Rationale for Correct Answer
The correct answer is: PPMS can be active or nonactive
There are 2 phenotypes for progressive MS: secondary progressive MS (SPMS), which develops in patients who previously had relapsing-remitting MS (RRMS), and primary progressive MS (PPMS).1 However, even with progressive MS, there may be periods when disease is not progressing.1 Similarly, both SPMS and PPMS can be active or nonactive, with activity defined by either relapse or new or enlarging MRI lesions.2 Relapsing and progressive phenotypes involve different but overlapping pathologic processes.3
References:
1. Lublin FD et al. Neurology. 2014;83:278-286.
2. Lublin FD et al. Neurology. 2020;94:1088-1092.
3. Yong HYF et al. Nat Rev Neurol. 2022;18:40-55.