Paramagnetic Rim Lesions and Choroid Plexus Volume at Diagnosis Are Associated With Cognitive Progression Independent of Relapse and MRI Activity in Early Relapsing-Remitting Multiple Sclerosis.

Paramagnetic rim lesions (PRLs) and choroid plexus (CP) enlargement reflect smoldering inflammation in multiple sclerosis. Their role in cognitive progression remains unexplored. Eighty-seven early relapsing-remitting MS patients were enrolled at diagnosis and followed longitudinally. PRLs and CP volume were evaluated at diagnosis using 3 T-MRI. Cognitive decline over time was classified as cognitive progression independent of relapse/MRI activity (PIRMA). Fifty-five patients (63.2%) showed meaningful cognitive decline: 44 (80.0%) were cognitive PIRMA. PRLs and CP volume at diagnosis were associated with cognitive PIRMA. PRLs and larger CP reflect cognitive progression independent of clinical/MRI activity, supporting their role as smoldering disease activity markers.