Background: Benign multiple sclerosis (MS) is defined by minimal or no disability after many years of observation, therefore a less degenerative disease process is suspected to be present in this subset of patients.
Objective: To compare brain atrophy rates in patients with long-standing benign MS vs typical early MS.
Design: A longitudinal prospective cohort study and a retrospective database review.
Setting: An academic MS center.
Patients: Thirty-nine patients with clinically defined benign MS and an age-matched group of 40 patients with early relapsing-remitting MS.
Main outcome measures: Baseline demographic, treatment, brain magnetic resonance imaging measures, and annualized atrophy rates, derived from serial brain parenchymal fraction measurements across 2 years, were compared.
Results: In the baseline analysis, patients with benign MS were matched to the early MS group on age, sex, treatment with immunomodulatory therapy, T2 lesion volume, and brain parenchymal fraction. The mean (SD) annualized brain atrophy rate in patients with benign MS (-0.16% [0.51%]) was lower than that in patients with early MS (-0.46% [0.72%]) (P = .02). The difference remained significant after controlling for age, sex, and treatment (P = .04).
Conclusions: Serial magnetic resonance imaging revealed a low 2-year rate of brain atrophy in patients with clinically benign MS, suggesting a less prominent degenerative component in its pathogenesis than in patients with typical early MS. Identification of patients with a low rate of brain atrophy may indicate a benign course.