Functional connectivity modulations during offset analgesia in chronic pain patients: an fMRI study

Investigating the brain functional abnormalities underlying pain hypervigilance in chronic neck and shoulder pain: a resting-state fMRI study

PURPOSE

To investigate pain hypervigilance in individuals suffering from chronic neck and shoulder pain (CNSP) and its underlying brain mechanism.

METHODS

The evaluation of pain vigilance was conducted through the utilization of pain vigilance and awareness questionnaires. Voxel-wise regional homogeneity (ReHo) from 60 CNSP patients and 60 healthy controls (HCs) using resting-state fMRI data. Voxel-wise two-sample T-test was conducted to reveal the ReHo variations between CNSP and HC. Correlation analyses were utilized to reveal the connection between brain abnormalities and medical measurements. Furthermore, a mediation analysis was conducted to elucidate the pathway-linking changes in brain function with medical measurements.

RESULTS

Our present study revealed three main findings. Firstly, patients with CSNP demonstrated a heightened vigilance of pain in comparison to healthy adults, a common occurrence among individuals with chronic pain conditions. Secondly, we observed brain abnormalities in various brain regions in CSNP patients, and these alterations were associated with the extent of pain vigilance. Lastly, the pain hypervigilance impact on the severity of pain was found to be controlled by regional neural activity in the anterior cingulate cortex (ACC) in subjects with CSNP.

CONCLUSION

Our findings suggested that long-term repetitive nociceptive input caused by chronic pain further aggravates the pain intensity by impairing the vigilance-related pain processing within the anterior cingulate cortex in CNSP patients.

Is the insomnia phenotype the common denominator in LUTS during transition periods? An expert NOPIA research group review

AIMS

As people age, sleep stages and characteristics transition over time, but sleep deficits can profoundly impact health and cognitive functioning. Chronic sleep deprivation is linked to impaired attention and productivity, weakened immunity, increased risk of cardiovascular disease, obesity, and mental health disorders. Insomnia, obstructive sleep apnea syndrome, hormonal changes, nocturia, neurological disorders, and life events interfere with sleep patterns and some are linked to lower urinary tract symptoms (LUTS). This NOPIA symposium on Lifelong LUTS aimed to analyze the literature on associations between sleep and LUTS, generate ideas for future research, and explore whether there is support for the concept of lifelong LUTS in relation to changes in sleep throughout the lifespan.

METHODS

An international panel of experts took part in an online meeting addressing the role of lifelong LUTS in relationship to sleep and the brain organized by the NOPIA research group. The manuscript summarizes existing literature, hypotheses, future research ideas, and clinical recommendations.

RESULTS

Insomnia, sleep fragmentation, hyperarousal, and sensory processing disorders emerged as potential factors in the relationship between sleep and LUTS. Insomnia is often a persistent factor and may have been the initial symptom; however, it is often unrecognized and/or unaddressed in healthcare settings. By recognizing insomnia as a primary driver of various health issues, including nocturia, transitional care aims to address root causes and underlying problems earlier to initiate appropriate treatment.

CONCLUSIONS

A multidisciplinary approach with collaboration between healthcare professionals from various disciplines, such as urology, sleep medicine, gynecology, pediatrics, and geriatrics, is needed and should include validated measurements such as the insomnia severity index and sleep and voiding diaries. Ensuring ongoing follow-up and monitoring through transitional care is crucial for individuals with persistent sleep problems and LUTS, allowing issues that arise or fluctuate over the lifespan to be addressed.

Preoperatively assessed offset analgesia predicts acute postoperative pain following orthognathic surgery

OBJECTIVES

High intensity and longer duration of acute postoperative pain are generally associated with a higher risk of developing chronic postoperative pain. Therefore, it is important to identify the preoperative predictors for acute postoperative pain. Preoperative evaluation of offset analgesia (OA) and the Pain Catastrophising Scale (PCS) may be potential predictors for acute postoperative pain. This study aimed to investigate the relationship between preoperative OA, PCS, and acute postoperative pain following orthognathic surgery.

METHODS

Thirty patients (19 females) scheduled to undergo orthognathic surgery were included in this study. OA and PCS were evaluated preoperatively, and the patients reported their postoperative pain intensity using the visual analogue scale [0-100 mm] until it reached zero (number of days with pain). OA was induced on the dominant forearm via three consecutive painful heat pulses delivered for 5 s (T1=46 °C), 5 s (T2=47 °C), and 20 s (T3=46 °C). Subsequently, the associations between OA, PCS, and the number of days with pain were analysed.

RESULTS

The median duration of postoperative pain was 10.3 days. Multiple linear regression analysis showed a significant (p=0.0019) predictive value of OA (p=0.008) for the number of days with pain. The PCS-magnification component was positively correlated with the number of days with pain (R=0.369, p=0.045), with no predictive values of PCS-total and PCS-subscale scores observed.

CONCLUSIONS

Preoperative evaluation of OA may be a new individualised, predictive tool for the number of days with acute postoperative pain following orthognathic surgery; hence, a possible biomarker for the patient's vulnerability to developing chronic postoperative pain.

ETHICAL COMMITTEE NUMBER

The study was approved by the Ethics Committee of Meikai University (A1624, A2113).

TRIAL REGISTRY NUMBER

This study was registered in the University Hospital Medical Information Network Clinical Trials Registry (UMIN-CTR) Clinical Trial (Unique ID: UMIN000026719, UMIN000046957).

Oxaliplatin causes increased offset analgesia during chemotherapy - a feasibility study

OBJECTIVES

Offset analgesia (OA) is the phenomenon where the perceived pain intensity to heat stimulation disproportionally decreases after a slight decrease in stimulation temperature. The neural mechanisms of OA are not fully understood, but it appears that both peripheral and central temporal filtering properties are involved. Chemotherapy with oxaliplatin often causes acute peripheral sensory neuropathy, and manifests primarily as a cold induced allodynia. The aim of this exploratory patient study was to investigate if OA was affected by the neurotoxic effects of adjuvant oxaliplatin treatment.

METHODS

OA was assessed in 17 colon cancer patients during 12 cycles of adjuvant oxaliplatin treatment. The OA response was estimated as the decrease in pain intensity caused by a temperature decrease from 46 °C to 45 °C. Changes in the OA during the treatment period was estimated using a mixed linear model and corrected for multiple comparisons by Sidak's test.

RESULTS

OA was increased significantly when assessed before the 2nd, 3rd, 5th, 6th, 9th, and 10th treatment cycle compared to the first (baseline) treatment (p<0.05).

CONCLUSIONS

OA is generally decreased in persons suffering from chronic pain or peripheral neuropathy as compared to healthy controls. But in the present study, OA increased during chemotherapy with oxaliplatin. The underlying mechanism of this unexpected increase should be further explored.

From Low-Grade Inflammation in Osteoarthritis to Neuropsychiatric Sequelae: A Narrative Review

Nowadays, osteoarthritis (OA), a common, multifactorial musculoskeletal disease, is considered to have a low-grade inflammatory pathogenetic component. Lately, neuropsychiatric sequelae of the disease have gained recognition. However, a link between the peripheral inflammatory process of OA and the development of neuropsychiatric pathology is not completely understood. In this review, we provide a narrative that explores the development of neuropsychiatric disease in the presence of chronic peripheral low-grade inflammation with a focus on its signaling to the brain. We describe the development of a pro-inflammatory environment in the OA-affected joint. We discuss inflammation-signaling pathways that link the affected joint to the central nervous system, mainly using primary sensory afferents and blood circulation via circumventricular organs and cerebral endothelium. The review describes molecular and cellular changes in the brain, recognized in the presence of chronic peripheral inflammation. In addition, changes in the volume of gray matter and alterations of connectivity important for the assessment of the efficacy of treatment in OA are discussed in the given review. Finally, the narrative considers the importance of the use of neuropsychiatric diagnostic tools for a disease with an inflammatory component in the clinical setting.

Moxibustion for primary dysmenorrhea: A resting-state functional magnetic resonance imaging study exploring the alteration of functional connectivity strength and functional connectivity

Introduction

Primary dysmenorrhea (PDM) is a common gynecological disease and chronic pain disorder. Moxibustion, a form of traditional Chinese medicine therapy, has proven to be effective for PDM. However, the central mechanisms of PDM and moxibustion for PDM are still unclear. This study aims to explore the potential central mechanism of PDM and clarify the possible mechanism of moxibustion for relieving pain.

Materials and methods

A total of 23 PDM patients and 23 matched healthy controls (HCs) were enrolled. For PDM patients, resting-state functional magnetic resonance imaging (rs-fMRI) data were collected pre- and post-moxibustion treatment of 3 consecutive menstrual cycles, respectively. For HCs, rs-fMRI data were collected in the baseline. The resting-state functional connectivity strength (rs-FCS) analysis and the resting-state functional connectivity (rs-FC) analysis based on the region of interest (ROI) were combined to be conducted.

Results

Compared to HCs, PDM patients showed weaker rs-FCS in the left inferior frontal gyrus (IFG). After the moxibustion treatment, rs-FCS in the left IFG was increased with clinical improvement. Then, the left IFG was chosen as ROI, and the rs-FC analysis was conducted. It showed that the left IFG rs-FC in the bilateral anterior cingulate cortex (ACC)/middle cingulate cortex (MCC), the left posterior cingulate cortex (PCC)/precuneus (PCU), and the left parahippocampal gyrus (PHG) decreased after moxibustion treatment, most of which belong to the default mode network (DMN).

Conclusion

Our results highlight the role of the left IFG and the DMN in PDM. Specifically, the central mechanism of moxibustion for analgesia may be related to modulating the disorders of the reappraisal and processing of pain stimuli through influencing the cognition of pain.