A longitudinal study of MRI-detected atrophy in secondary progressive multiple sclerosis

Abstract

MRI measures of tissue atrophy within the central nervous system may reflect the neurodegenerative process which underpins the progressive phase of multiple sclerosis (MS). There has been limited longitudinal investigation of MRI-detected atrophy in secondary progressive MS. This study includes 56 subjects with secondary progressive MS. Subjects were followed up for 2 years and MRI analysis was conducted at 12 month intervals using the following measures: (1) whole brain (WB) volume change; (2) grey and white matter (WM) volumes; (3) central brain volume; (4) upper cervical spinal cord (SC) area; (5) T2 lesion volumes. Clinical measures included the Expanded Disability Status Scale and the MS Functional Composite. All volumetric MRI measures were assessed for sensitivity, responsiveness, reliability and correlation with disability. The mean annual atrophy rate of WB was 0.59% per year and this was the most responsive atrophy measure assessed. Grey matter (GM) atrophy (-1.18% per year) was greater and more responsive than WM atrophy (0.12% per year). The SC demonstrated the highest atrophy rate at 1.63% per year. WB, GM and SC atrophy all correlated with change in the Multiple Sclerosis Functional Composite z score (r = 0.35, 0.42, 0.34), and GM atrophy was the only correlate of change in the 9 Hole Peg Test and Paced Auditory Serial Addition Test performance. None of the MRI measures correlated with Expanded Disability Status Score progression. Measures of WB, GM and SC atrophy all have attributes for use as surrogate markers in secondary progressive MS trials and improvement in the reliability of the GM and SC volume measurements may enhance these further.