CNS Imaging Characteristics in Fibromyalgia Patients With and Without Peripheral Nerve Involvement

Abstract

\n We tested the hypothesis that reduced skin innervation in fibromyalgia syndrome is associated with specific CNS changes. This prospective case-control study included 43 women diagnosed with fibromyalgia syndrome and 40 healthy controls. We further compared the fibromyalgia subgroups with reduced (n=21) and normal (n=22) skin innervation. Brains were analysed for cortical thickness, for white matter integrity, and for functional connectivity. Compared to controls, cortical thickness was decreased in the left pars opercularis in the fibromyalgia group as a whole, and decreased in the left superior frontal and left rostral middle frontal cortex in the fibromyalgia subgroup with reduced skin innervation. Diffusion tensor imaging revealed a significant increase in fractional anisotropy in the corona radiata, the corpus callosum, cingulum and fornix in patients with fibromyalgia compared to healthy controls. Using resting-state fMRI, the fibromyalgia group as a whole showed functional hypoconnectivity between the right midfrontal gyrus and the posterior cerebellum and the right crus cerebellum, respectively. The subgroup with reduced skin innervation showed hyperconnectivity between the right cuneal cortex and the anterior parahippocampal gyrus, between the left thalamus and the lateral parietal region in the default mode network and hypoconnectivity between the left frontal lobe and the right cerebellum crus 1. Our results suggest that the subgroup of fibromyalgia patients with pronounced pathology in the peripheral nervous system shows distinctly altered morphology, structural and functional connectivity also at the level of the brain. We propose considering these subgroups when conducting clinical trials.