Spinal cord stimulation: a review of the safety literature and proposal for perioperative evaluation and management

Ketamine for Complex Regional Pain Syndrome: A Narrative Review Highlighting Dosing Practices and Treatment Response

This is a narrative review of intravenous ketamine infusions for the treatment of complex regional pain syndrome (CRPS). It briefly covers the definition of CRPS, its epidemiology, and other treatments before introducing ketamine as the article's focus. A summary of ketamine's evidence base and its mechanisms of action is provided. The authors then review ketamine dosages reported in peer-reviewed literature for the treatment of CRPS, and their associated duration of pain relief. The observed response rates to ketamine and predictors of treatment response are also discussed.

Perioperative and anesthetic considerations for the management of neuromodulation systems

The use of neuromodulation systems is increasing for the treatment of various pathologies ranging from movement disorders to urinary incontinence to chronic pain syndromes. While the type of neuromodulation devices varies, they are largely categorized as intracranial (eg, deep brain stimulation), neuraxial (eg, spinal cord stimulation, dorsal root ganglion stimulation, and intrathecal drug delivery systems), or peripheral (eg, sacral nerve stimulation and peripheral nerve stimulation) systems. Given the increasing prevalence of these systems in the overall population, it is important for anesthesiologists, surgeons, and the perioperative healthcare team to familiarize themselves with these systems and their unique perioperative considerations. In this review, we explore and highlight the various neuromodulation systems, their general perioperative considerations, and notable special circumstances for perioperative management.

Perioperative Management of Spinal Cord Stimulators and Intrathecal Pain Pumps

Spinal cord stimulators (SCSs) and intrathecal pain pumps (IPPs) are implantable devices used in the management of chronic pain or spasticity. Complications, such as infection, lead migration/failure, cerebrospinal fluid leak, neurologic injury, and other medical complications, can occur after placement and may require surgical intervention. Orthopaedic surgeons may encounter patients with these devices and should have a basic understanding of their function. In addition, they should be aware that patients may have residual stenosis or deformity contributing to their symptoms; thus, spine surgery referral may be indicated. If a patient with a SCS or IPP is undergoing revision spinal surgery, a preoperative discussion regarding retention versus removal of the device is imperative because indications for device retention, revision, and removal are complex. This review summarizes potential complications and intraoperative considerations concerning the proper perioperative management of SCSs/IPPs and will provide evidence-based data regarding management strategies for these devices.

Mitigating Spinal Cord Stimulator Lead Migration Complications in Minimally Invasive Spine Surgery: Technical Note

Spinal Cord Stimulators (SCS) are a nonpharmacologic chronic pain management treatment modality that is well-validated and cost-effective within the surgeon’s armamentarium. The reported complication rates are between 5.3% to 40%, most commonly secondary to mechanical hardware failure. The most common mechanical complication is lead migration, which necessitates second surgery. The purpose of this technical note is to describe a minimally invasive spine surgery (MISS) implantation technique we believe to be more resilient to lead migration. We present a stepwise technique for SCS implantation with a maxillofacial screw and washer failsafe.

Ultra-Low Energy Cycled Burst Spinal Cord Stimulation Yields Robust Outcomes in Pain, Function, and Affective Domains: A Subanalysis From Two Prospective, Multicenter, International Clinical Trials

INTRODUCTION

DeRidder's burst stimulation design has become a key spinal cord stimulation (SCS) waveform because it reduces the intensity of pain as well as its associated emotional distress. The brain pathways underlying these outcomes may also allow for the effects of stimulation to carry over after stimulation is turned off, making it amenable to intermittent application. Here, the utility of intermittently cycled burst was evaluated using data from two large real-world prospective studies (TRIUMPH, REALITY).

MATERIALS AND METHODS

Subjects used intermittent dosing in a 1:3 ratio (30 sec on, 90 sec off; N = 100) in TRIUMPH and 1:12 ratio in REALITY (30-sec on, 360-sec off; N = 95) for six months. Pain intensity (0-10 numeric rating scale), pain-related emotions on the pain catastrophizing scale (PCS), and physical function on PROMIS questionnaires were compared with preimplant baseline ratings and by group.

RESULTS

In both groups, mean pain intensity decreased by nearly 50% relative to baseline, PCS scores significantly decreased, and physical function improved. Importantly, no differences between the 1:3 and 1:12 groups were identified. A high proportion, 80% and 77% of the 1:3 and 1:12 groups, respectively, were considered responders on a multiple measures. No adverse events were associated with intermittent stimulation.

DISCUSSION

Intermittent cycling of burst SCS lowers the overall electric charge delivered to the spinal cord and preserves battery consumption, without compromising pain relief and associated symptoms.

Acute Pain Management of Chronic Pain Patients in Ambulatory Surgery Centers

PURPOSE OF REVIEW

With the widespread growth of ambulatory surgery centers (ASCs), the number and diversity of operations performed in the outpatient setting continue to increase. In parallel, there is an increase in the proportion of patients with a history of chronic opioid use and misuse undergoing elective surgery. Patients with such opioid tolerance present a unique challenge in the ambulatory setting, given their increased requirement for postoperative opioids. Guidelines for managing perioperative pain, anticipating postoperative opioid requirements and a discharge plan to wean off of opioids, are therefore needed.

RECENT FINDINGS

Expert guidelines suggest using multimodal analgesia including non-opioid analgesics and regional/neuraxial anesthesia whenever possible. However, there exists variability in care, resulting in challenges in perioperative pain management. In a recent study of same-day admission patients, anesthesiologists correctly identified most opioid-tolerant patients, but used non-opioid analgesics only half the time. The concept of a focused ambulatory pain specialist on site at each ASC has been suggested, who in addition to providing safe anesthesia, could intervene early once problematic pain issues are recognized. This review focuses on perioperative pain management in three subsets of patients who exhibit opioid tolerance: those on large doses of opioids (including abuse-deterrent formulations) for chronic non-malignant or malignant pain; those who have ongoing opioid misuse; and those who were prior addicts and are now on methadone/suboxone maintenance. We also discuss perioperative pain management for patients who have implanted devices such as spinal cord stimulators and intrathecal pain pumps.

A Comprehensive Practice Guideline for Magnetic Resonance Imaging Compatibility in Implanted Neuromodulation Devices

OBJECTIVES

The evolution of neuromodulation devices in order to enter magnetic resonance imaging (MRI) scanners has been one of understanding limitations, engineering modifications, and the development of a consensus within the community in which the FDA could safely administer labeling for the devices. In the initial decades of neuromodulation, it has been contraindicated for MRI use with implanted devices. In this review, we take a comprehensive approach to address all the major products currently on the market in order to provide physicians with the ability to determine when an MRI can be performed for each type of device implant.

MATERIALS AND METHODS

We have prepared a narrative review of MRI guidelines for currently marketed implanted neuromodulation devices including spinal cord stimulators, intrathecal drug delivery systems, peripheral nerve stimulators, deep brain stimulators, vagal nerve stimulators, and sacral nerve stimulators. Data sources included relevant literature identified through searches of PubMed, MEDLINE/OVID, SCOPUS, and manual searches of the bibliographies of known primary and review articles, as well as manufacturer-provided information.

RESULTS

Guidelines and recommendations for each device and their respective guidelines for use in and around MR environments are presented.

CONCLUSIONS

This is the first comprehensive guideline with regards to various devices in the market and MRI compatibility from the American Society of Pain and Neuroscience.

Development of an Educational Curriculum for Spinal Cord Stimulation

BACKGROUND

Spinal cord stimulators (SCSs) are used for treating chronic pain. The number of SCSs implanted each year is on the increase. The North American Neuromodulation Society (NANS) education committee aimed to develop a SCS curriculum as a tool to guide physicians at different training levels, based on the most recent evidence.

MATERIAL AND METHODS

A multidisciplinary (anesthesiology, physical medicine, neurosurgery, and neurology), taskforce representing the education committee of the NANS met to develop a SCS curriculum following the Accreditation Council for Graduate Medical Education (ACGME) milestones. The task force used the best available evidence and knowledge to develop the curriculum. Once developed, the SCS curriculum was then approved by the NANS board.

RESULTS

The task force developed a SCS training curriculum. Milestones included patient care and procedural skills, system-based practice, medical knowledge, interpersonal communication, practice based learning and professionalism. Each milestone was defined for three categories, early learner, advanced learner, and practitioner.

CONCLUSION

A multidisciplinary task force of the NANS education committee developed a SCS training curriculum that defines ACGME milestones for basic learners, advanced learners, and practitioners.

Pacemakers, Deep Brain Stimulators, Cochlear Implants, and Nerve Stimulators: A Review of Common Devices Encountered in the Dermatologic Surgery Patient

BACKGROUND

In dermatologic and procedural surgery settings, there are commonly encountered devices in patients. Safe surgical planning requires familiarity with these devices.

OBJECTIVE

To review the current implanted devices in patients and recommendations for surgical planning around these devices.

METHODS AND MATERIALS

A comprehensive review using PubMed and published device recommendations was performed, searching for those most relevant to dermatologic surgery.

RESULTS

Devices such as pacemakers and implantable cardiac defibrillators, deep brain stimulators, cochlear implants, and various nerve stimulators are potential devices that may be encountered in patients and specific recommendations exist for each of these devices.

CONCLUSION

Dermatologic surgeons' knowledge of implanted devices in patients is paramout to safe surgical procedures.

Neuromodulation in multiple sclerosis

Neuromodulation, or the utilization of advanced technology for targeted electrical or chemical neuronal stimulation or inhibition, has been expanding in several neurological subspecialties. In the past decades, immune-modulating therapy has been the main focus of multiple sclerosis (MS) research with little attention to neuromodulation. However, with the recent advances in disease-modifying therapies, it is time to shift the focus of MS research to neuromodulation and restoration of function as with other neurological subspecialties. Preliminary research supports the value of intrathecal baclofen pump and functional electrical stimulation in improving spasticity and motor function in MS patients. Deep brain stimulation can improve MS-related tremor and trigeminal neuralgia. Spinal cord stimulation has been shown to be effective against MS-related pain and bladder dysfunction. Bladder overactivity also responds to sacral neuromodulation and posterior tibial nerve stimulation. Despite limited data in MS, transcranial magnetic stimulation and brain-computer interface are promising neuromodulatory techniques for symptom mitigation and neurorehabilitation of MS patients. In this review, we provide an overview of the available neuromodulatory techniques and the evidence for their use in MS.

Perioperative Surgical Home for the Patient with Chronic Pain

The management of acute pain for the phenotypically different patient who suffers from chronic pain is challenging. The care of these patients is expensive and siloed. The physician-led, multidisciplinary, patient-centric, care coordination framework of the perioperative surgical home is an optimal vehicle for the management of these patients. The engagement of physician anesthesiologists in the optimization, in-hospital management, and postdischarge care of the patient with chronic pain will lead to improved outcomes, reduced health care expenditures, and improve the health of this challenging population.

The primary diagnosis and the coexisting anxiety disorders have no impact on the additional surgical procedure after spinal cord stimulators implantation: An analysis of 11,029 patients

Studies have demonstrated superior outcomes and cost effectiveness of the spinal cord stimulation (SCS) for the treatment of chronic pain syndromes such as failed back surgery syndrome (FBSS) or complex regional pain syndrome (CRPS). However, little is known about the impact of primary diagnosis or mental disorders on the revision rate. This is the Retrospective cohort study to analyze the reintervention rates based on the primary diagnosis or comorbid mental disorder. Data of the annual trends of SCS use, revision and removal rate of SCS and additional surgical rate after removal was collected and analyzed for patients undergoing SCS between 2007 and 2015, within a private insurance billing database. Trial cases were excluded from this study. The results showed 11,029 patients received SCS implantation with percutaneous electrodes (PE, n = 7418) or surgical electrode (SE, n = 3611). There was a trend of increasing use of SCS from 2007 to 2013, followed by a decrease in last two years. There was no significant difference in the neither removal nor revision rate regardless between the patients with FBSS or CRPS at each time point. Although the removal rates within 2 years were significantly higher in the patients with anxiety disorders compared to the patients without any mental disorders (PE: p < .001, SE: 0.003), the rate of additional surgery after the removal showed no significant difference (PE: p = .532, SE: p = .262). Therefore, we concluded that the primary diagnosis and the presence of anxiety disorders did not have an impact on the additional surgical rate following SCS implantation.

Thoracic Radiculopathy following Spinal Cord Stimulator Implantation Treated with Corticosteroids

INTRODUCTION

Spinal cord stimulation has been used since 1967 to manage chronic neuropathic pain. Although effective, the literature describes the complication rate to be as high as 35%. One rare complication following spinal cord stimulator (SCS) implantation is the development of radicular pain. We present a case series of 2 patients implanted with SCSs who developed thoracic radiculopathy following implantation that resolved with corticosteroids.

CASE DETAILS

Although this complication was previously thought to require surgical intervention, this case series describes the use of corticosteroids to resolve postimplantation thoracic radiculopathy. Two patients were studied in this case series who received permanent thoracic implantation of a paddle lead SCS. Several days later, both developed back pain radiating toward the umbilicus in a dermatomal pattern consistent with thoracic radiculopathy. Corticosteroids were administered to relieve this pain. One received 6 mg dexamethasone intravenously every 6 hours followed by an oral dexamethasone taper for 1 week. The other was treated with an oral methylprednisolone taper for 2 weeks.

RESULTS

Upon follow-up, both patients no longer complained of the thoracic radiculopathy and were satisfied with the pain relief the stimulators provided.

CONCLUSION

In conclusion, postsurgical radicular pain is a rare but troubling complication of SCS implantation. In order to avoid further surgical complications or the need to explant a device that provides satisfactory paresthesia coverage, pharmacologic management is desirable. This case series has demonstrated that the use of corticosteroids can effectively resolve postimplantation thoracic radicular pain in a specific subgroup of patients.

Epidural Spinal Stimulation to Improve Bladder, Bowel, and Sexual Function in Individuals With Spinal Cord Injuries: A Framework for Clinical Research

While some recent studies that apply epidural spinal cord stimulation (SCS) have demonstrated a breakthrough in improvement of the health and quality of the life of persons with spinal cord injury (SCI), the numbers of people who have received SCS are small. This is in sharp contrast to the thousands of persons worldwide living with SCI who have no practical recourse or hope of recovery of lost functions. Thus, the vision is to understand the full potential of this new intervention and to determine if it is safe and effective in a larger cohort, and if it is scalable so that it can be made available to all those who might benefit. To achieve this vision, the National Institute of Biomedical Imaging and Bioengineering called for and organized a consortium of multiple stakeholder groups: foundations addressing paralysis, federal and public agencies, industrial partners, academicians, and researchers, all interested in the same goal. Based on input from consortium participants, we have reasoned that a first step is to define a scalable SCS approach that is effective in restoring lost autonomic physiology, specifically bladder, bowel, and sexual function. These functions are most critical for improving the quality of life of persons living with SCI. This report outlines a framework for conducting the research needed to define such an effective SCS procedure that might seek Food and Drug Administration approval and be implemented at the population level.

New modalities of neurostimulation: high frequency and dorsal root ganglion

PURPOSE OF REVIEW

Neurostimulation is a well tolerated, cost-efficient, and effective method to treat chronic pain. Although spinal cord stimulation (SCS) has been shown to help patients, newer modalities such as burst, kilohertz-frequency, and dorsal root ganglion stimulation may provide greater pain relief, fewer paresthesias, and better outcomes.

RECENT FINDINGS

Burst stimulation, programed as five-impulse burst at a frequency of 500 Hz, delivers more charge per second than conventional stimulation. Trials of burst stimulation have shown superior pain relief, decreased paresthesias, and patient preference compared with conventional SCS. Kilohertz-frequency SCS uses low-amplitude, high-frequency (10 kHz), and short-duration pulses. The SENZA trial showed superiority in both back and leg pain with greater pain relief as well as decreased opioid use. Dorsal root ganglion stimulation stimulates the ganglion cells allowing for precise targeting of pain regions. Multiple studies, including the ACCURATE trial, have shown superior pain relief in multiple conditions.

SUMMARY

Improvements in pain control and patient satisfaction suggest that these new stimulation patterns will greatly increase the utility of neurostimulation; however, clinical trials with broader patient populations have to be done to support more extensive use of these therapies.

Do we need to establish guidelines for patients with neuromodulation implantable devices, including spinal cord stimulators undergoing nonspinal surgeries?

Background:

Spinal cord stimulation is currently approved to treat chronic intractable pain of the trunk and limbs. However, such implantable electronic devices are vulnerable to external electrical currents and magnetic fields. Within the hospitals and modern operating rooms (ORs), there is an abundance of electrical devices and other types of equipment that could interfere with such devices. Despite the increasing number of patients with neuromodulation implantable devices, there are no written guidelines available or consensus of cautions for such patients undergoing unrelated surgery.

Case Descriptions:

A 60-year-old female with a permanent St. Jude's spinal cord stimulator (SCS) presented for open total abdominal hysterectomy. Both the anesthesia and gynecology staffs were aware of the device presence, but were unaware of any precautions regarding intraoperative management. The device was found to be nonmagnetic resonance imaging compatible, and bipolar cautery was used instead of monopolar cautery. A 59-year-old female with a 9-year-old permanent Medtronic SCS, presented for right total hip arthroplasty. The device was switched off prior to entering the OR, bipolar cautery was used, and grounding pads were placed away from her battery site. In each case, the manufacturer's representative was contacted preoperative. Both surgeries proceeded uneventfully.

Conclusions:

The Food and Drug Administration safety information manual warns about the use of diathermy, concomitant implanted stimulation devices, lithotripsy, external defibrillation, radiation therapy, ultrasonic scanning, and high-output ultrasound, all of which can lead to permanent implant damage if not turned off prior to undertaking procedures. Lack of uniform guidelines makes intraoperative management, as well as remote anesthesia care of patients with previously implanted SCSs unsafe.