Dorsal Column Stimulation and Cannabinoids in the Treatment of Chronic Nociceptive and Neuropathic Pain: a Review of the Clinical and Pre-clinical Data.

PURPOSE OF REVIEW: The main objective of this review is to appraise the literature on the role of spinal cord stimulation (SCS), cannabinoid therapy, as well as SCS and cannabinoid combination therapy for the management of chronic neuropathic and nociceptive pain. Current research suggests that SCS reduces pain and increases functional status in carefully selected patients with minimal side effects. RECENT FINDINGS: As cannabinoid-based medications become a topic of increasing interest in pain management, data remains limited regarding the clinical efficacy of cannabinoids for pain relief. Furthermore, from a mechanistic perspective, although various pain treatment modalities utilize overlapping pain-signaling pathways, clarifying whether cannabinoids work synergistically with SCS via shared mechanisms remains to be determined. In considering secondary outcomes, the current literature suggests cannabinoids improve quality of life, specifically sleep quality, and that SCS decreases opioid consumption, increases functional capacity, and decreases long-term healthcare costs. These findings, along with the high safety profiles of SCS and cannabinoids overall, incentivize further exploration of cannabinoids as an adjunctive therapy to SCS in the treatment of neuropathic and nociceptive pain.

Interventional Therapies for Pain in Cancer Patients: a Narrative Review.

PURPOSE OF REVIEW: Pain is a prevalent symptom in the lives of patients with cancer. In light of the ongoing opioid epidemic and increasing awareness of the potential for opioid abuse and addiction, clinicians are progressively turning to interventional therapies. This article reviews the interventional techniques available to mitigate the debilitating effects that untreated or poorly treated pain have in this population. RECENT FINDINGS: A range of interventional therapies and technical approaches are available for the treatment of cancer-related pain. Many of the techniques described may offer effective analgesia with less systemic toxicity and dependency than first- and second-line oral and parenteral agents. Neuromodulatory techniques including dorsal root ganglion stimulation and peripheral nerve stimulation are increasingly finding roles in the management of oncologic pain. The goal of this pragmatic narrative review is to discuss interventional approaches to cancer-related pain and the potential of such therapies to improve the quality of life of cancer patients.

Recent Advances in the Treatment of Opioid Use Disorder.

PURPOSE OF REVIEW: Opioid use disorder (OUD) remains a national epidemic with an immense consequence to the United States' healthcare system. Current therapeutic options are limited by adverse effects and limited efficacy. RECENT FINDINGS: Recent advances in therapeutic options for OUD have shown promise in the fight against this ongoing health crisis. Modifications to approved medication-assisted treatment (MAT) include office-based methadone maintenance, implantable and monthly injectable buprenorphine, and an extended-release injectable naltrexone. Therapies under investigation include various strategies such as heroin vaccines, gene-targeted therapy, and biased agonism at the G protein-coupled receptor (GPCR), but several pharmacologic, clinical, and practical barriers limit these treatments' market viability. This manuscript provides a comprehensive review of the current literature regarding recent innovations in OUD treatment.

Diversity of Pain Medicine Trainees and Faculty in the United States: A Cross-Sectional Analysis of Fellowship Training from 2009-2019.

OBJECTIVE: Diversity and equity in medicine remain pivotal to care delivery. Data analysis on sex and racial diversity of pain medicine fellowship trainees and faculty in the United States are scant. We sought to characterize demographic and retention patterns among pain medicine fellows and faculty, who represent the emerging chronic pain management workforce. DESIGN: cross-sectional retrospective analysis. METHOD: We conducted an analysis of data from the American Association of Medical Colleges (AAMC) and the United States Accreditation Council on Graduate Medical Education (ACGME)-approved residency and fellowship training-programs for each year from 2009 through 2019, inclusively. We compared changes in sex, racial/ethnicity composition and retention rates of fellows and faculty in the United States by practice setting. RESULTS: From 2009 to 2019, there was a 14% increase in the number of ACGME pain fellowship programs. From 2009 to 2019, the ratio of men to women pain fellows ranged from 5:1 to 3.7:1. Compared with their self-identified White peers, Asian (OR 0.44; 95% CI: 0.34-0.58), Black (OR 0.46; 95% CI: 0.30-0.72), and Native American/Alaskan Native (OR 0.26; 95% CI: 0.08-0.80) identifying individuals had significantly lower odds of being a pain fellow, P < 0.05. There was no significant difference in female (OR = 0.4, 95% CI: 0.148-1.09) and Black (OR 0.36; 95% CI: 0.11-1.12) program-directors. Pain-fellow in-state retention was 53%. CONCLUSIONS: The demographics of pain medicine training programs reflect a persistent male vs. female gap with underrepresentation of racial minorities. Further research is needed to elucidate reasons underlying these disparities.

Intravenous Lidocaine Infusion for the Management of Early Postoperative Pain: A Comprehensive Review of Controlled Trials.

Previously used as anti-arrhythmic, intravenous lidocaine infusion is becoming popular for use in management of acute pain. There is still much to be understood about its pharmacokinetics and pharmacodynamics, especially with regard to optimal dosing to avoid side effects. In this article, we selected and reviewed randomized controlled trials to summarize the pharmacokinetics, antinociceptive effects, anti-hyperalgesic effects, anti-inflammatory effects, side effects, and role of intravenous lidocaine in the management of early postoperative pain. The mechanisms of action of lidocaine are still unclear but there are many theories postulated. Optimal dosing of lidocaine is not known but general consensus indicates that a loading dose of 1-2 mg/kg, followed by 1-2 mg/kg/hr continuous infusion during early postoperative pain control while recovering from anesthesia to achieve therapeutic levels of 0.5-5 mcg/kg clearly improves analgesia in the immediate postoperative period. Although lidocaine was initially studied and proven to have clear analgesic effects following laparoscopic and open abdominal surgeries, it has now been shown to be applicable in different clinical settings perioperatively including following spinal, breast, ENT and other surgeries. It is generally safe, with hypotension, headache and vomiting being the more common side effects. Serious adverse effects include cardiovascular block and arrhythmias, neuro-excitability and hypersensitivity, although the frequency of these are not known.

Lumbosacral Radiculopathy: Inciting Events and Their Association with Epidural Steroid Injection Outcomes.

OBJECTIVE: Low back pain is the leading cause of worldwide disability, with lumbosacral radiculopathy accounting for over one-third of these cases. There are limited data on the relationship between etiologies and lumbosacral radiculopathy, and it is unknown whether specific causes predict treatment outcomes. DESIGN, SETTING, AND SUBJECTS: This study explores patient-reported etiologies for lumbosacral radiculopathy in a chronic pain clinic between January 2007 and December 2015 and examines whether these causes affected epidural steroid injection outcomes. METHODS: We reviewed the medical records of 1,242 patients with lumbosacral radiculopathy who received epidural steroid injections. The recording of an inciting event was done contemporaneously based on note templates. A positive outcome following an epidural steroid injection was defined as ≥30% pain relief sustained for six or more weeks without additional intervention. Factors associated with epidural steroid injection outcome were analyzed by multivariable logistic regression. RESULTS: Fifty point seven percent reported an inciting event, and 59.9% of patients experienced a positive epidural steroid injection outcome. The most commonly reported causes were falls (13.1%), motor vehicle collisions (10.7%), and lifting (7.8%). Individuals with a herniated disc (56.3%) were more likely to report a precipitating cause than those with stenosis (44.7%) or degenerative discs (47.8%, P = 0.012). An inciting event did not predict treatment outcome. Factors associated with negative treatment outcome included opioid consumption (odds ratio [OR] = 0.61, 95% confidence interval [CI] = 0.39-0.95, P = 0.027), secondary gain (OR = 0.69, 95% CI = 0.50-0.96, P = 0.030), and baseline pain score (OR = 0.90, 95% CI = 0.84-0.97, P = 0.006). The number of levels injected was associated with a positive outcome (OR = 2.72, 95% CI = 1.28-6.47, P = 0.008). CONCLUSIONS: Reported inciting events are common in patients with lumbosacral radiculopathy but are not associated with outcome following epidural steroid injection, and their occurrence is not always consistent with the purported mechanism of injury.

Trends of Opioid Use Disorder Among Hospitalized Patients With Chronic Pain.

BACKGROUND: Patients with chronic pain treated with opioids are at an increased risk for opioid misuse or opioid use disorder (OUD). Recent years have seen a stark increase in abuse, misuse, and diversion of prescription opioid medications. The aim of this study was to investigate trends in changing rates of opioid use disorder among patients with chronic pain. METHODS: The National Inpatient Sample (NIS) database identified chronic pain admissions with OUD from 2011 to 2015. Patients were identified from the NIS database using International Classification of Diseases (9th and 10th revisions) diagnosis codes for chronic pain and OUD. Annual estimates and trends were determined for OUD, patient characteristics, OUD among subgroups of chronic pain conditions, and discharge diagnosis. RESULTS: We identified 10.3 million patients with chronic pain. Of these, 680,631 patients were diagnosed with OUD. The number of patients with OUD increased from 109,222 in 2011 to 172,680 in 2015 (P < 0.001). Similarly, there were upward trends of OUD among females (53.2% to 54.5%; P = 0.09), patients 65 to 84 years of age (11.8% to 17%; P < 0.001), Medicare-insured patients (39.5% to 46.0%; P < 0.01), patients with low annual household incomes (27.8% to 33.3%; P < 0.001), and patients with cannabinoid use disorder (7.2% to 8.3%; P = 0.01). The prevalence of OUD increased from 2011 to 2015 in patients with chronic regional pain syndrome (5.53% to 7.46%; P = 0.01) and spondylosis (1.32% to 1.81%; P < 0.001). CONCLUSIONS: These findings suggest that the prevalence of OUD increased substantially from 2011 to 2015. Disparities of OUD with increasing opioid use among vulnerable populations including women, those with Medicare insurance, tobacco use disorder, and low annual income should be explored further.

Inciting Events Associated With Lumbar Facet Joint Pain.

BACKGROUND: Low back pain is the leading cause of years lost to disability with approximately 15%-25% of the chronic back pain population suffering from lumbar facet arthropathy. No large-scale study has sought to systematically identify inciting events for lumbar facet arthropathy. The aim of this study is to quantify the proportion of individuals with lumbar facetogenic pain who report a specific precipitating event(s) and to determine if there is a correlation between these events and treatment outcome. METHODS: Institutional electronic medical records were searched based on the current procedural terminology (CPT) codes representing lumbar facet joint radiofrequency ablation for procedures performed between January 2007 and December 2015. All patients had obtained ≥50% pain relief based on 6-hour pain diaries after 1 or more diagnostic facet blocks. A positive outcome was defined as ≥50% pain relief sustained for longer than 3-month after procedure, without additional procedural interventions. RESULTS: One thousand sixty-nine people were included in analysis. In the 52% of individuals who described an inciting event, the most commonly reported causes were falls (11%), motor vehicle collisions (11%), sports-related injuries (11%, of which weightlifting accounted for 62%), nonspine postsurgical injuries (2%), and "other" (17%). Six hundred seventeen (57.7%) individuals experienced ≥50% pain relief sustained for >3 months. Patients whose pain was preceded by an inciting event were more likely to have a positive outcome than those who could not recall a specific precipitating factor (odds ratio, 1.5; confidence interval, 1.02-2.1, P = .01). Another factor associated with outcome was shorter duration of pain (8.1 ± 9.2 vs 9.7 ± 10.1 years, P = .02), with an observed modifier effect of age on outcomes. For a 1-year increase in age, there was a 10% increase in the odds of a positive response. CONCLUSIONS: Inciting events are common in patients diagnosed with lumbar facetogenic pain and may be associated with a positive outcome.