Spinal Cord Stimulation for Refractory Angina Pectoris: A Shocking Experience

Spinal cord stimulation has been extensively utilized in the treatment of conditions including complex regional pain syndrome, ischemic limb pain, failed back surgery syndrome, and angina pectoris. Recognized complications include infection, dural tap, and electrode movement. We report the case of a patient who experienced a sensation of extremely enhanced stimulation in the area covered by the spinal cord stimulator while in the vicinity of a high‐tension electricity substation. Full resolution of symptoms occurred when the spinal cord stimulator was switched off, indicating that active stimulators may be susceptible to the effects of external electrical fields.     

Spinal Cord Stimulation in Severe,Inoperable Peripheral Vascular Disease

Objective. To assess the effect of spinal cord stimulation in patients with severe, inoperable peripheral vascular disease, and uncontrolled pain. Patients and methods. A case study of 20 patients with end‐stage peripheral vascular disease, either Fontaine Class 3 or 4 limb ischemia. All 20 patients implanted with spinal cord stimulation devices with follow‐up from one to five years (mean, 32 months) performed in a multidisciplinary pain treatment center. Results. In the 20 patients implanted with a spinal cord stimulator for peripheral vascular disease, overall there was 75% limb salvage; with Fontaine Class 3 patients there was 86% and with Fontaine Class 4 patients, 69% limb salvage of the treated limbs. Conclusions. Twenty patients with end‐stage peripheral vascular disease were implanted with spinal cord stimulators and followed for five years, until amputation or end of life, showing excellent results for limb salvage and minimal complications. The current literature regarding the use of spinal cord stimulation for peripheral vascular disease is reviewed, supporting its benefit for limb salvage and pain relief.     

Spinal Geometry and Paresthesia Coverage in Spinal Cord Stimulation

Objective . To test the following hypotheses, based on computer modeling studies of spinal cord stimulation, by the analysis of data from chronic pain patients: I. the probability-of-paresthesia in a dermatome is highest when the cathode is placed at the corresponding segmental level; II. variation of the rostrocaudal position of the cathode in the lower cervical/high thoracic region results in less variation of the probability-of-paresthesia in a dermatome than stimulation in more caudal regions; III. when stimulating in the midthoracic region, the probability-of-paresthesia in a dermatome is low in comparison to other regions when the cathode is not at the corresponding segmental level. Method . The probability-of-paresthesia in 16 body segments as a function of the rostrocaudal position of the cathode was analyzed from the paresthesia coverage with 3,897 bipolar and unipolar combinations from 106 chronic pain patients. Results . The distributions of the probability-of-paresthesia in the upper and lower limb are in accordance with the hypotheses, but different distributions were found in all trunk areas. Conclusion . The success to be expected from spinal cord stimulation in chronic pain management is inversely related to the thickness of the dorsal cerebrospinal fluid layer at the cathode level. Therefore, preoperative measurement from transverse images can be helpful as a predictor for success.     

Long-Term Outcome of Spinal Cord Stimulation for Chronic Pain Management

Study Design. This is a retrospective study on 102 patients subjected to implantation of a spinal cord stimulation system for nonmalignant chronic pain management. The study was conducted through an extensive questionnaire and telephone interviews by a neutral third party. All the patients were implanted with a complete spinal cord stimulation system without a preliminary trial with a temporarily implanted electrode. Diagnostic categories were neuropathic pain, failed back syndrome, spinal cord Injury pain, and miscellaneous. Average follow-up was 3.8 years (6 months to 8 years). Patients were divided in two groups: all the implanted patients in the survey (Group A) and the implanted patients who experienced some degree of pain relief with the stimulation (Group B). Group B (80 patients) closely matches previously published series where an initial temporary screening was performed. Results. Twenty-one percent of the patients never experienced any pain relief. Of the remaining 80, 75% were still using the stimulator. Fifty-one percent of the 80 patients were experiencing good to excellent results and 20% moderate results. There was no reduction over time in the amount of pain relief in patients who initially had at least 75% pain relief. Patients with initial pain relief between 50% and 74% observed a moderate reduction in their pain relief after two years. Patients who initially experienced less than 50% pain relief observed a dramatic reduction in their results in the long term follow-up. Psychological screening contributed to the success of the procedure. Conclusions. With proper medical and psychological screening and with demonstrated initial pain relief, spinal cord stimulation remains an effective modality in the long-term management of severe chronic pain.     

Cervical Spinal Cord Stimulation for Pain: A Report on 41 Patients

The objectives of this study were to assess the effectiveness of cervical spinal cord stimulation in the management of intractable pain syndromes affecting the upper limb and face and to assess the reliability of a specific electrode system in this mobile environment. Forty‐one patients, aged 26–76 years (median 48) with neuropathic or ischemic pain underwent the cervical epidural implantation of identical dual two‐contact paddle (four contacts per system) laminectomy electrodes. Follow‐up (from 5 months to 11 years, 3 months; median 4 years, 7 months) was by multiple consultations carried out by the surgeon and/or in a nurse‐led specialist clinic. Overall, 68% obtained sustained pain relief, rated as significant in 51% of the total. Facial pain did not respond. Ischemic syndromes responded well. Lead fracture rate was 15% of the original (11% of the total including replacements) and only 7% (5%) became dislodged.We conclude that the electrode system described provides reliable and sustained cervical cord stimulation. The outcomes are comparable with thoracic cord stimulation for neuropathic and ischemic syndromes.     

Sjögren Syndrome and Spinal Cord Stimulation: A Case Report

Sjögren syndrome is a chronic autoimmune disease. This disease mainly involves salivary and lacrimal glands, although it may also involve the musculoskeletal, respiratory, gastrointestinal, renal, hepato‐biliary, hematological, neurological, vascular, or both systems. Small vessel disease may appear in up to 30% of the cases. We present a case report of a 62‐year‐old female diagnosed with Sjögren syndrome. Systemic associated manifestations of her disease included interstiticial vessel vasculitis with a necrotic, sharp, and painful ulceration in her left heel. Because of refractory pain to common analgesic medical therapies (paracetamol, metamizol, and tramadol), she was referred to our pain unit for evaluation and treatment prior to limb amputation. In our pain unit, a percutaneous posterior spinal cord stimulator (SCS) was placed. SCS clinically reduced her pain by 90% and helped to improve her quality of life and significantly reduced her intake of analgesics. We conclude spinal cord stimulation may be a good alternative to conservative therapies in patients with vasculitis of Sjögren syndrome.     

Spinal Cord Injury Induced by a Cervical Spinal Cord Stimulator

Objective: The use of cervical spinal cord stimulators for the treatment of refractory neck and upper extremity pain is widely accepted and growing in use as a treatment modality. This case highlights a previously unreported potential complication of spinal cord stimulators. Methods: Analysis of a patient with a cervical spinal cord stimulator presenting with a spinal cord injury. Patient was followed from presentation in the emergency room until 1‐year follow‐up in the office. Results: The patient in this case presented after a fall and sustained a cervical spinal cord injury induced by the electrodes of her spinal cord stimulator working as a space occupying mass. Conclusion: As more patients are undergoing implantation of spinal cord stimulators we must be aware of the long‐term risks that can be encountered.     

Accidental Subdural Spinal Cord Stimulator Lead Placement and Stimulation

Objectives: Neuromodulation with spinal cord stimulation has become an increasingly employed intervention for treatment of a variety of neuropathic pain states. As prevalence increases, so does the incidence of complications. Currently, there is sparse literature describing spinal cord stimulation lead placement and stimulation characteristics in the subdural space. In this case report we describe subdural lead placement and the associated stimulation parameters, and provide evidence‐based support to initiate a dialog to further reduce procedural morbidity and mortality. Materials and Methods: This study is a case report following lead placement during permanent percutaneous spinal cord stimulator placement and stimulation testing. The lead placement and stimulation characteristics were suggestive of extra‐epidural lead placement. Results: Using the same cathode/anode configuration (1:anode, 3:cathode, 5:anode), frequency of 40 Hz and pulse width of 650 microseconds, sequential stimulation was performed. Summarizing, the testing demonstrated similar impedance for the left and right leads (within 30 ohms) of approximately 300 ohms, and a large discrepancy in current of 3.2 mA for the left and 0.9 mA for the right. The patient reported “painful intense” stimulation with right lead stimulation. Conclusions: Evidence suggesting subdural lead placement include the lack of cerebrospinal‐fluid despite lavage, the absence of post‐dural puncture headache, the recent evidence of intentional and reproducible subdural anesthesia, and the conductive properties of the dural spinal elements. It can be argued that subdural lead placement may occur unrecognized more frequently than originally anticipated.     

Spinal Cord Stimulation for the Treatment of Upper and Lower Extremity Neuropathic Pain due to Lyme Disease

Background. Lyme disease is caused by Borrelia, a bacterium transmitted by the bite of a deer tick. A slow developing encephalopathy or an axonal polyneuropathy with distal paresthesia and spinal or radicular pain rarely occurs and can be hard to treat. Materials and Methods. We report here the case of a 44‐year‐old woman with four‐limb, intolerable, neuropathic pain as sequelae to Lyme disease, which was resistant to conservative measures and was treated successfully with concurrent, thoracic, and cervical percutaneous spinal cord stimulation (SCS). Results. After 18 months of therapy and follow‐up, this patient's analgesia, as a result of SCS, continues to be excellent, with almost complete subjective pain relief and cessation of adjuvant analgesic medication. Conclusions. SCS may be efficacious for the treatment of neuropathic pain due to Lyme disease.     

Spinal Cord Stimulation Attenuates Below‐Level Mechanical Hypersensitivity in Rats After Thoracic Spinal Cord Injury

ObjectivesThe burden of pain after spinal cord injury (SCI), which may occur above, at, or below injury level, is high worldwide. Spinal cord stimulation (SCS) is an important neuromodulation pain therapy, but its efficacy in SCI pain remains unclear. In SCI rats, we tested whether conventional SCS (50 Hz, 80% motor threshold [MoT]) and 1200 Hz, low-intensity SCS (40% MoT) inhibit hind paw mechanical hypersensitivity, and whether conventional SCS attenuates evoked responses of wide-dynamic range (WDR) neurons in lumbar spinal cord.Materials and MethodsMale rats underwent a moderate contusive injury at the T9 vertebral level. Six to eight weeks later, SCS or sham stimulation (120 min, n = 10) was delivered through epidural miniature electrodes placed at upper-lumbar spinal cord, with using a crossover design. Mechanical hypersensitivity was examined in awake rats by measuring paw withdrawal threshold (PWT) to stimulation with von Frey filaments. WDR neurons were recorded with in vivo electrophysiologic methods in a separate study of anesthetized rats.ResultsBoth conventional SCS and 1200 Hz SCS increased PWTs from prestimulation level in SCI rats, but the effects were modest and short-lived. Sham SCS was not effective. Conventional SCS (10 min) at an intensity that evokes the peak Aα/β waveform of sciatic compound action potential did not inhibit WDR neuronal responses (n = 19) to graded or repeated electrical stimulation that induces windup.ConclusionsConventional SCS and 1200 Hz, low-intensity SCS modestly attenuated below-level mechanical hypersensitivity after SCI. Inhibition of WDR neurons was not associated with pain inhibition from conventional SCS.     

Spatiotemporal Distribution of Electrically Evoked Spinal Compound Action Potentials During Spinal Cord Stimulation

ObjectivesRecent studies using epidural spinal cord stimulation (SCS) have demonstrated restoration of motor function in individuals previously diagnosed with chronic spinal cord injury (SCI). In parallel, the spinal evoked compound action potentials (ECAPs) induced by SCS have been used to gain insight into the mechanisms of SCS-based chronic pain therapy and to titrate closed-loop delivery of stimulation. However, the previous characterization of ECAPs recorded during SCS was performed with one-dimensional, cylindrical electrode leads. Herein, we describe the unique spatiotemporal distribution of ECAPs induced by SCS across the medial-lateral and rostral-caudal axes of the spinal cord, and their relationship to polysynaptic lower-extremity motor activation.Materials and MethodsIn each of four sheep, two 24-contact epidural SCS arrays were placed on the lumbosacral spinal cord, spanning the L3 to L6 vertebrae. Spinal ECAPs were recorded during SCS from nonstimulating contacts of the epidural arrays, which were synchronized to bilateral electromyography (EMG) recordings from six back and lower-extremity muscles.ResultsWe observed a triphasic P1, N1, P2 peak morphology and propagation in the ECAPs during midline and lateral stimulation. Distinct regions of lateral stimulation resulted in simultaneously increased ECAP and EMG responses compared with stimulation at adjacent lateral contacts. Although EMG responses decreased during repetitive stimulation bursts, spinal ECAP amplitude did not significantly change. Both spinal ECAP responses and EMG responses demonstrated preferential ipsilateral recruitment during lateral stimulation compared with midline stimulation. Furthermore, EMG responses were correlated with stimulation that resulted in increased ECAP amplitude on the ipsilateral side of the electrode array.ConclusionsThese results suggest that ECAPs can be used to investigate the effects of SCS on spinal sensorimotor networks and to inform stimulation strategies that optimize the clinical benefit of SCS in the context of managing chronic pain and the restoration of sensorimotor function after SCI.     

Spinal Cord Stimulation for Intractable Pain Following Limb Amputation

Objective: Spinal cord stimulation (SCS) by high‐frequency electrical pulses has been used since the early 1970s for relief of chronic intractable pain following limb amputation. The long‐term effectiveness of SCS for amputation‐related pain with ongoing after‐care is reviewed by assessment of all such cases managed over 20 years in the Neurostimulator Clinic at the Royal London Hospital. Materials and Methods: Twelve amputation‐related pain patients had quadripolar paddle electrodes (Resume; Medtronic Inc., Minneapolis, MN, USA) inserted epidurally by laminectomy over the thoracic or cervical dorsal spinal cord and connected to remotely controlled subcutaneously implanted stimulators (Itrel2, Itrel3, Synergy; Medtronic). Results: Two of 12 patients had unsuccessful stimulation, one despite repeated electrode revisions. Two were subsequently lost to follow‐up, one had delayed spontaneous resolution of phantom limb pain, one had a technical fault, and one had gradually waning benefit over 19 years. In the remaining five patients having ongoing follow‐up, self‐reported initial and final magnitudes of pain relief were unchanged, with a mean (SD) of 66% (18.2%). Benefits calculated from local and general visual analogue pain scores were similarly unchanged (initial local 48.8% [18.7%]; final local 50.0% [17.6%]; initial general 60.8% [10.9%]; final general 57.9% [12.3%]). Continued successful stimulation often required frequent changes of stimulating electrode contacts. Revision procedures for technical problems or pain at the battery site were universally successful. Conclusions: Successful SCS in some patients with amputation‐related pain otherwise resistant to treatment indicates that the procedure merits continued use with further efforts to refine technique.     

Refractory Insomnia in a Patient with Spinal Cord Stimulator Lead Migration

This report outlines a case of refractory insomnia temporally related to migration of cervical spinal cord stimulator leads. To our knowledge this association is previously unreported. The patient had an intractable sleep disturbance until replacement of the leads. A brief review of insomnia and its complex relationship to chronic pain is presented. We hope that this case will stimulate further discussion and possibly bring to light new insights into spinal cord stimulation and insomnia and alert others to this possible clinical association of symptoms.     

Spinal Cord Stimulation for Post‐Herniorrhaphy Pain

Objective. Post‐herniorrhaphy pain syndrome can be difficult to treat. The exact mechanism of pain is not always apparent. Multiple therapeutic modalities have been suggested for the treatment of this syndrome. Method. This includes both conservative (medical management), surgical (scar revision, excision of neuroma), and/or interventional approaches (local blocks to the entrapped nerves or sympathetic ganglion). Results. Two cases of intractable post–herniorrhaphy pain syndrome which failed to respond to conservative therapy are reviewed. Both cases had a successful trial therapy with spinal cord stimulation for their pain. Both then had permanent implantable systems inserted with favorable outcomes. Conclusion. Post‐herniorrhaphy pain can have the same features of both nociceptive and neuropathic pain syndromes. In cases which have failed conservative therapy we believe that a trial of spinal cord stimulation is warranted as in other cases of neuropathic pain syndromes.     

Spinal Cord Stimulation for Pain Management in Ankylosing Spondylitis: A Case Report

Introduction. The classic presentation of ankylosing spondylitis not only impairs spinal mobility but also imposes functional limitations, and fatigue is common. Methods. We report here the outcomes of spinal cord stimulation (SCS) in the case of a 47‐year‐old man with low back and hip/thigh pain due to ankylosing spondylitis, with failed responses to conservative therapies aimed at treating this pain. Results. Spinal cord stimulation induced axial low back and bilateral hip paresthesia resulting in complete subjective pain relief, cessation of analgesic medications, reduced fatigue, and improved sleep patterns. SCS also resulted in improved socioeconomic outcomes with a return to work. Conclusions. With further research in patients with broader presentations of the disease, SCS may prove efficacious in suppressing intractable pain symptoms due to ankylosing spondylitis, thus improving quality of life measures.     

Dual Spinal Cord Stimulation for Complex Pain: Preliminary Study

Objectives To retrospectively analyze by indices of success, patients with chronic complex pain, including, axial low back pain, receiving dual spinal cord stimulation (SCS) systems. Methods Eighteen patients with dual spinal cord stimulators have been retrospectively and nonrandomly analyzed. The preponderance of patients in our study group had failed back surgery syndrome (FBSS). Parameters of success of our therapy included reduction of medication, if any, complications, if any, and satisfaction with therapy and improvement in the quality of life, measured by a visual analogical scale (VAS) from 0 to 10. Patients were asked to rate their overall experience with their SCS systems and were divided into four separate groupings according to their overall rating of their therapy. These four groupings included therapy ratings of excellent (70–100%), good (> 50%), fair (< 50%), and poor (< 30%). Satisfaction with therapy and improvement in quality of life were evaluated on a five‐point scale. Patients were asked to rate changes in their quality of life after therapy using the following normative scale: much better, better, no change, worse, and much worse. All the patients in our study were asked if they would repeat their therapy with dual spinal cord stimulation. Results Paresthesia coverage, overlapping the reported painful region, was obtained in 80% of the patients in our study. The VAS decreased an average of 5.6 (range 2–10) after 6 months and 4.9 (range 2–8) at the end of the study. Six patients (37.5%) reported excellent results; four patients (25%) reported good; three (18.7%), fair and poor. Seventy percent of the patients were satisfied with the treatment and reported an increase in their quality of life. Medications were reduced in 75% of the patients. Thirteen (81%) patients with dual lead SCS therapy were willing to repeat the SCS implant procedure. Complications occurred in 43.7%. Conclusions Dual spinal cord stimulation is appropriate and efficacious for treating complex pathology and complex pain that including pain of the low, axial back.     

Epidural Spinal Cord Stimulation: Anatomical and Electrical Properties of the Intraspinal Structures Relevant to Spinal Cord Stimulation and Clinical Correlations

Epidural spinal cord stimulation (SCS) has gained a secure place in the armamentarium of the surgeon treating chronic pain conditions 1 , 2 . The complexity of the intraspinal structures and their different susceptibility to electrical signals, however, has made it difficult to characterize the effects of the stimulation, Some important recent work has helped shed light on the electrical properties of the intraspinal structures and on the electrical field potentials generated with epidural spinal cord stimulation. This work, initially pioneered by Sin and Coburn, has successfully been expanded and perfected by Holsheimer and Strujik at the University of Twente, The Netherlands ( 3 - 8 ). The Dutch scientists developed a computerized volume conductor model of the spinal cord to represent in extreme detail the electrical properties of all the intraspinal structures, including the dorsal column and dorsal root fibers. The model can simulate the effects of epidural stimulation with different electrode geometries and configurations 8 . The data generated from the model were then validated by comparing them to a large number of data collected by the author in implanted subjects ( 9 - 12 ). The author also conducted a detailed analysis of the clinical properties of the activation of the intraspinal structures at various electrode positions in the spine 13 , 14 .     

Spinal Cord Stimulation for the Treatment of Chronic Pain in Patients with Lumbar Spinal Stenosis

Objective: Chronic back and leg pain associated with lumbar spinal stenosis (LSS) is common in the elderly. Surgical decompression is usually performed when conservative treatments fail. We present an evaluation of the long‐term outcome of patients suffering from symptomatic LSS treated with spinal cord stimulation (SCS). Materials and Methods: Data were collected prospectively in three independent registries in three European centers. Pooled data were analyzed retrospectively. Changes in pain intensity, functional status, and analgesic medication were compared at baseline and at the last available follow‐up. Demographic data as well as details regarding the implantation procedure and any adverse events were systematically recorded. Results: Data were recorded in 69 patients with a mean follow‐up period of 27 months. All patients showed clinically and statistically significant improvement in pain relief, the visual analog scale decreasing from 7.4 ± 2.3 to 2.8 ± 2.4 (p < 0.05). The use of analgesic medication decreased and the functional status improved. Conclusion: Spinal cord stimulation seems to be effective in the treatment of patients suffering from chronic pain associated with LSS. Being less invasive and reversible, SCS should be considered before surgical decompression, particularly in patients with increased risks associated with back surgery.     

Computer Assisted and Patient Interactive Programming of Dual Octrode Spinal Cord Stimulation in the Treatment of Chronic Pain

Objective. To evaluate the effectiveness of spinal cord stimulation using multiple independent programmable electrode selections compared to simple continuous stimulation. Design. Prospective case series 2 years. Setting. Ambulatory care center. Patients. All chronic pain patients who underwent spinal cord stimulation treatment at our center from February 1995 until October 1996 entered the study as a consecutive sample (n = 80). Interventions. Patients were evaluated in continuous stimulation mode (single stimulation program) vs. multi-stimulation mode, (patients activate a series of stimulation programs simultaneously to cover all of their pain) and patient-controlled stimulation mode (patients can select a program in response to their activities and pain level). Outcome measures. We collected visual analog pain scores, patient satisfaction scores by stimulation mode, and paresthesia maps. Results. Mean pain scores declined from 8.1 at baseline to 4.6 with continuous stimulation, and to 3.1 with multi-stimulation and with patient-controlled stimulation (p<0.05). Paresthesia overlap improved from 74% with continuous stimulation to 91% with multi-stimulation, and to 89% with patient-controlled stimulation (p<0.05). None of the patients selected continuous stimulation. Thirty-two patients preferred multi-stimulation, and 48 patients preferred patient-controlled stimulation. Lead revision rates declined from 15% in our previous experience using continuous stimulation to 3.8%. Conclusions. Continuous stimulation was not selected by any patient in favor of multi-stimulation or patient-controlled stimulation. This study indicates that in spinal cord stimulation the use of multiple electrodes together with advanced programmability increases paresthesia overlap, reduces pain scores, reduces revision rates, and improves patient satisfaction with spinal cord stimulation therapy.