An Integrative Neuroscience Framework for the Treatment of Chronic Pain: From Cellular Alterations to Behavior

The relationship between central sensitization and activity limitation in patients with knee osteoarthritis:The mediating role of pain catastrophizing

BACKGROUND

In patients with knee osteoarthritis, the most distressing symptom is activity limitation which exacerbates the global burden of the disease. Studies have shown that central sensitization has a negative effect on activity capabilities in patients with knee osteoarthritis. However, limited knowledge exists regarding the underlying mechanisms. Therefore, this study aimed to explore the mediating effect of pain catastrophizing on central sensitization and activity limitation among knee osteoarthritis patients.

OBJECTIVES

To explore the association between central sensitization and activity limitation by modelling three dimensions of pain catastrophizing as mediators among patients with knee osteoarthritis.

DESIGN

This is a cross-sectional study.

METHODS

A total of 392 patients were surveyed using the general demographic questionnaire, Animated Activity Questionnaire, Pain Catastrophizing Scale, and Central Sensitization Inventory. Multiple linear regression was used to determine covariates included in the mediating model. The mediating effect was tested using the SPSS PROCESS.

RESULTS

Age, duration of KOA, and K-L grade were included as covariates. The mediating model revealed that central sensitization had a direct effect on activity limitation (c' = -0.166; 95 % CI -0.271, -0.064). The relationship between central sensitization and activity limitation was primarily mediated by two indirect pathways: (1) rumination (a1b1 = -0.095; 95 % CI -0.176, -0.017) and (2) helplessness (a2b2 = -0.074; 95 % CI -0.137, -0.009). The indirect effect of the magnification dimension on activity limitation was not statistically significant (a3b3 = 0.002; 95 % CI -0.051, 0.054).

CONCLUSIONS

The study reveals rumination and helplessness in pain catastrophizing mainly mediate the relationship between central sensitization and activity limitation.

Multisite pain among United States Veterans with posttraumatic stress disorder: Prevalence, predictors, and associations with symptom clusters

Persistent pain in multiple distinct body sites is associated with poorer functional outcomes above and beyond pain intensity and interference. Veterans, and especially those with posttraumatic stress disorder (PTSD), may be at risk for multisite pain. However, the research to date characterizing this presentation is limited. This secondary analysis examined the prevalence of multisite pain in a cross-sectional sample of Veterans and explored demographic, military service-related, and PTSD symptom cluster variables associated with multisite pain among those with clinically significant PTSD symptoms. Participants were 4303 post-9/11 U.S. Veterans (16.55% female gender, 58.45% White/Caucasian, Mage = 35.52), of whom 1375 (31.95%) had clinically significant PTSD symptoms. Multisite pain was defined as endorsing pain that "bothered [me] a lot" in ≥3 body sites out of 5 on the Patient Healthcare Questionnaire-15. A total of 20.03% of all participants, and 40.00% of those with likely PTSD, reported multisite pain. Female gender (OR = 1.55), older age (OR = 1.70), minority race identification (White/Caucasian racial identity OR = 0.75), history of military sexual trauma (OR = 1.99), and spine, abdomen and joint/muscle injuries (ORs = 1.66-3.68) were associated with higher odds of multisite pain. Adjusting for these potential confounders, higher z-scores on the PTSD arousal/reactivity (OR = 1.58, p <.001) subscale was associated with higher multisite pain odds. In summary, multisite pain was common among Veterans with PTSD, especially those who experienced military sexual trauma or certain physical injuries. Multisite pain and PTSD may be associated due to a shared threat reactivity mechanism. PERSPECTIVE: This study investigates the rates and factors associated with having pain in three or more distinct body sites (multisite pain) among United States Veterans. The study findings highlight the unique importance of specific posttraumatic stress symptoms and experiences associated with multisite pain.

Regulatory role of electroacupuncture on satellite glial cell activity in the colon and dorsal root ganglion of rats with irritable bowel syndrome

OBJECTIVE

To investigate the role of satellite glial cells in irritable bowel syndrome (IBS) and the effect of electroacupuncture (EA) at the Tianshu (ST25) and Shangjuxu (ST37) combination.

METHODS

A model for visceral hypersensitivity in IBS was induced through colorectal distension (CRD) stimulation. Clean-grade male Sprague-Dawley (SD) rats were randomly divided into four groups: a normal group (NG), a model group (MG), an electroacupuncture group (EA), and a glial cell inhibitor group (FCA). Bilateral EA (2/100 Hz, 1 mA, 30 min) was administered at the Tianshu (ST25) and Shangjuxu (ST37) in week 6. Abdominal withdrawal reflex (AWR) scores were used to assess the behavioral response associated with visceral hyperalgesia, while hematoxylin-eosin staining was employed to evaluate pathological changes in the colon. The protein and mRNA levels of glial fibrillary acidic protein (GFAP) in the colon and colon-related dorsal root ganglion (DRG) were analyzed using immun-ofluorescence, immun-ohistochemistry, Western blotting, real-time polymerase chain reaction. The impact of EA on electrophysiological properties of colon-related DRG neurons was observed through whole-cell patch clamp analysis.

RESULTS

EA significantly reduced the visceral pain behavior scores in rats with IBS in response to graded (20, 40, 60, 80 mm Hg) CRD stimulation. Additionally, EA downregulated the protein and mRNA expression levels of GFAP in the colon and colon-related DRG of rats with IBS. EA also regulated the resting membrane potential, rheobase and action potential of colon-related DRG neurons in rats with IBS.

CONCLUSIONS

EA can regulate the excitatory properties of colon-related DRG neurons by downregulating the protein and mRNA expression of GFAP in the colon and colon-related DRG, indicating a potential neurobiological mechanism by which EA relieves visceral hypersensitivity in rats with IBS.

Redesigning the Care of Musculoskeletal Conditions With Lifestyle Medicine

Value-based health care has been accelerated by alternative payment models and has catalyzed the redesign of care delivery across the nation. Lifestyle medicine (LM) is one of the fastest growing medical specialties and has emerged as a high-value solution for root cause treatment of chronic disease. This review detailed a large integrated health care delivery system's value transformation efforts in the nonoperative treatment of musculoskeletal (MSK) conditions by placing patient-centric, team-based, lifestyle-focused care at the foundation. With an economic and treatment imperative to reimagine care, recognizing more intervention is not always better, a collaborative approach was designed, which placed functional improvement of the patient at the center. This article described the process of implementing LM into an MSK model of care. The change management process impacted clinical, operational, and benefit plan design to facilitate an integrated care model. A new understanding of patients' co-occurring physical impairments, medical comorbidities, and behavioral health needs was necessary for clinicians to make the shift from a pathoanatomic, transactional model of care to a biopsychosocial, longitudinal model of care. The authors explored the novel intersection of the implementation of a biopsychosocial model of care using LM principles to achieve greater value for the MSK patient population.

Pathology of pain and its implications for therapeutic interventions

Pain is estimated to affect more than 20% of the global population, imposing incalculable health and economic burdens. Effective pain management is crucial for individuals suffering from pain. However, the current methods for pain assessment and treatment fall short of clinical needs. Benefiting from advances in neuroscience and biotechnology, the neuronal circuits and molecular mechanisms critically involved in pain modulation have been elucidated. These research achievements have incited progress in identifying new diagnostic and therapeutic targets. In this review, we first introduce fundamental knowledge about pain, setting the stage for the subsequent contents. The review next delves into the molecular mechanisms underlying pain disorders, including gene mutation, epigenetic modification, posttranslational modification, inflammasome, signaling pathways and microbiota. To better present a comprehensive view of pain research, two prominent issues, sexual dimorphism and pain comorbidities, are discussed in detail based on current findings. The status quo of pain evaluation and manipulation is summarized. A series of improved and innovative pain management strategies, such as gene therapy, monoclonal antibody, brain-computer interface and microbial intervention, are making strides towards clinical application. We highlight existing limitations and future directions for enhancing the quality of preclinical and clinical research. Efforts to decipher the complexities of pain pathology will be instrumental in translating scientific discoveries into clinical practice, thereby improving pain management from bench to bedside.

Virtual Mindfulness-Based Therapy for the Management of Endometriosis Chronic Pelvic Pain: A Novel Delivery Platform to Increase Access to Care

OBJECTIVES

This study assessed the effectiveness of a virtual mindfulness-based stress reduction (MBSR) program to improve quality of life and pain in people with endometriosis.

METHODS

This was a multiple-method, before and after study design. Fifteen patients with a clinical or surgical diagnosis of endometriosis were recruited from a Canadian outpatient gynaecology clinic. Participants completed the Endometriosis Health Profile, a validated survey tool, and a pain medication use questionnaire before and after a virtual 8-week MBSR program run by an experienced social worker. A focus group was held upon completion of the program to assess participants' experiences using mindfulness for management of endometriosis symptoms. Quantitative data was analyzed with paired-samples t tests. Qualitative data was thematically analyzed.

RESULTS

A total of 67% of people enrolled completed the MBSR course (10/15). Following the MBSR program, participants had a statistically significant decrease in 4 components of the Endometriosis Health Profile: control and powerlessness (P = 0.012), emotional well-being (P = 0.048), social support (P = 0.030), and self-image (P = 0.014). There was no change in pain scores or medication use. Participants felt the program's benefits came from a sense of community, education about their condition, and application of mindfulness tools when approaching pain. Participants felt more comfortable with the virtual format over in-person sessions.

CONCLUSIONS

A virtual MBSR course can improve quality of life domains in people with endometriosis. The virtual format was effective and preferred by participants. Virtual MBSR programs may increase access to this type of care.

Astroglial Alterations in the Hippocampus of Rats Submitted to a Single Trans-Cranial Direct Current Stimulation Trial

Evidence indicates that transcranial direct current stimulation (tDCS) provides therapeutic benefits in different situations, such as epilepsy, depression, inflammatory and neuropathic pain. Despite the increasing use of tDCS, its cellular and molecular basis remains unknown. Astrocytes display a close functional and structural relationship with neurons and have been identified as mediators of neuroprotection in tDCS. Considering the importance of hippocampal glutamatergic neurotransmission in nociceptive pathways, we decided to investigate short-term changes in the hippocampal astrocytes of rats subjected to tDCS, evaluating specific cellular markers (GFAP and S100B), as well as markers of astroglial activity; glutamate uptake, glutamine synthesis by glutamine synthetase (GS) and glutathione content. Data clearly show that a single session of tDCS increases the pain threshold elicited by mechanical and thermal stimuli, as evaluated by von Frey and hot plate tests, respectively. These changes involve inflammatory and astroglial neurochemical changes in the hippocampus, based on specific changes in cell markers, such as S100B and GS. Alterations in S100B were also observed in the cerebrospinal fluid of tDCS animals and, most importantly, specific functional changes (increased glutamate uptake and increased GS activity) were detected in hippocampal astrocytes. These findings contribute to a better understanding of tDCS as a therapeutic strategy for nervous disorders and reinforce the importance of astrocytes as therapeutic targets.

Modern Principles of Diagnosis and Treatment in Complex Regional Pain Syndrome

BACKGROUND

Background: Complex regional pain syndrome (CRPS) is a relatively common complication, occurring in 5% of cases after injury or surgery, particularly in the limbs. The incidence of CPRS is around 5-26/100 000. The latest revision of the International Statistical Classification of Diseases and Related Health Problems (ICD-11) now categorizes CRPS as a primary pain condition of multifactorial origin, rather than a disease of the skeletal system or the autonomic nervous system.

METHODS

Method: Based on a selective search of the literature, we summarize current principles for the diagnosis and treatment of CRPS.

RESULTS

Results: Regional findings in CRPS are accompanied by systemic symptoms, especially by neurocognitive disorders of body perception and of symptom processing. The therapeutic focus is shifting from predominantly passive peripheral measures to early active treatments acting both centrally and peripherally. The treatment is centered on physiotherapy and occupational therapy to improve sensory perception, strength, (fine) motor skills, and sensorimotor integration/ body perception. This is supported by stepped psychological interventions to reduce anxiety and avoidance behavior, medication to decrease inflammation and pain, passive physical measures for reduction of edema and of pain, and medical aids to improve functioning in daily life. Interventional procedures should be limited to exceptional cases and only be performed in specialized centers. Spinal cord and dorsal root ganglion stimulation, respectively, are the interventions with the best evidence.

CONCLUSION

Conclusion: The modern principles for the diagnosis and treatment of CRPS consider both, physiological and psychological mechanisms, with the primary goal of restoring function and participation. More research is needed to strengthen the evidence base in this field.

A coordinate-based meta-analysis of acupuncture for chronic pain: Evidence from fMRI studies

Background

Chronic pain (CP) patients tend to represent aberrant functional brain activity. Acupuncture is an effective clinical treatment for CP, and some fMRI studies were conducted to discover the alternation of brain regions after acupuncture therapy for CP. However, the heterogeneity of neuroimaging studies has prevented researchers from systematically generalizing the central mechanisms of acupuncture in the treatment of CP.

Methods

We searched bibliographic databases, including PubMed, EMBASE, PsycINFO, Web of Science Core Collection, ScienceDirect, China Academic Journal Network Publishing Database, etc., and trials registration platforms (From inception to September 1^st, 2022). Two independent researchers assessed the study's bias and quality. Furthermore, activation likelihood estimation (ALE) analysis was applied to explore aberrant brain functional activity and acupuncture's central mechanism for CP.

Results

Totally 14 studies with 524 CP patients were included in the study. ALE analysis showed that CP patients presented with decreased ALFF/ReHo in the precuneus, posterior cingulate cortex, right inferior parietal lobule, right superior temporal gyrus, cingulate gyrus, superior frontal gyrus, left medial frontal gyrus including medial prefrontal gurus, left middle frontal gyrus.

Conclusion

This ALE meta-analysis pointed out that acupuncture could modulate the default mode network, the frontoparietal network to treat CP. This provided a systematic summary of the neuroimage biomarker of acupuncture for the treatment of CP.

Systematic review registration

PROSPERO, identifier: CRD42021239633.

Myofascial Pain Syndrome in Women with Primary Dysmenorrhea: A Case-Control Study

There is limited information on myofascial trigger points (MTrPs) and specific symptoms of chronic pelvic pain and, more specifically, dysmenorrhea. The objective of this study was to determine whether patients suffering from primary dysmenorrhea present alterations in mechanosensitivity and pain patterns, and greater presence of MTrPs in the abdominal and pelvic floor muscles. A case-control study was carried out with a total sample of 84 participants distributed based on primary dysmenorrhea and contraceptive treatment. The sample was divided into four groups each comprising 21 women. Data on pain, quality of life, and productivity and work absenteeism were collected; three assessments were made in different phases of the menstrual cycle, to report data on pressure pain threshold, MTrP presence, and referred pain areas. One-way ANOVA tests showed statistically significant differences (p < 0.01) between the groups, for the Physical Health domain and the total score of the SF-12 questionnaire, and for all the domains of the McGill questionnaire; but no significant differences were found in the data from the WPAI-GH questionnaire. Statistically significant data (p < 0.01) were found for mechanosensitivity in the abdominal area and limbs, but not for the lumbar assessment, within the group, with very few significant intergroup differences. The frequency of active MTrPs is higher in the groups of women with primary dysmenorrhea and during the menstrual phase, with the prevalence of myofascial trigger points of the iliococcygeus muscle being especially high in all examination groups (>50%) and higher than 70% in women with primary dysmenorrhea, in the menstrual phase, and the internal obturator muscle (100%) in the menstrual phase. Referred pain areas of the pelvic floor muscles increase in women with primary dysmenorrhea.

A Dysfunctional Descending Pain Modulation System in Chronic Nonspecific Low Back Pain: A Systematic Review and ALE Meta-Analysis

Pain, a physiological protective mechanism, turns into a complex dynamic neural response when it becomes chronic. The role of neuroplastic brain changes is more evident than the peripheral factors in the maintenance, modulation and amplification of chronic low back pain (cLBP). In this background, we summarise the brain changes in cLBP in a coordinate-based activation likelihood estimation (ALE) meta-analysis of previous functional magnetic resonance imaging (fMRI) studies. Databases ('PubMed', 'Scopus' and 'Sleuth') were searched till May 2022 and the activity pattern was noted under the 'without stimulation' and 'with stimulation' groups. A total of 312 studies were selected after removing duplicates. Seventeen (553 cLBP patients, 192 activation foci) studies were fulfilled the eligibility criteria and included in the 'without stimulation' group. Twelve statistically significant clusters are localized in the prefrontal cortex, primary somatosensory cortex, primary motor cortex, parietal cortex, anterior cingulate cortex, caudate, putamen, globus pallidus amygdala, occipital lobe, temporal lobe and associated white matter in this group. Ten studies (353 cLBP patients, 125 activation foci) were selected in the' with stimulation' groups. In this group, seven statistically significant clusters were found in the frontal cortex, orbitofrontal cortex, premotor cortex, parietal cortex, claustrum and insula. These statistically significant clusters indicate a probable imbalance in GABAergic modulation of brain circuits and dysfunction in the descending pain modulation system. This disparity in the pain neuro-matrix is the source of spontaneous and persisting pain in cLBP.

Communicating Endometriosis Pain in France and Australia: An Interview Study

Endometriosis is characterized by persistent, fluctuating pain associated with menstruation, a biological function which is socially invisible. The degree and quality of pain cannot easily be measured, observed, or documented. Difficulties in communicating pain pose particular challenges when seeking diagnosis and support from health professionals. In this paper we explore the experiences and characterization of pain by thirteen Australian and thirteen French women with endometriosis. Data were collected through semi-structured interviews using a life-history approach to illness symptoms, diagnosis and treatment. We explore the experiences of women with endometriosis in two phases: from onset of symptoms to seeking advice from a clinician, and from first consulting a clinician to receiving a diagnosis. On average, initial pain symptoms were identified 2.1 years before consulting a health practitioner, after which women reported pain symptoms 8.5 years prior to diagnosis; that is, the time between consulting a clinician and receiving a diagnosis was almost four times the period between experiencing symptoms and consulting a doctor. Pain was often “made real” to doctors by findings consistent with endometriosis on ultrasound and MRI, mostly used in France, or laparoscopy, the predominant diagnostic tool in Australia. No woman described her practitioner using standardized pain assessment tools. Thus, the validation of pain relies largely on disease visibility and the clinician-classified degree of severity rather than self-reported grades of pain or impact on activities of daily living. The invisible and enigmatic pain of this chronic women's disease remains difficult to communicate to doctors, and the recognition of severe pain is often key to timely diagnostic procedures. Clinicians need to be more proactive about severe pain related to menstruation, taking into consideration women's individual circumstances, and maintain a high index of suspicion of underlying endometriosis as a condition characterized primarily by pain.

[Investigacion de mindfulness en neurociencia cognitiva]

Mindfulness is a term that has become part of our society's vocabulary and its practice has become firmly established in educational, therapeutic and clinical contexts and as a tool for fostering well-being and personal growth. In this article we review the most relevant research conducted on mindfulness in cognitive neuroscience, classifying it in three broad areas: a) differential changes in default network activity due to the practice of mindfulness; b) functional or structural changes in the attentional network, and c) functional or structural changes in the frontal limbic network and the amygdala, related to emotion regulation. There is enough evidence in the literature to affirm the effect of mindfulness practice on the brain, but we still need to produce better experimental designs that allow us to find the mechanisms of action underlying specific practices.

The anatomy of pain and suffering in the brain and its clinical implications

Pain is an unpleasant sensory and emotional experience associated with actual or potential tissue damage. Chronic pain, with a prevalence of 20-30 % is the major cause of human suffering worldwide, because effective, specific and safe therapies have yet to be developed. It is unevenly distributed among sexes, with women experiencing more pain and suffering. Chronic pain can be anatomically and phenomenologically dissected into three separable but interacting pathways, a lateral 'painfulness' pathway, a medial 'suffering' pathway and a descending pain inhibitory pathway. One may have pain(fullness) without suffering and suffering without pain(fullness). Pain sensation leads to suffering via a cognitive, emotional and autonomic processing, and is expressed as anger, fear, frustration, anxiety and depression. The medial pathway overlaps with the salience and stress networks, explaining that behavioural relevance or meaning determines the suffering associated with painfulness. Genetic and epigenetic influences trigger chronic neuroinflammatory changes which are involved in transitioning from acute to chronic pain. Based on the concept of the Bayesian brain, pain (and suffering) can be regarded as the consequence of an imbalance between the two ascending and the descending pain inhibitory pathways under control of the reward system. The therapeutic clinical implications of this simple pain model are obvious. After categorizing the working mechanisms of each of the available treatments (pain killers, psychopharmacology, psychotherapy, neuromodulation, psychosurgery, spinal cord stimulation) to 1 or more of the 3 pathways, a rational combination can be proposed of activating the descending pain inhibitory pathway in combination with inhibition of the medial and lateral pathway, so as to rebalance the pain (and suffering) pathways.

Potential Alterations of Functional Connectivity Analysis in the Patients with Chronic Prostatitis/Chronic Pelvic Pain Syndrome

Background

Chronic prostatitis/chronic pelvic pain syndrome (CP/CPPS) is one of the most common diseases in urology, but its pathogenesis remains unclear. As a kind of chronic pain which the patients suffered for more than 3 months, we investigated the influence on patients' brain functional connectivity in resting state.

Methods

We recruited a cohort of 18 right-handed male patients with CP/CPPS and 21 healthy male right-handed age-matched controls. Their resting-state fMRI data and structural MRI data were preprocessed and processed by RESTPlus V1.22. To assess the integrity of the default mode network (DMN), we utilized the voxel-wised analysis that we set medial prefrontal cortex (mPFC) and posterior cingulate gyrus (PCC) as seed points to compare the global functional connectivity (FC) strength.

Results

Compared with healthy control, the FC strength between left mPFC and posterior DMN decreased in the group of CP/CPPS (P < 0.05, GFR correction, voxel P < 0.01, cluster P < 0.05), and the FC strength between the left anterior cerebellar lobe and posterior DMN increased (P < 0.05, GFR correction, voxel P < 0.01, cluster P < 0.05). In the patient group, there was a positive correlation between the increased FC strength and the score of the Hospital Anxiety and Depression Scale (HADS) anxiety subscale (r = 0.5509, P = 0.0178) in the left anterior cerebellar lobe, a negative correlation between the decreased FC strength and the score of the National Institutes of Health Chronic Prostatitis Symptom Index (r = -0.6281, P = 0.0053) in the area of left mPFC, and a negative correlation between the decreased FC strength and the score of HADS anxiety subscale (r = -0.5252, P = 0.0252).

Conclusion

Patients with CP/CPPS had alterations in brain function, which consisted of the default mode network's compromised integrity. These alterations might play a crucial role in the pathogenesis and development of CP/CPPS.

Functional connectivity and quality of life in young adults with cerebral palsy: a feasibility study

BACKGROUND

Cerebral Palsy (CP) is a group of disorders that affect the development of movement and posture. CP results from injuries to the immature brain during the prenatal, perinatal, or postnatal stage of development. Neuroimaging research in CP has focused on the structural changes of the brain during early development, but little is known about brain's structural and functional changes during late adolescence and early adulthood, a period in time when individuals experience major changes as they transition into adulthood. The work reported here served as a feasibility study within a larger program of research (MyStory Study). We aimed to determine whether it would be feasible to scan and obtain good quality data without the use of sedation during a resting state condition for functional connectivity (FC) analyses in young adults with CP. Second, we aimed to identify the FC pattern(s) that are associated with depressive mood ratings, indices of pain and fatigue, and quality of life in this group.

METHODS

Resting state functional images were collected from 9 young people with CP (18-29 years). We applied a stringent head motion correction and quality control methods following preprocessing.

RESULTS

We were able to scan and obtain good quality data without the use of sedation from this group of young individuals with CP who demonstrated a range of gross motor ability. The functional connectivity networks of interest were identified in the data using standard seed regions. Our analyses further revealed that higher well-being scores were associated with higher levels of FC between the Medial Pre-Frontal Cortex and the right Lateral Parietal regions, which are implicated in prosocial and emotion regulations skills. The implications of this association are discussed.

CONCLUSION

The findings of the present study demonstrate that it is feasible to conduct resting state functional connectivity in young adults with CP with different gross motor abilities without the use of sedation. Our results also highlight a neural circuitry that is associated with the self-report of quality of life and emotion regulation. These findings identify these regions/circuitries as important seeds for further investigations into mental health and wellbeing in CP.

Acupuncture Treatment Modulates the Connectivity of Key Regions of the Descending Pain Modulation and Reward Systems in Patients with Chronic Low Back Pain

Chronic low back pain (cLBP) is a common disorder with unsatisfactory treatment options. Acupuncture has emerged as a promising method for treating cLBP. However, the mechanism underlying acupuncture remains unclear. In this study, we investigated the modulation effects of acupuncture on resting state functional connectivity (rsFC) of the periaqueductal gray (PAG) and ventral tegmental area (VTA) in patients with cLBP. Seventy-nine cLBP patients were recruited and assigned to four weeks of real or sham acupuncture. Resting state functional magnetic resonance imaging data were collected before the first and after the last treatment. Fifty patients completed the study. We found remission of pain bothersomeness in all treatment groups after four weeks, with greater pain relief after real acupuncture compared to sham acupuncture. We also found that real acupuncture can increase VTA/PAG rsFC with the amygdala, and the increased rsFC was associated with decreased pain bothersomeness scores. Baseline PAG-amygdala rsFC could predict four-week treatment response. Our results suggest that acupuncture may simultaneously modulate the rsFC of key regions in the descending pain modulation (PAG) and reward systems (VTA), and the amygdala may be a key node linking the two systems to produce antinociceptive effects. Our findings highlight the potential of acupuncture for chronic low back pain management.

The effect of alexithymia and depressive feelings on pain perception in somatoform pain disorder

OBJECTIVE

To investigate the relationship between alexithymia and depression and their influence on the subjective versus experimental pain perception in somatoform pain disorder.

METHODS

Three groups consisting of 40 patients with somatoform pain disorder, 40 patients with depression, and 40 healthy controls were matched. They completed questionnaires regarding alexithymia (TAS26) and depressive feelings (BDI-II). In addition, pain patients rated their subjective pain intensity (NRS). Quantitative sensory testings were conducted in all participants examining temperature (CPT, HPT) and mechanical (MPT, PPT) thresholds.

RESULTS

Analysis of variance showed that alexithymia was significantly increased in both patient groups compared to healthy controls, but with the highest amount in somatoform pain. Regression analyses confirmed that this finding was in part due to a high comorbidity of depressive feelings in both patient groups. We found a discrepancy between increased clinical pain ratings and elevated pressure pain thresholds, indicating a less intense mechanical pain perception in somatoform pain. Correlation analyses demonstrated a significant connection of subjective pain ratings and pressure pain thresholds with depressive feelings.

CONCLUSION

Contrary to the results of other experimental pain studies on chronic muskuloskeletal pain syndromes, we could not confirm central sensitization in somatoform pain disorder. Our findings place the somatoform pain disorder more in the direction of affective disorder such as depression. These findings may improve a better understanding of the disease and also have direct therapeutic implications. The high occurrence of alexithymia and depressive feelings in somatoform pain should be considered in diagnostic and therapeutic regimens of these patients.

The release of exosomes in the medial prefrontal cortex and nucleus accumbens brain regions of chronic constriction injury (CCI) model mice could elevate the pain sensation

BACKGROUND

Brain function relies on the capacity of neurons to locally modulate each other at the level of synapses. Therefore, the exosomal pathway may constitute a well-designed mechanism for local and systemic interneuronal transfer of information within functional brain networks. Exosomes bind to and are endocytosed by neurons of different brain regions to play a definite role. The medial prefrontal cortex (mPFC) and nucleus accumbens (NAc) brain regions are known to involve in pain modulation. Our study observes the roles of exosomal activity in these two dominant regions of the pain-related pathway, and there influence on the analgesic effects in CCI mice.

METHODS

We induced pain exosomes in the mPFC and NAc in the mice of chronic constriction injury of the sciatic nerve model to produce neuropathic pain, and assessed changes that might affect analgesic behaviors. These changes were measured through a combination of behavioral, surgical, and other cellular testings.

RESULTS

Our study found that pain expression was elevated in mice given exogenous exosomes isolated from CCI mice, especially at the 2 h and 4 h time interval, in mice given exosomes at the mPFC and NAc, respectively. We also found that inhibiting formation of pain exosomes through GW4869 within the mPFC and NAc can elevate the pain threshold.

CONCLUSION

Results from our study supported the idea that the release of mPFC and NAc exosomes of CCI model has elevated the pain sensations in the subjected mice. This study will further help in designing new clinical trials, and will revolutionize the drug-induced anesthetic responses.