RESUMEN

Objective @#To construct a rat model of trigeminal neuralgia ( TN) to explore the expression of high mobility group box-1 (HMGB1) in the trigeminal ganglion (TG) and the possible mechanism of HMGB1 effect on pain . @*Methods @#TN model was constructed by infraorbital nerve constriction and divided into operation group (CCI group) and Sham group , and the success of the model construction was determined through mechanical pain thresh old assessment. Real time fluorescence quantitative PCR ( RT-qPCR) and Western blot were used to detect high mobility group protein B1 (HMGB1) , Toll receptor 4 (TLR4) , and Nuclear Factor Kappa B(NF-κB) mRNA and protein expression in the ipsilateral trigeminal ganglion (TG) of the Sham and CCI rats . 50 mg/kg HMGB1 inhibi tor glycyrrhizin (GL) was inj ected intraperitoneally every day for two week s , and normal saline (NS) was used as control . The patients were divided into CCI group , CCI + NS group and CCI + GL group . HMGB1 , TLR4 , and NF- κB mRNA and protein expression in the ipsilateral trigeminal ganglion (TG) were detected by RT-qPCR and West ern blot in CCI group , CCI + NS group , and CCI + GL group . @*Results @#The mechanical threshold on the operated side of the rat continued to decrease (P < 0.05) , and mechanical pain threshold identification model was success fully constructed . After chronic compressive injury to the infraorbital nerve in rats , HMGB1 , TLR4 , and NF-κB mRNA and protein expression in TG on the operated side increased ( P < 0.05) ; After administration of HMGB1 inhibitor Glcyrrhizin , HMGB1 , TLR4 , NF-κB showed a decrease (P < 0.05) .@*Conclusion @#HMGB1 is associat ed with TN , and HMGB1 may be involved in the pathogenesis of TN through TLR4/NF-κB signaling pathway.

RESUMEN

INTRODUCTION: Neuralgic amyotrophy (NA) is a painful non-traumatic peripheral nervous system condition affecting the brachial plexus. Signal abnormalities in nerves and muscles have been detected in these patients using magnetic resonance neurography (MRN). METHODS: Electronic medical records and MRN images obtained in a 3 T scanner, in 14 adult patients diagnosed with NA at our Neurological institution (Neuromuscular Disorders Section), between December 2015 and December 2019 were retrospectively reviewed. The study was first approved by our Institutional Ethics Committee. RESULTS: Subclinical, multifocal, and bilateral nerve signal anomalies were recorded in the brachial plexus of these patients. We identified four different types of nerve constriction without entrapment, which we categorized as follows: incomplete focal (type I), complete focal or hourglass (type II), multifocal or string of pearls (type III) and segmental (type IV). CONCLUSIONS: Given that MRN is an accurate diagnostic tool to detect nerve damage, we believe abnormal findings could improve early detection of NA patients.

Asunto(s)

RESUMEN

Trigeminal neuralgia is unilateral, lancinating, episodic pain that can be provoked by routine activities. Anticonvulsants, such as carbamazepine, are the drugs of choice; however, these possess side-effects. Microvascular decompression is the most effective surgical technique with a higher success rate, although occasionally causes adverse effects. The potential treatment for this type of pain remains unmet. Increased tetrahydrobiopterin (BH4) levels have been reported in association with axonal injury. This study aimed to evaluate the effect of tranilast on relieving neuropathic pain in animal models and analyze the changes in BH4 synthesis. Neuropathic pain was induced via infraorbital nerve constriction. Tranilast, carbamazepine, or saline was injected intraperitoneally to assess the rat's post-intervention pain response. In the von Frey's test, the tranilast and carbamazepine groups showed significant changes in the head withdrawal threshold in the ipsilateral whisker pad area. The motor coordination test showed no changes in the tranilast group, whereas the carbamazepine group showed decreased performance, indicating impaired motor coordination. Trigeminal ganglion tissues were used for the PCR array analysis of genes that regulate the BH4 pathway. Downregulation of the sepiapterin reductase (Spr) and aldoketo reductase (Akr) genes after tranilast injection was observed compared to the pain model. These findings suggest that tranilast effectively treats neuropathic pain.

Asunto(s)

RESUMEN

The mechanism of pain chronicity is largely unknown in lumbar radiculopathy (LR). The anatomical location of nerve injury is one of the important factors associated with pain chronicity of LR. Accumulating evidence has shown constriction distal to the dorsal root ganglion (DRG) caused more severe radiculopathy than constriction proximal to the DRG; thereby, the mechanism of pain chronicity in LR could be revealed by comparing the differences in pathological changes of DRGs between nerve constriction distal and proximal to the DRG. Here, we used 2 rat models of LR with nerve constriction distal or proximal to the DRG to probe how the different nerve injury sites could differentially affect pain chronicity and the pathological changes of DRG neuron subpopulations. As expected, rats with nerve constriction distal to the DRG showed more persistent pain behaviors than those with nerve constriction proximal to the DRG in 50% paw withdraw threshold, weight-bearing test, and acetone test. One day after the operation, distal and proximal nerve constriction showed differential pathological changes of DRG. The ratios of activating transcription factor3 (ATF3)-positive DRG neurons were significantly higher in rats with nerve constriction distal to DRG than those with nerve constriction proximal to DRG. In subpopulation analysis, the ratios of ATF3-immunoreactivity (IR) in neurofilament heavy chain (NFH)-positive DRG neurons significantly increased in distal nerve constriction compared to proximal nerve constriction; although, both distal and proximal nerve constriction presented increased ratios of ATF3-IR in calcitonin gene-related peptide (CGRP)-positive DRG neurons. Moreover, the nerve constriction proximal to DRG caused more hypoxia than did that distal to DRG. Together, ATF3 expression in NHF-positive DRG neurons at the acute stage is a potential bio-signature of persistent pain in rat models of LR.

Asunto(s)

RESUMEN

BACKGROUND: To observe the effects of MMP-9 (matrix metalloproteases-9) on the mechanical allodynia and thermal hyperalgesia and the expression of CX3CL1 (CX3C chemokine ligand 1) protein in the spinal dorsal root ganglion (DRG) in rats with chronic sciatic nerve constriction injury (CCI). METHODS: A total of 84 male SD rats were randomly divided into seven groups, namely the normal group , the sham operation group , the model group , the CCI + MMP-9 group, the CCI + TIMP-1 group , the CCI + siRNA group, and the CCI + MM-siRNA group. The CCI model was prepared 5 days after implantation of intrathecal catheter. The rat paw mechanical withdrawal threshold (PWMT) and paw thermal withdrawal latency (PWTL) were measured 1 day before CCI surgery and 1, 2, 3 and 5 days after CCI respectively. Western blot (WB) was used to detect the expressions of the MMP-9 and the CX3CL1 protein in the L5 DRG of the spinal cord 1 day after CCI operation. RESULTS: (I) Behavioral assessment of hyperalgesia: compared with the Sham group, the PWMT and PWTL of the CCI group were significantly reduced at each time point after CCI surgery; compared with the CCI group, the PWMT and PWTL of the CCI + MMP-9 group decreased 1 day after CCI; for the PWMT and PWTL of the CCI + TIMP-1 group and CCI + siRNA group, PWMT and PWTL increased 1 day after CCI; (II) The expressions of MMP-9 and CX3CL1 protein in the DRG of the spinal cord: compared with Sham group, the expressions of MMP-9 and CX3CL1 protein in the DRG of the CCI group increased significantly 1 day after CCI surgery; compared with the CCI group, the expressions increased in the CCI + MMP-9 group 1 day after CCI . However, the expressions of MMP-9 and CX3CL1 in the CCI + TIMP-1 group and CCI + siRNA group were reduced on the first postoperative day. CONCLUSIONS: The mechanism of MMP-9 participating in the early phase of neuropathic pain (NP) in CCI rats is related to the upregulation of CX3CL1.

Asunto(s)

RESUMEN

The impact of vitamin D on sensory function, including pain processing, has been receiving increasing attention. Indeed, vitamin D deficiency is associated with various chronic pain conditions, and several lines of evidence indicate that vitamin D supplementation may trigger pain relief. However, the underlying mechanisms of action remain poorly understood. We used inflammatory and non-inflammatory rat models of chronic pain to evaluate the benefits of vitamin D3 (cholecalciferol) on pain symptoms. We found that cholecalciferol supplementation improved mechanical nociceptive thresholds in monoarthritic animals and reduced mechanical hyperalgesia and cold allodynia in a model of mononeuropathy. Transcriptomic analysis of cerebrum, dorsal root ganglia, and spinal cord tissues indicate that cholecalciferol supplementation induces a massive gene dysregulation which, in the cerebrum, is associated with opioid signaling (23 genes), nociception (14), and allodynia (8), and, in the dorsal root ganglia, with axonal guidance (37 genes) and nociception (17). Among the identified cerebral dysregulated nociception-, allodynia-, and opioid-associated genes, 21 can be associated with vitamin D metabolism. However, it appears that their expression is modulated by intermediate regulators such as diverse protein kinases and not, as expected, by the vitamin D receptor. Overall, several genes-Oxt, Pdyn, Penk, Pomc, Pth, Tac1, and Tgfb1-encoding for peptides/hormones stand out as top candidates to explain the therapeutic benefit of vitamin D3 supplementation. Further studies are now warranted to detail the precise mechanisms of action but also the most favorable doses and time windows for pain relief.

Asunto(s)

RESUMEN

Vitamins of the B complex attenuate some neuropathic pain sensory aspects in various animal models and in patients, but the mechanisms underlying their effects remain to be elucidated. Herein it was investigated if the treatment with a vitamin B complex (VBC) reduces heat hyperalgesia in rats submitted to infraorbital nerve constriction and the possibility that TRPV1 receptors represent a target for B vitamins. In the present study, the VBC refers to a combination of vitamins B1, B6 and B12 at low- (18, 18 and 1.8mg/kg, respectively) or high- (180, 180 and 18mg/kg, respectively) doses. Acute treatment of rats with either the low- or the high-doses combination reduced heat hyperalgesia after nerve injury, but the high-doses combination resulted in a long-lasting effect. Repeated treatment with the low-dose combination reduced heat hyperalgesia on day four after nerve injury and showed a synergist effect with a single injection of carbamazepine (3 or 10mg/kg), which per se failed to modify the heat threshold. In naïve rats, acute treatment with the high-dose of VBC or B1 and B12 vitamins independently reduced heat hyperalgesia evoked by capsaicin (3µg into the upper lip). Moreover, the VBC, as well as, each one of the B vitamins independently reduced the capsaicin-induced calcium responses in HEK 293 cells transiently transfected with the human TRPV1 channels. Altogether, these results indicate that B vitamins can be useful to control heat hyperalgesia associated with trigeminal neuropathic pain and that modulation of TRPV1 receptors may contribute to their anti-hyperalgesic effects.

Asunto(s)

RESUMEN

STATE OF THE ART: The proximal radial nerve compression syndrome includes supinator syndrome and proximal radial nerve constrictions. This article presents a new endoscopic assisted radial nerve decompression surgical technique described for the first time by Leclère et al. in 2013. SURGICAL TECHNIQUE: Endoscopic scissor decompression of the proximal radial nerve is always performed under plexus anaesthesia. It includes 8 key steps documented in this article. We review the indications and limitations of the surgical technique. CONCLUSION: Early clinical results after endoscopic assisted decompression of the radial nerve appear excellent. However, they still need to be compared with conventional techniques. Clinical studies are likely to widely develop because of the mini-invasive nature of this new surgical technique.

Asunto(s)

RESUMEN

STATE OF THE ART: The proximal median nerve compression syndrome includes the pronator teres and the Kiloh-Nevin syndrome. This article presents a new surgical technique of endoscopic assisted median nerve decompression. MATERIAL AND SURGICAL TECHNIQUE: Endoscopic scissor decompression of the median nerve is always performed under plexus anaesthesia. It includes 6 key steps documented in this article. We review the indications and limitations of the surgical technique. RESULTS: Since 2011, three clinical series have highlighted the advantages of this technique. Functional and subjective results are discussed. We also review the limitations of the technique and its potential for future development. CONCLUSION: Although clinical results after endoscopic assisted decompression of the median nerve appear excellent they still need to be compared with conventional techniques. Clinical studies are likely to develop primarily due to the mini-invasive nature of this new surgical technique.

Asunto(s)

RESUMEN

Objective : Causes of nontraumatic posterior interosseous nerve (PIN) palsy include space-occupying lesions, constrictions of the PIN, and supinator syndrome. The purpose of this study was to identify these causes using Ultrasonography (US). Methods : We performed US in seven cases (seven elbows) with palsy and examined the PIN and surrounding structures. Results : We identified the three causes by the following US findings : 1) A space-occupying lesion in two elbows. Both were low-echoic and diagnosed as ganglion. In these two cases, the PIN was elevated by the lesion and compressed against the arcade of Frohse. 2) A diffusely swollen PIN with constrictions was found in three cases. 3) A PIN showing a reduction in caliber beneath and a swelling (pseudoneuroma) proximal to the arcade of Frohse, compatible with supinator syndrome was also identified. Conclusion : US is useful for the diagnosis of nontraumatic PIN palsy.