Cervical cord myelin water imaging shows degenerative changes over one year in multiple sclerosis but not neuromyelitis optica spectrum disorder.

Anna J.E Combes,Jimmy S Lee,Jacqueline Palace,Lucy Matthews,Anthony L Traboulsee,Gareth J Barker,Robert Carruthers,David K.B Li,Shannon Kolind

doi:10.1016/j.nicl.2017.06.019

Abstract

Spinal cord pathology is a feature of both neuromyelitis optica spectrum disorder (NMOSD) and relapsing-remitting multiple sclerosis (MS). While subclinical disease activity has been described in MS using quantitative magnetic resonance imaging measures, current evidence suggests that neurodegeneration is absent between relapses in NMOSD, although most evidence comes from brain studies. We aimed to assess cross-sectional differences and longitudinal changes in myelin integrity in relapse-free MS and NMOSD subjects over one year. 15 NMOSD, 15 MS subjects, and 17 healthy controls were scanned at 3 T using a cervical cord mcDESPOT protocol. A subset of 8 NMOSD, 11 MS subjects and 14 controls completed follow-up. Measures of the myelin water fraction (fM) within lesioned and non-lesioned cord segments were collected. At baseline, fM in lesioned and non-lesioned segments was significantly reduced in MS (lesioned: p = 0.002; non-lesioned: p = 0.03) and NMOSD (lesioned: p = 0.0007; non-lesioned: p = 0.002) compared to controls. Longitudinally, fM decreased within non-lesioned cord segments in the MS group (− 7.3%, p = 0.02), but not in NMOSD (+ 5.8%, p = 0.1), while change in lesioned segments fM did not differ from controls' in either patient group. These results suggest that degenerative changes outside of lesioned areas can be observed over a short time frame in MS, but not NMOSD, and support the use of longitudinal myelin water imaging for the assessment of pathological changes in the cervical cord in demyelinating diseases.

Highlights

Neuromyelitis optica spectrum disorder (NMOSD) is a relapsing autoimmune disease of the central nervous system that, due to similar clinical and neurological features, was long thought to be a rare variant of multiple sclerosis (MS) (Wingerchuk et al, 2015)
While subclinical disease activity has been described in MS using quantitative magnetic resonance imaging measures, current evidence suggests that neurodegeneration is absent between relapses in neuromyelitis optica spectrum disorder (NMOSD), most evidence comes from brain studies
These results suggest that degenerative changes outside of lesioned areas can be observed over a short time frame in MS, but not NMOSD, and support the use of longitudinal myelin water imaging for the assessment of pathological changes in the cervical cord in demyelinating diseases

Summary

Introduction

Neuromyelitis optica spectrum disorder (NMOSD) is a relapsing autoimmune disease of the central nervous system that, due to similar clinical and neurological features, was long thought to be a rare variant of multiple sclerosis (MS) (Wingerchuk et al, 2015). Serum antibodies to the aquaporin-4 water channel protein (AQP4-Ab), found on astrocytic foot processes, are detectable in a high proportion of patients (Pandit et al, 2015). Current clinical and neuroimaging evidence suggests that subclinical disease activity does not occur between attacks in NMOSD (Wingerchuk et al, 2007b), contrary to what is observed in MS (Filippi and Agosta, 2010; Matthews et al, 2015). It has been suggested that NMOSD attacks are so severe that the resulting sequelae hide the subtler changes that may accrue over time as a result of progressive axonal deterioration following inflammation (Wingerchuk et al, 1999)

Objectives

Methods

Discussion

Conclusion