Objective: To use the new consensus definitions of primary progressive multiple sclerosis (PPMS) and progressive relapsing multiple sclerosis (PRMS) to report the demographic, clinical, and natural history characteristics of multiple sclerosis (MS) that is progressive from the time of onset. Design: Retrospective study by database/chart review and telephone interview. Setting: Multiple sclerosis clinic at a university teaching hospital. Patients: Eighty-three patients (prevalence, 6.9%) with

more »

... S and 12 patients (prevalence, 1.0%) with PRMS were studied. Results: Fifty-nine percent of the patients with PPMS (n = 49) and 67% of the patients with PRMS (n = 8) were women. Mean ± SD ages at the time of onset were 41.2 ± 10.5 and 38.0 ± 7.3 years, respectively; mean disease duration was 14.2 ± 8.8 and 12.2 ± 6.5 years, respectively. The initial symptoms involved leg weakness in 94% of the patients with PPMS (n = 78) and 100% of the patients with PRMS (n = 12). For the PPMS cohort, a syndrome consistent with isolated myelopathy was found in 36% of patients (n = 30) and arm weakness without leg weakness did not occur. Mean ± SEM time of progression to a score of 6.0 on the Expanded Disability Status Scale was 10.2 ± 1.0 years for patients with PPMS and 10.9 ± 2.6 years for patients with PRMS. Conclusions: The clinical characteristics and disability progression of these MS subtypes were indistinguishable, with the exception of 1 or 2 relapses in patients with PRMS that occurred 8 months to 9 years after the onset of symptoms. We see little reason to consider PPMS and PRMS separate clinical entities; however, whether they can be better distinguished by radiological, histopathological, or immunological markers of disease activity remains unknown.