Systematic review and meta-analysis of controlled trials assessing spinal cord stimulation for inoperable critical leg ischaemia

Use of an Antibacterial Envelope in Spinal Cord Stimulation Reduces the Rate and Severity of Iatrogenic Infections

OBJECTIVE

To examine if the use of an antibacterial envelope (TYRX) decreases the rate of postoperative infection in chronic pain patients undergoing treatment with spinal cord stimulation (SCS) involving device implantation.

METHODS

Single-center retrospective cohort study comparing postoperative infections rates in non-TYRX recipients from 2018 to 2020 with recipients of a TYRX antibacterial envelope from 2020 to 2021. Infection was registered if a patient received any form of antibiotic treatment after hospital discharge within a follow-up period of 100 days.

RESULTS

A total of 198 patients were included: 100 in the TYRX group and 98 in the non-TYRX group. There were no significant differences between the 2 groups regarding age, body mass index (BMI), smoking, diabetes, and use of immunosuppression. The overall infection rate was 5.6%. The infection rate was 4% in the TYRX group and 7.1% in the non-TYRX group (P = 0.6). However, the 4 cases of postoperative infection in the TYRX group could be effectively managed with oral antibiotics alone, whereas 6 out of the 7 patients in the non-TYRX group required intravenous antibiotics. Moreover, device explantation was necessary in 3 of these patients suggesting the event of more severe infections in the non-TYRX group (P = 0.014).

CONCLUSIONS

The TYRX antibacterial envelope displayed infection rates reducing capabilities, along with a clear tendency to reduce revision surgeries and system removals due to infections.

Role of patient selection and trial stimulation for spinal cord stimulation therapy for chronic non-cancer pain: a comprehensive narrative review

Background/importance

Patient selection for spinal cord stimulation (SCS) therapy is crucial and is traditionally performed with clinical selection followed by a screening trial. The factors influencing patient selection and the importance of trialing have not been systematically evaluated.

Objective

We report a narrative review conducted to synthesize evidence regarding patient selection and the role of SCS trials.

Evidence review

Medline, EMBASE and Cochrane databases were searched for reports (any design) of SCS in adult patients, from their inception until March 30, 2022. Study selection and data extraction were carried out using DistillerSR. Data were organized into tables and narrative summaries, categorized by study design. Importance of patient variables and trialing was considered by looking at their influence on the long-term therapy success.

Findings

Among 7321 citations, 201 reports consisting of 60 systematic reviews, 36 randomized controlled trials (RCTs), 41 observational studies (OSs), 51 registry-based reports, and 13 case reports on complications during trialing were included. Based on RCTs and OSs, the median trial success rate was 72% and 82%, and therapy success was 65% and 61% at 12 months, respectively. Although several psychological and non-psychological determinants have been investigated, studies do not report a consistent approach to patient selection. Among psychological factors, untreated depression was associated with poor long-term outcomes, but the effect of others was inconsistent. Most RCTs except for chronic angina involved trialing and only one RCT compared patient selection with or without trial. The median (range) trial duration was 10 (0–30) and 7 (0–56) days among RCTs and OSs, respectively.

Conclusions

Due to lack of a consistent approach to identify responders for SCS therapy, trialing complements patient selection to exclude patients who do not find the therapy helpful and/or intolerant of the SCS system. However, more rigorous and large studies are necessary to better evaluate its role.

Treatment of end-stage peripheral artery disease by Neuromodulation

BACKGROUND: Neuromodulation is a therapeutic option to improve limb salvage in end-stage peripheral arterial disease (PAD), but there is no consensus on indication for spinal cord stimulation (SCS) in PAD patients. OBJECTIVE: The aim of this study was to present end-stage PAD patient outcomes treated with SCS. METHODS: This study is a retrospective analysis based on a local prospective registry. Neuromodulation was performed there was: [1] no revascularisation option, [2) no septicaemia, [3) Rutherford stage 4–6. The primary endpoint of the study was limb salvage. Secondary endpoints were improvement in pain symptoms (assessed using a visual anlog scale/VAS) and improvement in walking distance. RESULTS: Limb salvage was reached in 30/34 patients (88%). Patients reported a significant reduction in pain on the 10-point VAS scale from baseline (median = 7.5, IQR = 7–8) to follow-up at 2 years (median = 0, IQR 0–2.75), p <  0.001. Walking distance also improved from preoperative (median = 50 m, IQR = 20–50 m) to follow-up at 2 years (median = 150 m, IQR 50–272 m), p <  0.001. RESULTS: SCS implantation in patients with end-stage PAD can enable limb salvage in a high percentage of cases and increase mobility due to pain reduction. The role of microcirculation in these improvements needs to be investigated in further studies.

[Chronic spinal stimulation in treatment of lower limb critical ischaemia syndrome]

Obliterating peripheral artery disease is a commonly occurring pathological condition, most often resulting from an atherosclerotic lesion of vessels with progressive narrowing of their lumens. The consequences of decompensation of chronic arterial insufficiency such as ischaemic pain, claudication, and trophic impairments are in some instances difficult to treat, despite using multicomponent medicamentous therapy and/or performing revascularizing interventions. This article describes a clinical case report regarding the use of spinal stimulation in a patient presenting with stage IV chronic lower limb ischaemia according to the Fontaine classification. This is accompanied and followed by depicting the dynamics of the laboratory, instrumental, and clinical parameters over a two-year follow-up period. In order to explain the choice of the intervention and the causes of the described picture, discussed are the existing theories of the mechanisms of action of spinal stimulation. To this is added a literature review of using this method in treatment of lower limb critical ischaemia when performing reconstructive angiosurgical treatment is unavailable. Mention is also made of the incidence and types of probable complications, as well as possibilities and limitations of the method.

The Efficacy of the Transdermal Isosorbide Dinitrate Patch in Patients With Chronic Limb-Threatening Ischemia

Recently, the number of patients with peripheral artery disease (PAD), including those with chronic limb-threatening ischemia (CLTI), has increased because of the increasing number of diabetic or dialysis patients worldwide. Revascularization is an important therapy for patients with CLTI. However, we sometimes experience refractory cases with insufficient peripheral circulation or microcirculation after revascularization. In this situation, additional therapy can be administered, such as low-density lipoprotein apheresis, high-pressure oxygen therapy, and spinal cord stimulation. However, they are not effective in some cases. Some reports have also indicated that transdermal isosorbide dinitrate patch (ISDN-P) is a useful therapy for PAD. As the efficacy of ISDN-P for patients with CLTI is not well-known, we examined it in this study. We assessed the skin perfusion pressure (SPP) after affixing an ISDN-P on the foot, because SPP measurement has proved useful in the assessment of PAD and is a good indicator of wound healing potential. The SPP (dorsal and plantar aspects) after ISDN-P application on the foot of healthy volunteers increased (n = 8; mean ± SD, 12.6 ± 7.9 [P = .12], and 21.2 ± 7.7 mm Hg [P < .05], respectively), as did SPP of patients with CLTI (n = 10; mean ± SD, 19.8 ± 2.5 [P < .01], and 14.1 ± 5.9 mm Hg [P < .05], respectively). All the patients who received an ISDN-P on the foot had no major complication, and no significant change in blood pressure. In conclusion, the ISDN-P is one of the effective and safe therapies for patients with CLTI.

Long-Term Spinal Cord Stimulation Alleviates Mechanical Hypersensitivity and Increases Peripheral Cutaneous Blood Perfusion in Experimental Painful Diabetic Polyneuropathy

Objectives

This study utilizes a model of long‐term spinal cord stimulation (SCS) in experimental painful diabetic polyneuropathy (PDPN) to investigate the behavioral response during and after four weeks of SCS (12 hours/day). Second, we investigated the effect of long‐term SCS on peripheral cutaneous blood perfusion in experimental PDPN.

Methods

Mechanical sensitivity was assessed in streptozotocin induced diabetic rats (n = 50) with von Frey analysis. Hypersensitive rats (n = 24) were implanted with an internal SCS battery, coupled to an SCS electrode covering spinal levels L2–L5. The effects of four weeks of daily conventional SCS for 12 hours (n = 12) or Sham SCS (n = 12) were evaluated with von Frey assessment, and laser Doppler imaging (LDI).

Results

Average paw withdrawal thresholds (PWT) increased during long‐term SCS in the SCS group, in contrast to a decrease in the Sham group (Sham vs. SCS; p = 0.029). Twenty‐four hours after long‐term SCS average PWT remained higher in the SCS group. Furthermore, the SCS group showed a higher cutaneous blood perfusion during long‐term SCS compared to the Sham group (Sham vs. SCS; p = 0.048). Forty‐eight hours after long‐term SCS, no differences in skin perfusion were observed.

Discussion

We demonstrated that long‐term SCS results in decreased baseline mechanical hypersensitivity and results in increased peripheral blood perfusion during stimulation in a rat model of PDPN. Together, these findings indicate that long‐term SCS results in modulation of the physiological circuitry related to the nociceptive system in addition to symptomatic treatment of painful symptoms.

Minimally Invasive Placement of Spinal Cord Stimulator Paddle Electrodes Is Associated With Improved Perioperative and Long-Term Experience Among Neuropathic Pain Patients

STUDY DESIGN

Prospective, observational cohort study.

OBJECTIVE

This study compared in-hospital and long-term outcomes among spinal cord stimulation (SCS) patients undergoing paddle insertion by open or minimally invasive surgery (MIS) approaches.

SUMMARY OF BACKGROUND DATA

Patients with treatment-refractory extremity neuropathic pain may benefit from SCS. Conventional placement of surgical paddles for an external neurostimulation trial is through open laminectomy, but MIS techniques may offer advantages.

METHODS

Twenty SCS patients were prospectively assessed. Open patients underwent caudal thoracic laminectomy for multicolumnar electrode paddle placement. MIS patients underwent paddle placement through interlaminar flavectomy using tubular retractors. Demographic data included age, sex, underlying diagnosis, and preoperative visual analog scale (VAS) extremity scores. Intraoperative data included operative duration, blood loss, and number of device passages to achieve final position. Perioperative data included VAS back pain scores; trial data included time-to-trial and time-to-decision. Postoperative data included 1 month VAS back pain scores and 1 year follow-up device complications.

RESULTS

No demographic differences were observed among surgical cohorts. MIS procedures had shorter operative duration (P = 0.03), less blood loss (P < 0.001), and similar median number of device passages (2 vs 1.5, P = 0.71). MIS patients reported less perioperative surgical back pain (P < 0.05). External neurostimulation trials began sooner among MIS patients who also made sooner decision whether to implant the SCS device (2.8 ± 1.4 vs 4.3 ± 1.0 days, P = 0.013). Similar 1 month back pain scores were reported between surgical cohorts (P = 0.08).

CONCLUSION

MIS techniques for SCS surgical paddle implantation is associated with less perioperative morbidity and surgical site back pain, shorter external neurostimulator trial duration, and long-term device stability benefits.

LEVEL OF EVIDENCE

2.

The Advancing Role of Neuromodulation for the Management of Chronic Treatment-Refractory Pain

Neuropathic pain is a common cause of disability and health care utilization. While judicious pharmacotherapy and management of comorbid psychological distress can provide for improved quality of life, some patients with treatment-refractory disease require more invasive therapies. Spinal cord stimulation can provide for improvement in pain and decrease in medication utilization, with level 1 evidence supporting its use across various pain etiologies including persistent postoperative neuropathic pain, complex regional pain syndrome, chronic inoperable limb ischemia, treatment refractory angina, and painful diabetic neuropathy. These procedures can be done with acceptably low morbidity and provide a cost-effective solution for those patients in whom medical therapies have failed. Technological innovation in lead design, implantable pulse generator capability, and stimulation algorithms and parameters may further enhance the success of this therapy. Neuromodulation of distal targets such as dorsal root ganglion may permit greater anatomic specificity of the therapy, whereas subthreshold stimulation with high-frequency or burst energy delivery may eliminate noxious and off-target paresthesiae. Such new technologies should be subject to rigorous evaluation as their mechanisms of action and long-term outcomes remain hitherto undefined.

A Multidisciplinary Infection Control Bundle to Reduce the Number of Spinal Cord Stimulator Infections

OBJECTIVE

To investigate the effect of a quality improvement project that resulted in an infection control bundle to reduce the number of spinal cord stimulator (SCS) infections.

MATERIALS AND METHODS

The study was performed in a single center for neuromodulation from January 1, 2014, through May 31, 2016. In response to a high number of surgical site infections (SSIs) after SCS surgery, a multidisciplinary team analyzed the surgical process and developed an infection prevention bundle consisting of five items: 1) showering and decolonization for five days prior to surgery and showering in the hospital on the morning of surgery; 2) performing the SCS implantation as the first in the daily operating room (OR) program; 3) maintaining a minimal number of people in the OR; 4) providing home care nurses with a folder with SCS wound care instructions including pictures; 5) giving oral specific wound care instructions to patients. The number of infections was calculated for the baseline, implementation, and sustainability phases.

RESULTS

A total of 410 SCS surgeries were performed during the study period. In the preintervention phase, 26/249 (10.4%) SCS surgeries were infected. During the implementation and sustainability phase, 2/59 (3.4%) and 1/102 (1.0%) SCS surgeries were infected, respectively. The reduction in the number of infections in pre and postintervention phase was statistically significant (p = 0.003).

CONCLUSION

Multidisciplinary measures to reduce SSIs reduced the number of SCS associated infections in our study setting.

Complications related to the use of spinal cord stimulation for managing persistent postoperative neuropathic pain after lumbar spinal surgery

OBJECT

Structural spinal surgery yields improvement in pain and disability for selected patients with spinal stenosis, spondylolisthesis, or a herniated intervertebral disc. A significant fraction of patients exhibit persistent postoperative neuropathic pain (PPNP) despite technically appropriate intervention, and such patients can benefit from spinal cord stimulation (SCS) to alleviate suffering. The complication profile of this therapy has not been systematically assessed and, thus, was the goal of this review.

METHODS

A comprehensive literature search was performed to identify prospective cohorts of patients who had PPNP following structurally corrective lumbar spinal surgery and who underwent SCS device implantation. Data about study design, technique of SCS lead introduction, and complications encountered were collected and analyzed. Comparisons of complication incidence were performed between percutaneously and surgically implanted systems, with the level of significance set at 0.05.

RESULTS

Review of 11 studies involving 542 patients formed the basis of this work: 2 randomized controlled trials and 9 prospective cohorts. Percutaneous implants were used in 4 studies and surgical implants were used in 4 studies; in the remainder, the types were undefined. Lead migration occurred in 12% of cases, pain at the site of the implantable pulse generator occurred in 9% of cases, and wound-related complications occurred in 5% of cases; the latter 2 occurred more frequently among surgically implanted devices.

CONCLUSIONS

Spinal cord stimulation can provide for improved pain and suffering and for decreased narcotic medication use among patients with PPNP after lumbar spinal surgery. This study reviewed the prospective studies forming the evidence base for this therapy, to summarize the complications encountered and, thus, best inform patients and clinicians considering its use. There is a significant rate of minor complications, many of which require further surgical intervention to manage, including lead migration or implant infection, although such complications do not directly threaten patient life or function.

The appropriate use of neurostimulation of the spinal cord and peripheral nervous system for the treatment of chronic pain and ischemic diseases: the Neuromodulation Appropriateness Consensus Committee

INTRODUCTION

The Neuromodulation Appropriateness Consensus Committee (NACC) of the International Neuromodulation Society (INS) evaluated evidence regarding the safety and efficacy of neurostimulation to treat chronic pain, chronic critical limb ischemia, and refractory angina and recommended appropriate clinical applications.

METHODS

The NACC used literature reviews, expert opinion, clinical experience, and individual research. Authors consulted the Practice Parameters for the Use of Spinal Cord Stimulation in the Treatment of Neuropathic Pain (2006), systematic reviews (1984 to 2013), and prospective and randomized controlled trials (2005 to 2013) identified through PubMed, EMBASE, and Google Scholar.

RESULTS

Neurostimulation is relatively safe because of its minimally invasive and reversible characteristics. Comparison with medical management is difficult, as patients considered for neurostimulation have failed conservative management. Unlike alternative therapies, neurostimulation is not associated with medication-related side effects and has enduring effect. Device-related complications are not uncommon; however, the incidence is becoming less frequent as technology progresses and surgical skills improve. Randomized controlled studies support the efficacy of spinal cord stimulation in treating failed back surgery syndrome and complex regional pain syndrome. Similar studies of neurostimulation for peripheral neuropathic pain, postamputation pain, postherpetic neuralgia, and other causes of nerve injury are needed. International guidelines recommend spinal cord stimulation to treat refractory angina; other indications, such as congestive heart failure, are being investigated.

CONCLUSIONS

Appropriate neurostimulation is safe and effective in some chronic pain conditions. Technological refinements and clinical evidence will continue to expand its use. The NACC seeks to facilitate the efficacy and safety of neurostimulation.

Current challenges in spinal cord stimulation

OBJECTIVES

This study aims to review the current state of spinal cord stimulation for the treatment of chronic pain associated with failed back surgery syndrome (FBSS) and complex regional pain syndrome (CRPS) and to describe intraspinal targets and stimulation parameters, patient selection, therapy cost-effectiveness, and strategies to improve outcomes.

MATERIALS AND METHODS

We drew on professional literature spanning four decades, our work with national and international professional societies, and our own extensive clinical experience to summarize contemporary knowledge of the safety, efficacy, cost-efficiency, and challenges associated with spinal cord stimulation in treating chronic pain.

RESULTS

The safety, efficacy, and cost-efficiency of spinal cord stimulation in treating chronic pain associated with FBSS and CRPS are well established through randomized controlled trials and long-term observational studies. Challenges include reducing wait-times before implant, which are associated with lower success rates; increasing awareness of this therapy among referring physicians, patients, and payers; decreasing device-related complications by incorporating advanced technology, improved operative and trialing techniques, and appropriate patient selection; and capturing functional and quality-of-life outcomes. Spinal cord stimulation must be part of an overall treatment plan to manage chronic pain, and must engage physicians, patients, their families, pharmacists, nursing staff, and mental health experts in supporting a return to employment, if possible, and to a full domestic and social life.

CONCLUSIONS

Innovation in spinal cord stimulation therapy has intensified with numerous new technical capabilities, safety advances, and novel stimulation targets. This progress holds hope for the many sufferers of chronic pain.

[Painful ischemic neuropathy]

Chronic ischemia in patients with peripheral arterial disease (PAD) represents a common medical problem. Neuropathic changes and pain caused by chronic ischemia are often found in the lower extremities of these patients. Pain in patients with chronic critical limb ischemia fulfill the criteria of neuropathic pain. Diagnostic tools besides medical history and examination are questionnaires, quantitative sensory testing (QST) and measuring intraepidermal nerve fiber density (IENFD) when indicated. A pharmacological approach with non-opioids and opioids as well as antidepressive and anticonvulsive drugs (according to the recommendations for the therapy of neuropathic pain) seems to be indicated for treating painful ischemic neuropathy. Spinal cord stimulation (SCS) provides the best evidence for invasive procedures in treating chronic ischemic pain.

Spinal cord stimulation to achieve wound healing in a primary lower limb critical ischaemia referral centre

Critical lower limb ischaemia is a diffuse pathology that could cause claudication, severe ischaemic pain and tissue loss. The common treatment includes modification of risk factors, pharmacological therapy and endovascular or surgical revascularisation of the lower limb to restore a pulsatile flow distally. Spinal cord stimulator is seen as a valid alternative in patients unsuitable for revascularisation after endovascular or surgical revascularisation failure and as adjuvant therapy in the presence of a functioning bypass in patients with extensive tissue loss and gangrene presenting a slow and difficult wound healing. We report our experience on spinal cord stimulation (SCS) indication and implantation in patients with critical lower limb ischaemia, at a high-volume centre for the treatment of peripheral arterial disease.

The use of spinal cord stimulation in pain management

SUMMARY Pain is a complex behavior process, the anatomy and physiology of which is not completely understood, and is subject to continuous exploration and research. Following on the heels of Melzack and Wall's gate control theory of pain (1965), Shealey et al., in 1967, were the first to implant stimulation electrodes over the dorsal columns in an attempt to provide relief for patients with chronic, intractable pain. Since then, significant strides in both the technological and therapeutic sides have facilitated the evolution of spinal cord stimulation (SCS) in the management of a variety of pain pathologies. High-quality evidence attests to the efficacy and cost-effectiveness of this modality. In contrast to conventional medical management, SCS offers long-lasting symptom relief, improved quality of life and functional capability, often achieving these goals at a reduced cost. This article illustrates the present status, challenges and future of SCS.

Spinal cord stimulation for chronic limb ischemia

The treatment of chronic limb ischemia involves the restoration of pulsatile blood flow to the distal extremity. Some patients cannot be treated with endovascular means or with open surgery; some may have medical comorbidities that render them unfit for surgery, while others may have persistent ischemia or pain even in the face of previous attempts at reperfusion. In spinal cord stimulation (SCS), a device with electrodes is implanted in the epidural space to stimulate sensory fibers. This activates cell-signaling molecules that in turn cause the release of vasodilatory molecules, a decrease in vascular resistance, and relaxation of smooth muscle cells. SCS also suppresses sympathetic vasoconstriction and pain transmission. When patient selection is based on microcirculatory parameters, SCS therapy can significantly improve pain relief, halt the progression of ulcers, and potentially achieve limb salvage.

Predictors of improved quality of life and claudication in patients undergoing spinal cord stimulation for critical lower limb ischemia

BACKGROUND

The aim of this study was to determine predictors of improved quality of life and claudication in patients undergoing spinal cord stimulation (SCS) for critical lower limb ischemia.

METHODS

We retrospectively analyzed 101 consecutive patients with few meter claudication and nonhealing ulcer who underwent definitive SCS. These patients were selected among 274 SCS patients treated at our center from 1995 to 2012. All presented with non-reconstructable critical leg ischemia (NR-CLI) and underwent supervised exercise therapy, best medical care and regular ulcers standard or advanced medications for at least 1 month before SCS implantation. We measured self-perceived quality of life using the SF-36 questionnaire. Patients with an improved walking distance of at least 30 meters after SCS had significant improvement on SF-36 questionnaire scores. We considered 30 meters as the cut-off for clinically significant improvement in pain-free walking distance, and we defined this value as functional success. Logistic regression was applied to assess baseline and other patient variables as possible predictors of functional success.

RESULTS

Neither perioperative mortality nor significant complications were found. At a median follow-up of 69 months (range 1-202 months), mortality, major amputation, and minor amputation were 8.9%, 5.9%, and 6.9%, respectively. Functional clinical success was reported in 25.7% of cases. Independent predictors of functional success at univariate analysis included delay between the onset of the ulcer and SCS (P < 0.001) and the pain-free walking distance before SCS (P < 0.002). The only predictive factor of functional success at multivariate analysis was the delay between the onset of ulcer and SCS (median delay in patients with and without functional success was 3 and 15 months, respectively). In particular, comparable to pain-free walking distance before SCS, the success rate decreased by 40% for each month elapsed from onset of ulcer to SCS.

CONCLUSIONS

In our series of patients who underwent SCS, reduced delay between the onset of ulcer and SCS was associated with improved quality of life and walking distance. Larger series are required to confirm these data and to assess clinical implications.

Therapeutic angiogenesis in critical limb ischemia

Critical limb ischemia (CLI) is a severe form of peripheral artery disease associated with high morbidity and mortality. The primary therapeutic goals in treating CLI are to reduce the risk of adverse cardiovascular events, relieve ischemic pain, heal ulcers, prevent major amputation, and improve quality of life (QoL) and survival. These goals may be achieved by medical therapy, endovascular intervention, open surgery, or amputation and require a multidisciplinary approach including pain management, wound care, risk factors reduction, and treatment of comorbidities. No-option patients are potential candidates for the novel angiogenic therapies. The application of genetic, molecular, and cellular-based modalities, the so-called therapeutic angiogenesis, in the treatment of arterial obstructive diseases has not shown consistent efficacy. This article summarizes the current status related to the management of patients with CLI and discusses the current findings of the emerging modalities for therapeutic angiogenesis.

Cost-effectiveness of spinal cord stimulation therapy in management of chronic pain

OBJECTIVE

To evaluate the cost-effectiveness of spinal cord stimulation (SCS) and conventional medical management (CMM) compared with CMM alone for patients with failed back surgery syndrome (FBSS), complex regional pain syndrome (CRPS), peripheral arterial disease (PAD), and refractory angina pectoris (RAP).

DESIGN

Markov models were developed to evaluate the cost-effectiveness of SCS vs CMM alone from the perspective of a Canadian provincial Ministry of Health. Each model followed costs and outcomes in 6-month cycles. Health effects were expressed as quality-adjusted life years (QALYs). Costs were gathered from public sources and expressed in 2012 Canadian dollars (CAN$). Costs and effects were calculated over a 20-year time horizon and discounted at 3.5% annually, as suggested by the National Institute of Clinical Excellence. Cost-effectiveness was identified by deterministic and probabilistic sensitivity analysis (50,000 Monte-Carlo iterations). Outcome measures were: cost, QALY, incremental net monetary benefit (INMB), incremental cost-effectiveness ratio (ICER), expected value of perfect information (EVPI), and strategy selection frequency.

RESULTS

The ICER for SCS was: CAN$ 9,293 (FBSS), CAN$ 11,216 (CRPS), CAN$ 9,319 (PAD), CAN$ 9,984 (RAP) per QALY gained, respectively. SCS provided the optimal economic path. The probability of SCS being cost-effective compared with CMM was 75-95% depending on pathology. SCS generates a positive INMB for treatment of pain syndromes. Sensitivity analyses demonstrated that results were robust to plausible variations in model costs and effectiveness inputs. Per-patient EVPI was low, indicating that gathering additional information for model parameters would not significantly impact results.

CONCLUSION

SCS with CMM is cost-effective compared with CMM alone in the management of FBSS, CRPS, PAD, and RAP.

Occipital stimulation for chronic migraine: patient selection and complications

BACKGROUND

Chronic migraine is a significant cause of disability world-wide and occipital region stimulation (OS) has been proposed to treat it. While participating in an industry-sponsored pilot trial of OS, we aimed to collect data regarding our surgical complications and long term usage of OS in our chronic migraine patients.

METHODS

Ten patients (8 female, median age 46.5 years) were enrolled based on criteria established by the sponsoring company, screened in the headache clinic, and followed for a median of 33 months. We did not access data collected by industry for this report and instead collected our own data prospectively, including predominant location of headache, location of paresthesia evoked by OS, and complications.

RESULTS

Adverse events included three possible early infections requiring antibiotics but not hardware removal, one late implantable pulse generator erosion requiring removal, one generator malfunction requiring revision, and loss of paresthetic coverage requiring four revisions in four patients. Two patients experienced new symptoms requiring psychiatric intervention. Five patients had no benefit and have been explanted. Of those who remain using their device, the proportion of their pre-operative pain located in the occipital region was 0.62 ± 0.14, whereas in those patients who have been explanted, the proportion was 0.31 ± 0.18 (t = 3.15, p=0.01).

CONCLUSIONS

Complication rates with OS are higher than those seen with other stimulation techniques, despite identical hardware and similar surgery. The location of migraine pain did predict outcome, and suggests that only those with primarily occipital region headache are candidates for this therapy.

Dorsal column stimulator applications

Background:

Spinal cord stimulation (SCS) has been used to treat neuropathic pain since 1967. Following that, technological progress, among other advances, helped SCS become an effective tool to reduce pain.

Methods:

This article is a non-systematic review of the mechanism of action, indications, results, programming parameters, complications, and cost-effectiveness of SCS.

Results:

In spite of the existence of several studies that try to prove the mechanism of action of SCS, it still remains unknown. The mechanism of action of SCS would be based on the antidromic activation of the dorsal column fibers, which activate the inhibitory interneurons within the dorsal horn. At present, the indications of SCS are being revised constantly, while new applications are being proposed and researched worldwide. Failed back surgery syndrome (FBSS) is the most common indication for SCS, whereas, the complex regional pain syndrome (CRPS) is the second one. Also, this technique is useful in patients with refractory angina and critical limb ischemia, in whom surgical or endovascular treatment cannot be performed. Further indications may be phantom limb pain, chronic intractable pain located in the head, face, neck, or upper extremities, spinal lumbar stenosis in patients who are not surgical candidates, and others.

Conclusion:

Spinal cord stimulation is a useful tool for neuromodulation, if an accurate patient selection is carried out prior, which should include a trial period. Undoubtedly, this proper selection and a better knowledge of its underlying mechanisms of action, will allow this cutting edge technique to be more acceptable among pain physicians.

How process analysis could improve the implementation of spinal cord stimulation treatment for chronic pain

SUMMARY Spinal cord stimulation has been in clinical use for the treatment of chronic pain for over four decades. Since the initial use by Norman Shealy, the indications for its use have increased steadily over the decades to include neuropathic pain owing to failed back surgery syndrome, complex regional pain syndrome and painful diabetic peripheral neuropathies. To date, the precise mechanism of action of spinal cord stimulation remains unclear, yet it is still one of the most expensive interventional treatment modalities available in pain medicine with increasing application across the world. Given the worldwide focus on cost-effective care, there is an opportunity to focus on process analysis as a mechanism for optimizing the operations within and between all specialties engaged in the provision of care in pain medicine. Here, we propose a process analysis approach to model, measure and improve the delivery of disease-based care to enhance effective treatment with a costly modality. Systems-based process analysis is not widely utilized in pain medicine, and there is a limited body of evidence for its application. The purpose of this article is to generate interest in the discipline of process analysis in pain medicine, as it has found value in other healthcare settings and industries. We mention the applicability across countries and specialties that we hope will increase the awareness of this concept and possibly generate interest in further examination by investigators that will lead to the development of highly efficient and effective healthcare delivery processes and systems across the globe.

Spinal Cord Stimulation Is Effective in Management of Complex Regional Pain Syndrome I: Fact or Fiction

BACKGROUND:

Complex regional pain syndrome (CRPS) I is a debilitating neuropathic pain disorder characterized by burning pain and allodynia. Spinal cord stimulation (SCS) is effective in the treatment of CRPS I in the medium term but its long-term efficacy and ability to improve functional status remains controversial.

OBJECTIVE:

To evaluate the ability of SCS to improve pain, functional status, and quality of life in the long term.

METHODS:

We retrospectively analyzed 25 patients over a mean follow-up period of 88 months. The parameters for evaluation were visual analog scale (VAS), Oswestry Disability Index (ODI), Beck Depression Inventory (BDI), EuroQoL-5D (EQ-5D) and Short Form 36 (SF-36), and drug consumption. Evaluations were conducted at point of entry, 3 months, 12 months, and last follow-up at 88 months (mean).

RESULTS:

At baseline, the mean scores were VAS 8.4, ODI 70%, BDI 28, EQ-5D 0.30, and SF-36 24. In general, maximum improvement was recorded at follow-up at 3 months (VAS 4.8, ODI 45%, BDI 15, EQ-5D 0.57, and SF-36 45). At last follow-up, scores were 5.6, 50%, 19, 0.57, and 40, respectively. Despite some regression, at last follow-up benefits were maintained and found to be statistically significant (P &lt; .001) compared with baseline. Medication usage declined. SCS did not prevent disease spread to other limbs. Best results were achieved in stage I CRPS I, patients under 40 years of age, and those receiving SCS within 1 year of disease onset.

CONCLUSION:

SCS improves pain, quality of life, and functional status over the long term and consequently merits early consideration in the treatment continuum.

Always contact a vascular interventional specialist before amputating a patient with critical limb ischemia

Patients with severe critical limb ischemia (CLI) due to long tibial artery occlusions are often poor candidates for surgical revascularization and frequently end up with a lower limb amputation. Subintimal angioplasty (SA) offers a minimally invasive alternative for limb salvage in this severely compromised patient population. The objective of this study was to evaluate the results of SA in patients with CLI caused by long tibial occlusions who have no surgical options for revascularization and are facing amputation. We retrospectively reviewed all consecutive patients with CLI due to long tibial occlusions who were scheduled for amputation because they had no surgical options for revascularization and who were treated by SA. A total of 26 procedures in 25 patients (14 males; mean age, 70 ± 15 [SD] years) were evaluated. Technical success rate was 88% (23/26). There were four complications, which were treated conservatively. Finally, in 10 of 26 limbs, no amputation was needed. A major amputation was needed in 10 limbs (7 below-knee amputations and 3 above-knee amputations). Half of the major amputations took place within 3 months after the procedure. Cumulative freedom of major amputation after 12 months was 59% (SE = 11%). In six limbs, amputation was limited to a minor amputation. Seven patients (28%) died during follow-up. In conclusion, SA of the tibial arteries seem to be a valuable treatment option to prevent major amputation in patients with CLI who are facing amputation due to lack of surgical options.

[Medical and economic reflections on Restore and Itrel neurostimulation systems for neuropathic pain treatment]

In 2007, four patients where implanted with the Restore neurostimulation system for intractable chronic leg pain at the Poitiers Hospital. The potential for improving the patients' quality of life and medical-economic concerns motivated this choice for these highly selected patients. In this paper, we propose brief clinical case reports and discuss the reasons for choosing this new rechargeable system, even though it was initially more expensive than the standard neurostimulation system (Itrel 3). All patients receiving implants declared that they were very satisfied with the quality of stimulation provided by Restore and noted a significant improvement in their quality of life. If this solution becomes advantageous from an economic point of view, clinical data should lend support to the utility of this technological innovation for patients who have hitherto been in treatment failure.

What is the evidence on efficacy of spinal cord stimulation in (subgroups of) patients with critical limb ischemia?

The use of spinal cord stimulation (SCS) has been advocated for the management of ischemic pain and the prevention of amputations in patients with inoperable critical limb ischemia (CLI), although data on benefit are conflicting. Several reports described apparently differential treatment effects in subgroups. The purpose of this study was to analyze the data on the efficacy of SCS and to clarify preselection issues. Five randomized trials have been performed with a total number of 332 patients. Primary outcome measures were mortality and limb survival. In the largest multicenter randomized trial (n = 120), which compared SCS treatment and best medical treatment alone in patients with inoperable CLI, we determined the incidence of amputation and its relation to various predefined risk factors. We used Kaplan-Meier and Cox regression analyses to quantify prognostic effects and differential treatment effects. Meta-analysis yielded a relative risk for amputation of 0.79 and a risk difference of -0.07 (p = 0.15). The risk factor analysis clearly showed that patients with ischemic skin lesions (ulcerations or gangrene) had a worse prognosis (i.e., higher risk of amputation) (relative risk 2.30, p = 0.01). We did not observe significant interactions between this prognostic factor (or any other) and the effect of SCS. The analysis did not indicate a subgroup of patients who might specifically be helped by SCS. Meta-analysis including all randomized data shows insufficient evidence for higher efficacy of SCS treatment compared with best medical treatment alone. Although some factors provide prognostic information as to the risk of amputation in patients with CLI, there are no data supporting a more favorable treatment effect in any group.

The use of osteopathic manipulative treatment as adjuvant therapy in patients with peripheral arterial disease

Peripheral arterial disease (PAD) is a manifestation of systemic atherosclerosis associated with impaired endothelial function and intermittent claudication is the hallmark symptom. Hypothesizing that osteopathic manipulative treatment (OMT) may represent a non-pharmacological therapeutic option in PAD, we examined endothelial function and lifestyle modifications in 15 intermittent claudication patients receiving osteopathic treatment (OMT group) and 15 intermittent claudication patients matched for age, sex and medical treatment (control group). Compared to the control group, the OMT group had a significant increase in brachial flow-mediated vasodilation, ankle/brachial pressure index, treadmill testing and physical health component of life quality (all p<0.05) from the beginning to the end of the study. At univariate analysis in the OMT group there was a negative correlation between changes in brachial flow-mediated vasodilation and IL-6 levels (r=-0.30; p=0.04) and a positive one between claudication pain time and physical function score (r=0.50; p=0.05). In conclusion, despite the relatively few patients in our study, these results suggest that OMT significantly improves endothelial function and functional performance in intermittent claudication patients along with benefits in quality of life. This novel treatment combined with drug and lifestyle modification might be an effective alternative to traditional training based on exercise.

[Adenosine for treatment of ischemic pain in thromboangiitis obliterans. A case report]

Treating ischemic pain is often unsatisfactory. Current findings demonstrate that patients with chronic ischemia may develop sensory neuropathy and signs of central sensitization. This issue makes is reasonable treating with conventional analgesics and drugs against neuropathic pain. Adenosine has also a pain reducing effect in neuropathic pain which makes it a possible therapeutic option in ischemic pain.We report of a patient with thromboangiitis obliterans. We treated his pain with a broad analgesic therapy and administered adenosine intravenously, which resulted in a reduction of pain for several hours. Afterwards the patient received buflomedil to increase adenosine plasma levels. A long term pain reduction could be achieved. Modulation of adenosine demonstrates an experimental approach in the therapy of ischemic pain in thromboangiitis obliterans.

Introduction of Infection Control Measures to Reduce Infection Associated With Implantable Pain Therapy Devices

INTRODUCTION

Implantable pain therapy devices for chronic pain include spinal cord stimulators (SCS) and intrathecal drug delivery systems (IDDS). A number of different complications can occur after implantation of these devices, but among the most serious is infection. Based on Centers for Disease Control and Prevention guidelines for prevention of surgical site infection, published literature on infection risk with implantable pain therapy devices, and recommendations from groups within our own our institution, we introduced infection control measures for all patients receiving either SCS or IDDS.

METHODS

After approval from the Institutional Review Board, we performed a retrospective review of patients undergoing primary implantation of SCS or IDDS before and after introduction at our institution of safety measures designed to reduce device-related infection. We compared infection incidence and compliance to infection precautions before and after introduction of these measures.

RESULTS

Thirty-four SCS or IDDS were implanted before implementation of the infection control measures and 58 were placed after. Five device-related infections occurred. Adherence to most infection precautions improved during the study period, but 100% compliance was seen only with venue used for implantation. Infection incidence declined after introduction of the safety measures, but the reduction was not statistically significant.

CONCLUSIONS

Introduction of infection control measures for implantable pain therapy devices improved adherence to most infection precautions in our practice. Lack of specific documentation could have hindered practice surveillance within our group. A tool to document performance of infection control measures would be useful not only as a marker of compliance but could also serve as a reminder to perform certain safety measures.

Epidural spinal cord stimulation in lower limb ischemia

Epidural spinal cord stimulation (SCS) has been used as a method to improve microcirculatory blood flow, relieve ischemic pain and reduce amputation rate in patients with severe peripheral arterial occlusive disease (PAOD). In this article, the theories attempting to explain the mechanisms of SCS vasoactive action are presented. Our method of patient screening and our surgical technique for SCS implantation are described. In addition, the various published series reporting on the efficacy of SCS in PAOD are critically reviewed. The contemporary reports demonstrate the efficacy of SCS in ischemic pain relief. In the light of these results and our own experience, we conclude with an appraisal of modern techniques for assessing critical limb ischemia.

Late outcome of spinal cord stimulation for unreconstructable and limb-threatening lower limb ischemia

OBJECTIVES

To determine whether the initial benefits of spinal cord stimulation (SCS) treatment for critical limb ischemia (CLI) persist over years.

DESIGN

Analysis of data prospectively collected for every CLI patient receiving permanent SCS. Follow-up range 12 to 98 months (mean 46+/-23, median 50 months).

POPULATION

87 patients (28% stage III, 72%stage IV) with unreconstructable CLI due (83%) or not (17%) to atherosclerosis and with an initial sitting/supine transcutaneous pO2 gradient >15 mmHg.

METHODS

Assessment of actuarial patient survival (PS), limb salvage (LS) and amputation-free patient survival (AFPS). Analysis of the impact of 15 risk factors on long-term outcomes using the Fischer's exact test for categorical variables and the t test for continuous variables.

RESULTS

Follow-up was complete for patient and limb survival. A single non-atherosclerotic patient died during follow-up. Among atherosclerotic patients PS decreased from 88% at 1y, to 76% at 3y, 64% at 5y and 57% at 7y. LS reached 84% at 1y, 78% at 2y, 75% at 3y and remained stable thereafter. Diabetes was found to affect LS (p<0.05) and heart disease to reduce PS (p<0.01). AFPS was reduced in heart patients (p<0.01), diabetics (p<0.05) and in patients with previous stroke (p<0.05).

CONCLUSIONS

In CLI patients the beneficial effects of SCS persist far beyond the first year of treatment and major amputation becomes infrequent after the second year.

Spinal cord stimulation for ischemic heart disease and peripheral vascular disease

Ischemic disease (ID) is now an important indication for electrical neuromodulation (NM), particularly in chronic pain conditions. NM is defined as a therapeutic modality that aims to restore functions of the nervous system or modulate neural structures involved in the dysfunction of organ systems. One of the NM methods used is chronic electrical stimulation of the spinal cord (spinal cord stimulation: SCS). SCS in ID, as applied to ischemic heart disease (IHD) and peripheral vascular disease (PVD), started in Europe in the 1970s and 1980s, respectively. Patients with ID are eligible for SCS when they experience disabling pain, resulting from ischaemia. This pain should be considered therapeutically refractory to standard treatment intended to decrease metabolic demand or following revascularization procedures. Several studies have demonstrated the beneficial effect of SCS on IHD and PVD by improving the quality of life of this group of severely disabled patients, without adversely influencing mortality and morbidity. SCS used as additional treatment for IHD reduces angina pectoris (AP) in its frequency and intensity, increases exercise capacity, and does not seem to mask the warning signs of a myocardial infarction. Besides the analgesic effect, different studies have demonstrated an anti-ischemic effect, as expressed by different cardiac indices such as exercise duration, ambulatory ECG recording, coronary flow measurements, and PET scans. SCS can be considered as an alternative to open heart bypass grafting (CABG) for patients at high risk from surgical procedures. Moreover, SCS appears to be more efficacious than transcutaneous electrical nerve stimulation (TENS). The SCS implantation technique is relatively simple: implanting an epidural electrode under local anesthesia (supervised by the anesthesist) with the tip at T1, covering the painful area with paraesthesia by external stimulation (pulse width 210, rate 85 Hz), and connecting this electrode to a subcutaneously implanted pulse generator. In PVD the pain may manifest itself at rest or during walking (claudication), disabling the patient severely. Most of the patients suffer from atherosclerotic critical limb ischemia. All patients should be therapeutically refractory (medication and revascularization) to become eligible for SCS. Ulcers on the extremities should be minimal. In PVD the same implantation technique is used as in IHD except that the tip of the electrode is positioned at T10-11. In PVD the majority of the patients show significant reduction in pain and more than half of the patients show improvement of circulatory indices, as shown by Doppler, thermography, and oximetry studies. Limb salvage studies show variable results depending on the stage of the trophic changes. The underlying mechanisms of action of SCS in PVD require further elucidation.

Spinal cord stimulation in hemodialysis patients with critical lower-limb ischemia

BACKGROUND

Spinal cord stimulation (SCS) has been proposed for the treatment of ischemic pain and the prevention or delay of amputation in patients with peripheral arterial occlusive disease (PAOD) who are unsuitable for vascular reconstruction. PAOD is common in patients with end-stage renal disease and is associated with substantial morbidity and mortality. Furthermore, many patients are not candidates for limb-sparing procedures and have to undergo primary amputation.

METHODS

We report our experience with SCS in 8 hemodialysis patients with chronic lower-limb ischemia and not suitable for either primary surgical or angioplastic intervention or reintervention. Intensity of ischemic pain, quality of life, use of analgesic medications, limb survival, and outcome of skin ischemic lesions were evaluated before implantation of an SCS device and after 6 and 12 months of follow-up.

RESULTS

No complications from SCS device implantation occurred. Both intensity of pain and quality of life significantly improved during follow-up. SCS allowed a decrease in pain medication intake in all patients. Limb survival at 1 year was 75%. Ischemic skin lesions before implantation of an SCS device did not ameliorate during the follow-up period, but the appearance of new lesions was not observed.

CONCLUSION

Implantation of an SCS device in patients with end-stage renal disease with critical limb ischemia dramatically improves quality of life and pain relief. In patients assessed at Leriche-Fontaine stage 2 or 3, the treatment might delay the appearance of ischemic skin lesions and amputation. At these stages, presumed long-term benefits could justify the cost of SCS.

Meta-analysis of the Clinical Effectiveness of Venous Arterialization for Salvage of Critically Ischaemic Limbs

OBJECTIVE

The aim of this study is to assess the clinical effectiveness of venous arterialization in patients with critical limb ischaemia not reconstructable by conventional bypass.

DESIGN

Meta-analysis of observational studies.

MATERIALS

Eligible studies concerning treatment by venous arterialization for chronic critical leg ischaemia were identified from electronic database, cross-reference search and pertinent articles. There was no language restriction.

METHODS

All relevant studies were systematically reviewed and data extracted by two independent reviewers. Study endpoints were foot preservation, secondary graft patency, postoperative clinical improvement and complications.

RESULTS

A total of 56 studies were selected for comprehensive review. No RCTs were identified. Seven patient series, comprising 228 patients, matched the selection criteria. Overall 1-year foot preservation was 71% (95% CI: 64-77%) and 1-year secondary patency was 46% (95% CI: 39-53%). The large majority of patients in whom major amputation was avoided experienced successful wound healing, disappearance of rest pain and absence of serious complications.

CONCLUSION

On the basis of limited evidence, venous arterialization may be considered as a viable alternative before major amputation is undertaken in patients with 'inoperable' chronic critical leg ischaemia.

Spinal cord stimulation for critical leg ischemia: a review of effectiveness and optimal patient selection

Patients suffering from inoperable critical leg ischemia (CLI) ultimately face a major amputation. Spinal cord stimulation (SCS) has been introduced as a possible treatment option. This paper presents the best available evidence from a systematic review on the effectiveness of SCS in these patients and discusses the indications for SCS therapy. A meta-analysis of six controlled trials, including 444 patients, showed 11% (95% confidence interval: -0.02 to -0.20) lower amputation rate after 12 months compared to those treated with optimum medical treatment. In addition, SCS patients required significantly fewer analgesics and showed a significant clinical improvement. These positive effects have to be weighed against the higher costs and (generally minor) complications of SCS. TcpO(2) measurements were found to be useful in selecting the most respondent patients, yielding a 12-month limb salvage up to 83%. Hence, SCS should be considered as a possible treatment option in patients with CLI, particularly if their foot TcpO(2) is between 10 and 30 mmHg.

Spinal cord stimulation is not cost-effective for non-surgical management of critical limb ischaemia

OBJECTIVE

To quantify the costs of treatment in critical limb ischaemia (CLI) and to compare costs and effectiveness of two treatment strategies: spinal cord stimulation (SCS) and best medical treatment.

METHODS

One hundred and twenty patients with CLI not suitable for vascular reconstruction were randomised to either SCS in addition to best medical treatment or best medical treatment alone. Primary outcomes were mortality, amputation and cost. Cost analysis was based on resources used by patients for 2 years after randomisation. Both medical and non-medical costs were included.

RESULTS

Patient and limb survival were similar in the two treatment groups. Costs of in-hospital-stay and institutional rehabilitation constituted the predominant part (+/-70%) of the total costs of medical care in CLI. Cost of SCS-implantation and complications (7950 euro per patient) exceeded by far cost due to amputation procedures (410 euro per patient). The total costs of treatment were 36,600 euro per patient over 2 years for the SCS-group vs. 28,700 euro for best medical treatment alone (28% higher for SCS-group, p=0.009).

CONCLUSIONS

Total costs of treatment in CLI are high. Major components are hospital and rehabilitation costs. In contrast to recent reviews, there were no long-term benefits of SCS-treatment. Therefore, cost-effectiveness is reduced to cost-minimisation and SCS-treatment is considerably more expensive than best medical treatment.

Medical management of peripheral arterial disease

Whether symptomatic or not, peripheral arterial disease (PAD), atherosclerosis in the arteries of the lower extremities, is a common disorder in the general population. The prevalence increases with age and under the influence of vascular risk factors. The most classic symptomatic expression of PAD is intermittent claudication. However, the majority of patients with PAD is asymptomatic or has leg symptoms other than classic intermittent claudication. Both symptomatic and asymptomatic subjects with PAD have increased mortality rates, mainly due to cardiovascular and cerebrovascular expressions of atherosclerotic disease. This review focuses on the current available medical therapies for PAD, including risk-factor modification and antiplatelet therapies, as well as strategies for symptomatic relief in both patients with intermittent claudication and patients with critical limb ischemia. In general, risk factor modification and antiplatelet therapy is essential in all patients with PAD to prevent systemic atherosclerotic complications. Furthermore, for symptomatic relief exercise therapy is the main intervention while pharmacological treatment should be only complementary. In patients with critical limb ischemia, when revascularization therapy is not possible, an attempt should be made to avoid amputation with conservative treatment using analgesics, vasodilators and/or anticoagulants. In case of an acute onset of critical limb ischemia, thrombolysis is indicated.