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Pain Physician ; 25(1): E147-E156, 2022 01.
Artigo em Inglês | MEDLINE | ID: mdl-35051163


BACKGROUND: Neuropathic pain following brachial plexus avulsion injury (BPAI) induces plastic changes in multiple brain regions associated with somatosensory function, pain, or cognition at the group level. The alternation of the whole pattern of resting-state brain activity and the feasibility of a brain imaging, information-based diagnosis of pain following BPAI is poorly investigated. OBJECTIVES: To investigate whether brain pattern alternation can  identify neuropathic pain from healthy controls at an individual level and the specific regions that can be used as diagnostic neuroimaging biomarkers. STUDY DESIGN: Controlled animal study. SETTING: The research took place in the school of rehabilitation science of a university and affiliated hospitals. METHODS: A total of 48 female Sprague-Dawley rats weighing 180 g-200 g were randomly assigned to either the BPAI group (n = 24) or normal control group (n = 24). A neuropathic pain rat model following BPAI was established in the BPAI group and a mechanical withdrawal threshold (MWT) test was performed to verify the presence of neuropathic pain. Micro-positron emission tomography with [Fluorine-18]-fluoro-2-deoxy-D-glucose (18F-FDG-PET) was used to obtain the whole brain metabolic activity scans. Multivariate pattern analysis (MVPA) was performed with a linear support vector machine (SVM) analysis both in PRoNTo toolbox (based on regions of interests) and SearchlightSearchlight approach (based on voxels within the region). RESULTS: Compared with baseline status, MWT of the left (intact) forepaw was significantly reduced in the BPAI group (P < 0.001). The accuracy of a whole brain image that correctly discriminated BPAI from normal controls rats was 87.5% with both the PRoNTo toolbox and SearchlightSearchlight method. Pearson's correlation analysis revealed significant positive correlations (P < 0.05) between MWT and the standard taken values of brain regions including the left olfactory nucleus, right entorhinal cortex in the PRoNTo toolbox, and bilateral amygdala, right piriform cortex and right ventral hippocampus in Searchlight method. LIMITATIONS: The alternation of metabolic connectivity among regions and functional connectivity among different networks were not investigated in the present study. CONCLUSIONS: Our study indicated that MVPA based on the PET scans of rats' brains  could successfully identify neuropathic pain from health condition at the individual level and predictive regions could potentially be provided as neuroimaging biomarkers for the neuropathic pain following BPAI.

Plexo Braquial , Neuralgia , Animais , Plexo Braquial/diagnóstico por imagem , Plexo Braquial/lesões , Encéfalo , Feminino , Humanos , Neuralgia/metabolismo , Tomografia por Emissão de Pósitrons combinada à Tomografia Computadorizada , Ratos , Ratos Sprague-Dawley
Front Neural Circuits ; 14: 35, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32625066


Objective: The present study aimed to investigate the analgesic effect of electroacupuncture (EA) in neuropathic pain due to brachial plexus avulsion injury (BPAI) and related changes in the metabolic brain connectivity. Methods: Neuropathic pain model due to BPAI was established in adult female Sprague-Dawley rats. EA stimulations (2/15 Hz, 30 min/day, 5-day intervention followed by 2-day rest in each session) were applied to the fifth-seventh cervical "Jiaji" acupoints on the noninjured side from 1st to 12th weeks following BPAI (EA group, n = 8). Three control groups included sham EA (nonelectrical acupuncture applied to 3 mm lateral to the real "Jiaji" acupoints), BPAI-only, and normal rats (no particular intervention; eight rats in each group). Thermal withdrawal latency (TWL) of the noninjured forepaw was regularly tested to evaluate the threshold of thermalgesia. Small animal [fluorine-18]-fluoro-2-deoxy-D-glucose (18F-FDG) PET/CT scans of brain were conducted at the end of 4th, 12th, and 16th weeks to explore metabolic alterations of brain. Results: In the EA group, the TWL of the noninjured forepaw significantly decreased following BPAI and then increased following EA stimulation, compared with sham EA (P < 0.001). The metabolic brain connectivity among somatosensory cortex (SC), motor cortex (MC), caudate putamen (Cpu), and dorsolateral thalamus (DLT) in bilateral hemispheres decreased throughout the 16 weeks' observation in the BPAI-only group, compared with the normal rats (P < 0.05). In the EA group, the strength of connectivity among the above regions were found to be increased at the end of 4th week following BPAI modeling, decreased at 12th week, and then increased again at 16th week (P < 0.05). The changes in metabolic connectivity were uncharacteristic and dispersed in the sham EA group. Conclusion: The study revealed long-term and extensive changes of metabolic brain connectivity in EA-treated BPAI-induced neuropathic pain rats. Bilateral sensorimotor and pain-related brain regions were mainly involved in this process. It indicated that modulation of brain metabolic connectivity might be an important mechanism of analgesic effect in EA stimulation for the treatment of neuropathic pain.

Plexo Braquial/lesões , Encéfalo/metabolismo , Eletroacupuntura/métodos , Rede Nervosa/metabolismo , Neuralgia/metabolismo , Neuralgia/terapia , Animais , Encéfalo/diagnóstico por imagem , Feminino , Rede Nervosa/diagnóstico por imagem , Neuralgia/diagnóstico por imagem , Ratos , Ratos Sprague-Dawley
Polymers (Basel) ; 11(5)2019 May 01.
Artigo em Inglês | MEDLINE | ID: mdl-31052419


In recent years, poly(lactic acid) (PLA) has attracted more and more attention as one of the most promising biobased and biodegradable polymers. However, the inherent brittleness significantly limits its wide application. Here, ternary blends of PLA, poly(ε-caprolactone) (PCL) with various amounts of ethylene-methyl acrylate-glycidyl methacrylate (EMA-GMA) terpolymer were fabricated through reactive melt blending in order to improve the toughness of PLA. The effect of different addition amounts of EMA-GMA on the mechanical properties, interfacial compatibility and phase morphology of PLA/PCL blends were studied. The reactions between the epoxy groups of EMA-GMA and carboxyl and hydroxyl end groups of PLA and PCL were investigated thorough a Fourier transform infrared (FT-IR). The miscibility and thermal behavior of the blends were studied through a dynamic mechanical analysis (DMA), differential scanning calorimetric (DSC) and X-ray diffraction (XRD). The phase morphology and impact fracture surface of the blends were also investigated through a scanning electron microscope (SEM). With the addition of 8 phr EMA-GMA, a PLA/PCL (90 wt %:10 wt %)/EMA-GMA ternary blend presenting a suitable multiple stacked phase structure with an optimum interfacial adhesion exhibited an elongation at break of 500.94% and a notched impact strength of 64.31 kJ/m2 with a partial break impact behavior. Finally, the toughening mechanism of the supertough PLA based polymers have been established based on the above analysis.

J Pain Res ; 11: 3171-3179, 2018.
Artigo em Inglês | MEDLINE | ID: mdl-30588069


Background: Neuropathic pain is a common and intractable sequel of brachial plexus injury. Materials and methods: To investigate the underlying mechanisms, we established a unique model of neuropathic pain in rats by creating brachial plexus avulsion injury. Results: Behavioral test of mechanical stimulation suggested that all rats developed neuropathic pain, and the pain thresholds of bilateral hind limbs significantly decreased. GFAP expression in the cervical spinal cord appeared on day 1 post-injury and increased on day 4. Ionized calcium-binding adaptor molecule 1 expression appeared on day 1 post-injury and increased until day 28. Therefore, the brachial plexus avulsion injury model can imitate the development of neuropathic pain and maintain it. Conclusion: The activation of astrocyte and microglia in the spinal cord plays a key role in the mechanism and treatment of neuropathic pain.

Neurosurgery ; 83(4): 819-826, 2018 10 01.
Artigo em Inglês | MEDLINE | ID: mdl-29029335


BACKGROUND: Functional recovery after peripheral nerve injury and repair is related with cortical reorganization. However, the mechanism of innervating dual targets by 1 donor nerve is largely unknown. OBJECTIVE: To investigate the cortical reorganization when the phrenic nerve simultaneously innervates the diaphragm and biceps. METHODS: Total brachial plexus (C5-T1) injury rats were repaired by phrenic nerve-musculocutaneous nerve transfer with end-to-side (n = 15) or end-to-end (n = 15) neurorrhaphy. Brachial plexus avulsion (n = 5) and sham surgery (n = 5) rats were included for control. Behavioral observation, electromyography, and histologic studies were used for confirming peripheral nerve reinnervation. Cortical representations of the diaphragm and reinnervated biceps were studied by intracortical microstimulation techniques before and at months 0.5, 3, 5, 7, and 10 after surgery. RESULTS: At month 0.5 after complete brachial plexus injury, the motor representation of the injured forelimb disappeared. The diaphragm representation was preserved in the "end-to-side" group but absent in the "end-to-end" group. Rhythmic contraction of biceps appeared in "end-to-end" and "end-to-side" groups, and the biceps representation reappeared in the original biceps and diaphragm areas at months 3 and 5. At month 10, it was completely located in the original biceps area in the "end-to-end" group. Part of the biceps representation remained in the original diaphragm area in the "end-to-side" group. Destroying the contralateral motor cortex did not eliminate respiration-related contraction of biceps. CONCLUSION: The brain tends to resume biceps representation from the original diaphragm area to the original biceps area following phrenic nerve transfer. The original diaphragm area partly preserves reinnervated biceps representation after end-to-side transfer.

Plexo Braquial/fisiologia , Plexo Braquial/cirurgia , Córtex Motor/fisiologia , Regeneração Nervosa/fisiologia , Transferência de Nervo/tendências , Procedimentos Neurocirúrgicos/tendências , Animais , Neuropatias do Plexo Braquial/fisiopatologia , Neuropatias do Plexo Braquial/cirurgia , Membro Anterior/inervação , Membro Anterior/fisiologia , Masculino , Músculo Esquelético/inervação , Músculo Esquelético/fisiologia , Transferência de Nervo/métodos , Procedimentos Neurocirúrgicos/métodos , Nervo Frênico/fisiologia , Nervo Frênico/transplante , Distribuição Aleatória , Ratos , Ratos Sprague-Dawley , Procedimentos Cirúrgicos Reconstrutivos/métodos , Procedimentos Cirúrgicos Reconstrutivos/tendências , Recuperação de Função Fisiológica/fisiologia