Fatigue has been reported to be a common symptom and a major burden in neuromyelitis optica spectrum disorder (NMOSD). However, structural MRI substrates of fatigue in NMOSD are not well studied.
Herein, we explored brain subcortical structures and investigated their relationships with fatigue severity in patients with seropositive NMOSD using a surface-based shape analysis.
We prospectively studied patients with NMOSD who were in remission and seropositive for anti-aquaporin-4 antibody. All enrolled patients completed self-reported fatigue assessment using the Functional Assessment of Chronic Illness Therapy-fatigue (FACIT-fatigue) score and the demographic and clinical characteristics were also collected. MRI examination and analysis were done in all patients; the overall process of this study follows MR image processing for extracting subcortical shapes for each individual and registering them to template subcortical surface. After local shape volume extraction, together with demographic information, we implemented statistical analysis of subcortical regions with partial correlation computation and extracted significant sub-clusters via multiple comparison correction using cluster-based statistics.
A total of 28 patients were enrolled (mean age, 47.2±11.2 years; female:male=21:7). Their median disease duration was 2.9 years (IQR 1.3-8.9) and mean FACIT-fatigue score was 36.6±11.6. The volume of subcortical structures were significantly correlated with FACIT-fatigue score including caudate (r = 0.388, p = 0.050), pallidum (r = 0.391, p = 0.048), putamen (r = 0.511, p = 0.008), and thalamus (r = 0.393, p = 0.047). And subcortical local shape volume analysis using cluster-based statistics showed that the fatigue severity was correlated with both caudate and right thalamus (threshold 0.3; left caudate 0.006; right caudate 0.039; right thalamus 0.006) when controlling age, gender, intracranial volume.
The present study suggested that fatigue was common in patients with NMOSD, and local shape volume of subcortical structures in the caudate and thalamus might serve as a biomarker for fatigue in NMOSD.