Refractory Pain Research Articles

The contralateral oblique fluoroscopic view is associated with a lower incidence of postdural puncture headache in patients undergoing percutaneous spinal cord stimulation.

Spinal cord stimulation (SCS) is a minimally invasive therapy that is increasingly used to treat refractory neuropathic pain. Although this technique has a low incidence of serious long-term adverse sequelae, the risk of complications such as inadvertent dural puncture remains. The goal of this article was to determine the impact of the contralateral oblique (CLO) fluoroscopic view incidence of postdural puncture headache (PDPH) during spinal cord stimulator implantation as compared to lateral fluoroscopic view. This was a single academic institution retrospective analysis of electronic medical records spanning an approximate 20-year time period. Operative and postoperative notes were reviewed for details on dural puncture, including technique and spinal level of access, the development of a PDPH, and subsequent management. Over nearly two decades, a total of 1637 leads inserted resulted in 5 PDPH that were refractory to conservative measures but responded to epidural blood patch without long-term complications. The incidence of PDPH per lead insertion utilizing loss of resistance and lateral fluoroscopic guidance was 0.8% (4/489). However, adoption of CLO guidance was associated with a lower rate of PDPH at 0.08% (1/1148), p < 0.02. The incorporation of the CLO view to guide epidural needle placement can decrease the odds of a PDPH during percutaneous SCS procedures. This study further provides real-world data supporting the potential enhanced accuracy of epidural needle placement in order to avoid unintentional puncture or trauma to deeper spinal anatomic structures.

Paddle Lead Spinal Cord Stimulation in the Morbidly Obese Patient Population: Outcomes and Complications in a Single-Surgeon Cohort

Paddle lead spinal cord stimulation (SCS) is used to treat refractory chronic pain. Morbidly-obese patients seek SCS to reduce chronic pain. However, these patients face worse surgical outcomes, and the SCS literature has not evaluated safety and efficacy in this patient population. This study is the largest single-surgeon case series to date on morbidly obese patients with paddle lead SCS implantations. The primary objective is to report post-operative complication rates in morbidly-obese patients receiving SCS implants. The secondary objective is to report patient-reported pain scores and PROMIS Pain Interference and Physical Function scores in these patients. A retrospective chart review was conducted. The patient charts were reviewed from the day of procedure consent to 6 months post-op. Demographic information, pain scores, PROMIS scores, neurological complications, infections, and wound complications were documented. 67 patients were included. The mean pre-operative BMI was 44.47±4.02 kg/m2. The mean age was 58.9±11.4 years old. There were no neurological complications. 3/67 (4%) developed culture-positive infections. 9/67 (13%) patients developed superficial wound dehiscence without underlying infection. The mean post-op PROMIS PF score was 31.6±6.2 (n=16) and the mean post-op PROMIS PI score was 64.0±6.4 (n=16). There was a reduction in pain scores, from 7.9±1.7 pre-op to 5.7±2.5 post-op (n=22, p=0.004). Paddle lead SCS implantation is safe for morbidly-obese patients. The only minimal-risk complications present were post-operative infections and wound dehiscence. Surgical care can be modified to further reduce the rates of infection and dehiscence.

Optic Pathway Glioma Treatment: A Mini-review of the Current Literature

Background and Aim: Optic pathway glioma (OPG) is a chronic condition that needs a multidisciplinary management strategy. Most of these tumors are observed in the pediatric population and the tumor tends to stabilize after the child’s growth. This benign course can be observed mostly in neurofibromatosis 1 (NF1) patients, which are about half of the pediatric patients. Methods and Materials/Patients: The current literature in PubMed and Scopus databases was searched. The recent data regarding OPG and treatment options were reviewed to design this narrative mini-review. Results: The brief data extracted from 17 articles, cited in the reference list, were included in the study. Conclusion: Chemotherapy is the first and best treatment modality for patients with OPG. It is more useful at younger ages because it has lower rates of complications and cancer in the future compared with radiotherapy, the treatment of choice in previous decades for these patients. However, in recent practice, it has been substituted by chemotherapy because of its serious adverse effects on the pediatric population. Neurosurgical treatments for OPG are used for three main purposes, third ventricle obstruction-related hydrocephalus, biopsy, and tissue diagnosis for cases with an uncertain diagnosis, and tumor decompression due to mass effect on vital structures. Surgical decompression is not considered the first-line treatment in OPG. It can be used for patients with progressive exophthalmos with ipsilateral blindness or patients with refractory pain after adjuvant treatment. This short review discusses the main aspects of OPG treatment modalities.

Objective wearable measures and subjective questionnaires for predicting response to neurostimulation in people with chronic pain

BackgroundNeurostimulation is an effective therapy for treating and management of refractory chronic pain. However, the complex nature of pain and infrequent in-clinic visits, determining subject’s long-term response to the therapy remains difficult. Frequent measurement of pain in this population can help with early diagnosis, disease progression monitoring, and evaluating long-term therapeutic efficacy. This paper compares the utilization of the common subjective patient-reported outcomes with objective measures captured through a wearable device for predicting the response to neurostimulation therapy.MethodData is from the ongoing international prospective post-market REALITY clinical study, which collects long-term patient-reported outcomes from 557 subjects implanted by Spinal Cord Stimulator (SCS) or Dorsal Root Ganglia (DRG) neurostimulators. The REALITY sub-study was designed for collecting additional wearables data on a subset of 20 participants implanted with SCS devices for up to six months post implantation. We first implemented a combination of dimensionality reduction algorithms and correlation analyses to explore the mathematical relationships between objective wearable data and subjective patient-reported outcomes. We then developed machine learning models to predict therapy outcome based on the subject’s response to the numerical rating scale (NRS) or patient global impression of change (PGIC).ResultsPrincipal component analysis showed that psychological aspects of pain were associated with heart rate variability, while movement-related measures were strongly associated with patient-reported outcomes related to physical function and social role participation. Our machine learning models using objective wearable data predicted PGIC and NRS outcomes with high accuracy without subjective data. The prediction accuracy was higher for PGIC compared with the NRS using subjective-only measures primarily driven by the patient satisfaction feature. Similarly, the PGIC questions reflect an overall change since the study onset and could be a better predictor of long-term neurostimulation therapy outcome.ConclusionsThe significance of this study is to introduce a novel use of wearable data collected from a subset of patients to capture multi-dimensional aspects of pain and compare the prediction power with the subjective data from a larger data set. The discovery of pain digital biomarkers could result in a better understanding of the patient’s response to therapy and their general well-being.

Low-dose ketamine infusions for chronic pain management: Does this qualify as evidence-based practice?

Chronic pain is becoming increasingly prevalent and burdensome both worldwide and in the United Kingdom. Due to the complexity of chronic pain and the therapeutic challenge associated, management is often difficult and requires multidisciplinary care encompassing a combination of pharmacological and non-pharmacological strategies. Conventional analgesic treatments, such as opioids and anticonvulsants, are effective in less than half of chronic pain sufferers and are typically limited to short-term use to prevent complications associated with long-term use such as tolerance and dependence. Consequently, research and clinical interest in alternative management options for chronic pain have increased in recent years, with ketamine being one example under investigation. However, since ketamine has been licensed as an anaesthetic for decades, it has bypassed the traditional scrutinous drug development sequence that is typically seen for therapeutics marketed for pain. As such, data supporting the unlicensed administration of ketamine for chronic pain management is lacking and is being outpaced by the rates of off-label use in pain clinics. Recent limited evidence suggests that ketamine, when given as an intravenous infusion in subanaesthetic doses for refractory pain patients, may provide modest analgesic effects in nearly all aetiologies of chronic pain, with side effects common but typically mild. However, there are concerns over the safety of this practice due to the paucity of robust supportive evidence and the accompanying lack of clinical guidelines or standardised protocols. This review shall summarise the literature examining the use of subanaesthetic-dose ketamine infusions for chronic pain to comment on the current level of evidence, with limitations of existing research and future recommendations discussed.

Virtual Reality Treatment of Severe Neuropathic Pain in an Adolescent Child: A Case Report.

We describe virtual reality (VR) used as an effective intervention to treat severe chronic neuropathic pain in an otherwise healthy adolescent boy. The patient presented with severe pain and allodynia in the right foot after calcaneus extension surgery. Multiple medical and psychological interventions were unsuccessful over 3 years, with the pain leading the patient to drop out of school. VR gaming intervention provided the patient with significant pain relief and substantial improvement in functionality. This case report details the VR intervention and its effect on the patient's severe, medically refractory pain syndrome.

Cost-Effectiveness and Cost–Utility Analyses in Thailand of Continuous Intrathecal Morphine Infusion Compared with Conventional Therapy in Cancer Pain: A 10-year Multicenter Retrospective Study

ABSTRACT Background Because of the high initial cost of intrathecal drug delivery (ITDD) therapy, this study investigated the cost-effectiveness and cost–utility of ITDD therapy in refractory cancer pain management in Thailand over the past 10 years. Methods The retrospective study was conducted in patients with cancer pain who underwent ITDD therapy from January 2011 to 2021 at three university hospitals. Clinical outcomes included the numerical rating scale (NRS), Palliative Performance Scale, and the EQ-5D. The direct medical and nonmedical as well as indirect costs were also recorded. Cost-effectiveness and cost–utility analyses were performed comparing ITDD therapy with conventional therapy (extrapolated from costs of the same patient before ITDD therapy) from a societally oriented economic evaluation. Results Twenty patients (F:M: 10:10) aged 60 ± 15 years who underwent implantation of an intrathecal percutaneous port (IT port; n = 15) or programmable intrathecal pump (IT pump; n = 5) were included. The median survival time was 78 (interquartile range = 121–54) days after ITDD therapy. At 2-month follow-up, the incremental cost-effectiveness ratio (ICER)/pain reduction of an IT port (US$2065.36 (CA$2829.54)/2-point NRS reduction/lifetime) was lower than for patients with an IT pump (US$5479.26 (CA$7506.58)/2-point NRS reduction/lifetime) compared with continued conventional therapy. The ICER/quality-adjusted life years (QALYs) gained for an IT port compared with conventional treatment was US$93,999.31(CA$128,799.06)/QALY gained, which is above the cost-effectiveness threshold for Thailand. Conclusion The cost-effectiveness and cost–utility of IT port therapy for cancer pain was high relative to the cost of living in Thailand, above the cost-effectiveness threshold. Prospective cost analysis studies enrolling more patients with diverse cancers that investigate the benefit of early ITDD therapy with devices over a range of prices are warranted.

The establishment, maintenance, and adaptation of high- and low-impact chronic pain: a framework for biopsychosocial pain research.

The establishment, maintenance, and adaptation of high- and low-impact chronic pain: a framework for biopsychosocial pain research.

Treating refractory posterior sacroiliac joint complex pain in the current healthcare ecosystem: a call to action.

Treating refractory posterior sacroiliac joint complex pain in the current healthcare ecosystem: a call to action.

Phase II study about efficacy and safety of the continuous intravenous infusion of ketamine as adjuvant to opioids in terminally ill cancer patients with refractory cancer pain.

e24139 Background: The ketamine is used to control refractory cancer pain as adjuvant to opioids. However, usefulness of ketamine has not yet been confirmed due to lack of previous studies. Additionally, most of prior studies were studied in heterogenous patients, and continuous intravenous infusion (CIVI) method was rare. The CIVI method using gradual dose titrations of ketamine is safe. So, it is suitable to terminally ill cancer patients who have available IV access but vulnerable to AEs. This phase II single-arm study investigated efficacy and safety of CIVI of Ketamine in these population. Methods: Cancer patients with expected limited survival time within several months and refractory cancer pain were enrolled. Refractory cancer pain indicates requirements of breakthrough analgesics ≥ 4 times/day or average pain score &gt; personalized pain goal (PPG) in spite of intravenous Morphine Equivalent Daily Dose (MEDD) &gt; 120 mg/day. The CIVI of ketamine was increased from 0.05 mg/kg/hr to 0.5 mg/kg/hr by 0.05 mg/kg/hr every 8hr when average pain score exceeded PPG or breakthrough was needed ≥ 2 times/8hr during 5 days. The primary end-point was overall pain response rate, which indicates complete response (both breakthrough ≤ 3/day and NRS ≤ PPG) plus partial response (breakthrough ≤ 3/day), without unacceptable toxicities. A total of 26 patients are needed to verify assumption of response rate of 40% with width of 0.4 for two-sided 95% CI and assuming 5% drop-out rate. This study was prematurely terminated at enrollment of 21 patients. Results: Among 21 enrolled patients between SEP 2019 and JAN 2023, 20 were analyzed except 1 due to early transfer. Most pain mechanisms were mixed type (n = 15, 75%), while some reported nociceptive pain (n = 3, 15%) or neuropathic pain (n = 2, 10%). The baseline background opioids were MEDD 186 mg/day (range, 124-592), number of breakthrough opioids were 5 (IQR, 5-7). The median PPG were 4 (range, 3-6). After application of ketamine, overall pain response rate was 45% (n = 9), complete pain response was 35% (n = 7) and partial pain response was 10% (n = 2). The other 11 were non-responders (six failed to achieve overall pain response despite of maximal dose or completing 5 days of ketamine, five patients discontinued the treatment due to AEs). AEs included confusion (n = 9, 45%), dizziness (n = 3, 15%), and hypertension (n = 2, 10%). Communication capacities were sustained in 10 patients and decreased in other 10 patients. OS were 21 days (95% CI, 18.1-23.9). Conclusions: Our study showed efficacies and safeties of gradually increasing CIVI of ketamine for terminally ill cancer patients with refractory cancer pain. The CIVI of ketamine can be a useful tool in these patients considering limited treatment options. Further studies comparing usefulness of CIVI of ketamine and usual practice with opioids escalation are needed (NCT03362073). Clinical trial information: NCT03362073 .

ID: 218207 10kHz Spinal Cord Stimulation for Non-Surgical Refractory Back Pain: Objective Functional Outcome to 24-Months

Chronic refractory back pain causes significant disability and has a major negative impact on mental health. Few treatment options exist for chronic back pain patients who have failed conventional medical management (CMM) and who have not had and are not candidates for spine surgery, a condition we refer to as non-surgical refractory back pain (NSRBP). Access to spinal cord stimulation (SCS) is inconsistent in this population due to limited clinical evidence.1 Twenty-four-month outcomes including a functional test is reported from a RCT that compared 10kHz SCS to CMM in the treatment of NSRBP.

ID: 209382 FAST Therapy for Intractable Thoracic Pain

Since its inception, spinal cord stimulators (SCS) have evolved to become a robust therapy for refractory neuropathic pain when medical and invasive management has failed. As a result of its success, the number of SCS implants have continued to increase over the decades enhancing the quality of life and function in patients suffering from refractory neuropathic pain. Furthermore, these patients require less medical management with SCS therapy.

ID: 218085 Treating Non-Surgical Refractory Back Pain With 10kHz Spinal Cord Stimulation: 24 Month Follow-Up From RCT

Patients with moderate to severe chronic back pain, refractory to available nonsurgical therapies (medications, physical therapy, nerve blocks and radio frequency ablation) have limited options if they are not candidates for surgery. In addition, access to spinal cord stimulation (SCS) may be difficult due to limited clinical evidence for SCS in this patient population (1). Here, 24-month follow-up is reported from a RCT that was designed to compare clinical and cost-effectiveness of 10kHz SCS versus CMM to treat non-surgical refractory back pain (NSRBP).

Refractory cancer pain therapy with intrathecal neurolytic technique—a retrospective tertiary care cancer centre experience

Background: The objective of this study is to observe the efficacy of refractory cancer pain therapy with an intrathecal neurolytic technique. Methods: This was a retrospective study of patients who received an intrathecal neurolytic technique between December 2016 and June 2020 at the Department of Anesthesia and Pain Medicine of Shaukat Khanam Memorial Cancer Hospital and Research Center. The data of the patients were retrieved from hospital information system (HIS). Patients were included who had numerical rating score (NRS) ≥8, after monopharmacy or polypharmacy including opioids/neuropathic drugs. Follow-up was conducted by the pain consultant and pain resident post-procedure at 1 week and 4 weeks. Data were documented on a spreadsheet in Microsoft XL and analysed on SPSS version 20. Results: Among 23 patients, numerical rating scale pain score pre-procedure was 8.91 (1.24). It was 3.83 (3.20) and 4.82 (3.41) at 1 and 4 weeks follow-up, respectively. Oral medications were reduced to half of their pre-procedure consumption in 57% of the patients and totally stopped in 30% (n=7) of patients. Complications were reported in 17.4% patients. Hypotension in 13%, and bowel incontinence and leg numbness in 4.3% patients were recorded. Conclusion: This study showed that with appropriate patient selection, understanding of pathophysiology of pain, choice of correct treatment can result in higher success rate. Intrathecal chemical neurolysis can be offered to a subset of patients who have not benefited from other pharmacological therapies.

ID: 220477 Efficacy and Cost-Containment Assessment of 10kHz Spinal Cord Stimulation in Non-Surgical Refractory Back Pain Patients

Non-surgical refractory back pain (NSRBP) is persistent, severe back pain in patients for whom surgery is not deemed appropriate. Published studies, including a randomized controlled trial, have demonstrated clinically important long-term improvement in pain and functional capacity when 10kHz spinal cord stimulation (SCS) is used to treat NSRBP1. Here, we present real-world outcomes from patients in interventional pain practices and examine health care utilization (HCU) following 10kHz SCS implant.

ID: 196299 Axillary Peripheral Nerve Stimulation for Severe Glenohumeral Osteoarthritis Not Amenable to Surgery: A Case Report

Glenohumeral osteoarthritis (OA) is a common cause of chronic shoulder pain in the elderly (1). When conservative management fails to provide adequate pain relief, total shoulder arthropathy (TSA) may be considered (1). If surgical treatment is not feasible due to poor surgical candidacy, there are currently limited non-surgical options for end-stage shoulder OA (1,2,3). Peripheral nerve stimulation (PNS) has been utilized successfully for refractory shoulder pain, even when the pain is secondary to degenerative joint disease (2,3).

ID: 209150 Cervical and High Thoracic Spinal Cord Stimulation to Treat Refractory Failed Back Surgery Syndrome

Failed back surgery syndrome (FBSS) is defined as spinal pain of unknown origin, which persists following surgical intervention or newly presents after spine surgery. This pain may originate from surgery, or the surgery may worsen or insufficiently reduce prior pain (1). From 2004 to 2015, the volume of lumbar fusion surgery increased by 62.3% (2). With the frequency of lumbar fusion surgery comes an increased propensity to develop FBSS. The risk of developing FBSS in patients who have undergone lumbar spine surgery is as high as 50% (3). Spinal cord stimulation (SCS) is a well-established, safe, and effective treatment modality for refractory neuropathic pain conditions such as FBSS (4).

ID: 215295 Targeted Drug Delivery Pump Failure Post MRI - A Sentinel Event

Intrathecal drug delivery systems (IDDS) are commonly utilized for many refractory chronic pain conditions and cancer associated pain. Manufacturer recommendations are available for physicians and MRI facilities to review prior to obtaining a scan1. We discuss a case in which IDDS malfunction occurred following MRI, despite following manufacturer instructions prior to and after MRI, resulting in profound medication overdose.

ID: 214897 Peripheral Nerve Stimulation for Refractory Complex Regional Pain Syndrome Type I to Avoid Amputation

Peripheral nerve and dorsal root ganglion stimulation (DRG-s) are effective treatment modalities for focal complex regional pain syndrome (CRPS) that is limited to one or two dermatomes1,2,3. When deciding on a neural target for stimulation, consideration is given to the location of pain, MRI labeling, charge burden of external or internal pulse generator, spinal hardware, and medical comorbidities. While a reduction in pain of fifty percent or greater is often deemed a satisfactory response in the treatment of chronic pain, we describe a case were the patient sought amputation of her limb in the hopes a prosthetic extremity would provide improved function. Despite the risk of post amputation pain, there are patients that seek amputation for advanced CRPS that is refractory to treatment4,5,6. We proceeded with peripheral nerve stimulation (PNS) in addition to her DRG-s system in effort to avoid her upcoming amputation.

ID: 214134 Action Potential Fidelity as a Function of Pulse Frequency During Spinal Cord Stimulation

Spinal cord stimulation (SCS) is a neurostimulation treatment for refractory chronic pain in which pulses of electrical current are applied to the dorsal spinal cord. SCS frequencies vary substantially between patients and SCS paradigms, and it is well known that frequency selection will affect patient satisfaction and analgesia. It is also well known that action potentials within complex axonal arbors may be subject to frequency-dependent transmission failure, and emerging evidence suggests that primary afferent terminations within the dorsal horn are prone to such failure at SCS-relevant frequencies. In this study, we used a computational modeling approach to investigate the fidelity of action potential propagation within primary afferent arbor terminations.