The latest medical research on Pain Medicine

The research magnet gathers the latest research from around the web, based on your specialty area. Below you will find a sample of some of the most recent articles from reputable medical journals about pain medicine gathered by our medical AI research bot.

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Centralized pain and pain catastrophizing mediate the association between lifetime abuse history and self-reported pain medication side effects.

Regional Anesthesia and Pain Medicine

Self-reported side effects of pain medication are important determinants of treatment course that can affect patient adherence, medication discontinuation and physician decisions. Yet, few studies have investigated patient-level predictors of self-reported pain medication side effects. The present study sought to fill this gap by exploring the impact of physical or sexual abuse history on self-reported pain medication side effects and considered a mediation model in which those effects are transmitted through a centralized pain phenotype and pain catastrophizing.

We conducted a cross-sectional analysis of 3118 patients presenting to a tertiary-care, outpatient pain clinic.

Approximately 15% of the sample (n=479) reported a lifetime history of abuse. Patients with a lifetime history of abuse, particularly abuse that occurred in both childhood and adulthood, reported more pain medication side effects compared with patients reporting no abuse history. Furthermore, path analysis showed that a centralized pain phenotype and pain catastrophizing mediated the association between lifetime abuse history and the sum of pain medication side effects.

This suggests that individuals who experience abuse may develop a heightened physiological sensitivity to stimuli, as well as a tendency to interpret stimuli negatively, exaggerate the impact of aversive stimuli and undermine their ability to cope with the stressor. This study highlights the need for physicians to understand patient-level predictors of medication tolerance and to consider a history of abuse and trauma in decisions regarding treatment and medication management.

Current status of pain medicine training in anesthesiology and pain medicine residency programs in university hospitals of Korea: a survey of residents' opinions.

Regional Anesthesia and Pain Medicine

In Korea, anesthesiologists are expected to be mainstream pain medicine (PM) practitioners. However, anesthesiology and pain medicine (APM) residency programs mostly emphasize anesthesia learning, leading to insufficient PM learning. Therefore, this study evaluated the current status of PM training in APM residency programs in 10 Korean university hospitals.

Overall, 156 residents undergoing APM training participated anonymously in our survey, focusing on PM training. We assessed the aim, satisfaction status, duration, opinion on duration, desired duration, weaknesses of the training programs and plans of residents after graduating. We divided the residents into junior (first and second year) and senior (third and fourth year). Survey data were compared between groups.

Senior showed significantly different level of satisfaction grade than did junior (p=0.026). Fifty-seven (81.4%) residents in junior and forty (46.5%) residents in senior underwent PM training for ≤2 months. Most (108; 69.2%) residents felt that the training period was too short for PM learning and 95 (60.9%) residents desired a training period of ≥6 months. The most commonly expressed weakness of the training was low interventional opportunity (29.7%), followed by short duration (26.6%). After residency, 80 (49.1%) residents planned to pursue a fellowship.

Dissatisfaction with PM training was probably due to a structural tendency of the current program towards anesthesia training and insufficient clinical experience, which needs to be rectified, with a change in PM curriculum.

Probing the mechanisms underpinning recovery in post-surgical patients with cervical radiculopathy using Bayesian Networks.

Eur J Pain

Rehabilitation approaches should be based on an understanding of the mechanisms underpinning functional recovery. Yet, the mediators that drive an improvement in post-surgical pain-related disability in individuals with cervical radiculopathy (CR) is unknown. The aim of the present study is to use Bayesian Networks (BN) to learn the probabilistic relationships between physical and psychological factors, and pain-related disability in CR.

We analysed a prospective cohort dataset of 201 post-surgical individuals with CR. Fifteen variables were used to build a BN model: age, sex, neck muscle endurance, neck range of motion, neck proprioception, hand grip strength, self-efficacy, catastrophizing, depression, somatic perception, arm pain intensity, neck pain intensity, and disability.

A one point increase in a change of self-efficacy at six months was associated with a 0.09 point decrease in a change in disability at 12 months (t = -64.09, P < 0.001). Two pathways led to a change in disability: a direct path leading from a change in self-efficacy at six months to disability, and an indirect path which was mediated by neck and arm pain intensity changes at six and 12 months.

This is the first study to apply BN modelling to understand the mechanisms of recovery in post-surgical individuals with CR. Improvements in pain-related disability was directly and indirectly driven by changes in self-efficacy levels. The present study provides potentially modifiable mediators that could be the target of future intervention trials. BN models could increase the precision of treatment and outcome assessment of individuals with CR.

[EXPRESS] Spinal NF-kB upregulation contributes to hyperalgesia in a rat model of advanced osteoarthritis.

Molecular Pain

Knee osteoarthritis (OA) pain is the most common joint pain. Currently, dysfunction in the central nervous system rather than knee joint degenerati...

Pain assessment for cognitively impaired older adults: do items of available observer tools reflect pain-specific responses?

Eur J Pain

A number of observational tools is available to assess pain in cognitively impaired older adults, however, none of them can yet be regarded as a 'gold standard'. An international research initiative has created a meta-tool compiling the facial, vocalization and body movement items of the majority of available tools. Objective of the present study was to investigate the pain specificity and the validity of these items.

N = 34 older adults with or without cognitive impairment were videotaped in three different conditions (one reference, two painful conditions) in their nursing homes. They were further asked to self-report their pain in each condition. The occurrence of non-verbal behaviors was coded as present or absent using the items of the meta-tool.

The majority of non-verbal behaviors was not pain sensitive as they occurred less than three times across participants and conditions. Of the remaining items, two facial items ('pained expression' and 'raising upper lip'), one vocalization item ('using pain related words') and one body movement item ('guarding') were found to be pain specific and valid. One additional item, the vocalization item 'gasping', was pain-specific, but not associated with pain self-report, and three additional items, the facial items 'frowning' and 'narrowing eyes' and the vocalization item 'mumbling' were correlated with pain self-report but did not help to separate pain from non-pain conditions.

Systematic evaluation of items of existing observational pain assessment tools under naturalistic conditions seems a promising approach in the process of further investigating and improving tools.

Blockade of BDNF Signaling Attenuates Chronic Visceral Hypersensitivity in an IBS-like Rat Model.

Eur J Pain

Irritable bowel syndrome (IBS) is a common functional disease characterized by chronic abdominal pain and changes in bowel movements. Effective therapy for visceral hypersensitivity in IBS patients remains challenging. This study investigated the roles of brain-derived neurotrophic factor (BDNF) and tyrosine kinase receptor B (TrkB) and the effect of ANA-12 (a selective antagonist of TrkB) on chronic visceral hypersensitivity in an IBS-like rat model.

An IBS-like rat model was established through neonatal maternal separation (NMS), and visceral hypersensitivity was assessed by electromyographic (EMG) responses of the abdominal external oblique muscles to colorectal distention (CRD). Different doses of ANA-12 were injected intrathecally to investigate the effect of that drug on visceral hypersensitivity, and the open field test was performed to determine whether ANA-12 had side effects on movement. Thoracolumbar spinal BDNF, TrkB receptor and PKMζ expression were measured to investigate their roles in chronic visceral hypersensitivity. Whole-cell recordings were made from thoracolumbar superficial dorsal horn (SDH) neurons of lamina II.

The expression of BDNF and TrkB was enhanced in the thoracolumbar spinal cord of the NMS animals. ANA-12 attenuated visceral hypersensitivity without side effects on motricity in NMS rats. PKMζ expression significantly decreased after the administration of ANA-12. The frequency of spontaneous excitatory postsynaptic currents (sEPSCs) increased in the thoracolumbar SDH neurons of lamina II in NMS rats. The amplitude and frequency of sEPSCs were reduced after perfusion with ANA-12 in NMS rats.

ANA-12 attenuates visceral hypersensitivity via BDNF-TrkB-PKMζ signaling and reduces synaptic activity through AMPARs in NMS rats. This knowledge suggests that ANA-12 could represent an interesting novel therapeutic medicine for chronic visceral hypersensitivity.

Regional Increases in Brain Signal Variability Are Associated with Pain Intensity Reductions Following Repeated Eccentric Exercise Bouts.

Eur J Pain

Traditional pain interventions limit fluctuations in pain sensation, which may paradoxically impair endogenous pain modulatory systems (EPMS). However, controlled exposures to clinically relevant pain (e.g. delayed onset muscle soreness, DOMS) may build capacity in the EPMS. Emerging evidence suggests regional signal variability (RSV) may be an important indicator of efficiency and modulatory capacity within brain regions. The present study sought to determine the role of RSV in both susceptibility to and trainability of pain response following repeated DOMS inductions.

Baseline and follow-up resting-state fMRI was performed on 12 healthy volunteers ~40 days apart. Between scanning visits, participants received four weekly DOMS inductions in alternating elbow flexors and supplied seven days of post-induction pain ratings. Voxel-wise standard deviation of signal intensity was calculated to measure RSV. Associations among DOMS-related pain and RSV were assessed with regression. Relationships among baseline and change measurements were probed (i.e. susceptibility to DOMS; trainability following multiple inductions).

Significant association between baseline RSV in left MFG and right cerebellum and reductions in DOMS-related pain unpleasantness were detected. Furthermore, increases in RSV were associated with reduced DOMS pain intensity (left lingual gyrus, right MTG, left MTG, left precuneus) and unpleasantness (left MTG, right SFG).

Regional signal variability may be an important indicator of endogenous pain modulatory system responsivity to training following repeated bouts of clinically relevant pain and may in fact be responsive to training itself.

Factors Associated with Minimum Effective Volume of Lidocaine 1.5% for Sciatic Nerve Blocks.

Clin J Pain

The objectives of this study were to investigate the correlations between the minimum effective volume (MEV) of lidocaine 1.5% for an ultrasound-guided popliteal sciatic nerve block (PSNB) and individual factors including the cross-sectional nerve area, sex, age, body mass index (BMI) and the depth of the sciatic nerve and to evaluate the safety of combined femoral and sciatic nerve blocks by monitoring the plasma concentration of local anesthetics (LAs).

Forty patients received combined single-shot femoral and continuous sciatic nerve blocks. The femoral nerve block was performed with an in-plane technique and 15▒mL of lidocaine 1.5%. A continuous peripheral nerve block annular tube was positioned between the tibial and peroneal nerves inside the paraneural sheath. Thirty minutes after the femoral nerve block, a loading dose of 5▒mL of lidocaine 1.5% was given to block the sciatic nerve after obtaining the maximum compound muscle action potential (CMAP) amplitude using nerve conduction studies (NCSs). Additional lidocaine 1.5% was pumped at a rate of 30▒mL/h through the indwelling annular tube if after 8 minutes, the CMAP amplitude was still present. The CMAP amplitude monitored by the NCSs and pinprick tests were recorded every 2 minutes after the administration of lidocaine 1.5%. When the CMAP amplitude decreased to nearly 0▒mV, this MEV was recorded. The influences of the cross-sectional area of the sciatic nerve, sex, age, BMI and the depth of the sciatic nerve on the MEV were analyzed using stepwise multiple linear regression. Blood samples were collected from ten patients to evaluate the safety of combined femoral and sciatic nerve blocks by ultra-performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS). Blood was drawn at 0 minutes before femoral nerve injection, 0 minutes before sciatic nerve injection, 8 minutes after sciatic nerve injection and 0, 10, 20, 30, 45, 60, 75, 90, and 120 minutes after the pumping of lidocaine 1.5% stopped.

A significant correlation was found between the MEV of lidocaine 1.5% and the cross-sectional area of the sciatic nerve (r=0.459), with a regression equation of the MEV (mL)=5.969 + 0.095× (the cross-sectional area of the sciatic nerve). The coefficient of determination was 0.211 (P<0.05). The MEV of lidocaine 1.5% for complete sciatic nerve blocks ranged from 7 to 15▒mL. The maximum concentrations of lidocaine, monoethylglycinexylidide (MEGX) and glycinexylidide (GX) were 1672.9 (227.6), 265.7 (32.7) and 42.2 (22.4) ng/mL, respectively.

There is a positive correlation between the cross-sectional area of the sciatic nerve and the MEV. The regression equation can help to predict the MEV of lidocaine 1.5% for PSNBs. The maximum concentrations of lidocaine and its metabolites did not approach toxic threshold limits in this study.

Investigating the Effect of Perioperative Chlorzoxazone On Acute Postoperative Pain After Total Hip and Knee Replacement Surgery.

Clin J Pain

Severe pre- and acute postoperative pain have been associated with development of chronic postoperative pain. Chlorzoxazone (a muscle relaxant) has been suggested to enhance acute postoperative pain recovery but the lack of larger randomized controlled trials have however questioned the continued use. Despite this, chlorzoxazone is still used for acute postoperative pain management following total knee or hip replacement (TKR or THR). The currentrandomized, double blinded, placebo-controlled, parallel group, clinical trial aimed to assess the effect of chlorzoxazone for postoperative pain management following TKR or THR.

393 patients scheduled for TKR or THR were included in the trial. Patients were assigned to 250▒mg chlorzoxazone three times daily for the first seven days postoperative or placebo. The primary outcome was pain after 5 meter walk assessed 24-hours postoperative. Secondary outcomes included, changes in preoperative pain at rest, worst pain in the last 24 hours, and Oxford Knee or Hip Score compared with 12 months follow-up. In addition, adverse events were assessed in the perioperative period.

No significant differences were found for any of the outcome parameters after TKR or THR. For neither TKR or THR no effects were demonstrated for pain after 5 meters walk 24-hours after surgery (P>0.313), or for any of the secondary outcomes (P>0.288) or adverse event (P>0.112) in the group receiving chlorzoxazone compared with placebo.

The current study demonstrated no analgesic effects of postoperative chlorzoxazone administration compared with placebo on acute or chronic postoperative pain 12 months following TKR and THR.

Efficacy of Nalbuphine as an Adjuvant to Ropivacaine in Ultrasound Guided Supraclavicular Brachial Block - A Prospective Randomized Controlled Study.

Clin J Pain

A brachial plexus block provides anesthesia and analgesia with limited duration. Various opioids have been used as adjuvants of local anesthetics to improve the effects.

To evaluate the safety and effectiveness of nalbuphine used as an adjuvant to local anesthetic during the supraclavicular brachial plexus block.

In this prospective, double-blinded, randomized controlled study, ninety ASA Physical Status I and II patients (aged 20 to 65▒y) of either gender undergoing upper limb orthopedic surgeries under ultrasound guided supraclavicular brachial plexus block were randomly allocated into three groups: Group C (n=30), Group NL (n=30) and Group NH (n=30) for analyses. Each patient received 18▒mL of 100▒mg ropivacaine solution combined with 2▒mL normal saline, 2▒mL of 10▒mg nalbuphine, or 2▒mL of 20▒mg nalbuphine. The time of onset and block duration of sensory and motor blocks, duration of analgesia, hemodynamic variables, and any adverse effects were assessed.

Compared with Group C, onset time of both sensory and motor blocks were significantly shortened. The sensory block and motor block duration were significantly prolonged in group NL and group NH. There was no significant difference between the duration of analgesia in group NL and NH although the analgesia duration of both of groups was longer than group C. But incidence of side effects in group NH such as vomiting was significantly higher than group NL.

Nalbuphine is an effective adjuvant to 0.5% ropivacaine in US-guided supraclavicular brachial plexus block. The dosage of 10▒mg improves quality of the anesthesia with less incidence of side effects.

A Systematic Review of Clinical Practice Guidelines for Acute Procedural Pain on Neonates.

Clin J Pain

During hospitalization in neonatal intensive care units (NICU), neonates are exposed to many painful procedures within a stressful environment. To date, many evidence-based guidelines are available. However, the quality of these guidelines and their clinical application remain unclear. This systematic review aims at determining the quality of existing guidelines on the management of procedural pain in neonates and to summarize the recommendations provided by these guidelines.

A structured search was conducted in Embase, PubMed, CINAHL, JBI database and in grey literature resources in November 2018 to identify relevant guidelines published from 2007 onwards. Published guidelines and guidelines from complementary searches were included treating assessment or management of procedural pain in neonates. The methodological quality was analyzed using the Appraisal of Guidelines for Research and Evaluation (AGREE) II Instrument.

A total of 1154 records were identified. After screening for eligibility, 17 guidelines were included in this review. Among these, 11 were identified to be high quality guidelines. Besides the usual recommendations for pharmacological and non-pharmacological treatments, inclusion of parents, improving interprofessional collaboration and considering the setting were identified as important elements.

The results of this review show that there is a need to improve the methodological quality of guidelines for procedural pain in newborns. The set of recommendations for procedural pain prevention needs to involve not only pharmacological and non-pharmacological pain treatment but also parents and interprofessional collaboration. It is also essential to take into account facilitators, barriers and context to improve pain management.

The Relationship between Clinical and Quantitative Measures of Pain Sensitization in Knee Osteoarthritis.

Clin J Pain

Pain sensitization in knee osteoarthritis is associated with greater symptom severity and poorer clinical outcomes. Measures which identify pain sensitization and are accessible to use in clinical practice have been suggested to enable more targeted treatments. This merits further investigation. This study examines the relationship between Quantitative Sensory Testing (QST) and clinical measures of pain sensitization in people with knee osteoarthritis.

A secondary analysis of data from 134 participants with knee osteoarthritis was performed. Clinical measures included: manual tender point count (MTPC), the Central Sensitization Inventory (CSI) to capture centrally mediated co-morbidities, number of painful sites on a body chart, and neuropathic pain-like symptoms assessed using the modified PainDetect Questionnaire (mPD-Q). Relationships between clinical measures and QST measures of pressure pain thresholds (PPTs), temporal summation (TS) and conditioned pain modulation (CPM) were investigated using correlation and multivariable regression analyses.

Fair to moderate correlations, ranging from -0.331 to -0.577 (P<0.05), were identified between MTPC, the CSI, number of painful sites, and PPTs. Fair correlations, ranging from 0.28 to 0.30 (P<0.01), were identified between MTPC, the CSI, number of painful sites, and CPM. Correlations between the clinical and self-reported measures and TS were weak and inconsistent (0.09 to 0.25.). In adjusted regression models, MTPC was the only clinical measure consistently associated with QST and accounted for 11-12% of variance in PPTs.

MTPC demonstrated the strongest associations with QST measures and may be the most promising proxy measure to detect pain sensitization clinically.