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AJNR - American Journal of Neuroradiology

Published ahead of print on June 12, 2008
doi: 10.3174/ajnr.A1162

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American Journal of Neuroradiology 29:1465-1470, September 2008
© 2008 American Society of Neuroradiology

SPINE

Medulla Oblongata Volume: A Biomarker of Spinal Cord Damage and Disability in Multiple Sclerosis

Z. Liptak^a, A.M. Berger^a, M.P. Sampat^a, A. Charil^a, O. Felsovalyi^c, B.C. Healy^d, P. Hildenbrand^a,e, S.J. Khoury^b, H.L. Weiner^b, R. Bakshi^a and C.R.G. Guttmann^a

^a Center for Neurological Imaging, Brigham and Women's Hospital, Harvard Medical School, Boston, Mass
^b Partners Multiple Sclerosis Center, Brigham and Women's Hospital, Harvard Medical School, Boston, Mass
^c Massachusetts Institute of Technology, Cambridge, Mass
^d Brigham and Women's Hospital, Harvard Medical School, Boston, Mass
^e Lahey Clinic, Burlington, Mass

Please address correspondence to Charles R.G. Guttmann, MD, Center for Neurological Imaging, 221 Longwood Ave, RF 394, Boston, MA 02115; e-mail: guttmann{at}bwh.harvard.edu

BACKGROUND AND PURPOSE: While brain MR imaging is routinely performed, the MR imaging assessment of spinal cord pathology in multiple sclerosis (MS) is less frequent in clinical practice. The purpose of this study was to determine whether measurements of medulla oblongata volume (MOV) on routine brain MR imaging could serve as a biomarker of spinal cord damage and disability in MS.

MATERIALS AND METHODS: We identified 45 patients with MS with both head and cervical spinal cord MR imaging and 29 age-matched and sex-matched healthy control subjects with head MR imaging. Disability was assessed by the expanded disability status scale (EDSS) and ambulation index (AI). MOV and upper cervical cord volume (UCCV) were manually segmented; semiautomated segmentation was used for brain parenchymal fraction (BPF). These measures were compared between groups, and linear regression models were built to predict disability.

RESULTS: In the patients, MOV correlated significantly with UCCV (r = 0.67), BPF (r = 0.45), disease duration (r = –0.64), age (r = –0.47), EDSS score (r = –0.49) and AI (r = –0.52). Volume loss of the medulla oblongata was –0.008 cm³/year of age in patients with MS, but no significant linear relationship with age was found for healthy control subjects. The patients had a smaller MOV (mean ± SD, 1.02 ± 0.17 cm³) than healthy control subjects (1.15 ± 0.15 cm³), though BPF was unable to distinguish between these 2 groups. MOV was smaller in patients with progressive MS (secondary- progressive MS, 0.88 ± 0.19 cm³ and primary-progressive MS, 0.95 ± 0.30 cm³) than in patients with relapsing-remitting MS (1.08 ± 0.15 cm³). A model including both MOV and BPF better predicted AI than BPF alone (P = .04). Good reproducibility in MOV measurements was demonstrated for intrarater (intraclass correlation coefficient, 0.97), interrater (0.79), and scan rescan data (0.81).

CONCLUSION: MOV is associated with disability in MS and can serve as a biomarker of spinal cord damage.