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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Comparing outcomes after peripheral nerve block versus general anesthesia for lower extremity amputation: a nationwide exploratory retrospective cohort study in Japan.

Regional Anesthesia and Pain Medicine

The health benefits of peripheral nerve block (PNB) on postoperative complications after lower extremity amputation (LEA) compared with general anesthesia (GA) remains controversial. We performed a retrospective propensity score-matched cohort analysis to compare major outcomes after LEA with PNB versus GA.

We used a nationwide inpatient database in Japan to compare patient outcomes after LEA with PNB versus GA from 2010 to 2016. Our primary outcome was 30-day mortality after LEA. The incidence of composite morbidity from life-threatening complications and of delirium within 30 days after LEA were secondary outcomes. We conducted propensity score-matched analyses of patients who underwent below knee or foot amputation using 36 covariates. Logistic regression analyses fitted with generalized estimating equations were performed to calculate ORs and their 95% CIs.

Of 11 796 patients, 747 received PNB and 11 049 received GA. After one-to-four propensity score matching, 747 patients were included in the PNB group and 2988 in the GA group. The adjusted ORs for postoperative mortality, composite morbidity and delirium within 30 days after LEA were 1.11 (95% CI 0.75 to 1.64), 1.15 (95% CI 0.85 t o1.56) and 0.75 (95% CI 0.57 to 0.98), respectively, for the PNB group with reference to the GA group.

There was no significant difference between groups in 30-day mortality or composite morbidity. The PNB group showed a significantly lower risk of postoperative delirium than the GA group. Our findings suggest that PNB may have advantages over GA in preventing postoperative delirium among patients undergoing LEA.

Consensus practice guidelines on interventions for lumbar facet joint pain from a multispecialty, international working group.

Regional Anesthesia and Pain Medicine

The past two decades have witnessed a surge in the use of lumbar facet blocks and radiofrequency ablation (RFA) to treat low back pain (LBP), yet nearly all aspects of the procedures remain controversial.

After approval by the Board of Directors of the American Society of Regional Anesthesia and Pain Medicine, letters were sent to a dozen pain societies, as well as representatives from the US Departments of Veterans Affairs and Defense. A steering committee was convened to select preliminary questions, which were revised by the full committee. Questions were assigned to 4-5 person modules, who worked with the Subcommittee Lead and Committee Chair on preliminary versions, which were sent to the full committee. We used a modified Delphi method, whereby the questions were sent to the committee en bloc and comments were returned in a non-blinded fashion to the Chair, who incorporated the comments and sent out revised versions until consensus was reached.

17 questions were selected for guideline development, with 100% consensus achieved by committee members on all topics. All societies except for one approved every recommendation, with one society dissenting on two questions (number of blocks and cut-off for a positive block before RFA), but approving the document. Specific questions that were addressed included the value of history and physical examination in selecting patients for blocks, the value of imaging in patient selection, whether conservative treatment should be used before injections, whether imaging is necessary for block performance, the diagnostic and prognostic value of medial branch blocks (MBB) and intra-articular (IA) injections, the effects of sedation and injectate volume on validity, whether facet blocks have therapeutic value, what the ideal cut-off value is for a prognostic block, how many blocks should be performed before RFA, how electrodes should be oriented, the evidence for larger lesions, whether stimulation should be used before RFA, ways to mitigate complications, if different standards should be applied to clinical practice and clinical trials and the evidence for repeating RFA (see table 12 for summary).

Lumbar medial branch RFA may provide benefit to well-selected individuals, with MBB being more predictive than IA injections. More stringent selection criteria are likely to improve denervation outcomes, but at the expense of more false-negatives. Clinical trials should be tailored based on objectives, and selection criteria for some may be more stringent than what is ideal in clinical practice.

Optimizing the Treatment of CRPS with Ketamine.

Clin J Pain

This study aimed to develop a method that objectively measures the clinical benefits of ketamine infusions to treat complex regional pain syndrome (CRPS), thus making it possible, for the first time, to determine the optimal dosing of ketamine and duration of treatment to treat CRPS.

All patients were diagnosed with hyperalgesia associated with CRPS. Patients underwent an outpatient, 4-day, escalating dose ketamine infusion. Hyperalgesia was measured using pain thresholds. Clinical outcome was determined without knowledge of the patient's pain thresholds throughout treatment.

We found a correlation between pain thresholds and the intensity of pain reported by the patient at various sites of the body. We found that clinical outcomes correlated with improvement in pain thresholds. There was a plateau in pain thresholds between days 3 and 4 for the lower extremities. There was no plateau in pain thresholds observed for the upper extremities.

Our findings suggest that four days of treatment are sufficient for the treatment of CRPS of the lower extremities. For the upper extremities, more than four days may be required. Our study is the first to utilize quantitative sensory testing to direct the treatment of a chronic pain disorder.

Implementation of a patient-specific tapering protocol at discharge decreases total opioid dose prescribed for 6 weeks after elective primary spine surgery.

Regional Anesthesia and Pain Medicine

At our institution, we developed an individualized discharge opioid prescribing and tapering protocol for joint replacement patients and implemented the same protocol for neurosurgical spine patients. We then tested the hypothesis that this protocol will decrease the oral morphine milligram equivalent (MME) dose of opioid prescribed postdischarge after elective primary spine surgery.

In this retrospective cohort study, we identified all consecutive elective primary spine surgery cases 1 year before and after introduction of the protocol. This protocol used the patient's prior 24-hour inpatient opioid consumption to determine discharge opioid pill count and tapering schedule. The primary outcome was total opioid dose prescribed in oral MME from discharge through 6 weeks. Secondary outcomes included in-hospital opioid consumption in MME, hospital length of stay, MME prescribed at discharge, opioid refills, and rates of minor and major adverse events.

Eighty-three cases comprised the final sample (45 preintervention and 38 postintervention). There were no differences in baseline characteristics. The total oral MME (median (IQR)) from discharge through 6 weeks postoperatively was 900 (420-1440) preintervention compared with 300 (112-806) postintervention (p<0.01, Mann-Whitney U test), and opioid refill rates were not different between groups. There were no differences in other outcomes.

This patient-specific prescribing and tapering protocol effectively decreases the total opioid dose prescribed for 6 weeks postdischarge after elective primary spine surgery. Our experience also demonstrates the potential generalizability of this protocol, which was originally designed for joint replacement patients, to other surgical populations.

Efficacy and safety of propranolol for treatment of TMD pain: a randomized, placebo-controlled clinical trial.


Propranolol is a non-selective beta-adrenergic receptor antagonist. A multicenter, randomized, double-blind, placebo-controlled, parallel-group, ph...

Regulatory T cells counteract neuropathic pain through inhibition of the Th1 response at the site of peripheral nerve injury.


The inflammatory/immune response at the site of peripheral nerve injury participates in the pathophysiology of neuropathic pain. Nevertheless, litt...

Breakthrough pain is not a fixed fraction of constant cancer pain.

Eur J Pain

This journal recently published a paper by Currow et al., entitled "A randomised, double-blind, crossover, dose ranging study to determine the opti...

Dissociation proneness and pain hyposensitivity in current and remitted borderline personality disorder.

Eur J Pain

Stress-related dissociation has been shown to negatively co-vary with pain perception in current borderline personality disorder (cBPD). While remission of the disorder (rBPD) is associated with normalized pain perception, it remains unclear whether dissociation proneness is still enhanced in this group and how this feature interacts with pain sensitivity.

Twenty-five cBPD patients, 20 rBPD patients, and 24 healthy controls (HC) participated in an experiment using the script-driven imagery approach. We presented a personalized stressful and neutral narrative. After listening to the scripts, dissociation and heat pain thresholds (HPT) were assessed.

Compared to HC, cBPD patients showed enhanced dissociation and exhibited significantly enhanced HPT in the neutral condition, while rBPD participants were in between. After listening to the stress script, both clinical groups exhibited enhanced dissociation scores. Current BPD participants responded with significantly higher HPT, while rBPD only showed a trend in the same direction. However, both BPD groups showed significantly increased HPT compared to the HC in the stress condition, but did not differ from each other. Dissociation proneness correlated significantly positively with pain hyposensitivity only in cBPD.

Dissociation proneness is enhanced in both BPD groups. This feature is clearly positively related to pain hyposensitivity in cBPD, but not in rBPD. However, the data indicate that stress causes the pain perception in rBPD to drift away from that obtained in HC. These results highlight the volatile state of BPD remission and might have important implications for the care of BPD patients in the remitted stage.

Transcutaneous Vagus Nerve Stimulation in Patients With Severe Traumatic Brain Injury: A Feasibility Trial.


Preclinical studies have shown that surgically implanted vagus nerve stimulation (VNS) promotes recovery of consciousness and cognitive function following experimental traumatic brain injury (TBI). The aim of this study is to report the feasibility and safety of a noninvasive transcutaneous vagus nerve stimulation (tVNS) in patients with persistent impairment of consciousness following severe TBI.

The feasibility of tVNS was evaluated in five patients presenting with diffuse axonal injury and reduced dominant EEG activity one month following severe TBI. tVNS was applied to the left cymba conchae of the external ear using a skin electrode four hours daily for eight weeks. Possible effects of tVNS on physiological parameters and general side effects were recorded. In addition, we report the rate of recovery using coma recovery scale revised (CRS-R).

The tVNS regime of four hours daily for eight weeks was feasible and well tolerated with little side effects and no clinically relevant effects on physiological parameters. Three patients showed improvements (>3 points) in the CRS-R following eight weeks tVNS.

We demonstrated that tVNS is a feasible and safe VNS strategy for patients following severe TBI. Controlled studies are needed to clarify whether tVNS has a potential to promote recovery of consciousness following severe TBI.

Necessary Components of Psychological Treatment for Chronic Pain: More Packages for Groups or Process-Based Therapy for Individuals?

Eur J Pain

This journal recently published a paper by Sharpe et al., entitled "Necessary components of psychological treatments in chronic pain management pro...

Psychological and pain profiles in persons with patellofemoral pain as the primary symptom.

Eur J Pain

Patellofemoral pain (PFP) is defined biomechanically, but is characterised by features that fit poorly within nociceptive pain. Mechanisms associated with central sensitisation may explain why, for some, symptoms appear nociplastic. This study compares psychological and somatosensory characteristics between those with persistent PFP and controls.

150 adults with PFP were compared to 61 controls. All participants completed a survey evaluating participant characteristics, PFP-related constructs and psychological factors: anxiety, depression, pain catastrophizing, kinesiophobia, pain self-efficacy. Participants also attended a session of somatosensory testing, which included knee and elbow thermal and mechanical detection and pain thresholds, conditioned pain modulation (CPM), and temporal summation of pain (TSP). Differences were evaluated using analysis of covariance (sex as covariate). Multivariate backward stepwise linear regression examined how psychological and somatosensory variables relate to PFP (Knee injury & Osteoarthritis Outcome Score-patellofemoral).

The PFP group had multimodal reduced pain thresholds at the knee and elbow (Standardised Mean Difference (SMD), p: 0.86 to 1.2, <0.001), reduced mechanical detection at the elbow (0.43, 0.01) and higher TSP (0.41, 0.01). CPM was not different. Psychological features demonstrated small effects (0.47-0.59, 0.01-0.04). The PFP group had a 55% (95% CI: 0.47 to 0.62) risk of kinesiophobia and an 11% (0.06 to 0.15) reduced pain self-efficacy risk. Kinesiophobia, knee pressure pain threshold, pain self-efficacy and pain catastrophizing explained 40% of KOOS-PF variance (p = <0.001).

(1) Individuals with patellofemoral pain have widespread reduced pain thresholds to pressure and thermal stimuli. (2) Mechanically-induced pain is likely amplified in those with patellofemoral pain. (3) Pain-related fear is highly prevalent and helps explain patellofemoral pain-related disability. WHAT'S ALREADY KNOWN ABOUT THIS TOPIC?: (1) Pressure pain threshold can be lower in individuals with patellofemoral pain. WHAT DOES THIS STUDY ADD?: (1) This is the first study to explore a combined range of psychological and psychophysical tests in patellofemoral pain. (2) This study provides strong evidence of nociplastic pain in patellofemoral pain.

Interpretation biases and visual attention in the processing of ambiguous information in chronic pain.

Eur J Pain

Theories propose that interpretation biases and attentional biases might account for the maintenance of chronic pain symptoms, but the interactions between these two forms of biases in the context of chronic pain are understudied.

To fill this gap, sixty-three participants (40 females) with and without chronic pain completed an interpretation bias task that measures participants' interpretation styles in ambiguous scenarios and a novel eye-tracking task where participants freely viewed neutral faces that were given ambiguous pain-/health-related labels (i.e., "doctor", "patient" and "healthy people"). Eye movements were analysed with the Hidden Markov Models (EMHMM) approach, a machine-learning data-driven method that clusters people's eye movements into different strategy subgroups.

Adults with chronic pain endorsed more negative interpretations for scenarios related to immediate bodily injury and long-term illness than healthy controls, but they did not differ significantly in terms of their eye movements on ambiguous faces. Across groups, people who interpreted illness-related scenarios in a more negative way also focused more on the nose region and less on the eye region when looking at patients' and healthy people's faces and, to a lesser extent, doctors' faces. This association between interpretive and attentional processing was particularly apparent in participants with chronic pain.

In sum, the present study provided evidence for the interplay between multiple forms of cognitive biases. Future studies should investigate whether this interaction might influence subsequent functioning in people with chronic pain.