Researchers at the Montreal Neurological Institute, the Hospital for Sick Children, Toronto, Canada; and Department of Neurology, Rennes, France conducted MRI measurements of whole brain and regional white matter, gray matter, and deep gray matter structure volumes in 38 patients (mean age 15.2+/-2.4 years) with pediatric-onset relapsing-remitting multiple sclerosis (MS). Mean age at MS onset was 12.1 years; mean disease duration 3.1 years. Values obtained from sex-matched healthy controls enrolled in the MRI Study of Normal Brain Development were used as controls. The intracranial volume and normalized brain volume z scores were significantly lower in patients with MS compared with controls. Thalamic volumes in MS patients were lower even after correction for global brain volume decreases. Reduced thalamic and brain volumes correlate moderately with increased disease duration. Head size of pediatric MS patients is lower than controls. 
COMMENT. Onset of MS during childhood is associated with smaller head size, brain volume, and even smaller thalamic volume. Cognitive impairment is a notable feature of pediatric MS. , and thalamic volume correlates with cognitive performance of children with MS.