[Neurosurgical treatment of chronic pain]

Development and Validation of a Predictive Model of Pain Modulation Profile to Guide Chronic Pain Treatment: A Study Protocol

Introduction: Quantitative sensory testing is frequently used in research to assess endogenous pain modulation mechanisms, such as Temporal Summation (TS) and Conditioned Pain Modulation (CPM), reflecting excitatory and inhibitory mechanisms, respectively. Numerous studies found that a dysregulation of these mechanisms is associated with chronic pain conditions. In turn, such a patient's “profile” (increased TS and/or weakened CPM) could be used to recommend different pharmacological treatments. However, the procedure to evaluate these mechanisms is time-consuming and requires expensive equipment that is not available in the clinical setting. In this study, we aim to identify psychological, physiological and socio-demographic markers that could serve as proxies to allow healthcare professionals to identify these pain phenotypes in clinic, and consequently optimize pharmacological treatments.

Method: We aim to recruit a healthy participant cohort (n = 360) and a chronic pain patient cohort (n = 108). Independent variables will include psychological questionnaires, pain measurements, physiological measures and sociodemographic characteristics. Dependent variables will include TS and CPM, which will be measured using quantitative sensory testing in a single session. We will evaluate one prediction model and two validation models (for healthy and chronic pain participants) using multiple regression analysis between TS/CPM and our independent variables. The significance thresholds will be set at p = 0.05, respectively.

Perspectives: This study will allow us to develop a predictive model to compute the pain modulation profile of individual patients based on their biopsychosocial characteristics. The development of the predictive model is the first step toward the overarching goal of providing clinicians with a set of quick and cheap tests, easily applicable in clinical practice to orient pharmacological treatments.

Stress-related hormone reduces autophagy through the regulation of phosphatidylethanolamine in breast cancer cells

Background

An increasing number of studies indicate that adrenergic signaling plays a fundamental role in tumor progression and metastasis induced by chronic stress. However, despite the growing attention, an understanding of the mechanisms linking chronic stress and cancer is still insufficient.

Methods

Western blot analysis and transmission electron microscopy (TEM) were used to observe the changes in autophagy level in a breast cancer cell line (MCF-7) after epinephrine treatment. Non-targeted metabolomics was also used to detect MCF-7 metabolites after epinephrine treatment. The xenograft model was used to detect the level of autophagy after epinephrine intervention.

Results

The results showed that epinephrine treatment reduced the autophagy level of breast cancer cells. Epinephrine changed the level of phosphatidylethanolamine (PE) in breast cancer cells as detected by non-targeted metabolomics. Epinephrine also changed autophagy in breast cancer cells by decreasing the level of PE in cells. When autophagy decreased, the invasion and migration of breast cancer cells increased in vitro, and the progression of breast cancer accelerated in vivo.

Conclusions

These findings suggest that stress-related hormones affect the tumor progression of breast cancer. Therefore, strengthening the emotional management strategies of patients during the process of antitumor treatment as a supplement to the existing treatments may be beneficial.

Role of miR-145 in chronic constriction injury in rats

The present study aims to investigate the effects and underlying mechanisms of miRNA-145 (miR-145) in rat models of chronic constriction injury (CCI). Rats were randomly divided into control, sham, CCI, agomiRNA (agomiR)-normal control (NC) and agomiR-145 groups (n=25 in each group); in addition, 30 rats with CCI were divided into small hairpin (sh)RNA-NC and shRNA-ras responsive element binding protein 1 (RREB1) groups. Paw withdrawal thermal latency (PWTL) and paw withdrawal mechanical threshold (PWMT) were detected. Reverse transcription-quantitative polymerase chain reaction was used to detect miR-145 expression levels, and western blotting was performed to measure RREB1 and phosphorylated-protein kinase B (p-AKT) expression levels. In addition, a dual luciferase reporter assay was conducted to identify the target gene of miR-145. PWMT and PWTL were decreased in CCI rats and this decrease was alleviated by miR-145 injection. At 1, 3, 5 and 7 days after CCI, miR-145 expression level in the spinal cord tissue of rats in the CCI group was significantly decreased compared with 1 day before CCI (P<0.05). Compared with the CCI group, miR-145 expression level in the agomiR-145 group was significantly higher (P<0.05). In addition, expression levels of RREB1 and p-AKT were significantly increased in the CCI group and significantly decreased in the agomiR-145 group (P<0.05). Furthermore, knockdown of RREB1 expression by shRNA-RREB1 significantly increased values of PWMT and PWTL, decreased expression levels of RREB1 and p-AKT, and increased miR-145 expression levels (P<0.05). Further investigation demonstrated that miR-145 can bind with RREB1 mRNA. In conclusion, miR-145 may be involved in the development of CCI through regulating the expression of RREB1.

Ziconotide intrathecal delivery as treatment for secondary therapeutic failure of motor cortex stimulation after 6 years

INTRODUCTION

Motor cortex stimulation is a well-known treatment modality for refractory neuropathic pain. Nevertheless, some cases of therapeutic failure have been described but alternative therapies for these cases are rarely reported.

CASE REPORT

The patient presented with neuropathic pain in his right arm due to a cervical syrinx which was surgically treated by a shunt in 2003 with no clinical improvement. As alternative therapy, after an evaluation by repetitive magnetic transcranial stimulation with significant benefit, motor cortex stimulation was successfully implanted in 2004. In 2010, a similar pain occurred in the same territory. Local mean pain visual analogical scale (VAS) increased to 82/100. A newer generation stimulation device was then implanted and, within a period of 8months, different stimulation parameter settings were tested, without any pain relief. An intrathecal drug delivery pump was then implanted in 2011, and the upper extremity catheter was located at the cervicothoracic junction. There was no postoperative complication. A bitherapy was initiated at a daily dosage of 0.2mg morphine and 1.3μg ziconotide, not modified since August 2013. At 43months follow-up, mean VAS was 21/100 with improvement of daily life and spare-time activities, anxiety and depression, quality of life (as measured by the SF-36 survey and EQ5D-3L questionnaire).

DISCUSSION

Refractory neuropathic pain treated by motor cortex stimulation may be considered in palliative situations, and secondary therapeutic failure offers only a few perspectives. Intrathecal ziconotide, indicated as a first-line drug in non-cancer pain, could be proposed in such cases.

CONCLUSION

Intrathecal drug delivery including ziconotide in refractory neuropathic pain represents a reasonable option with a good clinical tolerance.