Our Experience with Spinal Cord Stimulation (SCS) In Peripheral Vascular Disease

Spinal cord stimulation (SCS) by epidural electrodes is being used more often in the treatment of patients with severe intractable ischemic pain. The promising clinical results and the objective increase in lower extremity blood flow (plethysmography, thelethermography, etc.), suggests that spinal cord stimulation may have an important role in the management of advanced arterial disease when other forms of treatment have failed. The selection criteria for implantation of SCS are very important. Our indications in patients with peripheral vascular disease are: 1. Peripheral vascular disease with severe, intractable symptoms that are untreatable by medical or surgical therapy. 2. Inflammatory or diabetic arterial disease resistant to medical treatment and/or sympathectomy. 3. Persistent and severe ischemic pain and/or ulcers in patients with patent grafts. 4. Patients for lumbar sympathectomy who have a high myocardial risk. Contraindications to implantation of SCS are claudication intermittent, large necrotic lesions (gan-grene) and patients who have undergone prolonged narcotic therapy.     

The Use of Spinal Cord Stimulation in Refractory Abdominal Visceral Pain: Case Reports and Literature Review

Abstract:   Patients will commonly seek medical attention for refractory abdominal pain. The many causes of abdominal pain include pathologies of the gastrointestinal, genitourinary, musculoskeletal, and nervous systems. Unfortunately, a large number of patients will develop chronic abdominal pain that is recalcitrant to definitive therapies and nonspecific treatments such as cognitive-behavioral, physical, and pharmacologic therapies. Although spinal cord stimulation is classically used for neuropathic and ischemic conditions, a growing number of reports describe its efficacy in visceral disease. We describe our experience with spinal cord stimulation in two patients with refractory abdominal pain. Although the exact etiology in these complex patients is not defined, it is theorized that visceral hypersensitivity is at least one component. Finally, we will summarize the applicable literature in order to explain a possible mechanism of analgesia in visceral disease.     

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.     

Peripheral Nerve Field Stimulation for Intractable Post‐Thoracotomy Scar Pain not Relieved by Conventional Treatment

Peripheral nerve field stimulation (PNFS) is being applied in individual cases where conventional treatments have failed to control pain localized to limited dermatomal distribution. We applied PNFS for unrelieved post‐thoracotomy scar pain. Although spinal cord stimulation may have resulted in good coverage in the same dermatomal distribution, we chose the more peripheral approach to minimize the risk of complications, avoiding the potential neurologic sequelae associated with stimulation of the spinal cord. In summary, PNFS was effective in relieving post‐thoractomy pain refractory to conventional pain management suggesting great potential of PNFS as a treatment option for chronic surgical‐scar pain.     

On the Therapeutic Viability of Peripheral Nerve Stimulation for Ilioinguinal Neuralgia: Putative Mechanisms and Possible Utility

▪ Abstract:   Injury to the ilioinguinal nerve commonly follows during lower abdominal and pelvic surgery, especially with inguinal hernia repair, appendectomy, and hysterectomy. Other potential causes include low abdominal blunt trauma, iliac crest bone graft, psoas abscess, Pott's disease, and prolonged wearing of abdominally constrictive clothing. The actual incidence of ilioinguinal neuralgia is uncertain, as reported percentage ranges between 12% and 62%. Prompt and accurate diagnosis is critical, and appropritate treatments range from conservative pharmacologic management with nonopioid (eg, gabapentin, topiramate) as well as opioid agents, to surgical neurectomy of the proximal portion of the ilioinguinal nerve. Pharmacological treatment is frequently unsuccessful (particularly if delayed) and while surgery is successful in approximately 73% of cases, it can result in problematic paresthesias, and pain may continue to persist in some patients. Thus, minimally invasive techniques, such as peripheral nerve stimulation, may be viable in those patients who are refractory to pharmacological management, as an option to surgery, and who have not gained satisfactory pain relief through surgical intervention. We present three cases of successful pain control of ilioinguinal neuralgia with peripheral nerve stimulation. These cases demonstrate the potential benefits of neurostimulation including durable effective pain relief and decreased use of medication. Putative mechanisms of effect(s) and caveats for continued research to inform prudent employment of this technique are presented. ▪     

Peripheral vascular pain

Peripheral vascular pain consists of complex factors, and may be divided into three types, i.e., arterial pain, microvessel pain and venous pain. Among these, arterial pain requires intensive pain control because of severe ischemic pain due to arterial obstruction. Under ischemic condition, adenosine is generated, and activates unmyelinated afferents to produce pain. In addition to adenosine, acidic pH itself produces pain and sensitization to mechanical stimuli. Moreover bradykinin generated by kallikurein in acidic pH can produce pain. Nerve block is indicated to improve tissue circulation and to relieve pain. Endoscopic thoracic sympathectomy is indicated for upper extremities, and high frequency thermocoagulation is applied for lumbar sympathectomy. Spinal cord stimulation and the gene therapy with vascular endothelial growth factor have also been reported effective.     

Chemical lumbar sympathectomy in patients with chronic ischemia of the lower extremities

The efficiency of lumbar chemical sympathectomy made within the complex therapy for ischemic pain in the lower extremities was analyzed versus lumbar sympathectomy, made surgically, in 84 male and female patients aged 33-84. The below parameters were studied: the dynamics of painless-walking distance in patients with ischemia, stages IIa and IIb, and rest-pain intensity in patients with ischemia, stages III and IV, according to Fontaine. The regional hemodynamics was registered in all patients by Duplex scanning of lower-extremities vessels before manipulation and on days 5 and 10 after sympathectomy performed by chemical and surgical techniques. An increased distance of painless walking, reduced intensity of rest pain and better parameters of regional hemodynamics were observed in the study and control groups; they were of the unidirectional nature. Thus, sympathectomy, made by the chemical technique, is not inferior by its efficiency to surgical lumber sympathectomy.     

Epidural Abscess Due to Spinal Cord Stimulator Trial

▪ Abstract:   Spinal cord stimulation is increasingly utilized as a treatment to alleviate low back pain and lumbar radiculopathy, particularly in patients with failed back surgery syndrome. We present an illustrative case of early, rapidly progressive methicillin-resistant Staphylococcus aureus (MRSA) infection after a brief stimulator trial lead implantation. Operators should maintain a high level of suspicion for deep infection, including epidural abscess, even when only minor symptoms and signs are present. Because of the poor ability to clear infections in the presence of a retained foreign body, the device must be explanted immediately. Subsequent surgical intervention, however, may nevertheless still be needed. While a variety of bacteria may cause epidural abscess, methicillin sensitive Staphylococcus aureus , and increasingly, MRSA and community-associated MRSA, are the most likely etiologic organisms. ▪     

Interventional management of neuropathic pain: NeuPSIG recommendations

Neuropathic pain (NP) is often refractory to pharmacologic and noninterventional treatment. On behalf of the International Association for the Study of Pain Neuropathic Pain Special Interest Group, the authors evaluated systematic reviews, clinical trials, and existing guidelines for the interventional management of NP. Evidence is summarized and presented for neural blockade, spinal cord stimulation (SCS), intrathecal medication, and neurosurgical interventions in patients with the following peripheral and central NP conditions: herpes zoster and postherpetic neuralgia (PHN); painful diabetic and other peripheral neuropathies; spinal cord injury NP; central poststroke pain; radiculopathy and failed back surgery syndrome (FBSS); complex regional pain syndrome (CRPS); and trigeminal neuralgia and neuropathy. Due to the paucity of high-quality clinical trials, no strong recommendations can be made. Four weak recommendations based on the amount and consistency of evidence, including degree of efficacy and safety, are: 1) epidural injections for herpes zoster; 2) steroid injections for radiculopathy; 3) SCS for FBSS; and 4) SCS for CRPS type 1. Based on the available data, we recommend not to use sympathetic blocks for PHN nor radiofrequency lesions for radiculopathy. No other conclusive recommendations can be made due to the poor quality of available data. Whenever possible, these interventions should either be part of randomized clinical trials or documented in pain registries. Priorities for future research include randomized clinical trials, long-term studies, and head-to-head comparisons among different interventional and noninterventional treatments.     

Neural Modulation by Stimulation

Abstract:   Spinal cord stimulation (SCS) for the treatment of neuropathic pain is supported by good-quality randomized controlled trials, prospective and retrospective case studies, and observational case series that confirm its efficacy and safety. SCS has been successfully used in various refractory neuropathic pain conditions, including failed back surgery syndrome (FBSS), neuropathic back and leg pain, and complex regional pain syndrome (CRPS) types I and II. According to the Harbour and Miller Scale (2001), the evidence for SCS in FBSS has been classified as grade B, while that for CRPS type I has been classified as grade A. Clinical evidence has shown that compared to conventional pain therapy, more than two-thirds of carefully selected patients treated with SCS achieved sustained pain relief of 50% or more, with minimal side effects. Many patients were able to reduce their analgesic consumption. Quality of life improved and the majority of patients were happy with their treatment; in some cases, patients were able to return to work. Trial stimulation, which is relatively inexpensive and completely reversible, provides predictive value for long-term efficacy and increases the cost-effectiveness of permanent implantation. Studies consistently report that over time, SCS is potentially cost saving to the healthcare system. At present, SCS is considered a "last resort" in the treatment of refractory neuropathic pain, yet evidence suggests that early intervention with SCS results in greater efficacy and, in the case of FBSS, should be considered before re-operation.     

Peripheral Neurostimulation in Supraorbital Neuralgia Refractory to Conventional Therapy

▪ Abstract:   Supraorbital neuralgia has been identified as an infrequent cause of headache that may prove very difficult to control pharmacologically. Peripheral nerve stimulation using electrodes to stimulate the nerve segmentally responsible for the zone of pain may constitute a management alternative in such cases. We present the case of a patient with headache because of posttraumatic supraorbital neuralgia, refractory to medical treatment, with good analgesic control after peripheral nerve stimulation.
Peripheral nerve stimulation may be considered a safe, reversible treatment for patients with headache secondary to supraorbital neuralgia who respond poorly to pharmacological treatment, thus avoiding irreversible alternatives such as surgery. ▪     

Other Surgical Interventions

Abstract:   Optimal management of patients with chronic neuropathic pain requires a multidisciplinary approach that may include surgery. Yet despite the fact that lumbosacral spinal surgery, for example, is performed in thousands of patients every year, there is very little controlled clinical data to support its use or that of other surgical techniques in the treatment of chronic nonmalignant pain, especially neuropathic pain. Nevertheless, there is evidence of some success for ablative techniques such as dorsal root entry zone lesioning for phantom limb pain and girdle-zone neuropathic pain, and sympathectomy for the treatment of complex regional pain syndrome, and a variety of operations for tic douloureux. However, before considering a surgical procedure, a nonsurgical approach should have been tried and the suitability of the patient must be carefully assessed. To fully establish the role of surgery in the treatment of chronic neuropathic pain, further well-designed, prospective, controlled trials are essential.     

Spinal Cord Stimulation as a Novel Approach to the Treatment of Refractory Neuropathic Mediastinal Pain

Spinal cord stimulation (SCS) offers new hope for patients with neuropathic pain. SCS "neuromodulates" the transmission and response to "painful" stimuli. The efficacy of SCS has been established in the treatment of a variety of neuropathic pain conditions and more recently in refractory angina pectoris, peripheral vascular disease, and failed back surgery syndrome. Recent publications suggest that visceral pain could be successfully treated with SCS. We report the first successful use of a spinal cord stimulator in the treatment of refractory neuropathic mediastinal, esophageal, and anterior neck pain following esophagogastrectomy.     

Spinal cord stimulation in a patient with persistent oesophageal pain

This study describes a man with a long history of oesophageal pain that led to inability to swallow food and drink. Over a period of 8 years, he had multiple oesophageal operations that were unsuccessful. He presented, to the pain management team, with persistent oesophageal pain and required jejunostomy tube feeding to maintain nutrition. Conservative pain management strategies failed. Spinal cord stimulation (SCS) was suggested, and after counseling, an electrode was placed in the high thoracic region. Stimulation covered the area of the chest pain. He achieved immediate reduced pain on swallowing water. A permanent system was implanted. In this case, SCS resulted in a significant improvement in pain on swallowing liquids. The patient can now also eat certain foods occasionally and enjoy the social aspect of eating; this was impossible previously. He feels that SCS has been worthwhile. The authors discuss the rationale for this treatment. The decision was based on the use of SCS for refractory angina, and the idea that the neural mechanisms that generate both these pain states may be similar.     

Exploration of the Evidence

Abstract:   Faced with rapidly escalating costs, healthcare policy makers are increasingly turning to research evidence to serve as a basis for their population-based decisions on access and funding of new and existing therapies—health technology assessment. A two-stage approach is often used to arrive at a policy recommendation for a given treatment. First, following a systematic review of literature, the "level of evidence" for the treatment is assessed according to epidemiological principles. Then a grade of policy recommendation is provided based on both the level of evidence and the applicability of the evidence to current clinical practice. To assess the current evidence basis for refractory neuropathic pain, a comprehensive search was undertaken for systematic reviews of pharmacological interventions and interventional procedures (ie, spinal cord stimulation, therapeutic blocks, radiofrequency procedures, and surgery). Of the 33 systematic reviews identified, the majority provided evidence for the use of drugs and spinal cord stimulation in the management of various neuropathic pain indications. Little evidence was found for either radiofrequency procedures or therapeutic blocks. By including randomized controlled trials, a number of these systematic reviews indicate a high grade of evidence. Nevertheless, more pragmatic clinical trials are needed to address the evidence needs of healthcare policy makers. These trials should address a direct comparison of the relative effectiveness of neuropathic pain therapies, particularly in combination with other therapies and at different points in the disease course.     

Treatment of Chronic Refractory Intractable Headache with Botulinum Toxin Type A: A Retrospective Study

Abstract:   Chronic refractory daily headache is a relatively common problem in the Australian population. Several million working hours per year are lost due to this illness. Generally not responding to conventional therapies. We treated 22 such patients diagnosed as severe refractory migraine and/or mixed tension headache at our multidisciplinary pain management center. Before inclusion to our study, they received maximal medical management, which included cognitive behavior therapy, but failed to respond. These patients received between 30 and 100 units of botulinum toxin type A. Our study showed 84% (19 of 22) achieved significant improvement in their pain complaint. There was significant reduction of medications particularly opioids. The duration of pain relief ranged from 1 to 6 months. Repeat injections were necessary in several of the patients. There were minor complications but these reversed spontaneously without further treatment.     

Absence of Histological Changes after the Administration of a Continuous Intrathecal Clonidine in Wistar rats

Background:   The administration of epidural and spinal clonidine has demonstrated an antinociceptive effect in animals and humans. For that reason, its spinal administration has been proposed as an adjuvant in chronic pain management. However, there is limited information about its possible neurotoxic effect after its continuous neuraxial administration.
Method:   Twelve male Wistar rats were randomly divided into two groups. Using an osmotic mini-pump a continuous infusion of intrathecal clonidine, (21.4 micrograms/day, Group A) or saline solution (Group B), was administered for 14 consecutive days. For evaluating the neurological damage a neuropathological analysis of the spinal cord was performed by light microscopy.
Results:   Neurohistopathologic examination of the spinal cord specimens failed to show evidence of neurotoxic damage in either group.
Conclusions:   These findings showed that continuous intrathecal administration of clonidine did not produce evidence of histological neurotoxicity; therefore it is possible that continuous administration of intrathecal clonidine might be a safe option for treatment of chronic intractable pain; however, further investigations are necessary for evaluating diverse doses and periods of time, and to define its possible behavioral effects.     

Spinal Cord Stimulator Relieves Neuropathic Pain in a Patient With Radiation-Induced Transverse Myelitis

▪ Abstract:   We present a patient with intractable neuropathic pain because of radiation-induced transverse myelitis unresponsive to medical treatment. After a successful trial of spinal cord stimulation, a permanent stimulator was implanted. Improvement was noted in verbal pain score, medication usage and function. Spinal cord stimulation may offer a therapeutic option for patients with neuropathic pain resulting from transverse myelitis and should be considered when other treatments fail. ▪     

Clinical Science (37)

Pain relief in complex regional pain syndrome due to spinal cord stimulation does not depend on vasodilation. (Maastricht University Hospital, Maastricht, The Netherlands) Anesthesiology 2000;92:1653–1660. This study aimed to assess whether pain relief in complex regional pain syndrome (CRPS after spinal cord stimulation (SCS) is, in fact, dependent on vasodilation. In addition, the study attempted to determine which of the potential mechanisms may cause the vasodilatory effect that is generally found after SCS. Twenty‐four of 36 patients with unilateral CRPS responded to the test of SCS. Twenty‐two of the 24 responders (hand, n = 14; foot, n = 8) who had undergone previous sympathectomy were enrolled in the study. In addition, 20 control subjects (10 controls for each extremity) were studied. By means of laser Doppler flowmetry, the skin microcirculation of the patients was measured bilaterally while the SCS system was switched off and while it was activated. Control subjects were tested only once. The ratio of the rest flow at heart level and the dependent position was defined as the vasoconstricted index. Both in affected hands and feet, patients were found to have lower vasoconstriction indices (P < 0.01) as compared with controls, indicating a decreased sympathetic tone. Applying SCS did not result in any microcirculatory change as compared with the baseline or the contralateral clinically unaffected side. Conclude that the study failed to show that SCS influences skin microcirculation in patients with CRPS and a low sympathetic tone. Therefore, it was also concluded that pain relief in CRPS due to SCS is possible without vasodilation. Because sympathetic activity was greatly decreased in the patients, these results support the hypothesis that the vasodilation that is normally found with SCS is due to an inhibitory effect on sympathetically maintained vasoconstriction. Comment by Hemmo A. Bosscher, MD. SCS probably provides pain relief independent of increases in blood flow to the affected area. There may be several weaknesses in this study. All patients underwent prior sympathectomy. As every pain management specialist knows, the results of these procedures are variable. That leaves a group of pain patients with CRPS I that is either predominantly sympathetically mediated or sympathetically independent, with variable degrees of sympathetic blockade. In addition, only part of the peripheral circulation is measured with a device which accuracy has not yet been confirmed. Many variables are introduced in this study making a statement that there are no differences between the treatment group and the control somewhat strong. In my opinion: pain relief in complex regional pain syndrome due to spinal cord stimulation may not depend on vasodilatation.     

Spinal Cord Stimulation: A Comparison of Efficacy versus Other Novel Treatments for Refractory Angina Pectoris

Abstract: Recently much attention has been directed toward novel treatment alternatives for refractory angina pectoris. Refractory angina is persistent stable class III or IV angina despite maximally tolerated medical treatment in patients with end-stage coronary artery disease. Transmyocardial laser revascularization (TMLR), gene therapy, intermittent urokinase therapy, enhanced external balloon counterpulsation, and spinal cord stimulation have all been employed to treat refractory angina pectoris. TMLR and gene therapy are invasive open-chest procedures that have yielded controversial results. Intermittent urokinase and enhanced external balloon counterpulsation studies have limited follow-up times and require multiple clinic visits for treatment. Spinal cord stimulation has a proven short- and long-term efficacy and cost-effectiveness in the treatment of refractory angina. When compared to coronary artery bypass grafting (CABG), it has been shown to decrease the frequency of anginal attacks and consumption of short-acting nitrates to the same extent in refractory angina. Spinal cord stimulation's safety profile has also been well established and it can be used concurrently with cardiac pacemakers or MRI systems, provided the proper precautions are taken. Since spinal cord stimulation is a minimally invasive procedure with a favorable efficacy and safety profile, it should be considered as a valid treatment alternative after medical management has failed in refractory angina prior to implementing invasive modalities such as TMLR or gene therapy.