Epidural spinal cord stimulation in the treatment of severe peripheral arterial occlusive disease

Spinal Cord Stimulation for Intractable Chronic Limb Ischemia: A Narrative Review

Critical limb ischemia (CLI) is the most severe form of peripheral arterial disease, significantly impacting quality of life, morbidity and mortality. Common complications include severe limb pain, walking difficulties, ulcerations and limb amputations. For cases of CLI where surgical or endovascular reconstruction is not possible or fails, spinal cord stimulation (SCS) may be a treatment option. Currently, SCS is primarily prescribed as a symptomatic treatment for painful symptoms. It is used to treat intractable pain arising from various disorders, such as neuropathic pain secondary to persistent spinal pain syndrome (PSPS) and painful diabetic neuropathy. Data regarding the effect of SCS in treating CLI are varied, with the mechanism of action of vasodilatation in the peripheral microcirculatory system not yet fully understood. This review focuses on the surgical technique, new modalities of SCS, the mechanisms of action of SCS in vascular diseases and the parameters for selecting CLI patients, along with the clinical outcomes and complications. SCS is a safe and effective surgical option in selected patients with CLI, where surgical or endovascular revascularization is not feasible.

Spinal Cord Stimulation in the Treatment of Peripheral Vascular Disease: Results of a Single-Center Study of 258 Patients

This report is of a retrospective study of data from 258 patients who received spinal cord stimulation (SCS) for the treatment of peripheral vascular disease as a result of arteriosclerosis. The patients’ clinical outcomes were monitored over a period of 18 months. In patients with a low baseline transcutaneous oxygen pressure (TcPO2) value of <10 mm Hg, limb survival at 18 months of follow-up (estimated by use of Kaplan-Meier survival analysis) was 77.8%, and this was even higher, at 89.5%, in patients with a medium baseline TcPO2 value of 10-30 mm Hg. This successful treatment was accompanied by a sustained increase in TcPO2 values to approximately 30 mm Hg in both of these groups. In looking at diabetic and nondiabetic patients, there is no difference in limb survival as a result of the treatment. It is concluded that SCS is an effective therapy in improving limb survival in patients with peripheral vascular disease. In addition, TcPO2 values at baseline may be a useful predictor of treatment outcome.

Treatment of Unreconstructible Upper Extremity Arterial Occlusive Disease by Spinal Cord Stimulation

Spinal cord stimulation (SCS) of peripheral arterial disease (PAD) of the lower limbs has been shown to be effective for pain reduction, limb salvage, and improvement of blood supply; however, treatment of PAD of the upper extremity by SCS has never been performed. Ten patients with unreconstructible severe PAD of the upper extremity were treated by SCS at the authors' institution.

Transcutaneous oxygen tension index (chest TcPo2/hand TcPo2), Doppler wrist pressure index (WPI), capillary microscopy (red blood cell velocity, capillary density), and a patient's pain score graded from 1 to 10 (1 =no pain) were used as follow-up parameters.

Pain reduction after SCS was excellent in all patients. TcPo2 index decreased from 1.95 ± 0.87 prior to implantation to 1.5 ± 1.1 at eighteen months. No significant improvement of capillary microscopy parameters or Doppler WPI could be observed.

SCS effectively reduced pain and provided limb salvage in patients with severe unreconstructible PAD of the upper extremity; however, reduction of pain was not paralleled by improvement of the studied microcirculatory parameters.

Electrical Stimulation and Motor Recovery

In recent years, several investigators have successfully regenerated axons in animal spinal cords without locomotor recovery. One explanation is that the animals were not trained to use the regenerated connections. Intensive locomotor training improves walking recovery after spinal cord injury (SCI) in people, and >90% of people with incomplete SCI recover walking with training. Although the optimal timing, duration, intensity, and type of locomotor training are still controversial, many investigators have reported beneficial effects of training on locomotor function. The mechanisms by which training improves recovery are not clear, but an attractive theory is available. In 1949, Donald Hebb proposed a famous rule that has been paraphrased as “neurons that fire together, wire together.” This rule provided a theoretical basis for a widely accepted theory that homosynaptic and heterosynaptic activity facilitate synaptic formation and consolidation. In addition, the lumbar spinal cord has a locomotor center, called the central pattern generator (CPG), which can be activated nonspecifically with electrical stimulation or neurotransmitters to produce walking. The CPG is an obvious target to reconnect after SCI. Stimulating motor cortex, spinal cord, or peripheral nerves can modulate lumbar spinal cord excitability. Motor cortex stimulation causes long-term changes in spinal reflexes and synapses, increases sprouting of the corticospinal tract, and restores skilled forelimb function in rats. Long used to treat chronic pain, motor cortex stimuli modify lumbar spinal network excitability and improve lower extremity motor scores in humans. Similarly, epidural spinal cord stimulation has long been used to treat pain and spasticity. Subthreshold epidural stimulation reduces the threshold for locomotor activity. In 2011, Harkema et al. reported lumbosacral epidural stimulation restores motor control in chronic motor complete patients. Peripheral nerve or functional electrical stimulation (FES) has long been used to activate sacral nerves to treat bladder and pelvic dysfunction and to augment motor function. In theory, FES should facilitate synaptic formation and motor recovery after regenerative therapies. Upcoming clinical trials provide unique opportunities to test the theory.

Electrical stimulation vs. standard care for chronic ulcer healing: a systematic review and meta-analysis of randomised controlled trials

BACKGROUND

We conducted a systematic review to investigate the effect of electrical stimulation on ulcer healing compared to usual treatment and/or sham stimulation. This systematic review also aimed to investigate the effect of different types of electrical stimulation on ulcer size reduction.

MATERIALS AND METHODS

MEDLINE, EMBASE and Cochrane Central Register of Controlled Trials (CENTRAL) were searched from inception to October 2013 on randomised controlled trials (RCTs), in English and on human subjects, which assessed the effect of electrical stimulation on ulcer size as compared to standard care and/or sham stimulation. Data from included RCTs were pooled with use of fixed and random effects meta-analysis of the weighted mean change differences between the comparator groups. Heterogeneity across studies was assessed with the I(2) statistic.

RESULTS

Twenty-one studies were eligible for inclusion in the meta-analysis. In six trials (n = 210), electrical stimulation improved mean percentage change in ulcer size over total studies periods by 24·62%, 95% confidence interval (CI) 19·98-29·27, P < 0·00001 with no heterogeneity. In three trials (n = 176), electrical stimulation insignificantly improved mean weekly change in ulcer size by 1·64%, 95% (CI) -3·81 to 7·09, P = 0·56 with significant heterogeneity (I(2) = 96%, P < 0·00001). In six trials (n = 266), electrical stimulation decreased ulcer size by 2·42 cm(2), 95% (CI) 1·66-3·17, P < 0·00001, with significant heterogeneity. In one trial (n = 16), electrical stimulation also insignificantly improved the mean daily percentage change in ulcer size by 0·63%, 95% (CI) -0·12 to 1·37, P = 0·10, with significant heterogeneity.

CONCLUSIONS

Electrical stimulation appears to increase the rate of ulcer healing and may be superior to standard care for ulcer treatment.

Spinal cord stimulation for non-reconstructable chronic critical leg ischaemia

BACKGROUND

Patients suffering from inoperable chronic critical leg ischaemia (NR-CCLI) face amputation of the leg. Spinal cord stimulation (SCS) has been proposed as a helpful treatment in addition to standard conservative treatment.

OBJECTIVES

To find evidence for an improvement on limb salvage, pain relief, and the clinical situation using SCS compared to conservative treatment alone.

SEARCH METHODS

For this update the Cochrane Peripheral Vascular Diseases Group Trials Search Co-ordinator searched the Specialised Register (last searched January 2013) and CENTRAL (2012, Issue 12).

SELECTION CRITERIA

Controlled studies comparing the addition of SCS with any form of conservative treatment to conservative treatment alone in patients with NR-CCLI.

DATA COLLECTION AND ANALYSIS

Both authors independently assessed the quality of the studies and extracted data.

MAIN RESULTS

Six studies comprising nearly 450 patients were included. In general the quality of the studies was good. No study was blinded due to the type of intervention.Limb salvage after 12 months was significantly higher in the SCS group (risk ratio (RR) 0.71, 95% confidence interval (CI) 0.56 to 0.90; risk difference (RD) -0.11, 95% CI -0.20 to -0.02). Significant pain relief occurred in both treatment groups, but was more prominent in the SCS group where the patients required significantly less analgesics. In the SCS group, significantly more patients reached Fontaine stage II than in the conservative group (RR 4.9, 95% CI 2.0 to 11.9; RD 0.33, 95% CI 0.19 to 0.47). Overall, no significantly different effect on ulcer healing was observed with the two treatments.Complications of SCS treatment consisted of implantation problems (9%, 95% CI 4 to 15%) and changes in stimulation requiring re-intervention (15%, 95% CI 10 to 20%). Infections of the lead or pulse generator pocket occurred less frequently (3%, 95% CI 0 to 6%). Overall risk of complications with additional SCS treatment was 17% (95% CI 12 to 22%), indicating a number needed to harm of 6 (95% CI 5 to 8).Average overall costs (one study) at two years were EUR 36,500 (SCS group) and EUR 28,600 (conservative group). The difference (EUR 7900) was significant (P < 0.009).

AUTHORS' CONCLUSIONS

There is evidence to favour SCS over standard conservative treatment alone to improve limb salvage and clinical situations in patients with NR-CCLI. The benefits of SCS must be considered against the possible harm of relatively mild complications and the costs.

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.

Spinal cord stimulation in pain management: a review

Spinal cord stimulation has become a widely used and efficient alternative for the management of refractory chronic pain that is unresponsive to conservative therapies. Technological improvements have been considerable and the current neuromodulation devices are both extremely sophisticated and reliable in obtaining good results for various clinical situations of chronic pain, such as failed back surgery syndrome, complex regional pain syndrome, ischemic and coronary artery disease. This technique is likely to possess a savings in costs compared with alternative therapy strategies despite its high initial cost. Spinal cord stimulation continues to be a valuable tool in the treatment of chronic disabling pain.

Technological innovation in spinal cord stimulation: use of a newly developed delivery device for introduction of spinal cord stimulation leads

OBJECTIVE

The use of multiple cylindrical leads and multicolumn and single column paddle leads in spinal cord stimulation offers many advantages over the use of a single cylindrical lead. Despite these advantages, placement of multiple cylindrical leads or a paddle lead requires a more invasive surgical procedure. Thus, the ideal situation for lead delivery would be percutaneous insertion of a paddle lead or multiple cylindrical leads. This study evaluated the feasibility and safety of percutaneous delivery of S-Series paddle leads using a new delivery device called the Epiducer lead delivery system (all St. Jude Medical Neuromodulation Division, Plano, TX, USA).

MATERIALS AND METHODS

This uncontrolled, open-label, prospective, two-center study approved by the AZ St. Lucas (Ghent) Ethics Committee evaluated procedural aspects of implantation of an S-Series paddle lead using the Epiducer lead delivery system and any adverse events relating to the device. Efficacy data during the patent's 30-day trial also were collected.

RESULTS

  Data from 34 patients were collected from two investigational sites. There were no adverse events related to the Epiducer lead delivery system. The device was inserted at an angle of either 20°-30° or 30°-40° and was entered into the epidural space at T12/L1 in most patients. The S-Series paddle lead was advanced four vertebral segments in more than 50% of patients. The average (±standard deviation [SD]) time it took to place the Epiducer lead delivery system was 8.7 (±5.0) min. The average (+SD) patient-reported pain relief was 78.8% (+24.1%).

CONCLUSIONS

This study suggests the safe use of the Epiducer lead delivery system for percutaneous implantation and advancement of the S-Series paddle lead in 34 patients.

Spinal Cord Stimulation for Chronic Pain

Spinal cord stimulation (SCS) is one of the most effective modalities for management of re- fractory neuropathic pain unresponsive to conservative therapies. The SCS has been successful in providing analgesia, improving function, and enhancing quality of life for patients suffering from chronic pain conditions such as failed back surgery syndrome, complex regional pain syndrome, ischaemic and phantom limb pain, and coronary artery disease. This technique has proven to be cost effective in the long term despite its high initial cost. In this review article, we discuss the history of SCS development, mechanism of action, and indications for SCS. Key words: Failed back surgery syndrome, Ischaemic pain, Neuropathic pain

Spinal cord stimulation for chronic intractable angina pectoris: a unified theory on its mechanism

The use of spinal cord stimulation (SCS) for chronic intractable anginal pain was first described in 1987. Numerous studies have demonstrated its efficacy in improving exercise tolerance, decreasing frequency of anginal episodes, and prolonging time to electrocardiographic signs of ischemia. This review will examine the potential mechanisms of this antianginal effect and propose a unified hypothesis explaining it. The effect of SCS involves a mutual interaction of decreased pain, decreased sympathetic tone, and a likely redistribution of myocardial blood flow to ischemic regions. Spinal cord stimulation reduces the transmission of nociceptive impulse via the spinothalamic tract due to an enhanced release of gamma aminobutyric acid (GABA) from dorsal horn interneurons. Improvement of myocardial blood flow at the microvascular level has been demonstrated by positron emission tomography (PET). A decreased sympathetic tone has been shown by norepinephrine kinetics, tests of sympathetic reflexes, and the use of ganglionic blockers. We hypothesize that SCS exerts its beneficial effects by decreasing pain and decreasing sympathetic tone, the result of which is decreased myocardial oxygen consumption along with an improved myocardial microcirculatory blood flow.

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.

Spinal cord stimulation: an update

Spinal cord stimulation has been used in the treatment of many chronic pain disorders since 1967. In this update, the indications for spinal cord stimulation are reviewed with attention to recent publications. A focused review of the literature on abdominal and visceral pain syndromes is also provided. Furthermore, the technology has evolved from the use of monopolar electrodes to complex electrode arrays. Similarly, the power source has changed from a radio frequency-driven system to a rechargeable impulse generator. These topics are covered, along with a short discussion of implant technique. Finally, we include a review of complications of such therapy. SCS as a technology and therapy continues to evolve.

Spinal cord stimulation in the treatment of chronic critical limb ischemia

This paper reviews the clinical experience and proposed working mechanisms of spinal cord stimulation (SCS) in the treatment of chronic critical limb ischemia (CCLI). SCS appears to provide a significant long-term relief of ischemic pain and to improve healing of small ulcers, most likely due to effects on the nutritional skin blood flow. Despite these observations, randomized trials were not able to show limb salvage. Assessment of the microcirculatory skin blood flow, by means of transcutaneous oxygen pressure measurements and videocapillaromicroscopy, is necessary to evaluate the remaining microcirculatory reserve capacity likely to be exploited by SCS and to help identify patients that will benefit most from this treatment and in whom stimulation could lead to limb salvage.

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 failed back surgery syndrome and other disorders

Chronic pain is a complex condition that requires a multi-disciplinary approach to management. Spinal cord stimulation (SCS) has evolved into a relatively easily implemented, reversible technique with low morbidity for the management of chronic, intractable pain in selected patients. Percutaneous placement of electrode arrays, under local anaesthesia. supported by programmable, implanted electronics has been a major technical advance. Multicenter prospective studies were conducted and demonstrated that SCS. as a neuromodulation procedure, is indeed a superior method for treatment of chronic pain if the patients are selected with caution and a proper strategy. Future development of innovative electrodes and pulse generation systems will continue to improve this therapy.

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 for non-reconstructable chronic critical leg ischaemia

BACKGROUND

Patients suffering from inoperable chronic critical leg ischaemia (NR-CCLI), face amputation of the leg. Spinal cord stimulation (SCS) has been proposed as a helpful treatment in addition to standard conservative treatment.

OBJECTIVES

To find evidence for an improvement of limb salvage, pain relief and clinical situation using SCS compared to conservative treatment alone.

SEARCH STRATEGY

We searched the Cochrane Peripheral Vascular Diseases Group's Specialised Register, (last searched May 2005), and the Cochrane Central Register of Controlled Trials (CENTRAL) (last searched Issue 2, 2005). Additional data were obtained from research institutes.

SELECTION CRITERIA

Controlled studies comparing additional SCS with any form of conservative treatment in patients with NR-CCLI.

DATA COLLECTION AND ANALYSIS

Both authors independently assessed the quality of the studies and extracted data.

MAIN RESULTS

Six studies comprising nearly 450 patients were included. In general, the quality of the studies was good. None was blinded due to the nature of the intervention. Limb salvage after 12 months was significantly higher in the SCS group (relative risk (RR) 0.71, 95% confidence interval (CI) 0.56 to 0.90; risk difference (RD) -0.11, 95% CI -0.20 to -0.02). Significant pain relief occurred in both treatment groups, but was more prominent in the SCS group, in which the patients required significantly less analgesics. In the SCS group, significantly more patients reached Fontaine stage II than in the conservative group (RR 4.9, 95% CI 2.0 to 11.9; RD 0.33, 95% CI 0.19 to 0.47). Overall, no significantly different effect on ulcer healing was observed between the two treatments. Complications of SCS treatment consisted of implantation problems (9%, 95% CI 4 to 15%) and changes in stimulation requiring re-intervention (15%, 95% CI 10 to 20%). Infections of the lead or pulse generator pocket occurred less frequently (3%, 95% CI 0 to 6%). The overall risk of complications of additional SCS treatment was 17% (95% CI 12 to 22%), indicating a number needed to harm of 6 (95% CI 5 to 8).A cost comparison was made in only one study. The average overall costs at two years were 36,500 Euros, (SCS group) and 28,600 Euros, (conservative group). The difference (7900 Euros) was significant (P<0.009).

AUTHORS' CONCLUSIONS

There is evidence to favour SCS over standard conservative treatment to improve limb salvage and clinical situation in patients with NR-CCLI. The benefits of SCS against the possible harm of relatively mild complications and costs must be considered.

The role of epidural spinal cord stimulation in the treatment of Buerger’s disease

PURPOSE

This clinical, retrospective study is evaluated the effect of epidural spinal cord stimulation (SCS) in the treatment of Buerger's disease.

METHODS

The clinical criteria of Shionoya were used to diagnose 29 patients (22 men, 7 women; mean age 33.7 years) with Buerger's disease. The patients underwent SCS. Complete physical examination and vascular laboratory data were available and recorded for all patients. Questions regarding the improvement of symptoms, in lifestyle, and in physical activities were asked direct interview or by telephone during mean follow-up of 4 years.

RESULTS

The regional perfusion index (RPI), the ratio between the foot and chest transcutaneous oxygen pressure at baseline (before SCS treatment) was 0.27 +/- 0.25. Three months after SCS implantation the RPI increased to 0.41 +/- 0.22. During the follow-up period, a sustained improvement in microcirculation was recorded: the RPI at 1-year follow-up was 0.49 +/- 0.34 and at 3-year follow-up was 0.52 +/- 0.21. The most pronounced improvement in the RPI values was found in the subgroup of 13 patients with trophic lesions. In this group, the RPI increased significantly from 0.17 +/- 0.21 to 0.4 +/- 0.18 (P < .023) after a mean follow-up of 5.7 years. Two patients underwent major amputation of the lower target limb. The limb survival rate was 93.1%. During the follow-up period of 4 years, 21 of the 29 patients continued to smoke, and only five patients stopped nicotine exposure.

CONCLUSIONS

We recorded a significant benefit in the microcirculation, a good limb survival rate, and the absence of new trophic lesions. During the follow-up period, no severe complications related to the implanted devices occurred. Because of the diffuse, distal, segmental nature of the disease, SCS should be considered as an alternative treatment modality in patients with Buerger's disease.

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

Background

Spinal cord stimulation (SCS) may have a place in the treatment of patients with inoperable chronic critical leg ischaemia.

Methods

A systematic review and meta-analysis was performed of all controlled studies comparing SCS in addition to any form of conservative treatment for inoperable chronic critical leg ischaemia. Main endpoints were limb salvage, pain relief and clinical situation. Systematic methodological appraisal and data extraction were performed by independent reviewers.

Results

Of the 18 reports found, nine trials, comprising 444 patients, matched the selection criteria. After pooling, limb salvage at 12 months appeared significantly greater in the SCS group (risk difference (RD) − 0·13 (95 per cent confidence interval (c.i.) − 0·04 to − 0·22)). Significant pain relief occurred in both treatment groups, but patients who received SCS required significantly less analgesia and reached Fontaine stage 2 more often than those who did not have SCS (RD 0·33 (95 per cent c.i. 0·19 to 0·47)). Complications of SCS were problems of implantation (8·2 per cent), changes in stimulation requiring reintervention (14·8 per cent) and infection (2·9 per cent).

Conclusion

The addition of SCS to standard conservative treatment improves limb salvage, ischaemic pain and the general clinical situation in patients with inoperable chronic critical leg ischaemia. These benefits should be weighed against the cost and the (minor) complications associated with the technique.

Thromboangiitis Obliterans (Buerger Disease) in a Female Mild Smoker Treated with Spinal Cord Stimulation

The authors report the case of a 42-year-old female mild smoker admitted to the Hospital of Ferrara for the onset of asymptomatic necrotic ulcerations localized to the second, third, and fourth toes of left foot. Physical examination showed asphygmia of inferior limb distal peripheral pulses, with localized extremity marbleized and cyanotic skin at the level of the left foot, where necrotic ulcers were present at the second, third, and fourth toes. Doppler ultrasonography and angiography revealed a severe obliterating arteriopathy of bilateral distal arterial circulation. Both blood chemistry panel (including autoimmune and hypercoagulable profile) and diagnostic examination findings were normal. Thus, the patient met several criteria to be diagnosed with Buerger disease. After an attempt at medical therapy with the intravenous administration of the prostaglandin-analogue iloprost, given the young age and the lack of viable distal target vessels for bypass grafting, a spinal cord stimulator was implanted. More than 2 years later, the patient has a normal life.

[Electrical stimulation for rapid assessment of extremity tissues vitality in critical ischemia]

INTRODUCTION

In cases of trauma of the extremities, the development of critical tissue ischemia is a frequent complication, requiring surgical intervention with possible amputation. The exact duration of blood supply loss is often difficult to evaluate. Therefore, an easily applicable simple and rapid method for tissues vitality assessment would be of appreciable importance. It could also be used during surgery for delimitation of viable from non-viable tissue.

METHOD

The well-known approach for nerve-muscle excitability assessment by electrical stimulation is adopted. Its simplest form is by visual observation of the tissue reaction to the respective excitation. A battery supplied electrical stimulator is built for this purpose, housed in two hand-held electrode holders. The stimuli parameters were selected for efficient excitation of denervated and partially denervated tissue structures.

RESULTS

The stimulator was used in assessment of the condition of 23 patients: 16 with severe critical arterial ischemia from arterial occlusive disease and seven with vessel trauma and injuries. Eight extremities were tested immediately after amputation.

CONCLUSION

The stimulator was shown to be very efficient for tissue vitality assessment in the diagnostic stage. The easiness of use makes it convenient for application in the ambulatory, during transportation, at the patient bedside, as well as during surgery. It can also be efficient in mass accidents, disasters, or in armed conflicts.

Safety and efficacy of spinal cord stimulation for the treatment of chronic pain: a 20-year literature review

OBJECT

The purpose of this report was to examine the available literature to determine the safety and efficacy of spinal cord stimulation (SCS) for the treatment of chronic pain of the trunk and limbs.

METHODS

The author identified 68 studies that fulfilled the efficacy inclusion/exclusion criteria, grouped on the basis of pain indication, with an overall population of 3679 patients. Fifty-one studies fulfilled all safety inclusion/exclusion criteria. Based on the literature review, the author found that SCS had a positive, symptomatic, long-term effect in cases of refractory angina pain, severe ischemic limb pain secondary to peripheral vascular disease, peripheral neuropathic pain, and chronic low-back pain, and that, in general, SCS was a safe and effective treatment for a variety of chronic neuropathic conditions.

CONCLUSIONS

Despite the positive findings, there is an urgent need for randomized, controlled, long-term studies on the efficacy of SCS involving larger patient sample sizes.

Spinal cord stimulation in the treatment of non-reconstructable stable critical leg ischaemia: results of the European Peripheral Vascular Disease Outcome Study (SCS-EPOS)

OBJECTIVE

To determine the effect of spinal cord stimulation (SCS) on limb survival in patients with non-reconstructable critical leg ischaemia, and the value of patient selection on the basis of transcutaneous oxygen pressure (TcpO2) measurements and trial screening.

DESIGN

A prospective, controlled, European multicentre study.

METHODS

Non-reconstructable patients with stable critical leg ischaemia were divided into three groups. The SCS-Match group comprised patients with a baseline forefoot TcpO2 of < 30 mmHg and both sufficient pain relief and sufficient paraesthesia coverage (> 75%) after a test stimulation period of at least 72 h. If baseline TcpO2 was < 10 mmHg, the TcpO2 should have exceeded 20 mmHg after test stimulation. The SCS-Match group was compared with patients not meeting these criteria, who were treated either with SCS (SCS-No-Match) or without SCS (No-SCS).

RESULTS

At baseline, the mean (+/- SD) supine TcpO2 was 14.9 +/- 8.3 mmHg in the SCS-Match group (n = 41), 11.3 +/- 13.3 mmHg in the SCS-No-Match group (n = 32) and 15.3 +/- 17.1 mmHg in the No-SCS group (n = 39). In the SCS-Match group a significant improvement in pain relief (p < 0.005) and TcpO2 (p < 0.001) was seen. After 12 months, cumulative limb survival of patients treated with SCS was significantly better than that of patients not treated with SCS (p < 0.03), and limb survival in the SCS-Match group was significantly higher (p < 0.03) than that in the SCS-No-Match and No-SCS groups (78, 55 and 45%, respectively).

CONCLUSION

SCS treatment of non-reconstructable critical leg ischaemia provides a significantly better limb survival rate compared with conservative treatment. Patient selection based on TcpO2 and the results of trial screening further increase the probability of limb survival after SCS therapy.

Spinal cord stimulation reducing infarct volume in a model of focal cerebral ischemia in rats

OBJECT

The authors previously showed that spinal cord stimulation (SCS) increases cerebral blood flow in rats, indicating that this technique may be useful in the treatment of focal cerebral ischemia. In the present study, the neuroprotective potential of SCS in the setting of middle cerebral artery occlusion (MCAO) was investigated.

METHODS

The authors induced permanent, focal cerebral ischemia by using either suture-induced occlusion or direct division of the MCA in Sprague-Dawley rats. Electrical stimulation of the cervical spinal cord was performed during cerebral ischemia. Cerebral blood flow was assessed using both laser Doppler flowmetry (LDF) and quantitative radiotracer analysis. Stroke volumes were analyzed after 6 hours of ischemia. Spinal cord stimulation resulted in a 52.7 +/- 13.3% increase in LDF values (nine animals). Following MCAO, LDF values decreased by 64.1 +/- 3.6% from baseline values (10 animals). Spinal cord stimulation subsequently increased LDF values to 30.9 +/- 13.5% below original baseline values. These findings were corroborated using radiotracer studies. Spinal cord stimulation in the setting of transcranial MCAO significantly reduced stroke volumes as well (from 203 +/- 33 mm3 [control] to 32 +/- 8 mm3 [MCAO plus SCS], seven animals in each group, p < 0.001). Similarly, after suture-induced MCAO, SCS reduced stroke volumes (from 307 +/- 29 mm3 [control] to 78 +/- 22 mm3 [MCAO plus SCS], 10 animals in each group, p < 0.001).

CONCLUSIONS

A strategy of performing SCS for the prevention of critical ischemia is feasible and may have the potential for the treatment and prevention of stroke.

Local cooling alters neural mechanisms producing changes in peripheral blood flow by spinal cord stimulation

This study was performed to investigate the respective role of sensory afferent and sympathetic fibers in peripheral vasodilatation induced by spinal cord stimulation at different hindpaw skin temperatures. Cooling the skin was used as a strategy to enhance sympathetic activity [Am. J. Physiol.: Heart Circ. Physiol. 263 (1992) H1197]. Cutaneous blood flow in the footpad of anesthetized rats was recorded using laser Doppler flowmetry. Local cooling (<25 degrees C) or moderate local cooling (25-28 degrees C) of the hindpaw was produced with a cooling copper coil. Spinal cord stimulation delivered at clinically relevant parameters and with 30%, 60%, and 90% of motor threshold induced the early phase of vasodilatation in the cooled and the moderately cooled hindpaw. In addition, spinal cord stimulation at 90% of motor threshold produced the late phase of vasodilatation only in the cooled hindpaw, which was possible to block by the autonomic ganglion-blocking agent, hexamethonium. The early responses to spinal cord stimulation in the moderately cooled hindpaw were not affected by hexamethonium. In contrast, both the early and the late phase responses were eliminated by CGRP (8-37), an antagonist of the calcitonin gene-related peptide receptor. After dorsal rhizotomy, spinal cord stimulation at 90% of motor threshold elicited hexamethonium-sensitive vasodilatation in the cooled hindpaw (late phase). These results suggest that spinal cord stimulation-induced vasodilatation in the cooled hindpaw (<25 degrees C) is mediated via both the sensory afferent (early phase of vasodilatation) and via suppression of the sympathetic efferent activity (late phase) although the threshold for vasodilatation via the sympathetic efferent fibers is higher than that via sensory nerves. In contrast, vasodilatation via sensory afferent fibers may predominate with moderate temperatures (25-28 degrees C). Thus, two complementary mechanisms for spinal cord stimulation-induced vasodilatation may exist depending on the basal sympathetic tone.

Role of primary afferents in spinal cord stimulation-induced vasodilation: characterization of fiber types

Selected patients with peripheral vascular disease can be treated with spinal cord stimulation (SCS) to improve blood flow in the limbs. However, the mechanisms producing these effects remain unclear. The present study was designed to investigate if SCS produces cutaneous vasodilation via antidromic activation of the unmyelinated C-fibers and/or the small myelinated fibers. SCS was applied to anesthetized rats with a ball electrode at the L2-L3 spinal level. In Protocol 1, effects of capsaicin were examined. Blood flow changes in the hindpaw induced by SCS were measured in the footpad with laser Doppler flowmeters. Topical application of capsaicin (1%) on the tibial nerve did not affect SCS-induced vasodilation at 30 and 60% of motor threshold (MT). However, the duration of vasodilation induced by SCS at 90% MT and at 10 times MT was significantly reduced after capsaicin application on the tibial nerve. In Protocol 2, antidromic compound action potentials (CAPs) of the tibial nerve were recorded in response to SCS. CAPs of the large and the small myelinated afferent fibers were observed in response to SCS at all intensities. However, even with SCS at ten times MT, CAPs of C-fibers could not be detected in the tibial nerve. In Protocol 3, antidromic CAPs of the dorsal root were measured in response to SCS. Antidromic CAPs of C-fibers in dorsal roots were evoked by SCS at >or=90% of MT. It is concluded that SCS-induced vasodilation at <or=60% of MT may be mediated via only the myelinated fibers, whereas vasodilation at >or=90% of MT may also involve antidromic activation of some unmyelinated C-fibers.

Spinal cord stimulation for non-reconstructable chronic critical leg ischaemia

BACKGROUND

Patients suffering from inoperable chronic critical leg ischaemia (NR-CCLI), face amputation of the leg. Spinal cord stimulation (SCS) has been proposed as a helpful treatment in addition to standard conservative treatment.

OBJECTIVES

To find evidence for an improvement of limb salvage, pain relief and clinical situation by means of SCS over conservative treatment alone.

SEARCH STRATEGY

The reviewers searched the Cochrane Peripheral Vascular Diseases Group Specialised Register, (last searched November 2002), the Cochrane Central Register of Controlled Trials (CENTRAL) (last searched Issue 4, 2002). Additional data were obtained from research institutes.

SELECTION CRITERIA

Controlled studies comparing additional SCS with any form of conservative treatment in patients with NR-CCLI.

DATA COLLECTION AND ANALYSIS

Two reviewers (DU, HV), independently assessed the quality of the studies and extracted the data.

MAIN RESULTS

Six studies comprising nearly 450 patients were included. In general the quality of the studies was good, although none of them was blinded due to the nature of the intervention. Limb salvage after 12 months was significantly higher in the SCS group (RR 0.71, 95%CI: 0.56 to 0.90; RD -0.13, 95%CI: -0.22 to -0.04). Significant pain relief occurred in both treatment groups, but was more prominent in the SCS group, in which the patients required significantly less analgesics. In the SCS group significantly more patients reached Fontaine stage II than in the conservative group (RR 4.9, 95%CI: 2.0 to 11.9; RD 0.33, 95%CI: 0.19 to 0.47). Overall, no significantly different effect on ulcer healing was observed between the two treatments. Complications of SCS treatment consisted of implantation problems (9%; 95%CI: 4 to 15%) and changes in stimulation requiring reintervention, (15%; 95%CI: 10 to 20%). Infections of the lead or pulse generator pocket occurred less frequently (3%; 95%CI: 0 to 6%). The overall risk of complications of additional SCS treatment was 17%, 95%CI: 12 to 22%, indicating a number needed to harm of six (95%CI: 5 to 8).A cost comparison was made in only one study. The average overall costs at two years were 36,500 euros, in the SCS group and 28,600 euros, in the conservative group. The difference (7,900 euros) was significant (p<0.009).

REVIEWER'S CONCLUSIONS

There is evidence to favour SCS over standard conservative treatment to improve limb salvage and clinical situation in patients with NR-CCLI. The benefits of SCS against the possible harm of relatively mild complications, and costs must be considered.

Spinal Cord Stimulation in Peripheral Vascular Disease: A Retrospective Analysis of 95 Cases

Spinal Cord Stimulation is one of the interventionist treatments used for treating diverse chronic pain syndromes. This study analyses retrospectively 95 patients diagnosed as suffering from grave peripheral arteriopathy in Fontaine state III (36 patients) and Fontaine state IV (56 patients). Eight patients required a minor amputation and 29 a major amputation. Those patients diagnosed as suffering from diabetes (diabetic arteriopathy) had a higher rate of amputation, above all those diagnosed as Fontaine group III. The most frequent complication was incorrect stimulation (22 cases), which necessitated the repositioning of the electrode.

Current and future trends in spinal cord stimulation for chronic pain

Spinal cord stimulation (SCS) is a reversible treatment for chronic pain that is gaining favor as a first-line therapy for many disease states. Because there are no addictive issues and no side effects systemically, the treatment is moving up the treatment continuum ladder. First used clinically in 1967, the procedure was used exclusively for failed back surgery syndrome. Over the past 30 years selection criteria, psychologic screening, and technology have improved. These advances have broadened the treatment options for many patients in pain. This review focuses on the selection, indications, techniques, new advances, complications, and outcomes involved with SCS. A review is provided for the treatment of radiculitis, failed back surgery syndrome, complex regional pain syndrome, peripheral neuropathies, pelvic pain, occipital neuralgia, angina, ischemic extremity pain, and spasticity. Technologic advances such as multi-lead and multi-electrode arrays are also discussed in regard to the impact these developments have on the clinical application of the therapy.

The results of spinal cord stimulation in critical limb ischaemia: a review

OBJECTIVES

to determine which patients with unreconstructible critical limb ischaemia (CLI) might benefit from spinal cord stimulation (SCS).

METHODS

literature review.

RESULTS

limb salvage in patients with an intermediate transcutaneous oxygen pressure (TcpO2) was not significantly higher with SCS (76%) than with conservative therapy (p=0.08). However, a limb salvage of 88% was achieved with SCS if the difference between the supine and sitting TcpO2 baseline values (DeltaTcpO2) was > or =15 mmHg. A rise in TcpO2 after trial stimulation of at least 15% resulted in a limb salvage of 77% at 18 months (p<0.01).

CONCLUSION

randomised studies show no benefit of SCS over conservative therapy in patients with non-reconstructible CLI. However, data from experimental and non-randomised studies suggest this may be due to sub-optimal patient selection for SCS. Further trials are needed to identify subgroups who may benefit from SCS.

Uncommon areas of electrical stimulation for pain relief

Uncommon stimulation refers to the use of peripheral nerve and spinal cord stimulation for nontraditional applications. There has been much interest recently with subcutaneous suboccipital stimulation for occipital neuralgia, sacral stimulation for pelvic pain, trigeminal stimulation for trigeminal neuralgia, and spinal cord stimulation for angina and peripheral ischemia. The indications and techniques used for accomplishing each method are discussed.

Effects of cervical spinal cord stimulation on cerebral blood flow in the rat

OBJECT

Spinal cord stimulation (SCS) is frequently used for the treatment of chronic pain. Although the mechanisms by which SCS alleviates pain are unclear, they are believed to involve changes within the dorsal horn of the spinal cord. Spinal cord stimulation has also been found to cause significant vasodilation in the peripheral vasculature. The mechanisms underlying this effect are thought to involve sympathetic blockade. A rostral vasodilatory effect has also been described, but changes in cerebral blood flow (CBF) have been poorly delineated. Using laser Doppler flowmetry (LDF), the authors examined the effects of cervical SCS on CBF in rats.

METHODS

Cervical SCS was found to result in a significant increase in cortical LDF values (83 +/- 11% [mean +/- standard error of the mean]). The increase in cortical LDF values was not accompanied by a significant increase in systemic blood pressure. Stimulation of the upper cervical spinal cord was more effective in inducing LDF changes than was that of the lower cervical cord. Changes in SDS-induced LDF values were significantly attenuated after spinal cord transection at the cervicomedullary junction and by the administration of the sympathetic blocker hexamethonium.

CONCLUSIONS

These results indicate that cervical SCS may induce cerebral vasodilation and that this effect may involve indirect effects on vasomotor centers in the brainstem as well as an alteration in sympathetic tone.