The Localization Research of Brain Plasticity Changes after Brachial Plexus Pain: Sensory Regions or Cognitive Regions?

Abstract

Objective Neuropathic pain after brachial plexus injury remains an increasingly prevalent and intractable disease due to inadequacy of satisfactory treatment strategies. A detailed mapping of cortical regions concerning the brain plasticity was the first step of therapeutic intervention. However, the specific mapping research of brachial plexus pain was limited. We aimed to provide some localization information about the brain plasticity changes after brachial plexus pain in this preliminary study. Methods 24 Sprague-Dawley rats received complete brachial plexus avulsion with neuropathic pain on the right forelimb successfully. Through functional imaging of both resting-state and block-design studies, we compared the amplitude of low-frequency fluctuations (ALFF) of premodeling and postmodeling groups and the changes of brain activation when applying sensory stimulation. Results The postmodeling group showed significant decreases on the mechanical withdrawal threshold (MWT) in the bilateral hindpaws and thermal withdrawal latency (TWL) in the left hindpaw than the premodeling group (P < 0.05). The amplitude of low-frequency fluctuations (ALFF) of the postmodeling group manifested increases in regions of the left anterodorsal hippocampus, left mesencephalic region, left dorsal midline thalamus, and so on. Decreased ALFF was observed in the bilateral entorhinal cortex compared to that of the premodeling group. The results of block-design scan showed significant differences in regions including the limbic/paralimbic system and somatosensory cortex. Conclusion We concluded that the entorhinal-hippocampus pathway, which was part of the Papez circuit, was involved in the functional integrated areas of brachial plexus pain processing. The regions in the “pain matrix” showed expected activation when applying instant nociceptive stimulus but remained silent in the resting status. This research confirmed the involvement of cognitive function, which brought novel information to the potential new therapy for brachial plexus pain.

Acupuncture Induces Reduction in Limbic-Cortical Feedback of a Neuralgia Rat Model: A Dynamic Causal Modeling Study

“…All protocols and procedures of animals followed the guidelines of the Biomedical Resource Center and were approved by the Institutional Animal Care and Use Committee. Model establishment damaging the right brachial plexus from C5 to T1 eliciting pain were conducted on 30 adult female Sprague-Dawley rats [19]. And we screened the rats based on the presence of self-harm behavior to distinguish which of them presented neuropathic pain syndrome.…”

“…We used a series of ascending force von Frey monofilaments (Stoelting, IL) to measure mechanical sensitivity on both hindpaws. The threshold of MWT was taken as the lowest force that evoked a brisk withdrawal response, at least two out of four times repetitive stimuli [19]. The MWT results were analyzed by nonparametric statistical analysis (P < 0:05) using the statistical package SPSS 20.0.…”

“…For each rat in the experiment, five minutes of fMRI recordings with a block design sequence was acquired on a 7 T (Bruker Corporation, Germany) MRI scanner. The parameter settings of blood oxygen level-dependent (BOLD) signal were referred to our prior work [19]. fMRI data were corrected for upscaling (magnification 10×), stripping none-brain tissue, reorientation, slice-timing, realignment, coregistration, spatially warped and resampled to the template in MNI space, and spatially smoothed with an isotropic Gaussian kernel (full width at half maximum) twice as the voxel size.…”

Shifted hub regions in the brain network of rat neuropathic pain model after electroacupuncture therapy

“…BPA established an animal model of neuropathic pain following Wang et al (2019). Surgical procedures were performed when adequate anesthesia (40 mg/kg sodium pentobarbital intraperitoneal injection) was achieved.…”

“…In consideration of the peripheral sensitization mechanism associated with neuropathic pain, the pain threshold of bilateral intact hindpaws was utilized as the indicator of the overall pain threshold aroused by BPA (Rodriguesfilho et al, 2003). Prior study has consistently demonstrated that the MWT of bilateral hindpaws significantly decreases after BPA when compared with pre-modeling (Wang et al, 2019).…”