b'Medicine and ResearchMMeeaassuurriinnggMMSSPPrrooggrreessssiioonn::PPIIRRAAvveerrssuussRRAAWWDDiissttiinngguuiisshhiinnggbbeettwweeeenntthheemmccaannpprroovveeddiiffifficcuullttBy Alexis Novak and Dr. Robert J. FoxMS can cause neurological impairmentssymptomscanoccurwithintherstfew including weakness, numbness, coordinationyears of relapsing-remitting MS. This silent problems, and blurry vision. These impairmentsworsening is now recognized as progression can be caused in one of two main ways, PIRAindependent of relapse activity, and is a key or RAW.component of progressive MS. We used to Eaassyyttooddeennee think progressive MS started decades after EClinical relapses can involve almost anyrelapsing MS, but we now realize in many MSsymptombutmostcommonlycausepatients, progressive MS is occurring during numbness, weakness, or blurry vision. Relapsesthe relapsing-remitting phase. PIRA shows are thought to be caused by the immune systemprogression can happen even when relapses attacking the nerves (neurons) and protectiveare controlled. This means therapies that sheathes around these nerves (myelin). Mostreduce relapses may not always stop the of these symptoms resolve after a relapse,progression of MS. but occasionally, even after the relapse endsNNootteeaassyyttoottrraacckkPPIIRRAAand most symptoms resolve, some symptomsWhen comparing PIRA and RAW, PIRA is can remain in the long term. Relapse associatedindependent of relapses, while RAW is directly worsening (RAW) shows that not all relapseslinked to them. PIRA is thought to be related are benign and some can lead to long-lastingto chronic neurodegenerative process, while disability.RAW is attributed to the immediate damage Sometimes, symptoms of MS can developfrom inammation related to an MS relapse. little by little, separate from relapses. The mostUnfortunately, PIRA is more challenging to commonstorypatientsexperienceisthetreat than relapses, although researchers are symptoms from an MS relapse that occurredtesting new treatments to help slow PIRA.years ago start to slowly come back. This can beA study looking at PIRA and RAW showed 10 to 20 years or more after the initial relapsethat most of the time, people with MS get but are similar to the symptoms of the relapse.worse over time because of PIRA, even in the For example, if a patient experiences right legearly stages of the disease. RAW happens less numbness and weakness very early in theiroften, likely because effective treatments are MS history, they may notice a slow return ofavailable that work well to stop relapses. It is these symptoms 20 years later. harder for doctors and researchers to track Sometimes, these gradual symptoms canPIRA, which may make it harder to study. One occur without a previous relapse involvingstudy found that the average rate of disability those symptoms, and sometimes these gradualprogression between patients with PIRA and msfocusmagazine.org 14'