Multiple Sclerosis Fatigue: A Longitudinal Structural MRI and Diffusion Tensor Imaging Study

BACKGROUND AND PURPOSE Previous cross-sectional studies have reported the involvement of thalamus, pallidum, superior cerebellar peduncle, temporal cortex, and fronto-parietal white matter in multiple sclerosis (MS)-related fatigue. However, the longitudinal imaging correlates of fatigue severity variation in MS remain unclear. METHODS RESULTS Structural and diffusion tensor imaging (DTI) data were collected from 43 relapsing remitting MS (RRMS) patients with fatigue (Fatigue Severity Scale [FSS] range: 1-7). Subcortical nuclei volume using FreeSurfer and cortical diffusion indices using a cross-modality technique were measured at baseline and year 1. The pallidal volume had significantly decreased (P = .002) by year 1, although the fatigue score variation was not significant. At year 1, the pallidal volume (P = .023) and fractional anisotropy (FA, P = .013) of right temporal cortex (RTC) correlated significantly with FSS. CONCLUSIONS The pallidal volume and the FA-RTC may be used to evaluate longitudinal fatigue severity variation. Our study proposes new biomarkers to monitor fatigue severity in MS patients.