Intrathecal drug delivery for pain management: recent advances and future developments

Intrathecal drug delivery systems: A case series advancing surgical, clinical, and technological safety with broader implications for invasive neuromodulation therapies

Intrathecal drug delivery systems (IDDS) represent an advanced modality of invasive pharmacological neuromodulation, providing efficacious treatment for terminal malignant pain as well as select chronic noncancer pain conditions. Although intrathecal drug delivery systems offer the potential for reduced systemic adverse effects compared to conventional routes, they are not without significant complications, including infections, device dysfunction, and severe neurological injuries. Moreover, the integration of network-based smart-device applications into intrathecal drug delivery system control interfaces introduces a concomitant elevation in risks associated with software errors and cybersecurity vulnerabilities. Case 1: a 77-year-old male receiving intrathecal methadone therapy, after the failure of first- and second-line agents, developed a catheter-tip spinal granuloma resulting in irreversible paraplegia secondary to thoracic spinal cord compression. Case 2: a 37-year-old female with a history of longstanding depression experienced a severe surgical site infection attributable to suboptimal surgical techniques during intrathecal drug delivery system implantation. This complication led to septic shock and meningitis, necessitating device removal and prolonged intravenous antibiotic therapy, though she ultimately recovered without permanent neurological deficits. Case 3: a 67-year-old female encountered acute opioid withdrawal and subsequent hospitalization as a consequence of a tablet-based interrogation platform's software error in timekeeping that miscalculated her intrathecal drug delivery system refill date and recovered without enduring neurological sequelae. Invasive neuromodulation therapies, including intrathecal drug delivery systems, present multifaceted challenges that necessitate rigorous patient and therapeutic agent selection, meticulous risk factor mitigation, continuous neuromonitoring, and prompt detection of subtle neurological changes indicative of potential complications. This analysis delineates three critical domains: first, clinical vigilance and enhanced monitoring protocols are essential for the early identification of severe complications, such as granuloma formation; second, an educational paradigm shift, standardized, comprehensive surgical training in fellowship programs is required to ensure technical proficiency, optimal postoperative management, and an in-depth understanding of psychosocial factors; and third, technological leadership, the adoption of app-based management systems on consumer platforms introduces vulnerabilities including software malfunctions and cybersecurity threats, thereby necessitating that physicians advocate for stringent safety standards and robust regulatory oversight. Collectively, these strategies are indispensable for enhancing the safety and efficacy of invasive neuromodulation therapies and transforming the landscape of chronic pain management.

Intrathecal Drug Delivery for Intractable Pain: Identified Patient Satisfaction Survey Study Comparing Intrathecal Dose With Satisfaction, Pain Relief, and Side Effects

OBJECTIVES

Past studies have shown the efficacy of spinal targeted drug delivery (TDD) in pain relief, reduction in opioid use, and cost-effectiveness in long-term management of complex chronic pain. We conducted a survey to determine treatment variables associated with patient satisfaction.

MATERIALS AND METHODS

Patients in a single pain clinic who were implanted with Medtronic pain pumps to relieve intractable pain were identified from our electronic health record. From November 2021 to February 2023, 973 patients with active TDD were identified; 564 completed the 23-question survey, and 560 were included in analyses. Most patients (96.4%) had intrathecal (IT) infusion admixtures containing bupivacaine and opioid. The survey compared satisfaction with IT medication dosages, pain relief, pain diagnosis, catheter tip location, side effects, mental clarity, physical functioning, and healthcare utilization. Outcomes were reported as proportions; p < 0.05 was considered significant.

RESULTS

Most respondents reported good-to-excellent pain relief (63.8%), high satisfaction with TDD (80.7%), improvement in physical functioning (75.0%), and better quality of life (89.7%); 78.5% of respondents reported complete discontinuation or substantial reductions in systemic opioid use. There was a statistically significant relationship between satisfaction and IT medication dose (p = 0.02), with the average dose increasing with higher satisfaction groups. We found that patients on higher doses of IT opioids did not have more bothersome side effects (p = 0.05).

CONCLUSIONS

Our data show that the most satisfied respondents had higher IT doses, fewer side effects, and longer duration of TDD therapy. This suggests that higher dose IT admixtures are safe and effective at relieving pain and improving quality of life in patients with complex chronic pain whose condition has failed to respond adequately to other treatments. TDD may be an effective alternative to long-term systemic opioids for well-selected patients willing to accept the risks of invasive procedures.

Efficacy and safety of single and double catheter intrathecal drug delivery systems in patients with refractory neck and abdominal cancer pain

Intrathecal drug delivery systems (IDDS) is a crucial for treating refractory cancer pain, but their effectiveness in patients with pain across multiple spinal segments is limited by the localized spread of pain relief medication. Our team innovatively implanted double-catheter IDDS to manage pain related to neck and abdominal cancer. While this may represent a new solution, the efficacy, safety, and cost-effectiveness remain unclear. A multi-center retrospective cohort study. Pain management and medical oncology departments of six hospitals in various regions of China. 62 patients with neck or abdominal cancer pain were enrolled from November 2019 to June 2024. Patients were divided into two groups: the double-catheter IDDS group (n = 26) and the single-catheter IDDS groups (n = 36). Propensity score matching was employed to create a balanced cohort of 48 patients. The primary outcome was pain control, assessed using Numeric Rating Scale [NRS]), breakthrough pain (BTP), and opioid consumption, including intrathecal morphine dose [IDMED] and oral daily morphine dose [ODMED]. No significant differences were observed in the NRS score and IDMED between the double-catheter and single-catheter groups prior to surgery, one day post-surgery, and at hospital discharge (p > 0.05). However, one-month post-surgery, the NRS score was significantly lower in the double-catheter group compared to the single-catheter group, while the IDMED was significantly higher compared to the single-catheter group (p < 0.05). A significantly higher number of BTP episodes and ODMED was observed in the single-catheter group compared to the two-catheter group at one day post-surgery, at hospital discharge, and one-month post-surgery (p < 0.05). The duration of hospitalization and the incidence of adverse events did not differ significantly between the two groups (p > 0.05). However, the cumulative hospitalization expenses, IDDS opioid costs per month, and refill costs calculated for a month were significantly higher in the double-catheter group compared to the single-catheter group. Conversely, the monthly oral opioid costs and total costs of analgesic were significantly lower in comparison to the single-catheter group (p < 0.05). The preliminary findings of this study, both single- and double-catheter IDDS effectively manage cancer pain in neck and abdominal cancer patients without increasing adverse events. Despite higher initial costs, double-catheter IDDS demonstrates superior long-term pain control, a reduced incidence of BTP, and lower overall monthly analgesic costs. However, due to the limitations of the study's sample size and patient survival time, further research is needed to assess the long-term benefits.

Spatially Precise and Minimally Invasive Delivery of Peptides to the Spinal Cord for Behavior Modulation

The blood-spinal cord barrier (BSCB) tightly regulates the transport of molecules from the blood to the spinal cord. Herein, we present an approach for transient modulation of BSCB permeability and localized delivery of peptides into the spinal cord for behavior modulation with high spatial resolution. This approach utilizes optical stimulation of vasculature-targeted nanoparticles and allows delivery of BSCB-impermeable molecules into the spinal cord without significant glial activation or impact on animal locomotor behavior. We demonstrate minimally invasive light delivery into the spinal cord using an optical fiber and BSCB permeability modulation in the lumbar region. Our method of BSCB modulation allows the delivery of bombesin, a centrally acting and itch-inducing peptide, into the spinal cord and induces a rapid and transient increase in itching behaviors in mice. This minimally invasive approach enables behavior modulation without genetic modifications and is promising for delivering a wide range of biologics into the spinal cord for potential therapy with high spatiotemporal resolution.

The Polyanalgesic Consensus Conference (PACC)®: Updates on Clinical Pharmacology and Comorbidity Management in Intrathecal Drug Delivery for Cancer Pain

INTRODUCTION

The International Neuromodulation Society convened a multispecialty group of physicians based on expertise with international representation to establish evidence-based guidance on using intrathecal drug delivery in chronic pain treatment. This Polyanalgesic Consensus Conference (PACC)® project's scope is to provide evidence-based guidance for clinical pharmacology and best practices for intrathecal drug delivery for cancer pain.

MATERIALS AND METHODS

Authors were chosen on the basis of their clinical expertise, familiarity with the peer-reviewed literature, research productivity, and contributions to the neuromodulation literature. Section leaders supervised literature searches using Medline, EMBASE, Cochrane CENTRAL, BioMed Central, Web of Science, Google Scholar, PubMed, Current Contents Connect, Meeting Abstracts, and Scopus from 2017 (when the PACC last published guidelines) to the present. Identified studies were graded using the United States Preventive Services Task Force criteria for evidence and certainty of net benefit. Recommendations were based on the strength of evidence, and when evidence was scant, recommendations were based on expert consensus.

RESULTS

The PACC evaluated the published literature and established evidence- and consensus-based expert opinion recommendations to guide best practices in treating cancer pain. Additional guidance will occur as new evidence is developed in future iterations of this process.

CONCLUSIONS

The PACC recommends best practices regarding the use of intrathecal drug delivery in cancer pain, with an emphasis on managing the unique disease and patient characteristics encountered in oncology. These evidence- and consensus-based expert opinion recommendations should be used as a guide to assist decision-making when clinically appropriate.

Multidimensional Analysis of Quality of Life in Patients with Chronic Non-Cancer Pain and Short- and Long-Term Intrathecal Analgesic Therapy

Background: Intrathecal drug delivery (IDD) is part of the fourth analgesic step. Evidence on the quality of life of patients with refractory chronic non-cancer pain (CNCP) using these devices and their long-term outcomes is scarce. This study aims to evaluate patients with IDD to assess their HRQoL. Additionally, the study seeks to understand the patients' satisfaction with the treatment and changes in pain magnitude over time. Methods: Adult patients with CNCP and intrathecal drug delivery systems (IDDS) were included. The study population was divided into two groups: less than and more than 15 years of treatment. HRQoL was analyzed using validated questionnaires. Pain reduction was assessed using the visual analog scale (VAS), and treatment satisfaction was evaluated using the Patient Global Impression of Improvement scale. Results: The results indicate a poor HRQoL in IDD patients, with better scores in the group with ≥15 years of treatment. Pain reduction was similar in both groups, and patients reported a positive satisfaction level with the treatment. Conclusions: HRQoL in CNCP patients is severely affected. Long-term IDD patients have a similar or even better HRQoL in some respects compared to those with shorter follow-ups. IDD patients experienced pain reduction, with most feeling better or much better.

Influencing factors of glymphatic system during perioperative period

The glymphatic system is a functional cerebrospinal fluid circulatory system that uses peri-arterial space for inflow of cerebrospinal fluid and peri-venous space for efflux of cerebrospinal fluid from brain parenchyma. This brain-wide fluid transport pathway facilitates the exchange between cerebrospinal fluid and interstitial fluid and clears metabolic waste from the metabolically active brain. Multiple lines of work show that the glymphatic system is crucial to normal brain functions, and the dysfunction of the glymphatic system is closely associated with various neurological disorders, including aging, neurodegeneration, and acute brain injury. Currently, it is common to explore the functional and molecular mechanisms of the glymphatic system based on animal models. The function of glymphatic system during perioperative period is affected by many factors such as physiological, pathological, anesthetic and operative methods. To provide a reference for the interpretation of the results of glymphatic system studies during perioperative period, this article comprehensively reviews the physiological and pathological factors that interfere with the function of the glymphatic system during perioperative period, investigates the effects of anesthetic drugs on glymphatic system function and the potential underlying mechanisms, describes operative methods that interfere with the function of the glymphatic system, and potential intervention strategies based on the glymphatic system. Future, these variables should be taken into account as critical covariates in the design of functional studies on the glymphatic system.

Strategies for enhanced gene delivery to the central nervous system

The delivery of genes to the central nervous system (CNS) has been a persistent challenge due to various biological barriers. The blood-brain barrier (BBB), in particular, hampers the access of systemically injected drugs to parenchymal cells, allowing only a minimal percentage (<1%) to pass through. Recent scientific insights highlight the crucial role of the extracellular space (ECS) in governing drug diffusion. Taking into account advancements in vectors, techniques, and knowledge, the discussion will center on the most notable vectors utilized for gene delivery to the CNS. This review will explore the influence of the ECS - a dynamically regulated barrier-on drug diffusion. Furthermore, we will underscore the significance of employing remote-control technologies to facilitate BBB traversal and modulate the ECS. Given the rapid progress in gene editing, our discussion will also encompass the latest advances focused on delivering therapeutic editing in vivo to the CNS tissue. In the end, a brief summary on the impact of Artificial Intelligence (AI)/Machine Learning (ML), ultrasmall, soft endovascular robots, and high-resolution endovascular cameras on improving the gene delivery to the CNS will be provided.

Treatment of Intrathecal Drug Pump Flipping Using Fascial Flaps: A Technical Description and Case Series

BACKGROUND AND OBJECTIVES

Intrathecal drug therapy is a common treatment for dystonia, pain, and spasticity using implanted pump and catheter systems. Standardized management of intrathecal drug pump (ITDP) migration and flipping has not been well established in the literature. This study reports the use of soft tissue to address less common pump complications such as pump flipping, migration, and difficulty in medication refill.

METHODS

A retrospective chart review of intrathecal pump cases performed by two surgeons between February 2020 and August 2022 was conducted. Patients with complications such as pump flipping, migration, or challenges in medication refill treated with soft tissue flaps were included. Patient demographics, comorbidities, and perioperative data were collected.

RESULTS

A total of five patients with ITDP complicated by pump flipping, migration, malposition, or difficulty in medication refill that were treated using fascial flaps were included in the study. Three technical considerations when revising ITDP complications are secure pump anchoring, reliable wound closure, and ease of pump medication refill. Cases 1 and 2 demonstrate the technique of secure pump anchoring with a rectus fascial flap. Cases 3 and 4 show a technique to achieve reliable vascularized wound closure, and case 5 describes a technique to solve an uncommon problem of a thick subcutaneous abdominal tissue preventing the refill of the ITDP medication.

CONCLUSION

Soft tissue flaps may serve as a treatment option for patients with uncommon ITDP complications. De-epithelialized dermal fasciocutaneous or fascial flaps may be developed to anchor the pump more securely. Cross-discipline collaboration may further delineate the technique, benefits, and outcomes of this approach.

Intrathecal morphine delivery at prepontine cistern to control refractory cancer-related pain: a case report of extensive metastatic and refractory cancer pain

BACKGROUND

Extensive metastatic and refractory cancer pain is common, and exhibits a dissatisfactory response to the conventional intrathecal infusion of opioid analgesics.

CASE PRESENTATION

The present study reports a case of an extensive metastatic esophageal cancer patient with severe intractable pain, who underwent translumbar subarachnoid puncture with intrathecal catheterization to the prepontine cistern. After continuous infusion of low-dose morphine, the pain was well-controlled with a decrease in the numeric rating scale (NRS) of pain score from 9 to 0, and the few adverse reactions to the treatment disappeared at a low dose of morphine.

CONCLUSIONS

The patient achieved a good quality of life during the one-month follow-up period.

Education and Experience in Intrathecal Drug Delivery Systems (IDDS) During Pain Medicine Fellowships

Objective

Targeted drug delivery (TDD) via intrathecal drug delivery systems (IDDS) exposure and clinical adoption remains low despite multiple well-designed trials that demonstrate safety, efficacy, reliability, and cost-saving benefits. This study aims to understand the possible contributing factors starting with Pain Medicine fellowship training.

Materials and Methods

An internet-based, anonymous pilot survey was distributed to pain medicine fellows enrolled in an Accreditation Council for Graduate Medical Education (ACGME) accredited pain medicine training program during the 2021-2022 academic year. Fellowship programs were identified using published online ACGME accreditation data. The survey was distributed via email to fellowship program directors and coordinators and was made available through pain medicine societies.

Results

Seventy-one of four hundred and twenty-three pain medicine fellows (17% response rate) completed the survey. Nine percent of respondents evidence-informed opinion coincided with the most recent Polyanalgesic Consensus Conference (PACC) guidelines recommendations for IDDS treatment indications. Fifty-one percent of respondents felt there was an unmet need for IDDS training. About one-third of respondents felt that lack of curriculum, faculty, and cases were barriers to IDDS use, respectively. Thirty-one percent of fellows reported sufficient training for IDDS in their fellowship programs. The majority (70%) of respondents somewhat or strongly support direct training by IDDS manufacturers.

Conclusion

A wide variability exists surrounding IDDS training during ACGME accredited pain medicine fellowship. Insufficient case exposure and lack of a standardized curriculum may play a role in future therapy adoption. The results from this study call for a more standardized training approach with an emphasis on adequate clinical exposure, utilization of peer reviewed educational curriculum and supplemental material to aid pain medicine fellows' education.

Chronic pain after spine surgery: Insights into pathogenesis, new treatment, and preventive therapy

Chronic pain after spine surgery (CPSS) is often characterized by intractable low back pain and/or radiating leg pain, and has been reported in 8-40% of patients that received lumbar spine surgery. We conducted a literature search of PubMed, MEDLINE/OVID with a focus on studies about the etiology and treatments of CPSS and low back pain. Our aim was to provide a narrative review that would help us better understand the pathogenesis and current treatment options for CPSS. This knowledge will aid in the development of optimal strategies for managing postoperative pain symptoms and potentially curing the underlying etiologies. Firstly, we reviewed recent advances in the mechanistic study of CPSS, illustrated both structural (e.g., fibrosis and scaring) and non-structural factors (e.g., inflammation, neuronal sensitization, glial activation, psychological factor) causing CPSS, and highlighted those having not been given sufficient attention as the etiology of CPSS. Secondly, we summarized clinical evidence and therapeutic perspectives of CPSS. We also presented new insights about the treatments and etiology of CPSS, in order to raise awareness of medical staff in the identification and management of this complex painful disease. Finally, we discussed potential new targets for clinical interventions of CPSS and future perspectives of mechanistic and translational research. CPSS patients often have a mixed etiology. By reviewing recent findings, the authors advocate that clinicians shall comprehensively evaluate each case to formulate a patient-specific and multi-modal pain treatment, and importantly, consider an early intraoperative intervention that may decrease the risk or even prevent the onset of CPSS.

Translational potential statement

CPSS remains difficult to treat. This review broadens our understanding of clinical therapies and underlying mechanisms of CPSS, and provides new insights which will aid in the development of novel mechanism-based therapies for not only managing the established pain symptoms but also preventing the development of CPSS.

Steering Toward Normative Wide-Dynamic-Range Neuron Activity in Nerve-Injured Rats With Closed-Loop Peripheral Nerve Stimulation

OBJECTIVES

Chronic pain is primarily treated with pharmaceuticals, but the effects remain unsatisfactory. A promising alternative therapy is peripheral nerve stimulation (PNS), but it has been associated with suboptimal efficacy because its modulation mechanisms are not clear and the current therapies are primarily open loop (ie, manually adjusting the stimulation parameters). In this study, we developed a proof-of-concept computational modeling as the first step toward implementing closed-loop PNS in future biological studies. When developing new pain therapies, a useful pain biomarker is the wide-dynamic-range (WDR) neuron activity in the dorsal horn. In healthy animals, the WDR neuron activity occurs in a stereotyped manner; however, this response profile can vary widely after nerve injury to create a chronic pain condition. We hypothesized that if injury-induced changes of neuronal response can be normalized to resemble those of a healthy condition, the pathological aspects of pain may be treated while maintaining protective physiological nociception.

MATERIALS AND METHODS

Using an in vivo electrophysiology data set of WDR neuron recordings obtained in nerve-injured rats and naïve rats, we constructed sets of linear phenomenologic models of WDR firing rate during windup stimulation for both conditions. Then, we applied robust control systems techniques to identify a closed-loop PNS controller, which can drive the dynamics of WDR neuron response in neuropathic pain model into ranges associated with normal physiological pain.

RESULTS

The sets of identified linear models can accurately predict, in silico, nonlinear neural responses to electrical stimulation of the peripheral nerve. In addition, we showed that continuous closed-loop control of PNS can be used to normalize WDR neuron firing responses in three injured cases.

CONCLUSIONS

In this proof-of-concept study, we show how tractable, linear mathematical models of pain-related neurotransmission can be used to inform the development of closed-loop PNS. This new application of robust control to neurotechnology may also be expanded and applied across other neuromodulation applications.

Nonsurgical Interventional Spine Pain Procedures: Outcomes and Complications

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Nonsurgical interventional spine pain procedures provide an additional treatment option for lower back pain at the traditional bifurcation of conversative vs. operative management.

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Transforaminal epidural steroid injections, radiofrequency ablations, intrathecal drug delivery, and spinal cord stimulation were found to be effective and safe techniques when applied to their specific indication.

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Thermal annuloplasty and minimally invasive lumbar decompression showed mixed support.

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Discography, sacroiliac joint injections, and spinous process spacers lacked sufficient evidence to support efficacy.

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Medial branch blocks and facet joint injections were found to be useful diagnostic tools.

Inflammation and histone modification in chronic pain

Increasing evidence suggests that epigenetic mechanisms have great potential in the field of pain. The changes and roles of epigenetics of the spinal cord and dorsal root ganglia in the chronic pain process may provide broad insights for future pain management. Pro-inflammatory cytokines and chemokines released by microglia and astrocytes, as well as blood-derived macrophages, play critical roles in inducing and maintaining chronic pain, while histone modifications may play an important role in inflammatory metabolism. This review provides an overview of neuroinflammation and chronic pain, and we systematically discuss the regulation of neuroinflammation and histone modifications in the context of chronic pain. Specifically, we analyzed the role of epigenetics in alleviating or exacerbating chronic pain by modulating microglia, astrocytes, and the proinflammatory mediators they release. This review aimed to contribute to the discovery of new therapeutic targets for chronic pain.

The American Society of Pain and Neuroscience (ASPN) Evidence-Based Clinical Guideline of Interventional Treatments for Low Back Pain

Introduction

Painful lumbar spinal disorders represent a leading cause of disability in the US and worldwide. Interventional treatments for lumbar disorders are an effective treatment for the pain and disability from low back pain. Although many established and emerging interventional procedures are currently available, there exists a need for a defined guideline for their appropriateness, effectiveness, and safety.

Objective

The ASPN Back Guideline was developed to provide clinicians the most comprehensive review of interventional treatments for lower back disorders. Clinicians should utilize the ASPN Back Guideline to evaluate the quality of the literature, safety, and efficacy of interventional treatments for lower back disorders.

Methods

The American Society of Pain and Neuroscience (ASPN) identified an educational need for a comprehensive clinical guideline to provide evidence-based recommendations. Experts from the fields of Anesthesiology, Physiatry, Neurology, Neurosurgery, Radiology, and Pain Psychology developed the ASPN Back Guideline. The world literature in English was searched using Medline, EMBASE, Cochrane CENTRAL, BioMed Central, Web of Science, Google Scholar, PubMed, Current Contents Connect, Scopus, and meeting abstracts to identify and compile the evidence (per section) for back-related pain. Search words were selected based upon the section represented. Identified peer-reviewed literature was critiqued using United States Preventive Services Task Force (USPSTF) criteria and consensus points are presented.

Results

After a comprehensive review and analysis of the available evidence, the ASPN Back Guideline group was able to rate the literature and provide therapy grades to each of the most commonly available interventional treatments for low back pain.

Conclusion

The ASPN Back Guideline represents the first comprehensive analysis and grading of the existing and emerging interventional treatments available for low back pain. This will be a living document which will be periodically updated to the current standard of care based on the available evidence within peer-reviewed literature.

Potential Association between Subclinical Hypothyroidism and Childhood Migraine

Background and Objectives: Migraine is caused by genetic susceptibility that is triggered by environmental as well as biological factors, and it is also linked to many somatic comorbidities, including clinical and subclinical hypothyroidism. We aimed to estimate the potential association between subclinical hypothyroidism (ScH) and migraine in children at our tertiary hospital. Materials and Methods: Using a case−control strategy, 200 children and adolescents were assigned to two equal groups: a case group (patients with migraine) of 100 patients and a control group of 100 patients without migraine. Clinical and biochemical parameters (TSH, FT4) were compared between the groups using statistical analysis. Results: Thyroid function comparison between the groups showed higher TSH but normal FT4 among children with migraine headache compared to the control group, which means more frequent ScH cases among the migraine group relative to the control (17% vs. 2%, p < 0.001). Obesity and overweight were more frequent among patients with migraine than the control group (8 and 5% vs. 2 and 1%, respectively). The (overweight/obese) patients with migraine had about 77% ScH and 15.4% overt hypothyroidism compared to 8% ScH and no overt hypothyroidism among normal body weight migraine patients (p < 0.001). No significant difference in the prevalence of nodular goiter between patients with migraine and controls was found. Conclusions: Based on our results, subclinical hypothyroidism is significantly linked to childhood migraine. Obesity and being overweight are more frequent among patients with migraine. Therefore, it may be logical to test the thyroid function in migraineur children, especially those with high BMI. Further studies are recommended to discover the mechanism of this association in children.

Noninvasive ultrasonic induction of cerebrospinal fluid flow enhances intrathecal drug delivery

Intrathecal drug delivery is routinely used in the treatment and prophylaxis of varied central nervous system conditions, as doing so allows drugs to directly bypass the blood-brain barrier. However, the utility of this route of administration is limited by poor brain and spinal cord parenchymal drug uptake from the cerebrospinal fluid. We demonstrate that a simple noninvasive transcranial ultrasound protocol can significantly increase influx of cerebrospinal fluid into the perivascular spaces of the brain, to enhance the uptake of intrathecally administered drugs. Specifically, we administered small (~1 kDa) and large (~155 kDa) molecule agents into the cisterna magna of rats and then applied low, diagnostic-intensity focused ultrasound in a scanning protocol throughout the brain. Using real-time magnetic resonance imaging and ex vivo histologic analyses, we observed significantly increased uptake of small molecule agents into the brain parenchyma, and of both small and large molecule agents into the perivascular space from the cerebrospinal fluid. Notably, there was no evidence of brain parenchymal damage following this intervention. The low intensity and noninvasive approach of transcranial ultrasound in this protocol underscores the ready path to clinical translation of this technique. In this manner, this protocol can be used to directly bypass the blood-brain barrier for whole-brain delivery of a variety of agents. Additionally, this technique can potentially be used as a means to probe the causal role of the glymphatic system in the variety of disease and physiologic processes to which it has been correlated.

Nanogels as Novel Nanocarrier Systems for Efficient Delivery of CNS Therapeutics

Nanogels have come out as a great potential drug delivery platform due to its prominently high colloidal stability, high drug loading, core-shell structure, good permeation property and can be responsive to environmental stimuli. Such nanoscopic drug carriers have more excellent abilities over conventional nanomaterials for permeating to brain parenchyma in vitro and in vivo. Nanogel-based system can be nanoengineered to bypass physiological barriers via non-invasive treatment, rendering it a most suitable platform for the management of neurological conditions such as neurodegenerative disorders, brain tumors, epilepsy and ischemic stroke, etc. Therapeutics of central nervous system (CNS) diseases have shown marked limited site-specific delivery of CNS by the poor access of various drugs into the brain, due to the presences of the blood-brain barrier (BBB) and blood-cerebrospinal fluid barrier (BCSFB). Hence, the availability of therapeutics delivery strategies is considered as one of the most major challenges facing the treatment of CNS diseases. The primary objective of this review is to elaborate the newer advances of nanogel for CNS drugs delivery, discuss the early preclinical success in the field of nanogel technology and highlight different insights on its potential neurotoxicity.

Best Practices for Minimally Invasive Lumbar Spinal Stenosis Treatment 2.0 (MIST): Consensus Guidance from the American Society of Pain and Neuroscience (ASPN)

Introduction

Methods

Results

Discussion

Conclusion

North American Neuromodulation Society Educational Curriculum for Intrathecal Drug Delivery Systems Implantation and Management

OBJECTIVES

Intrathecal drug delivery systems (IDDSs) are used for the treatment of pain and spasticity. A wide range of educational criteria exist for these devices. The North American Neuromodulation Society (NANS) Education Committee developed a comprehensive IDDS curriculum to function as a standard for physician graduate education and assessment through training and into practice.

MATERIAL AND METHODS

A multidisciplinary and diverse task force gathered by the NANS Education Committee met in person and virtually over several sessions and developed an IDDS curriculum modeling their previous work on spinal cord stimulation and following the Accreditation Council for Graduate Medical Education (ACGME) Milestones. There were iterative revisions and adaptations to the curriculum, and the final version was approved by the NANS Board of Directors.

RESULTS

The curriculum was developed with distinction between implanting physicians and managing physician and physicians who perform both tasks. There is a lateral temporal progression from early learner to practitioner, with advanced learner in the middle. In addition, there is a modular vertical organization that divides the curriculum into the six educational competencies outlined by the ACGME.

CONCLUSION

A comprehensive, modular, graduated, and segmented educational curriculum for IDDSs was developed by NANS. We propose the curriculum to be the standard for guidance and assessment of trainees and physicians pursuing training in implanting or managing IDDSs.

Intranasal Administration for Pain: Oxytocin and Other Polypeptides

Pain, particularly chronic pain, remains one of the most debilitating and difficult-to-treat conditions in medicine. Chronic pain is difficult to treat, in part because it is associated with plastic changes in the peripheral and central nervous systems. Polypeptides are linear organic polymers that are highly selective molecules for neurotransmitter and other nervous system receptors sites, including those associated with pain and analgesia, and so have tremendous potential in pain therapeutics. However, delivery of polypeptides to the nervous system is largely limited due to rapid degradation within the peripheral circulation as well as the blood–brain barrier. One strategy that has been shown to be successful in nervous system deposition of polypeptides is intranasal (IN) delivery. In this narrative review, we discuss the delivery of polypeptides to the peripheral and central nervous systems following IN administration. We briefly discuss the mechanism of delivery via the nasal–cerebral pathway. We review recent studies that demonstrate that polypeptides such as oxytocin, delivered IN, not only reach key pain-modulating regions in the nervous system but, in doing so, evoke significant analgesic effects. IN administration of polypeptides has tremendous potential to provide a non-invasive, rapid and effective method of delivery to the nervous system for chronic pain treatment and management.

Pre- and Post-Interventional Changes in Physiological Profiles in a Patient Presenting With Opioid Withdrawal After Intrathecal Drug Delivery System Failure Related to Assumed Catheter Microfracture

The intrathecal drug delivery system (IDDS) is successfully utilized for the treatment of chronic pain conditions; however, they are associated with complications related to human error and system failure. A case report is presented of a patient with opioid withdrawal (OW) secondary to assumed catheter microfracture. Interrogation of the IDDS allowed for the collection of pre- and post-treatment/stabilization cerebrospinal fluid (CSF), which is used to investigate the possible physiological determinants of OW.

A 46-year-old female with a history of low back pain after traumatic low back injury status post-IDDS placement for failed back surgery syndrome presented with signs and symptoms concerning for OW. After every other possible explanation was ruled out, it was hypothesized that there may be IDDS catheter microfracture(s), and catheter replacement led to symptom resolution. There were no significant differences in cytokine levels tested in pre-CSF versus post-CSF samples. Whole-cell patch-clamp electrophysiology analysis of human-induced pluripotent stem cell-derived nociceptors after treatment with pre- and post-CSF samples demonstrated modulation of action potential waveform.

In patients presenting with acute OW attribution IDDS malfunction, catheter microfracture must be in the differential, and non-conventional interrogation of the IDDS catheter should be considered. The possible differences in pre-CSF and post-CSF may be more complicated than previously postulated, as there were no significant differences in cytokine profiles; however, treatment of in vitro neurons with pre- and post-CSF resulted in differential neuronal excitability, which may account for some of the symptoms of OW.

Intrathecal pain management with ziconotide: Time for consensus?

This article summarizes recommendations made by six pain specialists who discussed the rationale for ziconotide intrathecal analgesia (ITA) and the requirement for evidence-based guidance on its use, from a European perspective. Riemser Pharma GmbH (Greifswald, Germany), which holds the European marketing authorization for ziconotide, hosted the meeting. The group agreed that ITA is under-used in Europe, adding that ziconotide ITA has potential to be a first-line alternative to morphine; both are already first-line options in the USA. Ziconotide ITA (initiated using a low-dose, slow-titration approach) is suitable for many patients with noncancer- or cancer-related chronic refractory pain and no history of psychosis. Adopting ziconotide as first-line ITA could reduce opioid usage in these patient populations. The group advocated a risk-reduction strategy for all candidate patients, including compulsory prescreening for neuropsychosis, and requested US-European alignment of the licensed starting dose for ziconotide: the low-and-slow approach practiced in the USA has a better tolerability profile than the fixed high starting dose licensed in Europe. Of note, an update to the European Summary of Product Characteristics is anticipated in early 2021. The group acknowledged that the Polyanalgesic Consensus Conference (PACC) treatment algorithms for ziconotide ITA provide useful guidance, but recommendations tailored specifically for European settings are required. Before a consensus process can formally begin, the group called for additional European prospective studies to investigate ziconotide in low-and-slow dosing strategies, in different patient settings. Such data would enable European guidance to have the most appropriate evidence at its core.

Narrative review of intrathecal drug delivery (IDD): indications, devices and potential complications

The management of chronic refractory pain (non-neoplastic and cancer-related pain) remains a therapeutic challenge. The continuous intrathecal (IT) administration of drugs may play an important role in the possible management options. Intrathecal drug delivery devices (IDDDs) may be effective for patients with refractory chronic pain. Therefore, they may be adopted for non-oncologic pain in patients with compression fractures, spondylolisthesis, spondylosis, back surgery failure syndrome and spinal stenosis. Oncologic patients can benefit from these treatments in a variable way according to tumor characteristics, prognosis, periprocedural imaging and risk of disease progression. In this review, we describe the most commonly used drugs (opioids and non-opioids), their pharmacokinetic and pharmacodynamic features and indications of use. The most used drugs are morphine, hydromorphone, fentanyl, methadone, bupivacaine, clonidine, and ketamine. Patient evaluation before the device implantation should be based on clinical examination, medical records assessment and psychometric evaluation. The infusion pumps available on the market are both non-programmable (with continuous IT deliver of drugs) and programmable (with variable deliver of drugs according to their flow rate). Moreover, we describe the procedure of implantation and the potential complications of IT drug delivery (such as bleeding, infection, loss of cerebrospinal fluid, wound seroma, loss of catheter pump propellant).

A Patient with an Intradural Tumor: An Unexpected Finding

Chronic back pain patients may require escalating doses of systemic opioids. In refractory cases, implantation of an intrathecal drug delivery system (IDDS) may provide effective relief of pain and improve overall function. This system infuses opioid directly into the cerebrospinal fluid via a catheter. While efficacious, it can be associated with complications, one of the most severe being the formation of a catheter-tip granuloma that can lead to permanent neurological deficits. We present a case of a 38-year-old male with an IDDS for pain related to retroperitoneal fibrosis, who began developing worsening back pain along with new-onset lower extremity weakness. A catheter-tip granuloma was suspected, and the patient was advised to obtain emergent spine imaging. He was non-compliant until the point of becoming wheelchair bound, whereupon imaging was finally obtained. Magnetic resonance imaging revealed an intradural mass causing spinal cord compression. After emergent surgical resection, pathology revealed a malignant tumor. Any patient with IDDS and escalating pain levels or new neurological deficits needs urgent neuroimaging to rule out catheter-tip granuloma. However, as this case demonstrates, the differential diagnosis should remain broad and always include neoplasm or abscess. 

Dendrimer-Based Drug Delivery Systems for Brain Targeting

Human neuroscience has made remarkable progress in understanding basic aspects of functional organization; it is a renowned fact that the blood-brain barrier (BBB) impedes the permeation and access of most drugs to central nervous system (CNS) and that many neurological diseases remain undertreated. Therefore, a number of nanocarriers have been designed over the past few decades to deliver drugs to the brain. Among these nanomaterials, dendrimers have procured an enormous attention from scholars because of their nanoscale uniform size, ease of multi-functionalization, and available internal cavities. As hyper-branched 3D macromolecules, dendrimers can be maneuvered to transport diverse therapeutic agents, incorporating small molecules, peptides, and genes; diminishing their cytotoxicity; and improving their efficacy. Herein, the present review will give exhaustive details of extensive researches in the field of dendrimer-based vehicles to deliver drugs through the BBB in a secure and effectual manner. It is also a souvenir in commemorating Donald A. Tomalia on his 80th birthday.