Chronic Spinal Cord Stimulation Research Articles

Functional mapping of the lower urinary tract by epidural electrical stimulation of the spinal cord in decerebrated cat model

Several neurologic diseases including spinal cord injury, Parkinson’s disease or multiple sclerosis are accompanied by disturbances of the lower urinary tract functions. Clinical data indicates that chronic spinal cord stimulation can improve not only motor function but also ability to store urine and control micturition. Decoding the spinal mechanisms that regulate the functioning of detrusor (Detr) and external urethral sphincter (EUS) muscles is essential for effective neuromodulation therapy in patients with disturbances of micturition. In the present work we performed a mapping of Detr and EUS activity by applying epidural electrical stimulation (EES) at different levels of the spinal cord in decerebrated cat model. The study was performed in 5 adult male cats, evoked potentials were generated by EES aiming to recruit various spinal pathways responsible for LUT and hindlimbs control. Recruitment of Detr occurred mainly with stimulation of the lower thoracic and upper lumbar spinal cord (T13-L1 spinal segments). Responses in the EUS, in general, occurred with stimulation of all the studied sites of the spinal cord, however, a pronounced specificity was noted for the lower lumbar/upper sacral sections (L7-S1 spinal segments). These features were confirmed by comparing the normalized values of the slope angles used to approximate the recruitment curve data by the linear regression method. Thus, these findings are in accordance with our previous data obtained in rats and could be used for development of novel site-specific neuromodulation therapeutic approaches.

Spinal cord stimulation for freezing of gait in Parkinson's disease and progressive supranuclear palsy: a case series

Background: Freezing of gait (FOG) in Parkinson's disease (PD) and progressive supranuclear palsy (PSP) exert a significant adverse impact on the patients quality of life, the degree of their disability, and the risk of falls. A specific characteristic of FOG is a poor response to medical treatment. According to the data of open-label clinical trials and clinical case series published in the last decade, spinal cord stimulation (SCS) can be considered as one of the methods to improve this type of movement disorders.
 Materials and methods: We present a clinical series of patients with PD and PSP, who underwent implantation of a chronic epidural SCS system at the mid-thoracic level to correct FOG. The efficacy of surgical treatment was assessed at 2 and 5 months with the following scales and questionnaires: part III Unified Parkinson's Disease Rating Scale of Movement Disorder Society (MDS-UPDRS), Freezing of Gait Questionnaire (FOG-Q), Activity-Specific Balance Confidence Scale (ABC), Parkinson's Disease Quality of Life Questionnaire-8 (PDQ-8), Time up and Go Test (TUG), 10 Meter Walk Test. The patients were asked to report possible adverse reactions after the procedure.
 Results: The results of a 5-month follow-up were obtained from 4 patients (2 with PD and 2 with PSP). There were no adverse events associated with SCS. Оnly one patient with PD experienced a decrease in the severity of motor symptoms according to the MDS-UPDRS part III scale. An increase in the speed of 10 meters' walking distance and TUG test performance was observed in 3 patients. All patients reported an improvement in the quality of life (according to the PDQ-8 questionnaire) and confidence in maintaining balance (according to the ABC questionnaire) by month 2 after surgery. However, at month 5, a negative trend was noted again.
 Conclusion: The SCS method was safe in all 4 clinical cases described. There was a positive effect of SCS on the improvement of FOG and postural balance in PD and PSP. However, the duration of the therapeutic effect may vary.

Abstract 11617: Chronic Spinal Cord Stimulation Mitigates Cardiac Sympathoexcitation and Reduces Ventricular Arrhythmias Induced by Myocardial Infarction

Introduction: Spinal cord stimulation (SCS) is effective neuromodulation therapy for pain, but little is known about the effectiveness of SCS for arrhythmia prevention in chronic myocardial infarction (MI). Hypothesis: Chronic SCS reduces MI-induced cardiac sympathoexcitation and reduces ventricular arrhythmias. Methods: Yorkshire pigs were randomized to chronic left circumflex coronary artery MI alone (n=11) or MI + chronic SCS (n=9). Epidural SCS lead was placed percutaneously T1-T4 of the spinal cord and reactive SCS was performed at 10 kHz, 0.03ms, and 2.5mA after MI. Holter ECG was recorded for heart rate variability (HRV) analysis, performed throughout 4-5 weeks post-MI. To create acute stress in chronic MI, epicardial extraventricular programmed stimulus (S1/S2 pacing), and acute left anterior descending coronary artery (LAD) ischemia(1h)+reperfusion(2h) (I/R) injury were conducted during terminal experiment. SCS was continued throughout terminal experiment. Cardiac electrophysiological data (activation recovery interval (ARI) and dispersion of repolarization (DOR)), as well as ventricular arrhythmia quantification were measured by placing a 56-electrode mesh sock over the heart . Data is shown as mean±SEM. Results: 1 week after MI, 30min HRV showed a higher high-frequency band and lower very-low and low-frequency band with SCS (%HF: MI 25±4 vs SCS 51±4, p=0.0028. %VLF: 50±4 vs 30±3, p=0.0015. %LF: 22±2 vs 14±2, p=0.047). In the terminal experiment, SCS reduced the maximum slope (Smax) of the electrical restitution curve described by S1/S2 pacing (Smax: MI 0.6±0.03 vs SCS 0.4±0.05, p=0.023). After acute LAD ischemia, SCS reduced global %ARI change (MI -19±3% vs SCS -11±1%, p=0.019), specifically in the ischemic region (MI -31±4% vs SCS -16±3%, p=0.008), and global %DOR (MI 1513±288% vs SCS 595±144%, p=0.011). Chronic SCS also reduced ventricular tachycardia and ventricular fibrillation during acute I/R (MI 15±3 vs SCS 5±0.8, p=0.014). Conclusions: Reactive SCS therapy mitigates cardiac autonomic imbalance in chronic MI and protects from new acute ischemia induced cardiac sympathoexcitation and ventricular arrhythmias.

ID:16343 Managing Chronic Spinal Cord Stimulation in the Cerebral Palsy Population: A Case Report

This is the case of a 58 year old female with a history of congenital Cerebral palsy complicated by spastic quadriplegia treated with a Intrathecal Baclofen pump. Her course had been complicated by a long history of painful bilateral peripheral neuropathy that had been relieved with a Spinal Cord stimulator five years prior. She also received periodic Botulinim toxin injections in her bilateral upper and lower extremities for spasticity. The patient presented to Rehabilitation clinic with persistent worsening bilateral leg pain after total knee surgery and physical therapy.

First experience with chronic epidural spinal cord stimulation in Khanty-Mansi autonomous okrug — clinical observations

Purpose of the work. The article is devoted to the first experience of epidural stimulation in the Khanty-Mansiysk Autonomous Okrug at the budgetary institution Surgut Clinical Trauma Hospital. Clinical examples are presented for two main indications for the application of this technique (disease of the operated spine, a consequence of spinal cord injury in combination with chronic neuropathic pain syndrome).
 Research methods. An assessment of the intensity of pain syndrome was given according to a visual analogue scale, the Pain Detect questionnaire; indicators of anxiety, depression on the HADS scale; quality of life according to the Oswestry questionnaire for a follow-up period of 6-12 months in patients with chronic epidural stimulation.
 Results. A positive assessment of the action during test neurostimulation was 63.3% (38 patients). Of the established permanent systems, a good result was achieved and persisted for 12 months or more in 96% (24 patients). It was necessary to change the stimulation parameters in 13% (3 patients). Revision of permanent systems was performed in 20% (5 patients), due to the progression of the degenerative-dystrophic process of the spine, damage and migration of system elements.
 Conclusions. Chronic epidural spinal cord stimulation has established itself as a personalized, highly effective, minimally invasive and safe method of treating chronic neuropathic pain syndromes. Multicomponent corrective action is of scientific interest and requires further study.

Long-Term Spinal Cord Stimulation After Chronic Complete Spinal Cord Injury Enables Volitional Movement in the Absence of Stimulation.

Background: Chronic spinal cord injury (SCI) portends a low probability of recovery, especially in the most severe subset of motor-complete injuries. Active spinal cord stimulation with or without intensive locomotor training has been reported to restore movement after traumatic SCI. Only three cases have been reported where participants developed restored volitional movement with active stimulation turned off after a period of chronic stimulation and only after intensive rehabilitation with locomotor training. It is unknown whether restoration of movement without stimulation is possible after stimulation alone.Objective: We describe the development of spontaneous volitional movement (SVM) without active stimulation in a subset of participants in the Epidural Stimulation After Neurologic Damage (ESTAND) trial, in which locomotor training is not prescribed as part of the study protocol, and subject’s rehabilitation therapies are not modified.Methods: Volitional movement was evaluated with the Brain Motor Control Assessment using sEMG recordings and visual examination at baseline and at follow-up visits with and without stimulation. Additional functional assessment with a motor-assisted bicycle exercise at follow-up with and without stimulation identified generated work with and without effort.Results: The first seven participants had ASIA Impairment Scale (AIS) A or B thoracic SCI, a mean age of 42 years, and 7.7 years post-injury on average. Four patients developed evidence of sustained volitional movement, even in the absence of active stimulation after undergoing chronic epidural spinal cord stimulation (eSCS). Significant increases in volitional power were found between those observed to spontaneously move without stimulation and those unable (p < 0.0005). The likelihood of recovery of spontaneous volitional control was correlated with spasticity scores prior to the start of eSCS therapy (p = 0.048). Volitional power progressively improved over time (p = 0.016). Additionally, cycling was possible without stimulation (p < 0.005).Conclusion: While some SVM after eSCS has been reported in the literature, this study demonstrates sustained restoration without active stimulation after long-term eSCS stimulation in chronic and complete SCI in a subset of participants. This finding supports previous studies suggesting that “complete” SCI is likely not as common as previously believed, if it exists at all in the absence of transection and that preserved pathways are substrates for eSCS-mediated recovery in clinically motor-complete SCI.Clinical Trial Registration: www.ClinicalTrials.gov, identifier NCT03026816.

Chronic pain and spinal cord stimulation.

Chronic pain can have a devastating impact and lead to patient isolation. Many people with chronic pain are predisposed to anxiety-depressant symptoms, due to a lower quality life. The aim of the study is to demonstrate how neuromodulation methods, can encourage the reduction of chronic pain and an improvement in the quality of life, therefore advancing the restoration of psychological well-being.We involved 50 patients with a diagnosis of pain that not respond to traditional pharmacological therapies. Interventions: All subject had depression and anxiety symptoms and a low-quality life. We used the spinal cord stimulation treatment and a psychological evaluation for assessment of depression-anxiety symptomatology and the level of quality life.We observed a significant difference in physical functioning, role limitations due to physical health, general health perceptions, vitality, social functioning, role limitations due to emotional problems and mental health.Our study affirms that the perception of chronic pain has a great impact on the perception of psychological well-being, quality of life, and the performance of normal daily social and professional activities.

Spinal cord stimulation in chronic pain: technical advances.

Chronic severe pain results in a detrimental effect on the patient’s quality of life. Such patients have to take a large number of medications, including opioids, often without satisfactory effect, sometimes leading to medication abuse and the pain worsening. Spinal cord stimulation (SCS) is one of the most effective technologies that, unlike other interventional pain treatment methods, achieves long-term results in patients suffering from chronic neuropathic pain. The first described mode of SCS was a conventional tonic stimulation, but now the novel modalities (high-frequency and burst), techniques (dorsal root ganglia stimulations), and technical development (wireless and implantable pulse generator-free systems) of SCS are becoming more popular. The improvement of SCS systems, their miniaturization, and the appearance of new mechanisms for anchoring electrodes results in a significant reduction in the rate of complications and revision surgeries, and the appearance of new waves of stimulation allows not only to avoid the phenomenon of addiction, but also to improve the long-term results of chronic SCS. The purpose of this review is to describe the current condition of SCS and up-to-date technical advances.

Spinal cord stimulation in failed back surgery syndrome

Introduction. A common cause of chronic pain after back surgery is failed back surgery syndrome, characterized by the development, persistence or recurrence of neuropathic pain in the absence of clear anatomical complications from the surgery. One of the most effective treatment methods for failed back surgery syndrome is permanent spinal cord stimulation. Study aim. To assess the efficacy and safety of chronic spinal cord stimulation in failed back surgery syndrome. Materials and methods. In our study, after a stimulation trial final neurostimulation was performed in 34 patients with neuropathic pain and lack of improvement from the pharmacological treatment. Results. Six months after the operation, there was a reduction in the average scores on the visual analogue scale for the daily average and maximum pain, as well as a reduction in the severity of neuropathic pain as measured by the PainDetect scale (by 54.4% 50.7% and 57.3%, respectively), which corresponds to the method’s efficacy criteria found in the literature. The majority of patients noted a significant improvement in their quality of life and a reduced need for pain relief. Complications occurred in 26.4% of patients overall, including intraoperative damage to the dura mater, infection at the generator implantation site, and electrode displacement relative to the initial position, requiring correction. None of the patients experienced worsening of the neurological symptoms.

Application of spinal cord stimulation in the treatment of persistent pain in failed back surgery syndrome

The study objectiveis to demonstrate our experience of the spinal cord stimulation in the treatment of drug-resistant pain in patients with the failed back surgery syndrome (FBSS) and to evaluate its effectiveness and complications.Materials and methods.Systems for chronic spinal cord stimulation were implanted in 78 patients suffering from FBSS in Federal Neurosurgical Center (Novosibirsk) during 2013–2015. All patients had a drug-resistant neurogenic pain syndrome character and were undergone surgical intervention on the spine. Evaluating of the treatment effectiveness was carried out by visual analogue scale (VAS) and a scale Douleur Neuropathique en 4 Questions (DN4). Catamnesis ranged from 6 to 18 months.Results.The median preoperative VAS score evaluation was 6.7, at hospital discharge – 3.1, after 6 months – 3.2, after 12 months – 3.5, after 18 months – 3.4. Evaluation on a scale DN4 before surgery was 5.3, at hospital discharge – 2.1, after 6 months – 2.4, after 12 months – 2.5, after 18 months – 2.4. Complications in the form of migration, fracture of the electrodes and development of hemorrhage or inflammation at the site of implantation of the system were observed in 12 (15.3 %) cases and required revision surgery.Conclusion.Spinal stimulation is an effective and safe method of treatment of pain in FBSS, but it has specific complications associated with implantable systems.

SPINAL CORD STIMULATION FOR FAIL BACK SURGERY SYNDROME: LITERATURE REVIEW AND CLINICAL STUDY

ABSTRACT Objective: Fail back surgery syndrome (FBSS) is a common cause of pain following spine surgery, and is associated with persistent or recurrent pain despite anatomically correct intervention. Spinal cord stimulation (SCS) is regarded as one of the most effective methods of treatment for fail back surgery syndrome. Methods: We studied 34 patients who underwent test stimulation and chronic SCS for FBSS. Results: Six months postoperatively, mean improvement by the visual analog scale (VAS) of average and maximum daily pain, and the painDETECT score, were 54.4%, 50.7% and 57.3%, respectively. This meets the criteria for effectiveness of the method, according to the literature. Most of patients reported significant improvements in life quality and less need for analgesics. Complications were seen in nine patients (26.4%) and included: intraoperative dura injury (one patient, 2.9%), wound infection (one patient, 2.9%), and electrode displacement (seven patients, 20.5%). No cases of postoperative neurological deterioration were seen. Conclusions: SCS is safe and effective for the treatment of neuropathic pain caused by FBSS. Level of Evidence IV; Case series.

Ovine model of neuropathic pain for assessing mechanisms of spinal cord stimulation therapy via dorsal horn recordings, von Frey filaments, and gait analysis.

BackgroundIt is becoming increasingly important to understand the mechanisms of spinal cord stimulation (SCS) in alleviating neuropathic pain as novel stimulation paradigms arise.PurposeAdditionally, the small anatomic scale of current SCS animal models is a barrier to more translational research.MethodsUsing chronic constriction injury (CCI) of the common peroneal nerve (CPN) in sheep (ovine), we have created a chronic model of neuropathic pain that avoids motor deficits present in prior large animal models. This large animal model has allowed us to implant clinical grade SCS hardware, which enables both acute and chronic testing using von Frey filament thresholds and gait analysis. Furthermore, the larger anatomic scale of the sheep allows for simultaneous single-unit recordings from the dorsal horn and SCS with minimal electrical artifact.ResultsDetectable tactile hypersensitivity occurred 21 days after nerve injury, with preliminary indications that chronic SCS may reverse it in the painful limb. Gait analysis revealed no hoof drop in the CCI model. Single neurons were identified and discriminated in the dorsal horn, and their activity was modulated via SCS. Unlike previous large animal models that employed a complete transection of the nerve, no motor deficit was observed in the sheep with CCI.ConclusionTo our knowledge, this is the first reported large animal model of chronic neuropathic pain which facilitates the study of both acute and chronic SCS using complementary behavioral and electrophysiologic measures. As demonstrated by our successful establishment of these techniques, an ovine model of neuropathic pain is suitable for testing the mechanisms of SCS.

Chronic softening spinal cord stimulation arrays

Objective. We sought to develop a cervical spinal cord stimulator for the rat that is durable, stable, and does not perturb the underlying spinal cord. Approach. We created a softening spinal cord stimulation (SCS) array made from shape memory polymer (SMP)-based flexible electronics. We developed a new photolithographic process to pattern high surface area titanium nitride (TiN) electrodes onto gold (Au) interconnects. The thiol-ene acrylate polymers are stiff at room temperature and soften following implantation into the body. Durability was measured by the duration the devices produced effective stimulation and by accelerated aging in vitro. Stability was measured by the threshold to provoke an electromyogram (EMG) muscle response and by measuring impedance using electrochemical impedance spectroscopy (EIS). In addition, spinal cord modulation of motor cortex potentials was measured. The spinal column and implanted arrays were imaged with MRI ex vivo, and histology for astrogliosis and immune reaction was performed. Main results. For durability, the design of the arrays was modified over three generations to create an array that demonstrated activity up to 29 weeks. SCS arrays showed no significant degradation over a simulated 29 week period of accelerated aging. For stability, the threshold for provoking an EMG rose in the first few weeks and then remained stable out to 16 weeks; the impedance showed a similar rise early with stability thereafter. Spinal cord stimulation strongly enhanced motor cortex potentials throughout. Upon explantation, device performance returned to pre-implant levels, indicating that biotic rather than abiotic processes were the cause of changing metrics. MRI and histology showed that softening SCS produced less tissue deformation than Parylene-C arrays. There was no significant astrogliosis or immune reaction to either type of array. Significance. Softening SCS arrays meet the needs for research-grade devices in rats and could be developed into human devices in the future.

CHRONIC ELECTRICAL STIMULATION OF THE SPINAL CORD IN THE TREATMENT OF FAILED BACK SURGERY SYNDROME

The paper presents a literature review on failed back surgery syndrome (FBSS). According to statistics, the proportion of cases of back pain recurrence after lumbar spine surgery ranges from 15 to 50 %. There are many causes of the FBSS development, the most common of these are misdiagnosis and incorrect selection of candidates for surgery. In accordance with international clinical protocols, FBSS is an indication for chronic epidural spinal cord stimulation (SCS) in case of conservative treatment failure, absence of direct unconditioned indications for reoperation, and neurogenic pain. High efficiency and economic feasibility of the given method is proved in multiple studies including in well-organized evidence-based researches. The wide international experience allows making assertions about long-term and stable analgesic effect of chronic electric stimulation of the spinal cord. It must be remembered that delaying a decision on application of the SCS method leads to poor results in catamnesis. In advanced cases, a care to such patients becomes simply impossible due to the centralization of pain syndromes.

Importance of Pharmacological Evaluation in the Treatment of Poststroke Pain by Spinal Cord Stimulation

Spinal cord stimulation (SCS) is not typically recommended for the treatment of central poststroke pain (CPSP). We examined whether the pharmacological evaluation of CPSP is useful for selecting the candidates for SCS. Changes in visual analog scale (VAS) scores for pain following pharmacological evaluation using morphine, thiopental, and ketamine were compared with those following SCS in 22 CPSP patients. Twelve of the 22 (54.5%) patients in the ketamine test and thiopental test, and 5 (22.7%) of the 22 patients in the morphine test showed a more than 40% reduction in VAS score and were judged as "sensitive." Pain relief by SCS was estimated as excellent (≧60% VAS score reduction) in three patients, good (30-59% reduction) in nine patients, and fair (10-29% reduction) in seven patients 24 months after the start of SCS. The remaining 3 patients evaluated as having poor pain relief (<10% reduction) only underwent test SCS. VAS score reduction induced by SCS was more significant in ketamine-sensitive patients than in ketamine-resistant patients during the test SCS (p < 0.01, Mann-Whitney's U test) and 24 months after the start of chronic SCS (p < 0.05). However, there were no significant differences in results for thiopental-sensitive/thiopental-resistant or morphine-sensitive/morphine-resistant patients during the test SCS and 24 months after chronic SCS. Analysis of the rate of VAS score reduction by pharmacological evaluation and SCS showed significant correlations with the results of the ketamine test (r = 0.670, p = 0.001, Pearson's correlation coefficient test), but not with those of the thiopental (r = 0.291, p = 0.231) or morphine test (r = 0.327, p = 0.175). We speculate that the pharmacological evaluation of CPSP patients can be a useful tool for selecting candidates for SCS.

Long-term follow-up of chronic spinal cord stimulation for medically intractable orthostatic tremor.

Orthostatic tremor (OT) is a rare form of tremor occurring in the legs when standing upright. Medical treatment frequently is unsatisfactory, thus in selected cases, surgical treatment, such as spinal cord stimulation (SCS) or thalamic deep brain stimulation has been proposed. We report the long-term results (follow-up (FU) 34-133months) of SCS in four patients with medically intractable OT. Outcome was assessed by recording the time tolerated to stand still pre- and post-operatively and by a patient self-rating (PSR) scale (0=poor to 6=excellent). Furthermore, surface electromyography (EMG) recordings of different leg muscles were performed to estimate tremor activity with and without SCS post-operatively. With chronic SCS, all four patients showed an improvement of unsteadiness occurring in the presence of stimulation-induced paraesthesia of the legs. The mean standing time improved from 51s (SD 47s, range 4-120s) pre-operatively to 220s (SD 184s, range 10-480s) with SCS at last available FU. Tremor activity in the EMG of the anterior tibial muscle was reduced by 30-60% with SCS compared with off SCS. PSR score was 4 or 5 in three patients and 3 in the other. In conclusion, SCS is an effective long-term treatment option in patients with otherwise intractable OT.

Spinal cord stimulation in the treatment of chronic pain syndromes

The study objective was to estimate the efficacy of chronic epidural spinal cord stimulation in the treatment of patients with neuropathic pain syndrome. A system for chronic spinal cord stimulation (St. Jude) was implanted to 75 patients with neuropathic pain syndrome. Fifty three (70.7%) patients were diagnosed with failed back surgery syndrome (FBSS); 9 (12.0%) patients had complex regional pain syndrome type II; 4 (5.3%) patients had diabetic polyneuropathy of the lower limbs; 3 (4.0%) patients had idiopathic pelvic-perineal pain; 2 (2.7%) patients had spinal stroke pain; 2 (2.7%) patients had postherpetic intercostal neuralgia; 1 (1.3%) patient had stump pain; 1 (1.3%) patient had spinal cord injury pain. The treatment efficacy was evaluated using the visual analog scale (VAS) and DN4 questionnaire. The follow-up period ranged from 6 to 18 months. 136 patients underwent test stimulation at the Center in 2014. A significant reduction in pain was observed in 75 (55.1%) patients. These patients underwent the second stage of surgery that included implantation of permanent electrodes and a generator. The mean VAS score was 6.5 (maximum: 10; minimum: 5) before surgery, 3.2 at discharge, and 3.1 after 3 and 6 months. The VAS score amounted to 3.6 after 12 months. Complications in the form of pain at the generator implantation site and the need for removal of the system occurred in 2 patients (2.6%), electrode migration was observed in 4 (5.3%) cases. Chronic epidural spinal cord stimulation is an effective and safe technique for the treatment of drug-resistant chronic neurogenic pain syndromes.

The rate of magnetic resonance imaging in patients with spinal cord stimulation.

Analysis of use of magnetic resonance imaging (MRI) in the chronic back and leg pain spinal cord stimulation (SCS)-implanted population was conducted using a propensity-matched cohort population. To project the percentage of patients with SCS expected to need at least 1 MRI within 5 years of implant. Patients experiencing pain, including those who underwent implantation with SCS systems, are likely to have comorbidities and ongoing pain issues that may require diagnostic imaging. MRI is the most common diagnostic imaging modality for evaluating patients with new or worsening low back pain. However, patients with SCS are typically excluded from receiving MRI because of the safety risks related to the interactions of MRI fields and implantable devices. To provide an accurate estimate of the need for MRI in the SCS-implanted population, Truven Health MarketScan Commercial Claims and Medicare Supplemental databases were used to perform analysis of SCS-implanted patients propensity score matched to a nonimplanted population-based cohort. Four years of paid and adjudicated claims data were used to determine the magnetic resonance (MR) images received, which was exponentially projected to estimate MRI within 5 and 10 years of implant. Approximately 82% to 84% of SCS-implanted patients are expected to need at least 1 MRI within 5 years of implant. Furthermore, 59% to 74% of patients will require nonspine MRI within 10 years. There is a high need for MRI in this chronic back and leg pain SCS population, with a significant portion being completed on locations outside of the spine. This analysis highlights a need for MRI-conditional SCS devices that grant access of patients with SCS to this imaging modality. 3.

Chronic Spinal Cord Stimulation in the Treatment of Cerebral and Spinal Spasticity

Objectives: The aim of this investigation is to assess the effectiveness of spinal cord stimulation (SCS) in different groups of patients with spasticity of different origin. Materials and Methods: A retrospective study of the use of the method of SCS in 71 patients. The patient population was divided into two groups: 52 cerebral palsy (CP) cases and 19 patients diagnosed with spasticity caused by spinal injury. The mean age was 7.14 ± 4.06 and 35.68 ± 12.42 years, respectively. The CP group included 41 cases of paraparesis and 11 cases tetraparesis. One quadripolar electrode was implanted into the posterior epidural space at Th10-Th12 level and an implantable pulse generator (Itrel3, Medtronic) was placed in a standard fashion. We performed 3-5 stimulation sessions per day; each lasted 30 min. The stimulation parameters were as follows: rate 100-130 Hz, pulse width 120-300 ms, amplitude 1.5-4 V. The follow-up ranged from 2 to 9 years. Results: Decrease in muscle tone was observed in all cases in the group of patients with spinal spasticity: from 3.71 ± 0.61 on the Ashworth scale before the operation to 2.26 ± 0.56 after the operation (p < 0.001). In the group of cerebral spasticity a significant decrease in muscle tone was observed only in patients with spastic lower paraparesis: from 3.36 ± 0.41 before the operation to 1.97 ± 0.91 after the operation (p < 0.005). In patients with spastic tetraparesis we did not observe any significant change in muscle tone. In 8 cases we discontinued the therapy several years after the procedure due to improvement in spasticity: in the CP group in 7 cases and in 1 spinal spasticity case, where SCS systems were explanted. Conclusion: Chronic SCS may be a method of choice for patients with moderate spinal and cerebral spasticity with predominant spastic lower paraparesis. In patients with spastic tetraparesis SCS therapy did not prove to be effective. We encountered improvement of the spasticity and no need for further SCS therapy in a small group of patients (11%). This phenomenon requires further investigation.

Spinal Cord Stimulation Failures in Refractory Chronic Pain

Background: Spinal cord stimulation (SCS) is a well-established modality for the treatment of refractory chronic pain and may utilize percutaneous or paddle leads. Methods: The study is conducted at the Unit of Functional Neurosurgery of University “Magna Graecia” of Catanzaro. We perform a retrospective review of our prospective database of 523 SCS patients undergoing surgery for routine indications between January 1993 and December 2013 to evaluate failures rates during trial period and during chronic stimulation. Results: SCS trial was less effective for patients with differentiation neuropathic pain and post herpetic pain. Patients with allodynic dominant pain can feel unpleasant or painful parenthesis during trial stimulation. SCS trial has presented a very low hardware-associated complication rate (lead migration 1.3%) and absence of biological complications. During chronic SCS 29% of cases had equipment failures. In particular mechanical failures occurred in 18% of cases with 8.5% of lead displacements or migrations and 9.5% of lead breakages; biological failures occurred in 11% of cases with 6% of skin erosions and 5% of infections. Conclusion: SCS is a minimally invasive procedure effective in managing medically intractable pain of various origins. Despite advances in the design and production of SCS systems, these devices remain prone to failure from various causes. A careful analysis of mechanical complications coupled to a clinical strategy to minimize the tensile loads on the components of the system should lead to an improvement of the performance of the SCS implanted system and the effectiveness of the stimulation and the long-term reduction in the rate of complications that currently it remains quite significant.