Objectives: This study investigated brain morphometry changes associated with fatigue severity in fibromyalgia (FM).
Methods: Clinical profiles and brain-MRI data were collected in patients with FM. Patients were divided into three groups based on their fatigue severity. Using voxel-based morphometry analysis and trend analysis, neural substrates showing volumetric changes associated with fatigue severity across the three groups were identified. Their seed-to-voxel structural covariance (SC) networks with the whole brain were studied in distribution and strength.
Results: Among the 138 enrolled patients with FM, 23, 57, and 58 were categorised into the mild, moderate, and severe fatigue groups, respectively. The number of musculoskeletal pain regions and intensity of pain were not associated with fatigue severity, but somatic symptoms and psychiatric distress, including waking unrefreshed, depression, and anxiety, were associated with fatigue severity. After adjusting for anxiety and depression, decreased bilateral thalamic volumes were associated with higher fatigue severity. The SC distributions of the thalamic seed were more widespread to the frontal, parietal, subcortical, and limbic regions in patients with higher fatigue severity. In addition, increased right inferior temporal cortex volumes were associated with higher fatigue severity. The SC distributions of the right inferior temporal seed were more over the temporal cortex and the SC strengths of the seed were higher with the bilateral occipital cortex in patients with higher fatigue severity.
Conclusions: The thalamus and the right inferior temporal cortex are implicated in the manifestation of fatigue severity in FM. Future therapeutic strategies targeting these regions are worthy of investigation.