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Showing papers in "Neuromodulation in 2009"


Book ChapterDOI
TL;DR: This chapter focuses on the process of neuromodulation, which is one of the fastest-growing areas of medicine, involving many diverse specialties and impacting hundreds of thousands of patients with numerous disorders worldwide.
Abstract: Publisher Summary This chapter focuses on the process of neuromodulation, which is one of the fastest-growing areas of medicine, involving many diverse specialties and impacting hundreds of thousands of patients with numerous disorders worldwide It is the process of inhibition, stimulation, modification, regulation or therapeutic alteration of activity, electrically or chemically, in the central, peripheral or autonomic nervous systems It is the science of how electrical, chemical, and mechanical interventions can modulate the nervous system function Neuromodulation is inherently nondestructive, reversible, and adjustable The INS (the International Neuromodulation Society) defines neuromodulation as a field of science, medicine, and bioengineering that encompasses implantable and nonimplantable technologies, electrical or chemical, for the purpose of improving quality of life and functioning of humans At the present time, neuromodulation implantable devices are either neural stimulators or microinfusion pumps These devices are being utilized for the management of chronic pain, movement disorders, psychiatric disorders, epilepsy, dismotility disorders, disorders of pacing, spasticity, and others Neuroprostheses such as cochlear implants and sacral root stimulators are also commonly included within the definition of neuromodulation Electrical neuromodulation is electrical stimulation of the brain, spinal cord, peripheral nerves, plexuses of nerves, the autonomic system, and functional electrical stimulation of the muscles, while chemical neuromodulation uses direct placement of chemical agents to neural tissues through utilization of technology of implantation such as epidural or intrathecal delivery systems

100 citations


Journal ArticleDOI
TL;DR: Progress in the development of closed‐loop FES walking systems has been impeded by their lack of practicality, but this obstacle could be overcome via implanted systems, especially if using controllers based on deterministic rule sets derived from motion sensor feedback.
Abstract: Objectives. To investigate the different approaches in the field of functional electrical stimulation (FES) control of gait and address fundamental perquisites to enable FES walking systems to become safer, more practical, and therefore clinically efficacious. Design. Systematic review was conducted from electronic data bases up to March 2008. Studies with innovative control strategies were highlighted for analysis, but all relevant literatures were described to deliver a broad viewpoint. Study Selection. FES studies applying 1) open and closed-loop controllers; 2) control algorithm techniques; or 3) feedback information to the control unit of neuromuscular stimulators via biological signals or artificial sensors. These studies were mostly associated to FES gait. Results. By far, more spinal cord-injured users have benefited from open-loop FES walking systems because they have had an easier and faster setup. However, because of their limitations over the control of knee extension, closed-loop control of gait may be a superior approach. The use of electromyogram to quantify quadriceps fatigue was not considered sufficiently appropriate to predict knee-buckle events; instead, the use of motion sensors for such purposes is recommended. Finite state controllers based on a set of deterministic rules to process feedback signals seemed more suitable to provide accurate command-and-control compared with dynamic or neural network controllers. Conclusions. Progress in the development of closed-loop FES walking systems has been impeded by their lack of practicality. In the near future, this obstacle could be overcome via implanted systems, especially if using controllers based on deterministic rule sets derived from motion sensor feedback.

70 citations


Journal ArticleDOI
TL;DR: Evaluating the usefulness of peripheral nerve stimulation as a treatment option for patients with chronic low back pain and its application in clinical practice is evaluated.
Abstract: Objective. This study aims to evaluate the usefulness of peripheral nerve stimulation as a treatment option for patients with chronic low back pain. Materials and Methods. More than 12 months, we collected data on consecutive patients who had successful trials and were subsequently implanted with octrode percutaneous leads placed subcutaneously within the major area of pain. Eleven patients met diagnostic criteria for failed back surgery syndrome. A questionnaire assessed outcomes including: pain, analgesic use, and patient satisfaction. The response rate was 93% (13/14): average follow-up time was seven months. Results. There was a significant decrease in pain levels: an average reduction of 3.77 visual analog scale points. Eleven patients (85%) reported successful outcomes and an average pain reduction of 4.18 points but two reported a poor response. Pain relief was highly correlated with reduced analgesia and patient satisfaction. No complications were reported. Conclusion. This study demonstrates a treatment option that is safe, nonpharmacologic, reversible, and effective for patients with chronic low back pain that have exhausted other treatment options.

66 citations


Journal ArticleDOI
TL;DR: This hypothesis states that therapeutic benefit is provided, at least in part, by activation of surviving nigrostriatal dopaminergic neurons, subsequent striatal dopamine release, and resumption of striatal target cell control by dopamine.
Abstract: Deep Brain Stimulation (DBS) provides therapeutic benefit for several neuropathologies including Parkinson's disease (PD), epilepsy, chronic pain, and depression. Despite well established clinical efficacy, the mechanism(s) of DBS remains poorly understood. In this review we begin by summarizing the current understanding of the DBS mechanism. Using this knowledge as a framework, we then explore a specific hypothesis regarding DBS of the subthalamic nucleus (STN) for the treatment of PD. This hypothesis states that therapeutic benefit is provided, at least in part, by activation of surviving nigrostriatal dopaminergic neurons, subsequent striatal dopamine release, and resumption of striatal target cell control by dopamine. While highly controversial, we present preliminary data that are consistent with specific predications testing this hypothesis. We additionally propose that developing new technologies, e.g., human electrometer and closed-loop smart devices, for monitoring dopaminergic neurotransmission during STN DBS will further advance this treatment approach.

64 citations


Journal ArticleDOI
TL;DR: The data suggest a promising outcome for simultaneous implantations of different basal ganglia nuclei in Parkinsonian and in progressive supranuclear palsy patients as well.
Abstract: Objective. The aim of the present study was to describe the surgical and clinical outcomes of the implantation and stimulation of the pedunculopontine tegmental nucleus in humans. Materials and Methods. Fourteen patients affected by movement disorders (12 Parkinson's disease and 2 progressive supranuclear palsy) underwent surgery for bilateral or monolateral implantation of stimulating electrodes in the pedunculopontine tegmental nucleus. The correct placement of electrodes was established and verified by combining angio-CT scans with magnetic resonance imaging. Intraoperative and postoperative evaluations were made to assess the clinical effectiveness of stimulation according to different Unified Parkinson's Disease Rating Scale items and neurophysiologic parameters. Results. No major complications occurred following the insertion of electrodes into the pedunculopontine tegmental nucleus. Neuroimaging showed that the electrode contacts were always correctly placed below the ponto-mesencephalic line. Stimulation of the pedunculopontine tegmental nucleus improved gait, posture, and speech, and modulated reflexes integrated at spinal or pontine levels. Conclusions. The surgical targeting of the pedunculopontine tegmental nucleus requires a careful adaptation of the traditional stereotactic approaches owing to the high variability of brainstem anatomy from one patient to another. The insertion of the leads in the pedunculopontine tegmental nucleus as well as their activation did not appear to induce serious adverse effects. The correct positioning of stimulating electrodes in pontine structures such as the pedunculopontine nucleus may be ascertained not only through neuroimaging techniques but also through clinical neurophysiology. The evolution of the surgical planning that we have developed emphasizes the limited value of single-unit recordings to identify the pedunculopontine tegmental nucleus and highlights the opportunities offered by functional evaluations of neurophysiologic parameters. As far as the clinical efficacy is concerned, our data suggest a promising outcome for simultaneous implantations of different basal ganglia nuclei in Parkinsonian and in progressive supranuclear palsy patients as well.

62 citations


Book ChapterDOI
TL;DR: In this article, the authors focus on the five mechanisms of action of deep brain simulation (DBS) which have gained widest acceptance form the scientific community, including depolarization block hypothesis, synaptic modulation, synaptic depression hypothesis, neural jamming/modulation hypothesis, and synaptic facilitation hypothesis.
Abstract: Publisher Summary This chapter focuses on the five mechanisms of action of deep brain simulation (DBS), which have gained widest acceptance form the scientific community. These hypothesis include depolarization block hypothesis, synaptic modulation hypothesis, synaptic depression hypothesis, neural jamming/modulation hypothesis, and synaptic facilitation hypothesis. Depolarization block hypothesis originated from the observation that the clinical effects of DBS are similar to those of a surgical lesion suggesting that this type of stimulation acts by silencing neurons of the stimulated structure. The synaptic modulation hypothesis states that DBS activates neuronal elements that are in close proximity to the stimulating electrode, which results in local synaptic inhibition via activation of axonal terminals within the stimulated nuclei that release inhibitory neurotransmitters such as GABA. The synaptic depression hypothesis is related to the synaptic modulation hypothesis and it states that a neuron that is activated by DBS is unable to sustain high frequency action on efferent targets due to depletion of terminal vesicular stores of neurotransmitters. The neural jamming or modulation hypothesis states that DBS regulates and corrects pathological activity in the basal ganglia network. Understanding the fundamental principles of neural jamming requires a detailed knowledge of neuronal ionic conductances, as well as normal firing patterns within the thalamocortical basal ganglia network. According to the synaptic facilitation hypothesis, DBS results in the release of dopamine from surviving dopaminergic neurons projecting to the basal ganglia to contribute to the therapeutic action of STN HFS in PD patients.

46 citations


Journal ArticleDOI
TL;DR: Findings indicate that women in this country who suffer from primary dysmenorrhea could benefit by using TENS, which is consistent with the previous studies, and indicates the immediate effects of TENS in women with primary Dysmenorrheal.
Abstract: Objectives. Dysmenorrhea is a disturbing problem among women of childbearing age. The purpose of this study is to investigate the effect of high-frequency transcutaneous electrical nerve stimulation (TENS) on primary dysmenorrhea and to compare the placebo effect by sham TENS in a randomized controlled study. Materials and Methods. Twenty-two women participated in the two-month experiment by using TENS or sham TENS in a random order for their dysmenorrhea. Outcome measures included self-reported pain intensity, symptom and function questionnaire related to dysmenorrhea, quality of life, satisfaction after TENS application, and other pain management agents adapted by the participants. Two-way repeated measures analysis of variance (two-way ANOVA) was conducted to compare pain intensity between pre-post values and groups (TENS vs. placebo). One-way repeated measures analysis of variance (one-way ANOVA) was conducted to compare scores from questionnaire of symptoms and quality of life at baseline, and after placebo or TENS stimulation. Results. Pain intensity in TENS is significantly decreased than in the placebo group (p= 0.018). The decrease of pain intensity after TENS and placebo TENS were both significant, with p < 0.00005 and p < 0.00005 respectively. Furthermore, TENS significantly changed the degree of autonomic symptoms (p= 0.048); but not after placebo TENS. Conclusion. This result supports that women in our country who suffer from primary dysmenorrhea could benefit by using TENS, which is consistent with the previous studies. In addition to pain-relieving effects, relief of the autonomic symptoms associated with dysmenorrhea also indicated that the mechanism of TENS might be different from the placebo effect of the sham TENS stimulation. These findings indicate the immediate effects of TENS in women with primary dysmenorrheal.

46 citations


Journal ArticleDOI
TL;DR: It is shown that the design of a neuroprosthesis for unsupported (arm‐free) standing is feasible and the degrees of freedom (DOF) of the redundant, closed‐chain dynamic system of bipedal stance that have to be regulated to facilitate stable standing are identified.
Abstract: Objectives. The purpose of the present study was to show that the design of a neuroprosthesis for unsupported (arm-free) standing is feasible. We review findings suggesting that a closed-loop controlled functional electrical stimulation (FES) system should be able to facilitate arm-free quiet standing in individuals with spinal cord injury (SCI). Particularly, this manuscript identifies: 1) a control strategy that accurately mimics the strategy healthy individuals apply to regulate the ankle joint position during quiet standing and 2) the degrees of freedom (DOF) of the redundant, closed-chain dynamic system of bipedal stance that have to be regulated to facilitate stable standing. Methods and Results. First, we utilized a single DOF model of quiet standing (inverted pendulum) to analytically identify a proportional and derivative (PD) feedback controller that regulates the ankle torque in a physiologic manner despite a long sensory-motor time delay. Second, these theoretic results were experimentally validated by implementing the proposed PD controller to stabilize an individual with SCI during quiet standing. Third, a realistic, three-dimensional dynamic model of quiet standing with 12 DOF was used to determine the optimal combination of the minimum number of DOF that need to be regulated with the PD controller to ensure stability during quiet standing. Finally, perturbation simulations confirmed that the kinematics of this system are similar to those of healthy individuals during perturbed standing. Conclusions. The presented results suggest that stable standing can be achieved in individuals with SCI by controlling only six DOF in the lower limbs using FES, and that a PD controller actuating these DOF can stabilize the system despite a long sensory-motor time delay. Our finding that not all DOF in the lower limbs need to be regulated is particularly relevant for individuals with complete SCI, because some of their muscles may be denervated or difficult to access.

45 citations


Journal ArticleDOI
TL;DR: Spinal cord stimulation is an effective treatment option for neuropathic pain, but it is unable to reach certain areas, such as the face, thorax, coccyx, the cervico‐dorsal and lumbar areas, and the sacral, abdominal, and inguinal regions.
Abstract: Introduction. Spinal cord stimulation (SCS) is an effective treatment option for neuropathic pain. However, because of the obvious procedural issues, SCS is unable to reach certain areas, such as the face, thorax, coccyx, the cervico-dorsal and lumbar areas, and the sacral, abdominal, and inguinal regions. On the other hand, these areas are easily reached by subcutaneous field stimulation. Methodology. We report the analgesic results, using a visual analog scale (VAS), of five patients with neuropathic pain treated with subcutaneous field stimulation to the area. We also discuss the probable mechanism of action, and highlight the technical issues inherent to this approach. Results. Significant pain reduction and reduction in analgesic medication were reported in all patients during the study period, with VAS scores consistently lowered by more than 50% from baseline levels. As a result of pain reduction, the patients’ quality of life improved. There were no adverse events reported except for early electrode array displacement in two of our patients. Conclusion. When SCS is not appropriate for certain neuropathic pain syndromes, subcutaneous field stimulation may be used with some degree of efficacy.

41 citations


Book ChapterDOI
TL;DR: This chapter focuses on the implantable neural stimulators, which are used by the clinicians to execute the various and diverse neuromodulation therapies.
Abstract: Publisher Summary This chapter focuses on the implantable neural stimulators, which are used by the clinicians to execute the various and diverse neuromodulation therapies. Implantable neurostimulators have their technical roots in cardiac pacing, and their primary function is to activate or inhibit the nervous system to augment, improve or replace function lost to a neurological disease or disorder. The neurostimulator generates appropriate electric fields within neural tissues through the application of prescribed currents or voltages to electrodes in contact with the neural tissue. The physical form of the neurostimulator is designed based on constraints, requirements, and ideals from both the engineering and clinical realms. The device design must balance the need for a biocompatible, hermetically sealed, and mechanically robust package that is capable of housing all of the stimulator components and meeting the clinical demands for minimal invasiveness, conformation to anatomy, facilitation of surgical installment, and device cosmesis. The power is supplied by a source that is either internal to the implantable device or external to the body. Internal power sources are batteries whereas the external power sources include inductive radio-frequency (RF) coupling. Some of the other power sources include the use of nuclear powered cells and systems that harvest power from the body. Inductive and RF antenna-coupled links are the most commonly used means of transferring data to and from an implanted device, which are appropriate for low to moderate data rate applications.

40 citations


Journal ArticleDOI
TL;DR: The problem of treating patients in a vegetative state remains grossly unresolved, and spinal cord stimulation (SCS) had seemed promising in some studies, suggesting, to us, further study.
Abstract: Objectives. The problem of treating patients in a vegetative state remains grossly unresolved, and spinal cord stimulation (SCS) had seemed promising in some studies, suggesting, to us, further study. Materials and Methods. A prospective uncontrolled and nonrandomized observational study for 20 consecutive years (1986–2005) was performed on the effect of SCS in 214 patients in persistent vegetative state (PVS) that resulted from global anoxia and/or, stroke and/or head injury. After confirming the condition of PVS, a spinal cord stimulator, at the C2–C4 level, was implanted, stimulating according to a protocol of 15-min on/15-min off during daytime only. The results were evaluated using an efficacy scale designed by us for our study, detecting signs of awareness of self and surrounding. Results. Excellent and positive results were obtained in 109 of 201 patients (54%), but better in those patients below the age of 35, those of PVS of traumatic origin and those patients with regional cerebral blood flow over 20 mL/100 g/min. Conclusions. These findings, though inconclusive of actual benefit of SCS for PVS, indicate to us that further evidence-based, randomized controlled trials are needed to confirm efficacy of the treatment and define those who are going to benefit from this treatment method.


Journal ArticleDOI
TL;DR: The reduction in the number and/or severity of seizures found in some studies supports further investigation into the effects of electrical stimulation on the brain and the continuation of testing in animals and humans.
Abstract: Introduction. There is renewed interest in the use of electrical stimulation to control seizures in patients with medically refractory epilepsy. The evidence indicates that multiple nuclei are involved in the onset, spread, or termination of seizures. Establishing electrical stimulation parameters tailored to these nuclei that best control seizures is ongoing. Methods. The aim of this article is to review the published literature on electrical stimulation of the brain for epilepsy in animals and humans. Results. Animal and human research efforts have focused primarily on the study of the cerebellum, anterior thalamus, centromedian thalamus, substania nigra, caudate nucleus, subthalamic nucleus, and amygdalo-hippocampal complex. Electrical stimulation of deep brain nuclei has in some instances controlled seizures and epilepsy. The advent of seizure detection devices used in closed-loop studies has in part redefined the strategy to prevent seizure occurrence and limit spread. Discussion. A number of studies in animals and humans indicate that electrical stimulation may be an alternative treatment for some patients with medically intractable epilepsy who are not candidates for conventional surgical options. Conclusion. The reduction in the number and/or severity of seizures found in some studies supports further investigation into the effects of electrical stimulation on the brain and the continuation of testing in animals and humans.

Journal ArticleDOI
TL;DR: A new model of thinking is offered when formulating algorithms of care that might include more invasive and costly interventions such as spinal cord stimulation, the SAFE principles.
Abstract: Currently accepted chronic pain treatment algorithms have positioned therapies according to levels of invasiveness and up-front costs. After reviewing updated literature on efficacy and cost outcomes of care for patients with chronic pain that include interventional implantable technologies, we offer a new model of thinking when formulating algorithms of care that might include more invasive and costly interventions such as spinal cord stimulation, the SAFE principles. These SAFE principles include "safety," "appropriateness," "fiscal neutrality," and "efficacy." Introductiontraditional role of the physician is to heal patients. To accomplish this goal, the physician synthesizes his or her knowledge base derived from education, experience, and extrapolation of the medical and scientific literature into an appropriate treatment plan. In this traditional model, accepted medical treatment is based on safety of the intervention, appropriateness to the diagnosis and individual patient, and effectiveness. In today's world of rapidly growing therapeutic options and increasing medical cost, the role of the physician has expanded to encompass consideration of cost-utility in an attempt to maximize the benefit for their patients in an environment of limited healthcare resources. In government-sponsored healthcare systems, government agencies dictate the allocation of care based on known efficacy data/safety, cost, and available resources. In the United States, health care for the insured patient is also limited by cost. Hospitals routinely deny certain therapies and technologies because of inadequate reimbursement, and third-party payers, including private and public payers; for example, the Centers for Medicare and Medicaid Services use cost to dictate the spectrum of medical coverage.

Book ChapterDOI
TL;DR: This chapter focuses on the electrodes used as neural interfaces, a critical component of any neuromodulation system and its development requires careful consideration of all aspects of the neural anatomy, gross physiology, molecular physiology, and electrophysiology.
Abstract: Publisher Summary This chapter focuses on the electrodes used as neural interfaces. The neural interface can be unidirectional or bidirectional with information from an engineered system transferred to the neural system and/or information from the neural system transferred to an engineered system. The electrode for the neural interface is a critical component of any neuromodulation system and its development requires careful consideration of all aspects of the neural anatomy, gross physiology, molecular physiology, and electrophysiology. Surface electrodes applied to the skin are widely used in many neuromodulation applications and clinical diagnostic procedures, which ranges from ECG and EEG measurement to transcutaneous electrical nerve stimulation (TENS) for pain management and physical therapy to EMG recording for control of amputee prostheses. Muscle-based electrodes are used in the somatic peripheral nervous system and take advantage of the somatic PNS characteristic of point-like innervations at the neuromuscular junctions. By placing an electrode at a few positions, i.e., at the motor points, of a muscle, the entire muscle can be activated. Peripheral Nervous System Electrodes are designed for implantation directly on the nerves of the peripheral nervous system. The electrode technologies applied to the superficial and distal CNS are similar to the electrodes described for the PNS. These paddle-like electrodes are applied to the dorsal and ventral columns of the spinal cord for stimulation of cough, and respiration function and chronic, and intractable pain. Arrays of the paddle-like discs are embedded in silicon sheeting and applied over the cortical surface for measurement of the cortical activity.

Journal ArticleDOI
TL;DR: This study aims to investigate the movements of hyolaryngeal structures during the surface electrical stimulation of suprahyoid muscles and to compare these with movements during liquid swallowing.
Abstract: Objective. This study aims to investigate the movements of hyolaryngeal structures during the surface electrical stimulation of suprahyoid muscles and to compare these with movements during liquid swallowing. Materials and methods. Twelve volunteers without dysphagia participated in this study. Volunteers swallowed 5 mL of diluted barium liquid, which was recorded videofluoroscopically. They then received surface electrical stimulation at midpoints between the chin and the bilateral edges of the hyoid, and movements were again recorded. Two-dimensional motion analysis was performed and displacements of the hyoid and of subglottic air-column and epiglottic rotations were calculated. Movements caused by surface stimulation were compared to those during liquid swallowing. Results. Elevation and anterior excursion of the hyoid by electrical stimulation were 66.8% and 45.2% of those during liquid swallowing, respectively, and rotation of the epiglottis by electrical stimulation was 24.0% of that during liquid swallowing. Elevation and anterior excursion of the subglottic air column during liquid swallowing were 24.1 mm and 4.6 mm, respectively, compared with 9.6 mm and 1.9 mm during electrical stimulation. All the movements during electrical stimulation were significantly smaller than those that occurred during liquid swallowing (p < 0.05). Trajectories of the hyoid and larynx during electrical stimulation were smaller than but similar to those that occurred during liquid swallowing. Conclusion. This study suggests that surface electrical stimulation of suprahyoid muscles causes the elevation and anterior excursion of hyolaryngeal structures, as is observed during normal physiologic swallowing, although the movements involved were smaller. Further studies are required to determine the effect of synchronized electrical stimulation on dysphagia patients with reduced laryngeal elevation to allow the development of a swallow-assisting neural orthosis.

Journal ArticleDOI
TL;DR: The effect of pain management leading to quick termination of pain using temporary spinal cord stimulation (SCS) which does not require implantation of a device is evaluated.
Abstract: Objectives. The pain associated with herpes zoster can be classified as acute phase, persistent phase, or chronic phase, but if it is prolonged, it becomes resistant to treatment. It is clinically important to prevent transition to postherpetic neuralgia after the onset of herpes zoster, and the outcome depends on whether continuous and potent pain management can be achieved between the acute and persistent phases. We evaluated the effect of pain management leading to quick termination of pain using temporary spinal cord stimulation (SCS) which does not require implantation of a device. Materials and Methods. We performed continuous epidural blocks (CEB) on 52 patients with severe persistent pain of postherpetic neuralgia in the thoracic nerve area, and also inserted spinal stimulation leads in 14 who showed no improvement in the severe pain with concomitant pharmacotherapy. We expected to see the termination of pain with adequate analgesic effects mainly with SCS, and secondarily with the epidural analgesia as rescue therapy. Results. Severe pain accompanied by sensory dysfunction remained in 14 cases. By introducing SCS to the CEB, the visual analog scale baseline was rapidly reduced. Less epidural analgesia was required and the adverse reactions of lowered blood pressure in three cases and urinary retention in seven cases disappeared soon. The self-rated satisfaction was higher with SCS than with CEB in all 14 cases, because it is highly controllable and has minimal activities of daily living–lowering effects. Conclusion. Temporary SCS, which does not require implantation of a device, may have a potent analgesic effect on severe pain in patients in the persistent phase after herpes zoster, and prevent transition to postherpetic neuralgia.

Book ChapterDOI
TL;DR: The voltages generated in the central nervous system by applied currents can be calculated using quantitative approaches, and the results can be used to interpret the observed effects of stimulation and to design electrodes and stimuli appropriate for the intended application.
Abstract: Publisher Summary This chapter focuses on the various principles of electric field generation for stimulation of the central nervous system (CNS). Electrical stimulation is used to study the form and function of the nervous system and is a technique to restore function following disease or injury. Applications of electrical stimulation for restoration of function include generation, inhibition, and modulation of brain activity. The electrical properties of the central nervous system are inhomogeneous, meaning that they vary at different positions within the tissue because the neuronal and glial elements have wide-ranging dimensions, varying orientations, and different packing densities. The electrical properties of the central nervous system are anisotropic, meaning that they vary along different directions through the tissue because of the nonrandom orientation of neural elements. In particular, the white matter has anisotropic conductivity as current can travel more easily in the direction parallel to the axons than in the direction transverse or perpendicular to the axons. The extracellular potentials are also dependent on the electrical properties of the tissue. The electrical conductivity of the tissue also varies with position within the CNS. The voltages generated in the central nervous system by applied currents can be calculated using quantitative approaches, and the results can be used to interpret the observed effects of stimulation and to design electrodes and stimuli appropriate for the intended application.

Journal ArticleDOI
TL;DR: Current concepts from the literature are utilizes to reinforce appropriate surgical practices, which are applicable to surgeons as well as interventional pain physicians, and a proposed simple one‐incision surgical technique for implantation of small internal pulse generators.
Abstract: The objective of this paper is to educate physicians who implant spinal cord stimulators in current surgical techniques. Many implanters have not gone through formal surgical residencies and learn their surgical techniques during a one year Fellowship or from proctoring experience. This paper utilizes current concepts from the literature to reinforce appropriate surgical practices, which are applicable to surgeons as well as interventional pain physicians. This should be a valuable resource for all Fellows whether they are in surgical programs or pain fellowship programs. In addition, a more detailed presentation is made at the end of this paper on a proposed simple one-incision surgical technique for implantation of small internal pulse generators. This is the first publication in the literature describing such a technique and may be useful for less-experienced implanters, as well as conferring potential advantages in surgical technique.

Book ChapterDOI
TL;DR: In this paper, the authors focus on the various ethical issues related to the clinical application and research of deep brain stimulation, and apply the proper ethical frame against which to evaluate the risks and benefits of neuromodulation, and determine whether a procedure constitutes established therapy or remains investigational.
Abstract: Publisher Summary This chapter focuses on the various ethical issues related to the clinical application and research of deep brain stimulation. DBS is recognized as therapeutic for the management of chronic pain, the evaluation and management of epilepsy, and the treatment of Parkinson's disease and other movement disorders. The Food and Drug Administration (FDA) has also approved the use of the deep brain stimulator for refractory Parkinson's disease and essential tremor in 1997. Clinical investigators are conducting trials for its use in obsessive–compulsive disorders, which awaits FDA approval, depression, and traumatic brain injury. The boundary between experimental work and therapeutic deployment rests on FDA approval of the device and the consensus of the medical community that the putative treatment is effective and safe and that the intended beneficial outcome will appear without adverse long or short-term effects. To apply the proper ethical frame against which to evaluate the risks and benefits of neuromodulation, it is necessary to determine whether a procedure constitutes established therapy or remains investigational. Determining this distinction is critical or else the investigator or clinician can inadvertently mislead a potential research participant or patient about the safety and efficacy of an intervention. A therapeutic misconception can also have its origins in the hopes and desperation of a patient eager for cure or in the manner within which consent is obtained for enrollment in a clinical trial. Usually, these misperceptions stem from both a combination of hope and hype, which may or may not be intended on the part of the investigator.

Journal ArticleDOI
TL;DR: The successful use of ultrasound as described in these two cases suggests an important role for ultrasound in localization of targeted nerves in percutaneous trial stimulation of injured peripheral nerve.
Abstract: Introduction. Peripheral nerve stimulation (PNS) has been used for many years to treat neuropathic pain syndromes. Technical advances in neurostimulation hardware have led to a renewed interest in the use of PNS for control of intractable pain caused by peripheral mononeuropathies. One such application includes intractable groin pain. This study identified two patients with chronic groin pain, secondary to trauma, referred for interventional pain management. For each patient, PNS trial was attempted using ultrasound guided localization of the inguinal nerve. Direct sonographic visualization of the inguinal nerve has been used in other studies to facilitate regional anesthesia, but to our knowledge, no studies have used this technique for localization of nerves for percutaneous lead placement for PNS. Methods. Each patient was chosen to undergo trial stimulation using percutaneously placed peripheral nerve stimulator leads. In these two cases, both patients presented with similar complaints of chronic groin pain consistent with ilioinguinal neuralgia. Both underwent multiple previous nerve blocks, all of which gave good but transient relief using traditional block techniques. Both patients were trialed on multiple medications, which either gave incomplete relief of pain or were limited by side-effects. Results. Both patients had relatively easy localization of ilioinguinal nerves affected using ultrasound and were provided with stimulating paresthesias which covered their normal pain. Discussion. The successful use of ultrasound as described in these two cases suggests an important role for ultrasound in localization of targeted nerves in percutaneous trial stimulation of injured peripheral nerve. The use of ultrasound may also play a role in permanent lead placement as well. Conclusion. More studies are needed to further qualify the role of ultrasound in isolating peripheral nerves, but the success of trial stimulation in these two cases holds promise for continued advancements in the field of neuromodulation.

Journal ArticleDOI
TL;DR: A case of a patient with history of long‐standing axial neck pain with previous cervical spine operation and confirmed discogenic pain, and a trial of peripheral subcutaneous field stimulation (PSFS), which represents a new and promising modality in treatment of axial head pain.
Abstract: Objective. To present a novel technique of neuromodulation for the treatment of axial neck pain. Materials and Methods. A case of a patient with history of long-standing axial neck pain with previous cervical spine operation and confirmed discogenic pain is presented. Traditional treatment measures did not provide adequate pain relief. A trial of peripheral subcutaneous field stimulation (PSFS) was performed. Following an excellent response during a week-long trial, a permanent PSFS system was implanted. The patient was followed for nine months after internalization. Results. Seven-day trial of PSFS resulted in complete relief of the patient's pain. This 100% relief of pain continued after the implantation of permanent PSFS system consisting of two quadripolar electrodes, one placed over the paraspinal muscles parallel to midline, and the other positioned horizontally over the ipsilateral trapezius muscle. The patient was gradually weaned off of all opioid medications and continues to report 100% reduction in pain intensity at the nine-month follow-up. Conclusion. PSFS represents a new and promising modality in treatment of axial neck pain. Exact mechanism of the pain relief remains unclear.

Journal ArticleDOI
TL;DR: This research presents a novel, scalable, and scalable approach to regenerative neurosurgery that aims to provide real-time information about the dynamic response of the central nervous system to injury and disease.
Abstract: *Stanford University School of Medicine, Stanford, CA, USA; †Feinberg School of Medicine, Northwestern University, Chicago, IL, USA; ‡Bedder Medicine Consulting, Poulsbo, WA, USA; §Departments of Anesthesiology and Critical Care Medicine and Oncology, Johns Hopkins University, Baltimore, MD, USA; ¶Department of Neurosurgery, University of Illinois at Chicago, Chicago, IL, USA; ††Pain Clinic of Monterey Bay, Aptos, CA, USA; ‡‡LifeBridge Health Brain & Spine Institute, Baltimore, MD, USA; and §§Johns Hopkins University School of Medicine, Baltimore, MD, USA

Book ChapterDOI
TL;DR: SCS is effective in some pain syndromes that are otherwise resistant to other treatments, and it is well tolerated by patients, is minimally invasive, is reversible and, when compared to chronic pharmacotherapies, has fewer adverse effects.
Abstract: Publisher Summary This chapter focuses on the use of spinal cord stimulation (SCS) in neuropathic and ischemic pain syndromes. SCS has long been utilized for neuropathic pain of peripheral origin, in ischemic pain states, e.g. peripheral arterial occlusive disease and in vasospastic conditions, and in angina pectoris. SCS may induce effects in multiple organ systems and the benefit for a certain condition may depend on the site of spinal cord activated and the relevance of the released transmitters and other neuronal changes for a certain painful syndrome. It is effective in some pain syndromes that are otherwise resistant to other treatments, and it is well tolerated by patients, is minimally invasive, is reversible and, when compared to chronic pharmacotherapies, has fewer adverse effects. In some syndromes, SCS can also lead to the improvement of organ function, resulting in reduction of pain and other uncomfortable symptoms associated with the disease. In pain syndromes with signs of autonomic disturbance, SCS may hypothetically act on the symptoms through a direct inhibitory action onto central hyperexcitable neurons, by decreasing sympathetic efferent output acting on the sensitized adrenoreceptors on the damaged sensory neurons, and by reducing peripheral ischemia both by a sympaticolytic action and via antidromic mechanisms.

Journal ArticleDOI
TL;DR: The use of subcutaneous peripheral nerve stimulation as a viable treatment alternative in certain cases of chronic neuropathic pain should continue to be rigorously evaluated.
Abstract: Introduction. Chronic pain is a prevalent medical condition in the general population and is one of the most common reasons patients visit their primary care doctors. When the pain is resistant to the common treatment modalities, it presents a challenge for the physician and may have profound consequences for the quality of life of the patient. Methods. We present four case reports in which subcutaneous peripheral nerve stimulation was successfully used to treat chronic neuropathic pain after all other treatment efforts had failed. Results. In all cases, the patients underwent a trial of peripheral nerve stimulation with good results. The patients reported decreased use of pain medications, increased quality of life, and high satisfaction with the procedure results. Conclusion. The use of subcutaneous peripheral nerve stimulation as a viable treatment alternative in certain cases of chronic neuropathic pain should continue to be rigorously evaluated.

Journal ArticleDOI
TL;DR: A 37‐year‐old man who did not have adequate axial back stimulation with a subcutaneously placed small diameter cylindric lead had excellent stimulation and reduction of his pain after the device was replaced with an insulated subcutaneous paddle lead.
Abstract: Introduction. Peripheral nerve stimulation has become a useful tool in neuromodulation in the treatment of chronic and intractable pain syndromes. Method. While most of the reports in the literature describe the use of a subcutaneously placed small diameter cylindric lead, we present a case report of a 37-year-old man who did not have adequate axial back stimulation with such a lead. Conclusion. He had excellent stimulation and reduction of his pain after the device was replaced with an insulated subcutaneous paddle lead.

Journal ArticleDOI
TL;DR: A technique using electromagnetic (EM) navigation as a guidance technique for interventional pain management, using CT and/or magnetic resonance (MRI) images uploaded on the navigation station, and developed a technique using a stylet with two magnetic coils suitable for EM navigation.
Abstract: Introduction. Interventional pain management techniques require precise positioning of needles or electrodes, therefore fluoroscopic control is mandatory. This imaging technique does however not visualize soft tissues such as blood vessels. Moreover, patient and physician are exposed to a considerable dose of radiation. Computed tomography (CT)-scans give a better view of soft tissues, but there use requires presence of a radiologist and has proven to be laborious and time consuming. Objectives. This study is to develop a technique using electromagnetic (EM) navigation as a guidance technique for interventional pain management, using CT and/or magnetic resonance (MRI) images uploaded on the navigation station. Methods. One of the best documented interventional procedures for the management of trigeminal neuralgia is percutaneous radiofrequency treatment of the Gasserian ganglion. EM navigation software for intracranial applications already exists. We developed a technique using a stylet with two magnetic coils suitable for EM navigation. The procedure is followed in real time on a computer screen where the patient's multislice CT-scan images and three-dimensional reconstruction of his face are uploaded. Virtual landmarks on the screen are matched with those on the patient's face, calculating the precision of the needle placement. Discussion. The experience with EM navigation acquired with the radiofrequency technique can be transferred to other interventional pain management techniques, for instance, for the placement of a neuromodulation electrode close to the Gasserian ganglion. Currently, research is ongoing to extend the software of the navigation station for spinal application, and to adapt neurostimulation hardware to the EM navigation technology. This technology will allow neuromodulation techniques to be performed without x-ray exposure for the patient and the physician, and this with the precision of CT/MR imaging guidance.

Journal ArticleDOI
TL;DR: An account on the development of surgical neuromodulation therapy for dystonia, surgical approaches, hardware‐related problems, DBS programming and patient management, and clinical outcome, and the implications of intra‐operative microelectrode recordings and pallidal field potentials for the pathophysiology of dySTONia are discussed.
Abstract: Among the surgical treatment options for patients with medically refractory dystonia chronic deep brain stimulation (DBS) of different targets in the basal ganglia circuitry has become one of the most important tools. The globus pallidus internus nowadays is the target of choice, while there is only limited experience with other targets. At this time, patients with primary (genetic or sporadic) generalized and segmental dystonia, and patients with (complex) cervical dystonia are thought to be the best candidates for pallidal DBS. Advantages of DBS are its reversibility, its adjustability, and the continuous access to modify the target in the basal ganglia. The present review gives an account on the development of surgical neuromodulation therapy for dystonia, surgical approaches, hardware-related problems, DBS programming and patient management, and clinical outcome. Studies conducted according to the practices of evidence-based medicine confirm the results of early pilot studies. The wide majority of patients achieve beneficial lasting outcome at a relatively low rate of manageable side-effects. Along with improvement of the movement disorder, studies report on amelioration of quality-of-life surrogates. We also provide an overview on DBS surgery in less common dystonic syndromes, such as craniofacial dystonia, status dystonicus, task-specific dystonia, paroxysmal dystonia, camptocormia, and secondary dystonias, including choreoathetosis, hemidystonia, tardive dystonia, and pantothenate kinase-associated neurodegeneration. Furthermore, we discuss the implications of intra-operative microelectrode recordings and pallidal field potentials for the pathophysiology of dystonia and the particular possible mechanisms of DBS in dystonia. Finally, future perspectives are outlined.

Journal ArticleDOI
TL;DR: SCS seems to be safe in the first two trimesters of pregnancy based on these two case reports and the abdominal wall should be avoided as a site for IPG implantation in these patients, however, more cases are required to establish the safety of SCS in pregnancy.
Abstract: Introduction. Spinal cord stimulation (SCS) is an accepted cost-effective therapy for many chronic pain syndromes. Its effects on pregnancy have not been studied because of stringent regulation and manufacturers' recommendations. However, childbearing women who had SCS become or choose to become pregnant despite these policies. It is paramount to monitor, document, and report these effects of SCS during pregnancy to build clinical experience and guide recommendations and management. Methods. We reviewed the literature for SCS in pregnancy and added new case report of a young woman who had SCS implanted for chronic pain, became pregnant and at the end of the second trimester the lead extender had to be divided to relief pain at the lead site. Results. We found only one previous case report in this field and we add another case. Discussion. Our case is different from the previously reported case in that the implantable pulse generator (IPG) of our case was implanted in the anterior abdominal wall, while the previously reported case was implanted in the subclavicular fossa. Therefore our case highlights the need to implant the IPG in a way that avoids stretching the lead extender by the expanding abdomen. Conclusion. SCS seems to be safe in the first two trimesters of pregnancy based on these two case reports and the abdominal wall should be avoided as a site for IPG implantation in these patients. However, more cases are required to establish the safety of SCS in pregnancy.

Journal ArticleDOI
TL;DR: It is suggested that VN stimulation can reduce bronchoconstriction and may prove useful as a rescue therapy in the treatment of acute asthma.
Abstract: Objective. Smooth muscle help regulate the diameter of the airways and their constriction can contribute to the pathology of acute asthma attacks. This study sought to determine if applying a specific electrical signal to the vagus nerve (VN) could minimize histamine-induced bronchoconstriction. Methods. Sixteen guinea pigs and three swine were anesthetized and had bipolar electrodes positioned on the cervical VNs. After the animals stabilized, i.v. histamine was titrated to elicit a moderate 2-4 cm H(2) O increase in pulmonary inflation pressure (Ppi). Histamine was then dosed with or without concurrent low voltage VN stimulation. Results. The peak change in Ppi following a histamine challenge was reduced in the guinea pig by VN stimulation (3.4 ± 0.4 vs. 2.1 ± 0.2 cm H(2) O, p < 0.001). The results were confirmed in a limited study in swine and indicate VN treatment is applicable to larger animals. Conclusion. This study suggests that VN stimulation can reduce bronchoconstriction and may prove useful as a rescue therapy in the treatment of acute asthma.