title: Gray matter atrophy correlates with MS disability progression measured with MSFC but not EDSS.
abstract: BACKGROUND
  Gray matter (GM) pathology is an important component of the multiple sclerosis (MS) disease process. Accelerated gray matter atrophy has been observed in MS patients, but its relationship to neurological disability is not defined. This study was done to determine the relationship between whole brain, GM, and white matter (WM) atrophy and MS disability progression.
  
  
  METHODS
  Patients with MS and Clinically Isolated Syndromes (CIS), and age- and gender-matched healthy controls were entered into an observational protocol. Baseline brain parenchymal fraction (BPF), GM fraction, and WM fraction, and change over 4 years were correlated with sustained disability progression over the entire study duration. Disability progression was measured using the Multiple Sclerosis Functional Composite (MSFC) and the Expanded Disability Status Scale (EDSS).
  
  
  RESULTS
  Seventy MS and CIS patients and 17 HCs were studied for an average of 6.6 years (range, 3.6-7.8 years). At the final visit, 7 patients were classified as CIS, 36 as relapsing-remitting MS (RRMS), and 27 as secondary progressive MS (SPMS). Baseline whole brain, GM, and WM atrophy predicted EDSS >6.0 at the last study visit. Twenty-one (33%) patients worsened using the EDSS to define disability progression; 29 (46%) worsened using MSFC to define disability progression. Patients with MSFC progression had significantly higher GM atrophy rates compared with patients who were stable on MSFC. White matter atrophy was similar in patients with and without disability progression. Atrophy rates were not different in patients with or without disability progression defined using EDSS.
  
  
  CONCLUSIONS
  Whole brain, GM, and WM atrophy predicted MS disability progression observed over the next 6.6 years. Gray matter atrophy rates over 4 years correlated with disability progression measured with the MSFC, but not EDSS. This indicates that MSFC defined disability progression is more closely linked to brain atrophy than EDSS defined disability progression, and provides important new insight into the poor correlation between MRI and clinical disability in MS. The findings confirm the clinical relevance of gray matter atrophy in MS.
authors.affiliation: Mellen Center for MS Treatment and Research U10, Neurologic Institute, Cleveland Clinic, Cleveland, Ohio 44195, USA. rudickr@ccf.org
authors.forename: Richard A
authors.initials: RA
authors.lastname: Rudick
authors.forename: Jar-Chi
authors.initials: JC
authors.lastname: Lee
authors.forename: Kunio
authors.initials: K
authors.lastname: Nakamura
authors.forename: Elizabeth
authors.initials: E
authors.lastname: Fisher
mesh_terms: D000328:Adult; D000704:Analysis of Variance; D001284:Atrophy / Q000473:pathology; D001921:Brain / Q000473:pathology*; D003711:Demyelinating Diseases / Q000175:diagnosis / Q000473:pathology; D004185:Disability Evaluation; D018450:Disease Progression; D005260:Female; D006801:Humans; D008137:Longitudinal Studies; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D009103:Multiple Sclerosis / Q000175:diagnosis* / Q000473:pathology*; D009413:Nerve Fibers, Myelinated / Q000473:pathology; D011379:Prognosis; D012720:Severity of Illness Index; D013997:Time Factors