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The article explores the spread of ultrasound-guided injectate from the adductor canal to the genicular branch of the posterior obturator nerve and the popliteal plexus. Topics include cadaveric study and the predictive value of genicular nerve blocks for cooled radiofrequency ablation outcomes in chronic knee pain due to osteoarthritis.

The article informs about radicular pain is defined as pain caused by ectopic activation of nociceptive afferent fibers in a spinal nerve, its roots, or neuropathic mechanisms. Topics include piercing in quality, travels along with a narrow band in a neuroanatomically plausible distribution, and can be episodic, recurrent, or paroxysmal; and less invasive treatment option with a more favorable clinical outcome profile for managing radicular symptoms secondary.

Chronic neuropathic pain (NP) is debilitating and impacts sleep health and quality of life. Treatment with gabapentinoids (GBs) has been shown to reduce pain, but its effects on sleep health have not been systematically evaluated. The objective of this systematic review and meta-analysis was to assess the relationship between GB therapy dose and duration on sleep quality, daytime somnolence, and intensity of pain in patients with NP. Subgroup comparisons were planned for high- vs low-dose GBs, where 300 mg per day or more of pregabalin was used to classify high-dose therapy. Trial data were segregated by duration less than 6 weeks and 6 weeks or greater. Twenty randomized controlled trials were included. Primary outcome measures included pain-related sleep interference and incidence of daytime somnolence. Secondary outcomes included daily pain scores (numerical rating scale 0-10) and patient global impression of change. Significant improvement in sleep quality was observed after 6 weeks of GB treatment when compared with placebo (standardized mean difference 0.39, 95% confidence interval 0.32-0.46 P < 0.001). Increased daytime somnolence was observed among all GB-treated groups when compared with placebo. Treated patients were also more likely to report improvement of patient global impression of change scores. Pain scores decreased significantly in patients both after 6 weeks of treatment (P < 0.001) and in trials less than 6 weeks (P = 0.017) when compared with placebo. Our data demonstrate that GBs have a positive impact on sleep health, quality of life, and pain in patients with NP syndromes. However, these benefits come at the expense of daytime somnolence. [ABSTRACT FROM AUTHOR]

Therapeutic interventions for neuropathic pain, such as the N-methyl-D-aspartate (NMDA) antagonist ketamine, can vary widely in effectiveness. In this study, we conducted a longitudinal functional MRI study to test the hypothesis that the pain-relieving effect of ketamine is the result of reversal of abnormalities in regional low-frequency brain oscillations (LFOs) and abnormal cross-network functional connectivity (FC) of the dynamic pain connectome. We found that (1) ketamine decreased regional LFOs in the posterior cingulate cortex of the default mode network, (2) a machine-learning algorithm demonstrated that treatment-induced brain changes could be used to make generalizable inferences about pain relief, (3) treatment responders exhibited a significant decrease in cross-network static FC between the posterior cingulate cortex and regions of the sensorimotor and salience networks following treatment, (4) the degree of reduced cross-network FC correlated with the amount of pain relief, and (5) ketamine treatment did not produce significant differences in static or dynamic FC within the ascending nociceptive or descending antinociceptive pathway. These findings support the proposition that regional LFOs contribute to cross-network connectivity that underlie the effectiveness of ketamine to produce significant relief from neuropathic pain. Together with our recent findings that pretreatment dynamic FC of the descending antinociceptive pathway can predict ketamine treatment outcomes, these new findings indicate that pain relief from ketamine arises from a combination of flexible pretreatment FC of the descending antinocieptive pathway together with plasticity (reduction) of cross-network connectivity of the default mode network with sensorimotor and salience networks. [ABSTRACT FROM AUTHOR]

Imaging techniques frequently employ contrast agents to improve image resolution and enhance pathology detection. These gadolinium- and iodine-based media, although generally considered safe, are associated with a number of adverse effects ranging from mild to severe. Reactions are classified as either anaphylactoid (“anaphylaxis-like”) or nonanaphylactoid, depending on a number of elements that will be reviewed. Herein, we have summarized predisposing risk factors for adverse events resulting from the use of contrast, their associated pathophysiological mechanisms as well as known prophylaxis for the antitreatment of high-risk patients. In the unlikely event that a serious adverse reaction does occur, we have provided a comprehensive summary of treatment protocols. Our goal was to thoroughly evaluate the current literature regarding adverse reactions to radiocontrast agents and provide an up to date review for the health care provider. [ABSTRACT FROM AUTHOR]

Background: Perineural local anaesthetic and steroid injections around ilioinguinal (II), iliohypogastric (IH), and genitofemoral (GF) nerves are often performed to treat chronic refractory neuropathic pain in the lower abdomen and groin, but there is a lack of published data on outcomes of these interventions. Aims: The objective of this retrospective study was to evaluate analgesic outcomes of ultrasound-guided II, IH, and GF nerve blocks in patients with chronic neuropathic pain in the lower abdominal wall and groin. Methods: Analgesic outcomes were assessed at 6 weeks after injections and patients were classified as "responders" if the numerical rating scale for pain score reduced by 30% or more. Variables analyzed for impact on outcomes included demographics, intensity of pain and duration, etiology, dose of opioid, presence of anxiety, depression, and diabetes mellitus. Results: In this cohort of 54 patients with severe baseline pain who had failed to receive analgesic benefit from recommended first- and second-line medications for neuropathic pain, 30 patients had history of surgery and 24 had pain secondary to visceral inflammatory pathologies. Twenty-five (46.3%) patients were identified as responders. A majority of the patients in this cohort had pain for more than one year. There was a higher incidence of diabetes mellitus in nonresponders compared to responders but the difference was not significant (14% and 0%, respectively; P = 0.115). Conclusions: Ultrasound-guided perineural steroids can ameliorate chronic refractory abdominal wall and groin neuropathic pain in patients who have failed to respond to conventional medical management at 6 weeks after the procedures. [ABSTRACT FROM AUTHOR]

Background and Objectives Sacroiliac joint ( SIJ) arthritis is a common cause of chronic mechanical low back pain ( LBP) that is often treated with injection of local anesthetic and steroids. Ultrasound ( US) has emerged as a viable alternative to fluoroscopy ( FL) to guide SIJ injections; however, few studies have compared these modalities. In this prospective randomized, controlled trial, we compared both accuracy and efficacy of US and FL guidance for SIJ injections. Methods Forty patients with chronic moderate-to-severe LBP secondary to SIJ arthritis were randomized to receive US- or FL-guided unilateral SIJ injections. Primary outcomes included pain at 1 month measured by numerical rating scale ( NRS) scores. Secondary outcomes included NRS scores at 24 hours, 72 hours, 1 week, and 3 months after injection, physical functioning at 1 month after the procedure, procedure time, incidence of intra-articular and peri-articular needle placement, patient discomfort, overall patient satisfaction, and daily opioid consumption. Results There was no significant difference in NRS pain scores between the 2 groups at 1 month or at any other follow-up points. A significant reduction from baseline mean NRS scores was observed in both groups at 1 month after injection ( US 22.7%, P = 0.025; FL 37.3%, P < 0.001). There was no significant difference in procedure-related variables, physical functioning, discomfort, opioid utilization, and patient satisfaction between the 2 groups. Conclusions Ultrasound-guided SIJ injection with fluoroscopic confirmation has similar accuracy and efficacy to fluoroscopy alone for SIJ injections in patients with chronic low back pain secondary to SIJ arthritis. [ABSTRACT FROM AUTHOR]

Background: There is a lack of information about the prevalence, manifestations, and management of chronic pain in children in the UK. We surveyed consultants with an interest in chronic pain management and general practitioners (GPs) in the UK in order to understand their perspective on chronic pain in children. Methods: We conducted a postal survey of clinicians with an interest in chronic pain management and GPs in the UK. The survey contained questions relating to the following aspects of managing children with chronic pain: (i) clinicians’ training and experience; (ii) available resources; (iii) perceived prevalence, presentation, and referral patterns; (iv) interventions; and (v) outcomes. Results: 472 pain clinicians and 131 GPs were contacted. The response rates were 55% and 61% respectively. Of the respondents, 77% of pain clinicians and 95% of GPs acknowledged a lack of adequate training for managing children with chronic pain. 57% of the pain clinicians and 63% of the GPs reported that the prevalence of chronic pain in children was <5%. In the comments section, 22% of those respondents who frequently manage children with chronic pain reported an increase in the incidence of this problem over the last 5 years. The common chronic pain syndromes in children were reported to be: musculoskeletal and limb pain, recurrent abdominal and pelvic pain, and headache. 15% of the respondents advised that children with chronic pain would be best managed in specialist pediatric centers and 75% opined that majority of children with chronic pain have a fair to good prognosis. Conclusions: More information is required about prevalence, manifestations and long-term effects of chronic pain in children in the UK. There is a need for increasing training and resources amongst GPs and pain clinicians for managing chronic pain in the pediatric age group. [ABSTRACT FROM AUTHOR]

▪ Abstract: The case report describes use of real-time ultrasound guidance to facilitate percutaneous ablation of cervical nerve roots in a patient with Pancoast's syndrome. Distortion of anatomy by the tumor made it difficult to perform the procedure safely using fluoroscopy. A 64-year-old right-handed male patient with carcinoma of the left lung presented with severe pain in the left shoulder and the arm. A clinical diagnosis of the left brachial plexopathy secondary to tumor involvement of C5 to C8 nerve roots was made. Radiological appearance of the cervical spine revealed distorted anatomy because of severe degeneration of the cervical spine and guarding torticollis. Diagnostic prognostic block of the C4 to C7 exiting nerve roots was done under ultrasound guidance and resulted in more than 75% reduction in pain intensity for 4 hours. Ultrasound-guided percutaneous cervical rhizotomy was performed later. At 3-month follow-up, the patient still had complete pain relief as well as improvement in quality of sleep. Ultrasound-guided cervical nerve roots ablation is a feasible approach for patients with intractable neuropathic pain secondary to Pancoast's tumor. It can be a useful alternative to fluoroscopy in patients in whom a fluoroscopy-guided approach is deemed difficult and hazardous. ▪ [ABSTRACT FROM AUTHOR]

Background: Monitoring the injured brain is an integral part of the management of severely brain injured patients in intensive care. There is increasing interest in methods to monitor global and regional cerebral oxygenation. There have been significant advances in analysing tissue oxygenation and local metabolites in the injured brain over the past decade.Discussion: Cerebral oxygenation can be assessed on a global or regional basis by jugular venous oximetry and near infra-red spectroscopy respectively. Techniques of brain tissue oxygenation monitoring and microdialysis are also covered in this review.Conclusions: Various modalities are available to monitor oxygenation and the local milieu in the injured brain in the intensive care unit. Use of these modalities helps to optimise brain oxygen delivery and metabolism in patients with acute brain injury. [ABSTRACT FROM AUTHOR]

Background: Monitoring the injured brain is an integral part of the management of severely brain injured patients in intensive care. Brain-specific monitoring techniques enable focused assessment of secondary insults to the brain and may help the intensivist in making appropriate interventions guided by the various monitoring techniques, thereby reducing secondary brain damage following acute brain injury.Discussion: This review explores methods of monitoring the injured brain in an intensive care unit, including measurement of intracranial pressure and analysis of its waveform, and techniques of cerebral blood flow assessment, including transcranial Doppler ultrasonography, laser Doppler and thermal diffusion flowmetry.Conclusions: Various modalities are available to monitor the intracranial pressure and assess cerebral blood flow in the injured brain in intensive care unit. Knowledge of advantages and limitations of the different techniques can improve outcome of patients with acute brain injury. [ABSTRACT FROM AUTHOR]

Study objective: To study the role of magnesium sulphate (MgSO4) on analgesic requirement, pain, discomfort, and sleep during perioperative period.Design: prospective, double-blinded, randomized study.Settings: Operating room and recovery ward at a university teaching hospital.Patients: 50 ASA physical status I and II patients scheduled for elective open cholecystectomy with general anesthesia.Interventions: patients were randomly allocated to receive MgSO4 or saline intravenously (IV). Patients in the magnesium group received 50% MgSO4 (50 mg kg-1) in 100 mL saline and those in the control group received an equal volume of saline IV during the preoperative period followed by 50 mL hr-1 infusion of either MgSO4 (15 mg kg-1 hr-1) or saline until the end of surgery.Measurements and main results: Morphine requirement, pain during rest and on coughing, discomfort, and insomnia were assessed during the postoperative period for 24 hours. Intravenous morphine 40 μg kg-1 increments were given to all patients in the postoperative period for analgesia. Patients in the magnesium and control groups had similar morphine requirement during the first 24 hours postoperatively (p = 0.07). Patients in the magnesium group experienced less discomfort during the first hour after the operation. They also had better sleep quality during the first postoperative night than did the control group patients (p < 0.05). The frequency of side effects was similar in the two groups.Conclusion: Administration of intraoperative MgSO4 as an adjuvant analgesic in patients undergoing open cholecystectomy resulted in better pain relief and comfort in the first postoperative hour, but it did not significantly decrease the postoperative morphine requirement. Magnesium sulphate resulted in better sleep quality during the postoperative period, without any significant adverse effects. The role of MgSO4 as an adjuvant analgesic in open cholecystectomy needs to be studied further. [Copyright &y& Elsevier]

Background: An optimal opioid-sparing multimodal analgesic regimen to treat severe pain can enhance recovery after total knee arthroplasty. The hypothesis was that adding five recently described intravenous and regional interventions to multimodal analgesic regimen can further reduce opioid consumption.Methods: In a double-blinded fashion, 78 patients undergoing elective total knee arthroplasty were randomized to either (1) a control group (n = 39) that received spinal anesthesia with intrathecal morphine, periarticular local anesthesia infiltration, intravenous dexamethasone, and a single injection adductor canal block or (2) a study group (n = 39) that received the same set of analgesic treatments plus five additional interventions: local anesthetic infiltration between the popliteal artery and capsule of the posterior knee, intraoperative intravenous dexmedetomidine and ketamine, and postoperatively, one additional intravenous dexamethasone bolus and two additional adductor canal block injections. The primary outcome measure was 24-h cumulative opioid consumption after surgery and secondary outcomes were other analgesics, patient recovery, functional outcomes, and adverse events.Results: Opioid consumption was not different between groups at 24 h (oral morphine equivalents, mean ± SD; study: 23.7 ± 18.0 mg vs. control: 29.3 ± 18.7 mg; mean difference [95% CI], -5.6 mg [-2.7 to 13.9]; P = 0.189) and all other time points after surgery. There were no major differences in pain scores, quality of recovery, or time to reach rehabilitation milestones. Hypotensive episodes occurred more frequently in the study group (25 of 39 [64.1%] vs. 13 of 39 [33.3%]; P = 0.010).Conclusions: In the presence of periarticular local anesthesia infiltration, intrathecal morphine, single-shot adductor canal block and dexamethasone, the addition of five analgesic interventions-local anesthetic infiltration between the popliteal artery and capsule of the posterior knee, intravenous dexmedetomidine, intravenous ketamine, an additional intravenous dexamethasone dose, and repeated adductor canal block injections-failed to further reduce opioid consumption or pain scores or to improve functional outcomes after total knee arthroplasty.Editor’s Perspective: [ABSTRACT FROM AUTHOR]

BackgroundAimsMethodsResultsConclusionsDespite the established efficacy of multidisciplinary chronic pain care, barriers such as inflated referral wait times and uncoordinated care further hinder patient healthcare access.Here we describe the evolution of a Single-Entry Model (SEM) for coordinating access to chronic pain care across 7 hospitals in Toronto and explore the impact on patient care six-years after implementation.In 2017 an innovative SEM was implemented for chronic pain referrals in Toronto and surrounding areas. Referrals are received centrally, triaged by a clinical team, and assigned an appointment according to the level of urgency and the most appropriate care setting/provider. To evaluate the impact of the SEM, a retrospective analysis was undertaken to determine referral patterns, patient characteristics, and referral wait times over the past six-years.Implementation of a SEM streamlined the number of steps in the referral process and led to a standardized referral form with common inclusion and exclusion criteria across sites. Over the six-year period, referrals increased by 93% and the number of unique providers increased by 91%. Chronic pain service wait times were reduced from 299 (± 158) days to 176 (± 103) days. However, certain pain diagnoses such as chronic pelvic pain and fibromyalgia far exceed the average.The results indicate the SEM helped reduce wait times for pain conditions and standardized the referral pathway. Continued data capture efforts can help identify gaps in care to enable further healthcare refinement and improvement. [ABSTRACT FROM AUTHOR]

Background: Cervical facet joint disease is a common source of neck pain and its prevalence increases with aging. Conservative multimodal management options (e.g., strengthening of neck muscles, non-steroidal anti-inflammatory medications, massage, and thermal modalities) often fail to relieve pain. Cervical medial branch nerve (CMBN) radiofrequency neurotomy (RFN) is an effective minimally invasive technique for treating chronic neck pain secondary to facet joint disease. An end-on approach for this procedure has been proposed that may be technically easier and require less time while reducing post-procedural discomfort. The protocol presented here is for a study that aims to compare the efficacy of a new end-on approach using multi-tined cannulae, against the conventional parallel technique that employs straight cannulae for RFN of the CMBN in patients with chronic neck pain due to cervical facet joint disease. Methods: A multicentre randomized, non-inferior, active comparator-controlled trial will be conducted with two parallel groups and blinding of participants and outcome assessor. The study will include 72 adults with chronic neck pain secondary to facet joint disease who are candidates for RFA of the CMBN. Participants will be randomized to either the conventional parallel or the end-on approach in a 1:1 ratio. The intensity of pain and pain-related domains (function, quality of life, sleep, adverse effects of the interventions, analgesic intake) will be measured at 1, 3, 6, and 12 months after the procedure. Discussion: Neck pain secondary to cervical facet joint disease is prevalent and RFA of the CMBN is a validated treatment for relieving it. The conventional parallel technique can be technically challenging, and it can be associated with adverse effects while the newer end-on approach has the potential of being a simpler technique with less adverse effects. This trial will be the first non-inferiority study to compare the clinical efficacy of the end-on approach against the conventional parallel approach for RFN of CMBN in patients with chronic neck pain due to cervical facet joint disease. Trial registration: ClinicalTrials.gov NCT05818774. Registered on April 20, 2023. [ABSTRACT FROM AUTHOR]

Objective To evaluate the effectiveness and safety of radiofrequency (RF) ablation and neuromodulation modalities for knee osteoarthritis (OA). Methods The Pubmed, Medline, Embase, and Cochrane Library databases were searched from inception to August 2018. All comparative and noncomparative studies that reported clinical outcome measures and adverse events related to RF modalities for knee OA were included. Pain scores, physical function measures, quality of life (QOL), patient satisfaction, and adverse events for three months and beyond of postprocedure follow-up were analyzed qualitatively. Results Thirty-three studies, including 13 randomized controlled trials (RCTs), two nonrandomized comparative studies, and 18 noncomparative cohort studies, were identified, with 1,512 patients (mean age = 64.3 years, 32.5% males). All 33 studies were considered to be of moderate or high methodological quality. All 33/33 (100%) studies reported alleviation of OA-related knee pain from baseline until three to 12 months with RF modalities, with six comparative studies reporting 194/296 (65.5%) and 29/150 (19.3%) RF and control patients achieving >50% pain relief, respectively. Three of the 33 studies reported QOL, with three of three studies (100%) achieving improvements in disease-specific QOL from baseline until three to 12 months. Twenty-eight of the 33 studies reported functional outcomes, with 27/28 (96%) studies obtaining enhanced functionality from baseline up until three to 12 months. Ten of the 33 studies reported patient satisfaction, with eight of 10 studies (80%) indicating that patients were significantly satisfied after RF procedures, and from these eight studies, four were comparative studies that indicated that 86/154 (56%) and 33/104 (32%) RF and control patients were extremely satisfied or satisfied, respectively. Regarding adverse events (AEs), 29 of the 33 studies reported AEs, with 20/29 (69%) studies indicating no AEs related to the RF modalities and the remaining nine studies only indicating minor localized AEs. Twenty-nine of the 33 studies indicated no serious knee-related AEs pertaining to RF modalities. Conclusions Current evidence substantiates that RF modalities for knee OA potentially improve pain, functionality, and disease-specific QOL for up to three to 12 months with minimal localized complications. This suggests that RF modalities are perhaps an effective adjunct therapy for patients with knee OA who are unresponsive to conservative therapies. Further RCTs with larger sample sizes and long-term follow-up that directly compare the three primary RF modalities are warranted to confirm the clinical efficaciousness and superiority of these RF modalities for knee OA. [ABSTRACT FROM AUTHOR]

Two letters to the editor is presented, one in response to the article "Clinical identifiers for detecting underlying closed cervical fractures" by C. E. Cook in the 2014 issue and other its response from the author.

A letter is presented in response to the article "The Noninferiority of the Nonparticulate Steroid Dexamethasone VS The Particulate Steroids Betamethasone and Triamcinolone in Lumbar Transforaminal Epidural Steroid Injections" by C. El-Yahchouchi, et al, published in a 2013 issue of "Pain Medicine."

Background: Paresthesia-based spinal cord stimulation (PB-SCS) is used for the treatment of complex regional pain syndrome (CRPS), but many patients are refractory to PB-SCS or experience attenuation of analgesic effect over time due to tolerance. Novel SCS modes including high-frequency, BurstTM, and high-density (HDTM) stimulation were introduced recently and this systematic review was conducted to summarize the evidence on their role for CRPS. Materials and Methods: We searched MEDLINE and other databases (up to September 21, 2017) for studies including adults with refractory CRPS treated by paresthesia-free SCS (PF-SCS) modes compared to placebo, conventional medical treatment, or PB-SCS. We determined the posttreatment intensity of pain (up to 24 months after intervention), changes in CRPS-associated symptoms, and associated domains. Sustainability and adverse effects were also assessed. Results: We identified 13 studies (seven case series, five conference abstracts, one randomized controlled trial) including 62 patients with upper or lower limb CRPS. Eleven papers reported on outcomes of high-frequency stimulation at 10 kHz (HF-10) and other high frequencies, two papers were on Burst, and one paper was on HD. In 59 patients, pain intensity with novel SCS modes was reduced by 30% to 100% with a corresponding reduction in analgesic medications. Novel SCS modes also attenuated CRPS-associated symptoms and six papers reported significant improvement of quality of life. Conclusions: Novel SCS modes have the potential to provide analgesia in patients with CRPS. However, the low quality of available evidence necessitates definitive and prospective comparative effectiveness studies to establish the role of these modes in CRPS. [ABSTRACT FROM AUTHOR]

A letter to the editor is presented in response to the article "Ultrasound-guided pararadicular injection in the lumbar spine: a comparative study of the paramedian sagittal and paramedian sagittal oblique approaches" by Y.H. Kim and others, in a 2015 issue.

A letter to the editor is presented in response to a paper by K. Van Boxem et al on the results of pulsed radiofrequency (PRF) for chronic intractable pain.

Background: Low back pain (LBP) is commonly experienced during pregnancy and is often poorly managed. There is much ambiguity in diagnostic work-up, appropriate management and decision-making regarding the use of neuraxial analgesia and anaesthesia during labour and delivery in these patients. This systematic review summarises the evidence regarding investigations, management strategies and considerations around performing neuraxial blocks for pregnant women with LBP.Methods: We searched 3 databases and reviewed literature concerning LBP in pregnancy with regards to diagnostic modalities, management strategies and use of neuraxial techniques for facilitating labour and delivery.Results: In all, we included 78 studies in this review, with 32 studies concerning diagnostic investigations, 56 studies involving management strategies, and 4 studies regarding the use of neuraxial techniques for labour and delivery.Summary: MRI is the safest investigative modality for LBP in pregnancy. Antenatal educational programmes, exercise and steroid injections into the epidural space or sacroiliac joints may help with pain management. Worsening neurological deficits, vertebral fractures and tumours may need surgical management. There is limited evidence on challenges of performing neuraxial blocks in the peripartum period for analgesia and anaesthesia, but there is a potential for increased risk of neurological complications in parturients with pre-existing neurological deficits. [ABSTRACT FROM AUTHOR]

Background: Chronic daily headaches (CDH) are common and associated with significant morbidity, poor quality of life, and substantial burden on the healthcare system. CDH tends to be refractory to conventional medical management and/or patients cannot afford expensive treatments. It is stipulated that CDH share a mechanism of central sensitization in the trigeminocervical complex, mediated by activation of the N-methyl-d-aspartate (NMDA) receptors. Ketamine, a non-competitive NMDA antagonist, has been used in the treatment of chronic pain, but its role in CDH has not been completely established. This trial aims to evaluate the effect of high-dose IV ketamine infusions (compared to placebo) on the number of headache days at 28 days post-infusion. Methods: A multicenter, placebo-controlled, randomized controlled trial will be conducted with two parallel groups and blinding of participants and outcome assessors. The study will include 56 adults with a CDH diagnosis as per ICHD-3 criteria. Participants will be randomized (1:1) to either ketamine (1 mg. kg−1 bolus followed by infusion of 1 mg. kg−1. h−1 for 6 h) or placebo (0.9% saline in the same volume and infusion rate as the trial medication) bolus and infusion for 6 h. The impact on the number of monthly headache days, headache intensity, physical activity, mood, sleep, quality of life, analgesic consumption, and adverse effects will be recorded at baseline, immediately post-infusion, and from 1 to 28 days, 29 to 56 days, and 57 to 84 days after the infusion Discussion: Despite advancements in treatment, many patients continue to suffer from CDH. This trial investigates whether high-dose IV ketamine infusions can effectively and safely improve the CDH burden as compared to a placebo infusion. This treatment could become a safe, affordable, and widely available option for patients living with refractory headache. Trial registration: ClinicalTrials.gov NCT05306899. Registered on April 1, 2022 [ABSTRACT FROM AUTHOR]

Neuronal populations in the brain are engaged in a temporally coordinated manner at rest. Here we show that spontaneous transitions between large-scale resting-state networks are altered in chronic neuropathic pain. We applied an approach based on the Hidden Markov Model to magnetoencephalography data to describe how the brain moves from one activity state to another. This identified 12 fast transient (~80 ms) brain states including the sensorimotor, ascending nociceptive pathway, salience, visual, and default mode networks. Compared to healthy controls, we found that people with neuropathic pain exhibited abnormal alpha power in the right ascending nociceptive pathway state, but higher power and coherence in the sensorimotor network state in the beta band, and shorter time intervals between visits of the sensorimotor network, indicating more active time in this state. Conversely, the neuropathic pain group showed lower coherence and spent less time in the frontal attentional state. Therefore, this study reveals a temporal imbalance and dysregulation of spectral frequency-specific brain microstates in patients with neuropathic pain. These findings can potentially impact the development of a mechanism-based therapeutic approach by identifying brain targets to stimulate using neuromodulation to modify abnormal activity and to restore effective neuronal synchrony between brain states. A comparative analysis on resting-state magnetoencephalography data from healthy controls and patients with chronic pain reveals spectral frequency-specific dysregulation and a temporal imbalance of brain microstates in chronic neuropathic pain. [ABSTRACT FROM AUTHOR]

Synthetic cannabinoids are compounds made in the laboratory to structurally and functionally mimic phytocannabinoids from the Cannabis sativa L. plant, including delta-9-tetrahydrocannabinol (THC). Synthetic cannabinoids (SCs) can signal via the classical endogenous cannabinoid system (ECS) and the greater endocannabidiome network, highlighting their signalling complexity and far-reaching effects. Dronabinol and nabilone, which mimic THC signalling, have been approved by the Food and Drug Administration (FDA) for treating nausea associated with cancer chemotherapy and/or acquired immunodeficiency syndrome (AIDS). However, there is ongoing interest in these two drugs as potential analgesics for a variety of other clinical conditions, including neuropathic pain, spasticity-related pain, and nociplastic pain syndromes including fibromyalgia, osteoarthritis, and postoperative pain, among others. In this review, we highlight the signalling mechanisms of FDA-approved synthetic cannabinoids, discuss key clinical trials that investigate their analgesic potential, and illustrate challenges faced when bringing synthetic cannabinoids to the clinic. [ABSTRACT FROM AUTHOR]

Abstract: Alpha oscillatory activity (8-13 Hz) is the dominant rhythm in the awake brain and is known to play an important role in pain states. Previous studies have identified alpha band slowing and increased power in the dynamic pain connectome (DPC) of people with chronic neuropathic pain. However, a link between alpha-band abnormalities and sex differences in brain organization in healthy individuals and those with chronic pain is not known. Here, we used resting-state magnetoencephalography to test the hypothesis that peak alpha frequency (PAF) abnormalities are general features across chronic central and peripheral conditions causing neuropathic pain but exhibit sex-specific differences in networks of the DPC (ascending nociceptive pathway [ANP], default mode network, salience network [SN], and subgenual anterior cingulate cortex). We found that neuropathic pain (N = 25 men and 25 women) was associated with increased PAF power in the DPC compared with 50 age- and sex-matched healthy controls, whereas slower PAF in nodes of the SN (temporoparietal junction) and the ANP (posterior insula) was associated with higher trait pain intensity. In the neuropathic pain group, women exhibited lower PAF power in the subgenual anterior cingulate cortex and faster PAF in the ANP and SN than men. The within-sex analyses indicated that women had neuropathic pain-related increased PAF power in the ANP, SN, and default mode network, whereas men with neuropathic pain had increased PAF power restricted to the ANP. These findings highlight neuropathic pain-related and sex-specific abnormalities in alpha oscillations across the DPC that could underlie aberrant neuronal communication in nociceptive processing and modulation. [ABSTRACT FROM AUTHOR]

Background Recent studies have suggested that neuropathic pain exhibits a daily diurnal pattern, with peak levels usually occurring in the late afternoon to evening and the trough in the morning hours, although literature on this topic has been sparse. This scoping review examines current evidence on the chronobiology of neuropathic pain both in animal models and in humans with neuropathic pain. Methods A literature search was conducted in major medical databases for relevant articles on the chronobiology of neuropathic pain both in animal models and in humans with neuropathic pain. Data extracted included details of specific animal models or specific neuropathic pain conditions in humans, methods and timing of assessing pain severity, and specific findings of diurnal variation in pain intensity or its surrogate markers. Results Thirteen animal and eight human studies published between 1976 and 2020 were included in the analysis. Seven of the 13 animal studies reported specific diurnal variation in pain intensity, with five of the seven studies reporting a trend toward increased sensitivity to mechanical allodynia or thermal hyperalgesia in the late light to dark phase. All eight studies in human subjects reported a diurnal variation in the intensity of neuropathic pain, where there was an increase in pain intensity through the day with peaks in the late evening and early night hours. Conclusions Studies included in this review demonstrated a diurnal variation in the pattern of neuropathic pain that is distinct from the pattern for nociceptive pain. These findings have implications for potential therapeutic strategies for neuropathic pain. [ABSTRACT FROM AUTHOR]

BackgroundMethodsResultsConclusionChronic pain is a complex disease that requires interprofessional care for effective management. Despite the need for multidisciplinary care, disease and healthcare inequities can prevent individuals from attaining adequate treatment. Factors such as mental health, cost, and distance to a healthcare center can contribute to healthcare accessibility inequality. The aim of this study is to examine declined referrals at the Toronto Academic Pain Medicine Institute (TAPMI) to determine the reason for declining care and number of declined referrals.A retrospective chart review of all declined referrals at TAPMI in 2018 and 2022 was conducted. Referral documentation and the intake decision was extracted from the electronic medical charts by the research team and verified by the clinical intake team. Chi-square tests were conducted to determine if the proportion of declined referrals changed between the years reviewed.The number of declined referrals due to mental health complexities increased significantly from 51 (11%) in 2018 to 180 (18%) in 2022 (χ2 = 10.9, P = .0009). A significant rise in the number of declines due to mental health service requests was also observed (ꭓ2 = 24.53, P < .00001). Other common reasons for declined referrals in 2018 and 2022 included duplicate service, no primary care provider, and healthcare service changes.: Mental health complexities continue to be a significant barrier to healthcare service acquisition for individuals living with chronic pain. The increase in patient complexity from 2018 to 2022 highlights the need for integrated healthcare resources. [ABSTRACT FROM AUTHOR]

Spasticity is a form of muscle hypertonia secondary to various diseases, including traumatic brain injury, spinal cord injury, cerebral palsy, and multiple sclerosis. Medical treatments are available; however, these often result in insufficient clinical response. This review evaluates the role of epidural spinal cord stimulation (SCS) in the treatment of spasticity and associated functional outcomes. A systematic review of the literature was performed using the Embase, CENTRAL, and MEDLINE databases. We included studies that used epidural SCS to treat spasticity. Studies investigating functional electric stimulation, transcutaneous SCS, and animal models of spasticity were excluded. We also excluded studies that used SCS to treat other symptoms such as pain. Thirty-four studies were included in the final analysis. The pooled rate of subjective improvement in spasticity was 78% (95% confidence interval, 64%–91%; I 2 = 77%), 40% (95% confidence interval, 7%–73%; I 2 = 88%) for increased H-reflex threshold or decreased Hoffman reflex/muscle response wave ratio, and 73% (65%–80%; I 2 = 50%) for improved ambulation. Patients with spinal causes had better outcomes compared with patients with cerebral causes. Up to 10% of patients experienced complications including infections and hardware malfunction. Our review of the literature suggests that SCS may be a safe and useful tool for the management of spasticity; however, there is significant heterogeneity among studies. The quality of studies is also low. Further studies are needed to fully evaluate the usefulness of this technology, including various stimulation paradigms across different causes of spasticity. [ABSTRACT FROM AUTHOR]

Background The past two decades have witnessed a surge in the use of cervical spine joint procedures including joint injections, nerve blocks and radiofrequency ablation to treat chronic neck pain, yet many aspects of the procedures remain controversial. Methods In August 2020, the American Society of Regional Anesthesia and Pain Medicine and the American Academy of Pain Medicine approved and charged the Cervical Joint Working Group to develop neck pain guidelines. Eighteen stakeholder societies were identified, and formal request-for-participation and member nomination letters were sent to those organizations. Participating entities selected panel members and an ad hoc steering committee selected preliminary questions, which were then revised by the full committee. Each question was assigned to a module composed of 4–5 members, who worked with the Subcommittee Lead and the Committee Chairs on preliminary versions, which were sent to the full committee after revisions. 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 Chairs, who incorporated the comments and sent out revised versions until consensus was reached. Before commencing, it was agreed that a recommendation would be noted with >50% agreement among committee members, but a consensus recommendation would require ≥75% agreement. Results Twenty questions were selected, with 100% consensus achieved in committee on 17 topics. Among participating organizations, 14 of 15 that voted approved or supported the guidelines en bloc, with 14 questions being approved with no dissensions or abstentions. Specific questions addressed included the value of clinical presentation and imaging in selecting patients for procedures, whether conservative treatment should be used before injections, whether imaging is necessary for blocks, diagnostic and prognostic value of medial branch blocks and intra-articular joint injections, the effects of sedation and injectate volume on validity, whether facet blocks have therapeutic value, what the ideal cut-off value is for designating a block as positive, how many blocks should be performed before radiofrequency ablation, the orientation of electrodes, whether larger lesions translate into higher success rates, whether stimulation should be used before radiofrequency ablation, how best to mitigate complication risks, if different standards should be applied to clinical practice and trials, and the indications for repeating radiofrequency ablation. Conclusions Cervical medial branch radiofrequency ablation may provide benefit to well-selected individuals, with medial branch blocks being more predictive than intra-articular injections. More stringent selection criteria are likely to improve denervation outcomes, but at the expense of false-negatives (ie, lower overall success rate). Clinical trials should be tailored based on objectives, and selection criteria for some may be more stringent than what is ideal in clinical practice. [ABSTRACT FROM AUTHOR]

The article presents comments on a perioperative approach to the opioid crisis in Canada in 2018. It blames overprescribing for the increasing risk of adverse effects, dependence and opioid use disorders. The challenge of providing balanced analgesia after surgery facing clinicians is discussed. Possible solutions for addressing the opioid crisis are provided, including the use of predictive tools to individualize opioid prescriptions and improved community follow-ups.

Background: Intrathecal morphine is commonly and effectively used for analgesia after joint arthroplasty, but has been associated with delayed respiratory depression. Patients with obstructive sleep apnea may be at higher risk of postoperative pulmonary complications. However, data is limited regarding the safety of intrathecal morphine in this population undergoing arthroplasty.Methods: This retrospective cohort study aimed to determine the safety of intrathecal morphine in 1,326 patients with documented or suspected obstructive sleep apnea undergoing hip or knee arthroplasty. Chart review was performed to determine clinical characteristics, perioperative events, and postoperative outcomes. All patients received neuraxial anesthesia with low-dose (100 μg) intrathecal morphine (exposure) or without opioids (control). The primary outcome was any postoperative pulmonary complication including: (1) respiratory depression requiring naloxone; (2) pneumonia; (3) acute respiratory event requiring consultation with the critical care response team; (4) respiratory failure requiring intubation/mechanical ventilation; (5) unplanned admission to the intensive care unit for respiratory support; and (6) death from a respiratory cause. The authors hypothesized that intrathecal morphine would be associated with increased postoperative complications.Results: In 1,326 patients, 1,042 (78.6%) received intrathecal morphine. The mean age of patients was 65 ± 9 yr and body mass index was 34.7 ± 7.0 kg/m. Of 1,326 patients, 622 (46.9%) had suspected obstructive sleep apnea (Snoring, Tired, Observed, Pressure, Body Mass Index, Age, Neck size, Gender [STOP-Bang] score greater than 3), while 704 of 1,326 (53.1%) had documented polysomnographic diagnosis. Postoperatively, 20 of 1,322 (1.5%) patients experienced pulmonary complications, including 14 of 1,039 (1.3%) in the exposed and 6 of 283 (2.1%) in the control group (P = 0.345). Overall, there were 6 of 1 322 (0.5%) cases of respiratory depression, 18 of 1,322 (1.4%) respiratory events requiring critical care team consultation, and 4 of 1,322 (0.3%) unplanned intensive care unit admissions; these rates were similar between both groups. After adjustment for confounding, intrathecal morphine was not significantly associated with postoperative pulmonary complication (adjusted odds ratio, 0.60 [95% CI, 0.24 to 1.67]; P = 0.308).Conclusions: Low-dose intrathecal morphine, in conjunction with multimodal analgesia, was not reliably associated with postoperative pulmonary complications in patients with obstructive sleep apnea undergoing joint arthroplasty. [ABSTRACT FROM AUTHOR]

Background: Iliac crest bone graft (ICBG) harvesting is associated with significant perioperative pain and opioid consumption. This randomized controlled trial sought to determine if the transversalis fascia plane (TFP) block provides effective analgesia for anterior ICBG harvesting. Methods: Fifty patients undergoing wrist fusion surgery with anterior ICBG harvesting were randomized to receive a TFP block with either 20 ml of 0.5% ropivacaine or 5% dextrose. Patients additionally received a brachial plexus block for primary surgical-site anesthesia and either a general or spinal anesthetic depending on patient preference. Primary outcomes of interest were perioperative opioid consumption (measured as intravenous morphine equivalents [IME]), pain intensity at the ICBG harvest site for up to 48 h postoperatively, and the incidence of persistent postoperative pain at 6 and 12 months after surgery. Results: The TFP group used less opioid in the post-anesthetic care unit (PACU) (median 0 vs. 2.5 mg IME, P = 0.01) and in the first 8 h following PACU discharge (median 2.5 vs. 13.0 mg IME, P = 0.02). The patients who received a TFP block also had lower pain scores in PACU (median 0 vs. 4.0 out of 10, P < 0.001). Although opioid consumption and pain scores were lower in the TFP group at later timepoints, this difference was not statistically significant. Persistent pain at the ICBG site was reported in only 4.3% and 6.5% of all patients at 6 and 12 months, respectively. Conclusions: The TFP block provides effective early analgesia for anterior ICBG harvesting. The incidence of persistent postoperative pain was low. [ABSTRACT FROM AUTHOR]

What We Already Know About This Topic: WHAT THIS ARTICLE TELLS US THAT IS NEW: BACKGROUND:: Ketamine is an N-methyl-D-aspartate receptor antagonist that reduces temporal summation of pain and modulates antinociception. Ketamine infusions can produce significant relief of neuropathic pain, but the treatment is resource intensive and can be associated with adverse effects. Thus, it is crucial to select patients who might benefit from this treatment. The authors tested the hypothesis that patients with enhanced temporal summation of pain and the capacity to modulate pain via the descending antinociceptive brain pathway are predisposed to obtain pain relief from ketamine.Methods: Patients with refractory neuropathic pain (n = 30) and healthy controls underwent quantitative sensory testing and resting-state functional magnetic resonance imaging and then completed validated questionnaires. Patients then received outpatient intravenous ketamine (0.5 to 2 mg · kg · h; mean dose 1.1 mg · kg · h) for 6 h/day for 5 consecutive days. Pain was assessed 1 month later. Treatment response was defined as greater than or equal to 30% pain relief (i.e., reduction in pain scores). We determined the relationship between our primary outcome measure of pain relief with pretreatment temporal summation of pain and with brain imaging measures of dynamic functional connectivity between the default mode network and the descending antinociceptive brain pathway.Results: Approximately 50% of patients achieved pain relief (mean ± SD; Responders, 61 ± 35%; Nonresponders, 7 ± 14%). Pretreatment temporal summation was associated with the effect of ketamine (ρ = -0.52, P = 0.003) and was significantly higher in Responders (median [25th, 75th] = 200 [100, 345]) compared with Nonresponders (44 [9, 92]; P = 0.001). Pretreatment dynamic connectivity was also associated with the clinical effect of ketamine (ρ = 0.51, P = 0.004) and was significantly higher in Responders (mean ± SD, 0.55 ± 0.05) compared with Nonresponders (0.51 ± 0.03; P = 0.006). Finally, the dynamic engagement of the descending antinociceptive system significantly mediated the relationship between pretreatment pain facilitation and pain relief (95% CI, 0.005 to 0.065).Conclusions: These findings suggest that brain and behavioral measures have the potential to prognosticate and develop ketamine-based personalized pain therapy. [ABSTRACT FROM AUTHOR]

Abstract Introduction/Aim Methods Results Discussion/Conclusions Primary care providers (PCPs), who provide the bulk of care for patients with chronic noncancer pain (CNCP), often report knowledge gaps, limited resources, and difficult patient encounters while managing chronic pain. This scoping review seeks to evaluate gaps identified by PCPs in providing care to patients with chronic pain.The Arksey and O’Malley framework was used for this scoping review. A broad literature search was conducted for relevant articles on gaps in knowledge and skills of PCPs and in their healthcare environment for managing chronic pain, with multiple search term derivatives for concepts of interest. Articles from the initial search were screened for relevance, yielding 31 studies. Inductive and deductive thematic analysis was adopted.The studies included in this review reflected a variety of study designs, settings, and methods. However, consistent themes emerged with respect to gaps in knowledge and skills for assessment, diagnosis, treatment, and interprofessional roles in chronic pain, as well as broader systemic issues including attitudes toward CNCP. A general lack of confidence in tapering high dose or ineffective opioid regimes, professional isolation, challenges in managing patients with CNCP with complex needs, and limited access to pain specialists were reported by PCPs.This scoping review revealed common elements across the selected studies that will be useful in guiding creation of targeted supports for PCPs to manage CNCP. This review also yielded insights for pain clinicians at tertiary centres for supporting their PCP colleagues as well as systemic reforms required to support patients with CNCP. [ABSTRACT FROM AUTHOR]