Computational modelling and analysis of thermal characteristics of DBS electrode in application to Parkinson's disease
19 Jun 2014-pp 1-4
TL;DR: In this paper, the authors presented a finite element model (FEM) for DBS electrode in monopolar, bipolar and quadripolar configuration and compared the effect of temperature and current density distribution for each of the electrode configuration.
Abstract: Worldwide over 6.3 million people are diagnosed with Parkinson disease (PD) and irrespective of races, every year there is an increase of 75,000 new diagnosis [1]. Deep Brain Stimulation (DBS) has emerged as an effective intervention for treating neurological and motor disorders like PD. It involves surgically implanting Platinum electrode to create an electric field to activate the targeted nerve cells and fibers with minimized side effects. Some of the important stimulation parameters to monitor include temperature, electric field intensity and the current density [2]. Selective partial activation of the target could be optimally achieved in segmented electrode design. This paper presents a Finite Element Model (FEM) for DBS electrode in monopolar, bipolar and quadripolar configuration and the comparative effect of temperature and current density distribution for each of the electrode configuration is given. This study shows an increase in the tissue temperature to a maximum of 37.16 °C as the electrode segmentation increases. Monopolar electrode configuration provides a better uniformity in the current density distribution at the surface of the electrodes at a lower value than the rest of the configurations.
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01 Jan 2012
117 citations
TL;DR: In this article, the potential distribution of electric field distribution for electrodes with various combinations of active contacts was analyzed to get an optimum electrode for greater therapeutic efficacy of the neurological patients, and the simulation results confirm that tripolar electrode configuration provides highly concentrated electric field and electrical current at the surface of the electrodes than the rest of the configurations.
Abstract: Deep brain stimulation provides electrical stimulation to the target brain region through implant electrode. Some of the electrodes cannot produce desired field distribution for greater therapeutic efficacy because of their configuration. This paper aims at analyzing electric field distribution for electrodes with various combinations of active contacts to get an optimum electrode for greater therapeutic efficacy of the neurological patients. Various electrode configurations including monopolar, bipolar, tripolar, and quadripolar are simulated by COMSOL multiphysics (5.0 a). The potential distribution is calculated by using Laplace’s equation. The current density on the electrode contacts is determined by integrating the total amount of current delivered by the electrode. The simulation results confirm that tripolar electrode configuration provides highly concentrated electric field distribution and electrical current at the surface of the electrodes than the rest of the configurations. The tripolar electrode configuration can localize the current delivery into specific populations of neurons to avoid undesirable axon activation. Hence, it can be applied to obtain maximum therapeutic efficacy for particular neurological disorders.
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01 Jan 1995
1,613 citations
"Computational modelling and analysi..." refers background in this paper
...The electric field depends on the electrode contact geometry, distribution of the anode and cathode contacts and the physical property of the tissue medium [10]....
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TL;DR: Chronic high‐frequency stimulation of the ventral intermedius nucleus of the thalamus is safe and highly effective in ameliorating essential and parkinsonian tremor and measures of function were significantly improved in patients with essential tremor.
Abstract: Pharmacologic treatment for essential tremor and the tremor of Parkinson's disease is often inadequate. Stereotaxic surgery, such as thalamotomy, can effectively reduce tremors. We performed a multicenter trial of unilateral high-frequency stimulation of the ventral intermedius nucleus of the thalamus in 29 patients with essential tremor and 24 patients with Parkinson's disease, using a blinded assessment at 3 months after surgery to compare clinical rating of tremor with stimulation ON with stimulation OFF and baseline and a 1-year follow-up. Six patients were not implanted because of lack of intraoperative tremor suppression (2 patients), hemorrhage (2 patients), withdrawal of consent (1 patient), and persistent microthalamotomy effect (1 patient). A significant reduction in both essential and parkinsonian tremor occurred contralaterally with stimulation. Patients reported a significant reduction in disability. Measures of function were significantly improved in patients with essential tremor. Complications related to surgery in implanted patients were few. Stimulation was commonly associated with transient paresthesias. Other adverse effects were mild and well tolerated. Efficacy was not reduced at 1 year. Chronic high-frequency stimulation is safe and highly effective in ameliorating essential and parkinsonian tremor.
488 citations
"Computational modelling and analysi..." refers methods in this paper
...Electrical pulses in the frequency range of 130 Hz to 185 Hz with a pulse width of 60s to 450s are used to regulate the brain activity [8]....
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TL;DR: Thalamic stimulation was shown to be an effective and relatively safe treatment for disabling tremor and initially applied in a very limited number of centres has been successfully used in 13 participating centres.
Abstract: Objectives—Thalamic stimulation has been proposed to treat disabling tremor. The aims of this multicentre study were to evaluate the eYcacy and the morbidity of thalamic stimulation in a large number of patients with parkinsonian or essential tremor. Methods—One hundred and eleven patients were included in the study and 110 were implanted either unilaterally or bilaterally. Patients were evaluated with clinical scales, before and up to 12 months after surgery. Results—Upper and lower limb tremor scores were reduced in both groups. Eighty five per cent of the electrodes satisfied the arbitrary criteria of two point reduction in rest tremor reduction in the parkinsonian tremor group and 89% for postural tremor reduction in the essential tremor group. In the parkinsonian tremor group, limb akinesia and limb rigidity scores were moderately but significantly reduced. Axial scores were unchanged. In the essential tremor group, head tremor was significantly reduced only at 3 months and voice tremor was non-significantly reduced. Activities of daily living were improved in both groups. Changes in medication were moderate. Adverse eVects related to the surgery were mild and reversible. Conclusions—Thalamic stimulation was shown to be an eVective and relatively safe treatment for disabling tremor. This procedure initially applied in a very limited number of centres has been successfully used in 13 participating centres. (J Neurol Neurosurg Psychiatry 1999;66:289‐296)
479 citations
"Computational modelling and analysi..." refers background in this paper
...Some of the important stimulation parameters to monitor include temperature, electric field intensity and the current density [2]....
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...Parkinson Disease (PD) is a nervous system disorder that progressively causes degeneration of the nerve cells and fibers resulting in tremors, coordination problems, stiff muscles [2] and progresses to deterioration of all the brain functions affecting mainly the vocal [3] and olfactory functions [4]....
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TL;DR: This study developed a theoretical understanding of the impact of changes in the DBS electrode contact geometry on the volume of tissue activated (VTA) during stimulation and provided the foundation necessary to customize electrode design and VTA shape for specific anatomical targets.
Abstract: Deep brain stimulation (DBS) is an established clinical treatment for a range of neurological disorders. Depending on the disease state of the patient, different anatomical structures such as the ventral intermediate nucleus of the thalamus (VIM), the subthalamic nucleus or the globus pallidus are targeted for stimulation. However, the same electrode design is currently used in nearly all DBS applications, even though substantial morphological and anatomical differences exist between the various target nuclei. The fundamental goal of this study was to develop a theoretical understanding of the impact of changes in the DBS electrode contact geometry on the volume of tissue activated (VTA) during stimulation. Finite element models of the electrodes and surrounding medium were coupled to cable models of myelinated axons to predict the VTA as a function of stimulation parameter settings and electrode design. Clinical DBS electrodes have cylindrical contacts 1.27 mm in diameter (d) and 1.5 mm in height (h). Our results show that changes in contact height and diameter can substantially modulate the size and shape of the VTA, even when contact surface area is preserved. Electrode designs with a low aspect ratio (d/h) maximize the VTA by providing greater spread of the stimulation parallel to the electrode shaft without sacrificing lateral spread. The results of this study provide the foundation necessary to customize electrode design and VTA shape for specific anatomical targets, and an example is presented for the VIM. A range of opportunities exist to engineer DBS systems to maximize stimulation of the target area while minimizing stimulation of non-target areas. Therefore, it may be possible to improve therapeutic benefit and minimize side effects from DBS with the design of target-specific electrodes.
383 citations
14 Apr 2006
TL;DR: The electrical properties of biological tissues and cell pensions have been of interest for over a century for manyreasons, such as the ability to determine the pathways of current flow through the body and, thus, are very important in theanalysis of a wide range of biomedical applications such as functional electrical stimulation and the diagnosis and treatment of various physiological conditions with weakelectric currents, radiofrequency hyperthermia, electro-cardiography, and body composition as mentioned in this paper.
Abstract: 1. INTRODUCTIONThe electrical properties of biological tissues and cell sus-pensions have been of interest for over a century for manyreasons. They determine the pathways of current flowthrough the body and, thus, are very important in theanalysis of a wide range of biomedical applications such asfunctional electrical stimulation and the diagnosis andtreatment of various physiological conditions with weakelectric currents, radio-frequency hyperthermia, electro-cardiography, and body composition. On a more funda-mental level, knowledge of these electrical properties canlead to an understanding of the underlying basic biologicalprocesses. Indeed, biological impedance studies have longbeen important in electrophysiology and biophysics; one ofthe first demonstrations of the existence of the cell mem-brane was based on dielectric studies on cell suspensions(1).To analyze the response of a tissue to electric stimula-tion, we need data on the specific conductivities and rel-ative permittivities of the tissues or organs. A microscopicdescription of the response is complicated by the variety ofcell shapes and their distribution inside the tissue as wellas the different properties of the extracellular media.Therefore, a macroscopic approach is most often used tocharacterize field distributions in biological systems.Moreover, even on a macroscopic level, the electrical prop-erties are complicated. They can depend on the tissue ori-entation relative to the applied field (directionalanisotropy), the frequency of the applied field (the tissueis neither a perfect dielectric nor a perfect conductor), orthey can be time- and space-dependent (e.g., changes intissue conductivity during electropermeabilization).2. BIOLOGICAL MATERIALS IN AN ELECTRIC FIELDThe electrical properties of any material, including bio-logical tissue, can be broadly separated into two catego-ries: conducting and insulating. In a conductor, theelectric charges move freely in response to the applicationof an electric field, whereas in an insulator (dielectric), thecharges are fixed and not free to move. A more detaileddiscussion of the fundamental processes underlying theelectrical properties of tissue can be found in Foster andSchwan (2).If a conductor is placed in an electric field, charges willmove within the conductor until the interior field is zero.In the case of an insulator, no free charges exist, so netmigration of charge does not occur. In polar materials,however, the positive and negative charge centers in themolecules do not coincide. An electric dipole moment, p,issaid to exist. An applied field, E
349 citations
"Computational modelling and analysi..." refers background in this paper
...The electrical and the thermal properties of the tissues [17] are given in Table 1are assigned to its respective domains....
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