Abstract
Objective To investigate the reorganization of insular subregions in individuals suffering from neuropathic pain (NP) after incomplete spinal cord injury (ISCI) and further to disclose the underlying mechanism of NP. Method The 3D high-resolution T1-weighted structural images and resting-state functional magnetic resonance imaging (rs-fMRI) of all individuals were obtained using a 3.0 Tesla MRI system. A comparative analysis of structure and function connectivity (FC) with insular subareas as seeds in 10 ISCI individuals with below-level NP (ISCI-P), 11 ISCI individuals without NP (ISCI-N), and 25 healthy controls (HCs) was conducted. Associations between the structural and functional alteration of insula subregions and visual analog scale (VAS) scores were analyzed using the Pearson correlation in SPSS 20. Results Compared with ISCI-N patients, when the left posterior insula as the seed, ISCI-P showed increased FC in right cerebellum VIIb and cerebellum VIII, Brodmann 37 (BA 37). When the left ventral anterior insula as the seed, ISCI-P indicated enhanced FC in right BA18 compared with ISCI-N patients. These increased FCs positively correlated with VAS scores. Relative to HCs, ISCI-P presented increased FC in the left hippocampus when the left dorsal anterior insula was determined as the seed. There was no statistical difference in the volume of insula subregions among the three groups. Conclusion Our study indicated that distinctive patterns of FC in each subregion of insula suggest that the insular subareas participate in the NP processing through different FC following ISCI. Further, insula subregions could serve as a therapeutic target for NP following ISCI.
Highlights
Individuals with spinal cord injury (SCI) often have varying degrees of neuropathic pain (NP), which seriously affects the quality of life and functional rehabilitation [1, 2]
Our study indicated that distinctive patterns of function connectivity (FC) in each subregion of insula suggest that the insular subareas participate in the nociceptive processing through different connectivity following incomplete spinal cord injury (ISCI)
The left posterior insula (PI) is interconnected with the right cerebellum VIIb and VIII and BA37, and the left anterior insula (AI) is part of the cortical network mainly involved in the regulation of pain through the FC with BA18 and hippocampus gyrus
Summary
Individuals with spinal cord injury (SCI) often have varying degrees of neuropathic pain (NP), which seriously affects the quality of life and functional rehabilitation [1, 2]. Some studies suggest that the sensitization of central and peripheral nervous system and associated cortical remodeling are considered main reasons in the development of NP following SCI [3,4,5]. These reorganizations located in areas associated with nociceptive processing [4, 6, 7], such as primary sensory cortex (S1), secondary somatosensory cortex (S2), and thalamus. Other studies about NP following SCI have not found any changes in these areas [8, 9]. NP management may be involved in the complex connections associated with the key node of pain network rather than structural changes [10]
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