing you with a bucket load of information specifically about Progressive Relapsing MS or Primary Progressive -not active and or not even explaining to you why you have this specific type of MS and what it means for you, and then calls Rituximab a 'miracle' drug that will not let the disease progress!
From my understanding Rituximab is not yet approved for Primary Progressive though it is being prescribed for PPMS because disease modifying drugs for PPMS is still in it's early days, i know of one trial that failed "did not slow disability progression compared with placebo"..... https://www.mssociety.org.uk/ms-research/treatments-in-the-pipeline/rituximab
....the latest trial is expected to be completed sometime this year. I do know of a few people with Secondary Progressive who are happy to be on Rituximab but more than that i'm sorry i do not know enough about PP treatment options to really say anything.
I do hope i have helped a little and not added confusion......JJ