title: Slowly eroding lesions in multiple sclerosis.
abstract: BACKGROUND
  At autopsy, 20%-40% of chronic multiple sclerosis (MS) lesions are labeled "slowly expanding" and feature myelin phagocytosis at the lesion edge. As pathological lesion classification relies on a single, terminal time point, the rate of lesion expansion cannot be directly measured.
  
  
  OBJECTIVE
  To study long-term volume changes in individual MS lesions.
  
  
  METHODS
  Volumes of individual lesions on proton density magnetic resonance imaging (MRI) acquired between 1992 and 2015 were measured in 22 individuals (one lesion per person). After correction for acquisition protocol, a mixed model evaluated lesion volume changes.
  
  
  RESULTS
  The mean (standard deviation) lesion volume at baseline was 142 (82) mL, falling to 74 (51) mL after 16 (3) years. All lesions shrank over time. Change in lesion volume did not correlate with change in supratentorial brain volume ( p = 0.33). In simulations, the results could be explained by a process of slow radial expansion superimposed on substantially more rapid resorption of damaged tissue.
  
  
  CONCLUSIONS
  We noted sustained radiological contraction of MS lesions, a surprising result given that fresh myelin breakdown products within chronic active lesions are observed relatively frequently at autopsy. Therefore, the primary pathological process in chronic lesions, even those described as "slowly expanding," is likely to be tissue loss.
authors.affiliation: National Institute of Neurological Disorders and Stroke (NINDS), National Institutes of Health (NIH), Bethesda, MD, USA.
authors.forename: Varun
authors.initials: V
authors.lastname: Sethi
authors.affiliation: National Institute of Neurological Disorders and Stroke (NINDS), National Institutes of Health (NIH), Bethesda, MD, USA.
authors.forename: Govind
authors.initials: G
authors.lastname: Nair
authors.affiliation: National Institute of Neurological Disorders and Stroke (NINDS), National Institutes of Health (NIH), Bethesda, MD, USA.
authors.forename: Martina
authors.initials: M
authors.lastname: Absinta
authors.affiliation: National Institute of Neurological Disorders and Stroke (NINDS), National Institutes of Health (NIH), Bethesda, MD, USA.
authors.forename: Pascal
authors.initials: P
authors.lastname: Sati
authors.affiliation: National Institute of Neurological Disorders and Stroke (NINDS), National Institutes of Health (NIH), Bethesda, MD, USA.
authors.forename: Arun
authors.initials: A
authors.lastname: Venkataraman
authors.affiliation: National Institute of Neurological Disorders and Stroke (NINDS), National Institutes of Health (NIH), Bethesda, MD, USA.
authors.forename: Joan
authors.initials: J
authors.lastname: Ohayon
authors.affiliation: National Institute of Neurological Disorders and Stroke (NINDS), National Institutes of Health (NIH), Bethesda, MD, USA.
authors.forename: Tianxia
authors.initials: T
authors.lastname: Wu
authors.affiliation: National Institute of Neurological Disorders and Stroke (NINDS), National Institutes of Health (NIH), Bethesda, MD, USA.
authors.forename: Kelly
authors.initials: K
authors.lastname: Yang
authors.affiliation: National Institute of Neurological Disorders and Stroke (NINDS), National Institutes of Health (NIH), Bethesda, MD, USA.
authors.forename: Colin
authors.initials: C
authors.lastname: Shea
authors.affiliation: National Institute of Neurological Disorders and Stroke (NINDS), National Institutes of Health (NIH), Bethesda, MD, USA.
authors.forename: Blake E
authors.initials: BE
authors.lastname: Dewey
authors.affiliation: National Institute of Neurological Disorders and Stroke (NINDS), National Institutes of Health (NIH), Bethesda, MD, USA.
authors.forename: Irene Cm
authors.initials: IC
authors.lastname: Cortese
authors.affiliation: National Institute of Neurological Disorders and Stroke (NINDS), National Institutes of Health (NIH), Bethesda, MD, USA.
authors.forename: Daniel S
authors.initials: DS
authors.lastname: Reich
mesh_terms: D000293:Adolescent; D000328:Adult; D000367:Age Factors; D001921:Brain / Q000473:pathology*; D004185:Disability Evaluation; D005260:Female; D006801:Humans; D008279:Magnetic Resonance Imaging / Q000379:methods; D008297:Male; D008875:Middle Aged; D009103:Multiple Sclerosis / Q000000981:diagnostic imaging*; D013997:Time Factors; D055815:Young Adult
keywords: Slowly expanding lesion; magnetic resonance imaging; multiple sclerosis; proton density