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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The Accuracy and Feasibility of Robotic Assisted Lead Implantation in Nonhuman Primates.

Neuromodulation

Deep brain stimulation (DBS) and stereo-electroencephalography (SEEG) electrode implantation are the most important and frequent manipulations in nonhuman primates (NHP) neuromodulation research. However, traditional methods tend to be arduous and inaccurate.

Twelve adult male rhesus monkeys were selected for the study, with six subthalamic nucleus (STN) DBS, six anterior nucleus of the thalamus (ANT) DBS and six hippocampus-SEEG (Hippo-SEEG) electrodes implantation. Mean Euclidean errors of entrance and the target were calculated by postoperative image fusion, and the correlation between entrance and target error, as well as the differences among the various manipulations, were analyzed. The accuracy of target was further confirmed by gross anatomy examination. Moreover, the time consumption was recorded.

The mean (±SD) Euclidean errors of the target point and entry point of the three manipulations were STN-DBS: 1.05 ± 0.54 mm and 0.52 ± 0.17 mm; ANT-DBS: 1.12 ± 0.74 mm and 0.58 ± 0.24 mm; and Hippo-SEEG: 2.68 ± 1.03 mm and 1.47 ± 0.63 mm. Significant differences were observed in both target and entry point errors between the DBS and Hippo-SEEG groups, with superior accuracy in the DBS group. The entrance errors had a significantly positive correlation with the target errors in the STN-DBS and Hippo-SEEG groups. Moreover, the time consumption in robotic surgery was much shorter than that in the traditional method, without any severe complications.

The application of robot-assisted lead implantation in NHP neuromodulation research is feasible, accurate, safe, and efficient, and can prospectively be beneficial to neurological studies.

A Retrospective Database Review of the Indications, Complications, and Incidence of Subsequent Spine Surgery in 12,297 Spinal Cord Stimulator Patients.

Neuromodulation

A nationally representative sample of Medicare patients who had an open (via laminectomy) SCS placement for degenerative spine disease between 2005 and 2014 were studied. Indications, complications, and the rate of subsequent spinal surgery within 90 days, one year, two years, and three years postoperatively were studied using Current Procedural Terminology (CPT) and International Classification of Diseases (ICD) codes.

To analyze the indications, incidence of minor and major complications, and rate of subsequent spinal surgery or revision after spinal cord stimulator (SCS) placement for degenerative spine disease.

Despite the application of SCS in various chronic pain conditions, there remains a growing debate on the efficacy and necessity of SCS in degenerative spine disease.

We included 12,297 SCS patients in our study cohort. The most common indications for SCS placement were postlaminectomy syndrome (25.2%) and chronic pain syndrome (20.2%). There was a 4.2 and 17.2% incidence of postoperative back or spine emergency department (ED) visits, and a 0.3 and 3.4% incidence of SCS electrode removal or reimplantation within 90 days and 1 year, respectively. Other reported surgical complications were wound infection (4.3%), hematoma (0.5%), and seroma (0.4%) at one year postoperatively. Within 90 days after SCS implantation, the rate of subsequent spine surgery or revision was 0.9%. This incidence was 7.1, 11.7, and 15.5% at one, two, and three years, respectively.

In our retrospective analysis of Medicare patients, the most common indication for SCS implantation was postlaminectomy syndrome. Common postoperative complications included wound infection, and removal of SCS electrodes at one year postoperatively. About 17% patients had an ED visit for spine-related symptoms within one year of device implantation, and 15.5% underwent subsequent spinal decompression and/or fusion within 3 years after primary SCS placement.

Review of concentration yields in commercially available platelet-rich plasma (PRP) systems: a call for PRP standardization.

Regional Anesthesia and Pain Medicine

Platelet-rich plasma (PRP) has become increasingly popular in pain medicine with hopes of becoming a safe, effective alternative to routine treatme...

Early experiences with the use of continuous erector spinae plane blockade for the provision of perioperative analgesia for pediatric liver transplant recipients.

Regional Anesthesia and Pain Medicine

Pediatric liver transplantation presents a number of anesthetic challenges, especially in providing adequate perioperative analgesia. In an effort to reduce opioid consumption and improve functional outcomes following pediatric liver transplantation, we have instituted a novel analgesia protocol centered on the provision of continuous regional analgesia with erector spinae plane (ESP) blockade.

We describe preincisional bilateral ESP catheter placement in two pediatric patients undergoing orthotopic liver transplantation. The first case was a 12-year-old boy with maple syrup urine disease undergoing initial transplantation and the second case was an 8-year-old boy who underwent an 11 hours complex redo liver transplant in the setting of glycogen storage disease type 1A requiring initial liver transplant in 2014. The 8-year-old boy presented to the operating suite with acute Budd-Chiari syndrome with comorbid ascites and a large right pleural effusion. In both cases, ESP blockade resulted in good analgesia, markedly reduced intraoperative and postoperative opioid consumption as compared with institutional data and published rates of consumption and was associated with rapid return of bowel function.

These early experiences suggest a role for continuous ESP blockade to improve analgesia and potentially change the paradigm of treatment in this fragile patient population. The technique should be considered in similar interventions. Further study will be undertaken to validate our observation.

Complications associated with stellate ganglion nerve block: a systematic review.

Regional Anesthesia and Pain Medicine

Stellate ganglion nerve blockade (SGNB) is a vital tool in our armamentarium for the treatment of various chronic pain syndromes. SGNB can be perfo...

Prognostic value of hypersensitivity reactions on epidural steroid injection outcomes: a phenotypic signature? A prospective cohort study.

Regional Anesthesia and Pain Medicine

Studies have found that diffuse pain, indicative of central sensitization, portends poor interventional outcomes. Multiple chemical sensitivities are associated with signs of central sensitization. We sought to prospectively determine whether hypersensitivity reactions (HR) were associated with epidural steroid injection (ESI) outcomes.

HR were classified as immune-related or non-immune-related and categorized by number (0=low, 1 or 2=intermediate, ≥3=high). The primary outcome measure was mean reduction in average leg pain score 1 month post-procedure. A positive outcome was defined as a two-point or greater decrease in average leg pain accompanied by satisfaction 1 month post-procedure.

The mean number of immune-mediated and non-immune-mediated HR were 0.6±1.2 and 0.8±1.4, respectively. Individuals in the high (n=24) total HR group had a mean reduction in average leg pain of 0.1±2.7, compared with those in the low (n=61; 1.8±2.1, p=0.025) and intermediate groups (n=52; 1.6±3.1, p=0.060). For back pain and categorical successful outcome, those with fewer HR experienced greater benefit. There were no differences in outcomes when patients were stratified by immune-related HR. Among participants in the low, intermediate and high non-immune-mediated HR groups, the mean reductions in average leg pain scores were 1.7±2.5, 1.6±3.0, and -0.2±2.3, respectively (p = 0.002). 51%, 35%, and 12% of people with low, intermediate and high numbers of non-immune-mediated HR experienced a positive categorical outcome, respectively (p=0.007).

Non-immune-related HR were inversely correlated with some ESI outcome measures.

Magnetic Resonance Imaging Exploration of the Human Brain During 10 kHz Spinal Cord Stimulation for Failed Back Surgery Syndrome: A Resting State Functional Magnetic Resonance Imaging Study.

Neuromodulation

Apart from the clinical efficacy of high frequency spinal cord stimulation at 10 kHz, the underlying mechanism of action remains unclear. In parallel with spinal or segmental theories, supraspinal hypotheses have been recently proposed. In order to unveil hidden altered brain connectome patterns, a resting state functional magnetic resonance imaging (rsfMRI) protocol was performed in subjects routinely treated for back and/or leg pain with high-frequency spinal cord stimulation (HF-SCS) HF-SCS at 10 kHz.

RsfMRI imaging was obtained from ten patients with failed back surgery syndrome who were eligible for HF-SCS at 10 kHz. Specifically-chosen regions of interest with different connectivity networks have been investigated over time. Baseline measurements were compared with measurements after 1 month and 3 months of HF-SCS at 10 kHz. Additionally, clinical parameters on pain intensity, central sensitization, pain catastrophizing, and sleep quality were correlated with the functional connectivity strengths.

The study results demonstrate an increased connectivity over time between the anterior insula (affective salience network) and regions of the frontoparietal network and the central executive network. After 3 months of HF-SCS, the increased strength in functional connectivity between the left dorsolateral prefrontal cortex and the right anterior insula was significantly correlated with the minimum clinically important difference (MCID) value of the Pittsburgh sleep quality index.

These findings support the hypothesis that HF-SCS at 10 kHz might influence the salience network and therefore also the emotional awareness of pain.

Burst and Tonic Spinal Cord Stimulation in the Mechanical Conflict-Avoidance System: Cognitive-Motivational Aspects.

Neuromodulation

Clinical research suggests that a novel spinal cord stimulation (SCS) waveform, known as Burst-SCS, specifically targets cognitive-motivational aspects of pain. The objective of the present study was to assess the cognitive-motivational aspects of Tonic- and Burst SCS-induced pain relief, by means of exit latency in the mechanical conflict-avoidance system (MCAS), in a rat model of chronic neuropathic pain.

Exit latency on the MCAS operant testing setup was evaluated at various probe heights for rats (n = 26) with chronic neuropathic pain induced by a partial sciatic nerve ligation (PSNL). Von Frey paw withdrawal analysis was performed to assess mechanical hypersensitivity. In a second experiment (n = 12), the behavioral effect of Tonic SCS or biphasic Burst SCS on both Von Frey analysis and MCAS exit latency was assessed.

Burst SCS exit latencies differed significantly from Tonic SCS exit latencies at 4 mm probe height (3.8 vs. 5.8 sec, respectively; p < 0.01) and 5 mm probe height (3.2 vs. 5.4 sec respectively; p < 0.05). This difference was not detected with reflex-based Von Frey testing (Tonic-SCS vs. Burst-SCS at 30 min stimulation: p = 0.73, and at 60 min stimulation; p = 0.42).

Testing of MCAS exit latency allows for detection of cognitive-motivational pain relieving aspects induced by either Tonic- or Burst-SCS in treatment of chronic neuropathic rats. Our behavioral findings strongly suggest that Burst-SCS specifically affects, much more than Tonic-SCS, the processing of cognitive-motivational aspects of pain.

Percutaneous peripheral nerve stimulation for the treatment of chronic neuropathic postamputation pain: a multicenter, randomized, placebo-controlled trial.

Regional Anesthesia and Pain Medicine

Chronic neuropathic pain is a common challenging condition following amputation. Recent research demonstrated the feasibility of percutaneously implanting fine-wire coiled peripheral nerve stimulation (PNS) leads in proximity to the sciatic and femoral nerves for postamputation pain. A multicenter, double-blinded, randomized, placebo-controlled study collected data on the safety and effectiveness of percutaneous PNS for chronic neuropathic pain following amputation.

Twenty-eight lower extremity amputees with postamputation pain were enrolled. Subjects underwent ultrasound-guided implantation of percutaneous PNS leads and were randomized to receive PNS or placebo for 4 weeks. The placebo group then crossed over and all subjects received PNS for four additional weeks. The primary efficacy endpoint evaluated the proportion of subjects reporting ≥50% pain reduction during weeks 1-4.

A significantly greater proportion of subjects receiving PNS (n=7/12, 58%, p=0.037) demonstrated ≥50% reductions in average postamputation pain during weeks 1-4 compared with subjects receiving placebo (n=2/14, 14%). Two subjects were excluded from efficacy analysis due to eligibility changes. Significantly greater proportions of PNS subjects also reported ≥50% reductions in pain (n=8/12, 67%, p=0.014) and pain interference (n=8/10, 80%, p=0.003) after 8 weeks of therapy compared with subjects receiving placebo (pain: n=2/14, 14%; pain interference: n=2/13, 15%). Prospective follow-up is ongoing; four of five PNS subjects who have completed 12-month follow-up to date reported ≥50% pain relief.

This work demonstrates that percutaneous PNS therapy may provide enduring clinically significant pain relief and improve disability in patients with chronic neuropathic postamputation pain.

NCT01996254.

Effect of Long-Term Intrathecal Bupivacaine Infusion on Blood Pressure.

Neuromodulation

The local anesthetic bupivacaine is a common analgesic adjuvant medication used in combination with opioids in intrathecal drug delivery systems (IDDSs). While the acute effects of spinal bupivacaine injection on blood pressure (BP) have been studied, there is a dearth of data regarding long-term effects of continuous intrathecal bupivacaine infusion.

A retrospective review of all noncancer pain patients receiving bupivacaine through IDDSs from January 2013 to November 2017 was performed. Blood pressure values before implantation, and after implant at the 1-week, 3-month, 6-month and 1-year time points are recorded as well as corresponding bupivacaine and opioid doses in the IDDS.

Eighty-two patients were included in the study; median patient age was 64 years and intrathecal catheter tips were located predominantly in the lower thoracic spine. Significant decreases in systolic blood pressure (SBP) and mean arterial pressure (MAP) relative to baseline occurred in patients receiving chronic lower thoracic intrathecal bupivacaine delivery at 3, 6, and 12 months post-implant (-12.96 ± 18.21; p < 0.001 and - 6.38 ± 12.04; p < 0.001, respectively). The only significant decrease in DBP was observed at 1 year post-implant (-3.09 ± 11.76; p < 0.05). Similar decreases in BP values occurred in patients with or without hypertension.

Long-term thoracic intrathecal infusion of bupivacaine likely exerts a lowering effect on BP, primarily because of a significant decrease in SBP. This effect is likely due to efferent sympathetic blockade by bupivacaine.

Therapeutic Window of Deep Brain Stimulation Using Cathodic Monopolar, Bipolar, Semi-Bipolar, and Anodic Stimulation.

Neuromodulation

To compare the therapeutic window (TW) of cathodic monopolar, bipolar, anodic monopolar, and a novel "semi-bipolar" stimulation in ten Parkinson's disease patients who underwent deep brain stimulation of the subthalamic nucleus.

Patients were assessed in the "OFF" L-dopa condition. Each upper limb was tested separately for therapeutic threshold, TW and side-effect threshold (SET). Battery consumption index (BCI) also was documented.

Compared to cathodic stimulation, therapeutic threshold was significantly higher for anodic, bipolar, and semi-bipolar stimulation (3.8 ± 1.6 vs. 4.9 ± 2.1, 5.0 ± 1.9, and 5.2 ± 1.9 mA, p = 0.0006, 0.0002, and 0.008, respectively). SET was significantly higher for bipolar stimulation (10.9 ± 2.5 mA) vs. cathodic (6.8 ± 2.2 mA, p < 0.0001) and anodic stimulation (9.2 ± 2.6 mA, p = 0.005). The SET of anodic and semi-bipolar stimulation was significantly higher vs. cathodic stimulation (p < 0.0001). TW of cathodic stimulation (2.5 ± 1.5 mA) was significantly narrower vs. bipolar (5.4 ± 2.0 mA, p < 0.0001), semi-bipolar (4.6 ± 2.6 mA, p = 0.001) and anodic stimulation (4.3 ± 2.3 mA, p < 0.0001). Bipolar (p = 0.005) and semi-bipolar (p = 0.0005) stimulation had a significantly wider TW vs. anodic stimulation. BCI of cathodic stimulation (5.9 ± 1.3) was significantly lower compared to bipolar (13.7 ± 6.8, p < 0.0001), semi-bipolar (11.0 ± 4.3, p = 0.0005), and anodic stimulation (8.1 ± 3.0, p < 0.0001). Anodic BCI was significantly lower than bipolar (p = 0.005) and semi-bipolar (p = 0.0002) stimulation while semi-bipolar BCI was lower than bipolar stimulation (p = 0.0005).

While awaiting further studies, our findings suggest that cathodic stimulation should be preferred in light of its reduced battery consumption, possibly followed by semi-bipolar in case of stimulation-induced side-effects.

Greater analgesic effect with intermittent compared with continuous mode of lumbar plexus block for total hip arthroplasty: a randomized controlled trial.

Regional Anesthesia and Pain Medicine

Lumbar plexus block (LPB) is an effective perioperative analgesic therapy for patients undergoing total hip arthroplasty (THA). However, the analgesic efficacy of intermittent administration compared with continuous infusion of LPB in patients remains unclear.

Forty adult patients who underwent THA were randomly divided into two groups: continuous infusion group (6 mL/hour continuous infusion of levobupivacaine [0.125%] in LPB, n=20) and intermittent infusion group (12 mL of levobupivacaine [0.125%] bolus delivered every 2 hours in LPB, n=20). The primary outcome was the cumulative fentanyl consumption administered for rescue analgesia during the first 48 hours after surgery. Secondary outcomes were the number of demands for rescue analgesia and successfully delivered rescue analgesia; extent of sensory blockade (cold tests); and pain score on the visual analog scale (VAS) at rest and during mobilization during the first 48 hours after surgery.

Both the cumulative fentanyl consumption administered for rescue analgesia (mean [SD]: 81.5 [58.5] μg vs 438 [101.2] μg among the intermittent infusion and the continuous infusion groups, respectively) and the number of demanded and delivered fentanyl boluses for rescue analgesia were lower in intermittent infusion group than in continuous infusion (p<0.001 for both). The extent of sensory blockade remained constant in intermittent infusion group, but gradually narrowed in continuous infusion. VAS was lower in intermittent infusion group than in continuous infusion, except at 1 and 12 hours postoperatively (p<0.05).

Greater analgesic effect was achieved using the intermittent mode than the continuous mode of LPB administration.