Impact of MS during the critical window of brain development

Abstract

In this issue of Neurology ®, Aubert-Broche et al.1 study the longitudinal change in brain volume in 36 children with multiple sclerosis (MS) (mean age at scan 13.77 years) compared to 25 local healthy children and 339 healthy children from an NIH-sponsored database. This is the first study to compare the trajectory of brain growth in pediatric MS compared to normative controls. The same 1.5T MRI protocol was utilized for all study groups, and the preprocessed T1-weighted images of each time point were linearly coregistered to a subject-specific linear template. Mixed effect models, adjusting for age and sex, were used to estimate and compare growth trajectories. The major findings in the study were that brain volumes were lower in children with MS compared to healthy children of comparable age, and that, in children with MS, there was a downward trajectory in brain volume compared to the growth observed in healthy children. This downward trajectory in brain volume in the patients with MS was due to both a failure of age-expected brain growth as well as subsequent and progressive atrophy. These findings may differ from those of adult patients with MS in whom we assume that the brain is fully developed, and then atrophy ensues; however, this assumption needs to be tested through comparative studies. Deep gray matter structure volumetrics, adjusted for whole brain volume, showed lesser thalamic growth and marginal changes in the globus pallidus, compared to no change in the caudate and putamen. Higher T2 lesion load was associated with smaller thalamic volumes longitudinally. The main limitation of this study is the small number of patients assessed.