Introduction:Neuromodulation has been a staple of treatment for moderate-to-severe chronic refractory pain since the introduction of the first spinal cord stimulator by Norman Shealy in 1967. Appreciating the dynamic nature of electrical modulation of the nervous system from the epidural space, the goal has been consistent, reliable, and therapeutic neural activation of the spinal cord. This has proven to be extremely difficult. Recently, the Food and Drug Administration (FDA) released a guidance on physiologic closed loop controlled (PCLC) devices, highlighting the potential for these therapies to deliver accurate, consistent, real-time therapy, enhancing medical care and reducing variability. Because of the growing neuromodulation market focus on PCLC strategies, the American Society of Pain and Neuroscience (ASPN) sought to develop guidance on safety and efficacy, along with a taxonomy surrounding PCLC systems (PCLCSs) and to develop an evidence-based best practice review. Methods:A librarian-assisted literature search was performed to identify manuscripts relevant to the topic of PCLC stimulation for management of chronic pain. Initial literature search was performed utilizing MEDLINE, EMBASE, Cochrane database, BioMed Central, and Web of Science. Included manuscripts encompassed meta-analyses, systematic reviews, randomized controlled trials (RCTs), prospective or retrospective studies with follow-up to 12 months, limited to the English language. MESH terms utilized included "closed-loop", "physiologic closed loop controlled", "spinal cord stimulation", "closed loop feedback", "feedback controlled", "neuromodulation", "pain", "persistent pain", "neuropathic pain", and "chronic pain". The modified USPSTF evidence and recommendation grading strategy previously utilized was again employed. Results:Four studies were identified for review, 2 prospective, one retrospective, and one randomized controlled study with at least 12-month follow-up. Conclusion:PCLC neuromodulation is an innovation that requires a responsible introduction. As commercial access grows, there is a responsibility that requires consistency with definition, evidence generation, focused on safety and efficacy.
Peripheral nerve stimulation (PNS) has evolved with various applications and durations of therapy. In recent years, extensive data has been developed on a 60-day treatment using a novel approach. Confusion exists on the use of a trial therapy, a permanent implant, and a 60-day duration treatment. The American Society of Pain and Neuroscience (ASPN) seeks to clarify the literature associated with this neuromodulation approach. A diverse group of experts was nominated to provide opinions and guidance based on evidence-graded assessment and clinical knowledge. This guidance is the first to specifically assess the clinical use of 60-day PNS and best medical practice.
Background: Chronic knee pain from osteoarthritis (OA) affects a significant proportion of adults over 40. Total knee arthroplasty (TKA) remains the standard for advanced OA, yet up to 20% of patients experience chronic postsurgical pain (CPSP). Genicular nerve radiofrequency ablation (GNRFA) can alleviate pain in those unresponsive to conservative treatments or TKA. However, anatomical variability of the genicular nerves may limit treatment durability. This retrospective, single-center observational study investigated whether using a novel V-shaped active tip needle-which creates larger lesions-could improve outcomes. Methods: Fifty patients with symptomatic knee OA or CPSP, who had a >= 50% reduction in pain after diagnostic genicular nerve blocks, underwent GNRFA with a V-shaped active tip needle between September 2020 and January 2022. Pain and function were assessed using the visual analogue scale (VAS) at rest and during movement, Western Ontario and McMaster Universities Arthritis Index (WOMAC), Douleur Neuropathique en 4 Questions (DN4), and EuroQol-5 Dimensions (EQ-5D) at baseline and 1, 3, 6, and 9 months post-procedure. Results: By 6 months, 64% of patients showed >= 50% reduction in VAS pain scores, sustained at 9 months (p< 0.0001). Median WOMAC scores improved from 62.0 at baseline to 40.0 at 6 months (p< 0.0001). DN4 scores declined from a median of 4.0 at baseline to 2.0 at 6 months and 1.0 at 9 months (p< 0.001). EQ-5D scores demonstrated significant enhancement in quality of life (p< 0.01). Pain intensity differences at rest and during movement remained substantially improved at 9 months (p< 0.0001). Conclusion: GNRFA using a V-shaped active tip needle is a promising intervention for chronic knee pain, offering significant and sustained pain relief and functional improvement. Larger lesions created by the novel needle may overcome anatomical challenges, though further randomized studies are warranted to validate efficacy and safety.
Patients with cancer pain refractory to conventional medical management may benefit from spinal analgesia, although there are some critical points regarding some aspects which cannot be examined by an evidence-based approach. A group of experts was selected by MASSC to provide clinical practice advice on the use of spinal drug delivery in patients with cancer-related pain. Refractory cancer pain should be considered a condition in which a patient has failed to receive adequate analgesia or has developed uncontrolled side effects after comprehensive pain management. The intrathecal route (IT) with an implantable drug delivery system allows the administration of minimal doses of analgesics with significant clinical effects while avoiding major adverse effects and lower risks with prolonged use. Morphine and hydromorphone are the opioids of choice for IT treatment. Local anesthetics are an added value because of their additive-synergic effect on segmental areas. The efficacy of adding small amounts of local anesthetics to an ITDD relies on the positioning of the tip of the catheter close to the dermatome where the origin of the pain comes from. Their use, however, depends on the delivery system, because larger volumes are necessary. Ziconotide requires a slow dose titration, but it can be used in small volumes. In addition, once doses are stabilized, no tolerance occurs. A conversion ratio of 100:1 between oral and IT morphine is suggested for patients who receive high doses of systemic opioids. A higher ratio (300:1) should be used in patients prevalently switched to the IT route for uncontrollable adverse effects, receiving lower doses of systemic opioids. The use of boluses of hydrophilic opioids, like morphine, for treating breakthrough pain may be inadequate, as intrathecal opioids alone may be unable to adequately treat an episode of rapid pain onset and duration. The decision-making process for employing interventional therapies, like spinal analgesia, should be shared, taking into account the actual indications and needs, previous treatments, prognosis, timing, advantages and disadvantages, and complications, in any individual situation, managing all the aspects of care.
Peripheral nerve stimulation (PNS) has evolved substantially over recent decades in terms of hardware and evidence supporting efficacy. Treatment targets continue to expand and address both pain and functional applications. The American Society of Pain and Neuroscience (ASPN) seeks to substantially update and expand upon a review of the evidence supporting PNS as well as provide guidelines for clinical practice. A diverse multidisciplinary panel of experts was selected to provide opinions and guidance based on evidence-graded assessment and clinical knowledge. This document aims to serve as a resource for clinicians and payors in the interest of expanding awareness of the breadth of research in the field of PNS and expanding access to therapy.
