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Effects of somatosensory stimulation on the excitability of the unaffected hemisphere in chronic stroke patients

CONFORTO, Adriana B.; SANTOS, Renata Laurenti dos; FARIAS, Suzete Nascimento; MARIE, Suely Kazue Nagahashi; MANGINI, Nadia; COHEN, Leonardo G.
Fonte: Faculdade de Medicina / USP Publicador: Faculdade de Medicina / USP
Tipo: Artigo de Revista Científica
ENG
Relevância na Pesquisa
36.34%
INTRODUCTION: Somatosensory stimulation of the paretic upper limb enhances motor performance and excitability in the affected hemisphere, and increases activity in the unaffected hemisphere, in chronic stroke patients. We tested the hypothesis that somatosensory stimulation of the paretic hand would lead to changes in excitability of the unaffected hemisphere in these patients, and we investigated the relation between motor function of the paretic hand and excitability of the unaffected hemisphere. METHODS: Transcranial magnetic stimulation was administered to the unaffected hemisphere of nine chronic stroke patients. Patients were submitted to 2-h somatosensory stimulation in the form of median nerve stimulation and control stimulation using a cross-over design. Baseline Jebsen-Taylor test scores were evaluated. Resting motor threshold, intracortical facilitation, short-interval intracortical inhibition, and visual analog scores for attention, fatigue and drowsiness were measured across conditions. RESULTS: Better pre-stimulation baseline motor function was correlated with deeper SICI in the unaffected hemisphere. We found no overt changes in any physiological marker after somatosensory stimulation. There was increased drowsiness in the control session...

Non-pharmacological approach to neuropathic pain: the use of repetitive transcranial magnetic stimulation

ANDRADE, D. Ciampi De; ATTAL, N.; BOUHASSIRA, D.
Fonte: SPRINGER Publicador: SPRINGER
Tipo: Artigo de Revista Científica
FRA
Relevância na Pesquisa
36.34%
Neuromodulation is the branch of neurophysiology related to the therapeutic effects of electrical stimulations of the nervous system. There are currently different practical applications of neuromodulation techniques for the treatment of various neurological disorders, such as deep brain stimulation for Parkinson`s disease and repetitive transcranial magnetic stimulation (rTMS) for major depression. An increasing number of studies have been devoted to the analgesic effects of rTMS in chronic pain patients. RTMS has been used either as a therapeutic tool per se, or as a preoperative test in patients undergoing epidural precentral gyrus stimulation. High-frequency rTMS (a parts per thousand yen5 Hz) is considered to be excitatory, while low-frequency stimulation (a parts per thousand currency sign1 Hz) is considered to exert an inhibitory effect over neuronal populations of the primary motor cortex. However, other parameters of stimulation may play a central role on its clinical effects such as the type of coil, its orientation over the scalp, and the total number of rTMS sessions performed. Experimental data from animals, healthy volunteers, and neuropathic pain patients have suggested that stimulation of the primary motor cortex by rTMS is able to activate brain regions implicated in the processing of the different aspects of chronic pain...

Transcranial DC Stimulation Coupled With TENS for the Treatment of Chronic Pain A Preliminary Study

BOGGIO, Paulo S.; AMANCIO, Edson J.; CORREA, Clauo F.; CECILIO, Sofia; VALASEK, Claudia; BAJWA, Zahid; FREEDMAN, Steven D.; PASCUAL-LEONE, Alvaro; EDWARDS, Dylan J.; FREGNI, Felipe
Fonte: LIPPINCOTT WILLIAMS & WILKINS Publicador: LIPPINCOTT WILLIAMS & WILKINS
Tipo: Artigo de Revista Científica
ENG
Relevância na Pesquisa
36.37%
Objective: Based on evidence showing that electrical stimulation of the nervous system is an effective method to decrease chronic neurogenic pain, we aimed to investigate whether the combination of 2 methods of electrical stimulation-a method of peripheral stimulation [transcutaneous electrical nerve stimulation (TENS)] and a method of noninvasive brain stimulation (transcranial direct current stimulation (tDCS)]-induces greater pain reduction as compared with tDCS alone and sham stimulation. Methods: We performed a preliminary, randomized, sham-controlled, crossover, clinical study in which 8 patients were randomized to receive active tDCS/active TENS (""tDCS/TENS"" group), active tDCS/sham TENS (""tDCS"" group), and sham tDCS/sham TENS (""sham"" group) stimulation. Assessments were performed immediately before and after each condition by a blinded rater. Results: The results showed that there was a significant difference in pain reduction across the conditions Of stimulation (P = 0.006). Post hoc tests showed significant pain reduction as compared with baseline after the tDCS/TENS condition [reduction by 36.5% (+/- 10.7), P = 0.004] and the tDCS condition [reduction by 15.5% (+/- 4.9), P = 0.014], but not after sham stimulation (P = 0.35). In addition...

Estimulação multidirecional de celulas cardiacas : instrumentação e experimentação; Multidirectional stimulation of cardiac cells : instrumentation and experimentation

Alexandra Valenzuela Santelices da Fonseca
Fonte: Biblioteca Digital da Unicamp Publicador: Biblioteca Digital da Unicamp
Tipo: Dissertação de Mestrado Formato: application/pdf
Publicado em 03/12/2009 PT
Relevância na Pesquisa
36.36%
O procedimento mais efetivo para reverter arritmias cardíacas consiste na aplicação de choques elétricos de alta intensidade, como e o caso da desfibrilação. Estimulação com campos elétricos (E) elevados, entretanto, exerce efeitos deletérios sobre o músculo cardíaco, podendo causar disfunções elétrica e contrátil e até a morte celular. Privilegiar a estimulação na direção longitudinal, para qual o limiar de excitação das células cardíacas e menor, seria uma forma de se reduzir a amplitude do estimulo sem perder a efetividade da estimulação. Para isto, foi desenvolvido e testado, em miócitos ventriculares orientados de maneira aleatória, um sistema de estimulação multidirecional automática que permite o chaveamento controlado de estímulos sequênciais para três diferentes pares de eletrodos (cada um correspondendo a uma direção) em um intervalo de tempo inferior a duração do potencial de ação (período em que a célula se encontra eletricamente refrataria). A estimulação multidirecional com uma intensidade de E 20% acima do limiar estimulatório (1,2× ETM) dobrou o recrutamento (excitação) de células (80 vs. 40% com estimulação unidirecional, p<0,001). Adicionalmente, o recrutamento com a estimulação multidirecional automática foi maior (p< 0...

Polymeric piezoelectric actuator substrate for osteoblast mechanical stimulation.

Frias, C; Reis, J; Capela e Silva, F; Potes, J; Simões, J; Marques, AT
Fonte: Polymeric piezoelectric actuator substrate for osteoblast mechanical stimulation. Publicador: Polymeric piezoelectric actuator substrate for osteoblast mechanical stimulation.
Tipo: Artigo de Revista Científica
ENG
Relevância na Pesquisa
46.22%
Bone mass distribution and structure are dependent on mechanical stress and adaptive response at cellular and tissue levels. Mechanical stimulation of bone induces new bone formation in vivo and increases the metabolic activity and gene expression of osteoblasts in culture. A wide variety of devices have been tested for mechanical stimulation of cells and tissues in vitro. The aim of this work was to experimentally validate the possibility to use piezoelectric materials as a mean of mechanical stimulation of bone cells, by converse piezoelectric effect. To estimate the magnitude and the distribution of strain, finite numerical models were applied and the results were complemented with the optical tests (Electronic Speckle Pattern Interferometric Process). In this work, osteoblasts were grown on the surface of a piezoelectric material, both in static and dynamic conditions at low frequencies, and total protein, cell viability and nitric oxide measurement comparisons are presented.

Modulation of hormone secretion by functional electrical stimulation of the intact and incompletely dysfunctional dog pancreas

Rozman,J.; Bunc,M.; Zorko,B.
Fonte: Associação Brasileira de Divulgação Científica Publicador: Associação Brasileira de Divulgação Científica
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/03/2004 EN
Relevância na Pesquisa
36.34%
The purpose of the present study was to modulate the secretion of insulin and glucagon in Beagle dogs by stimulation of nerves innervating the intact and partly dysfunctional pancreas. Three 33-electrode spiral cuffs were implanted on the vagus, splanchnic and pancreatic nerves in each of two animals. Partial dysfunction of the pancreas was induced with alloxan. The nerves were stimulated using rectangular, charge-balanced, biphasic, and constant current pulses (200 µs, 1 mA, 20 Hz, with a 100-µs delay between biphasic phases). Blood samples from the femoral artery were drawn before the experiment, at the beginning of stimulation, after 5 min of stimulation, and 5 min after the end of stimulation. Radioimmunoassay data showed that in the intact pancreas stimulation of the vagal nerve increased insulin (+99.2 µU/ml) and glucagon (+18.7 pg/ml) secretion and decreased C-peptide secretion (-0.15 ng/ml). Splanchnic nerve stimulation increased insulin (+1.7 µU/ml), C-peptide (+0.01 ng/ml), and glucagon (+50 pg/ml) secretion, whereas pancreatic nerve stimulation did not cause a marked change in any of the three hormones. In the partly dysfunctional pancreas, vagus nerve stimulation increased insulin (+15.5 µU/ml), glucagon (+11 pg/ml)...

Electrical Stimulation for Urinary Incontinence in Women: A Systematic Review

Schreiner,Lucas; Santos,Thais Guimaraes dos; Souza,Alessandra Borba Anton de; Nygaard,Christiana Campani; Filho,Irenio Gomes da Silva
Fonte: Sociedade Brasileira de Urologia Publicador: Sociedade Brasileira de Urologia
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/08/2013 EN
Relevância na Pesquisa
36.35%
Background Electrical stimulation is commonly recommended to treat urinary incontinence in women. It includes several techniques that can be used to improve stress, urge, and mixed symptoms. However, the magnitude of the alleged benefits is not completely established. Objectives To determine the effects of electrical stimulation in women with symptoms or urodynamic diagnoses of stress, urge, and mixed incontinence. Search Strategy: Our review included articles published between January 1980 and January 2012. We used the search terms “urinary incontinence”, “electrical stimulation”, “intravaginal”, “tibial nerve” and “neuromodulation” for studies including female patients. Selection Criteria We evaluated randomized trials that included electrical stimulation in at least one arm of the trial, to treat women with urinary incontinence. Data Collection and Analysis Two reviewers independently assessed the data from the trials, for inclusion or exclusion, and methodological analysis. Main Results A total of 30 randomized clinical trials were included. Most of the trials involved intravaginal electrical stimulation. Intravaginal electrical stimulation showed effectiveness in treating urge urinary incontinence...

Effects of somatosensory stimulation on the excitability of the unaffected hemisphere in chronic stroke patients

Conforto,Adriana B.; Santos,Renata Laurenti dos; Farias,Suzete Nascimento; Marie,Suely Kazue Nagahashi; Mangini,Nadia; Cohen,Leonardo G.
Fonte: Faculdade de Medicina / USP Publicador: Faculdade de Medicina / USP
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/01/2008 EN
Relevância na Pesquisa
36.34%
INTRODUCTION: Somatosensory stimulation of the paretic upper limb enhances motor performance and excitability in the affected hemisphere, and increases activity in the unaffected hemisphere, in chronic stroke patients. We tested the hypothesis that somatosensory stimulation of the paretic hand would lead to changes in excitability of the unaffected hemisphere in these patients, and we investigated the relation between motor function of the paretic hand and excitability of the unaffected hemisphere. METHODS: Transcranial magnetic stimulation was administered to the unaffected hemisphere of nine chronic stroke patients. Patients were submitted to 2-h somatosensory stimulation in the form of median nerve stimulation and control stimulation using a cross-over design. Baseline Jebsen-Taylor test scores were evaluated. Resting motor threshold, intracortical facilitation, short-interval intracortical inhibition, and visual analog scores for attention, fatigue and drowsiness were measured across conditions. RESULTS: Better pre-stimulation baseline motor function was correlated with deeper SICI in the unaffected hemisphere. We found no overt changes in any physiological marker after somatosensory stimulation. There was increased drowsiness in the control session...

Effets neurophysiologiques de la stimulation du nerf vague : implication dans le traitement de la dépression résistante et optimisation des paramètres de stimulation

Manta, Stella
Fonte: Université de Montréal Publicador: Université de Montréal
Tipo: Thèse ou Mémoire numérique / Electronic Thesis or Dissertation
FR
Relevância na Pesquisa
36.37%
La dépression est une pathologie grave qui, malgré de multiples stratégies thérapeutiques, demeure résistante chez un tiers des patients. Les techniques de stimulation cérébrale sont devenues une alternative intéressante pour les patients résistants à diverses pharmacothérapies. La stimulation du nerf vague (SNV) a ainsi fait preuve de son efficacité en clinique et a récemment été approuvée comme traitement additif pour la dépression résistante. Cependant, les mécanismes d’action de la SNV en rapport avec la dépression n’ont été que peu étudiés. Cette thèse a donc eu comme premier objectif de caractériser l’impact de la SNV sur les différents systèmes monoaminergiques impliqués dans la pathophysiologie de la dépression, à savoir la sérotonine (5-HT), la noradrénaline (NA) et la dopamine (DA), grâce à l’utilisation de techniques électrophysiologiques et de la microdialyse in vivo chez le rat. Des études précliniques avaient déjà révélé qu’une heure de SNV augmente le taux de décharge des neurones NA du locus coeruleus, et que 14 jours de stimulation sont nécessaires pour observer un effet comparable sur les neurones 5-HT. Notre travail a démontré que la SNV modifie aussi le mode de décharge des neurones NA qui présente davantage de bouffées...

Impact d’une sieste sur plasticité cérébrale induite par stimulation magnétique transcrânienne

Sekerovic, Zoran
Fonte: Université de Montréal Publicador: Université de Montréal
Tipo: Thèse ou Mémoire numérique / Electronic Thesis or Dissertation
FR
Relevância na Pesquisa
36.34%
Chez l’humain, différents protocoles de stimulation magnétique transcrânienne répétée (SMTr) peuvent être utilisés afin de manipuler expérimentalement la plasticité cérébrale au niveau du cortex moteur primaire (M1). Ces techniques ont permis de mieux comprendre le rôle du sommeil dans la régulation de la plasticité cérébrale. Récemment, une étude a montré que lorsqu’une première session de stimulation SMTr au niveau de M1 est suivie d’une nuit de sommeil, l’induction subséquente de la plasticité par une deuxième session SMTr est augmentée. La présente étude a investigué si ce type de métaplasticité pouvait également bénéficier d’une sieste diurne. Quatorze sujets en santé ont reçu deux sessions de intermittent theta burst stimulation (iTBS) connue pour son effet facilitateur sur l’excitabilité corticale. Les sessions de stimulation étaient séparées par une sieste de 90 minutes ou par une période équivalente d’éveil. L’excitabilité corticale était quantifiée en terme d’amplitude des potentiels évoqués moteurs (PEM) mesurés avant et après chaque session de iTBS. Les résultats montrent que la iTBS n’est pas parvenue à augmenter de manière robuste l’amplitude des PEMs lors de la première session de stimulation. Lors de la deuxième session de stimulation...

Increased cortical excitability induced by transcranial DC and peripheral nerve stimulation

Uy, J.; Ridding, M.
Fonte: Elsevier Science BV Publicador: Elsevier Science BV
Tipo: Artigo de Revista Científica
Publicado em //2003 EN
Relevância na Pesquisa
36.36%
This study investigated the effect of short periods of simultaneous weak anodal direct current (DC) stimulation and peripheral ulnar nerve (ES) stimulation on corticospinal excitability. The experiments involved repeated testing of ten normal subjects with four different protocols: (1) No Stimulation; (2) DC only; (3) ES only; (4) DC plus ES. Motor evoked potentials (MEP) were recorded from the First Dorsal Interosseous (FDI); Abductor Digiti Minimi (ADM) and Flexor Carpi Ulnaris (FCU). The baseline MEP amplitude was compared with that obtained immediately after the first set of stimulation, after the second set of stimulation, 15 min post stimulation and 30 min after stimulation. No significant change was seen with the No Stimulation and ES Only protocols. FDI showed a significant change in the DC protocol after the second set of stimulation but the changes were not present 15 or 30 min after. The DC plus ES protocol showed FDI changes that were significant after the second set of stimulation with the elevations persisting when tested 15 and 30 min post intervention. These observations show that a period of anodal DC stimulation preceding a period of ulnar nerve stimulation resulted in significant and persistent elevations in cortical excitability.; J. Uy and M. C. Ridding; Copyright © 2003 Elsevier Science B.V. All rights reserved.

Suppression of motor evoked potentials in a hand muscle following prolonged painful stimulation

Svensson, P.; Miles, T.; McKay, D.; Ridding, M.
Fonte: W B Saunders Co Ltd Publicador: W B Saunders Co Ltd
Tipo: Artigo de Revista Científica
Publicado em //2003 EN
Relevância na Pesquisa
36.36%
Earlier investigations have shown that stimulation of peripheral afferent nerves induces prolonged changes in the excitability of the human motor cortex. The present study compared the effect of experimental pain and non-painful conditioning stimulation on motor evoked potentials (MEPs) elicited by transcranial magnetic stimulation (TMS) in the relaxed first dorsal interosseous (FDI) and flexor carpi ulnaris (FCU) muscles. The MEPs were measured in 10 healthy subjects, and stimulus-response curves were generated before and after each of four stimulation paradigms conducted in random order on separate occasions: (a) control; (b) "dual stimulation" consisting of electrical stimulation of the FDI motor point paired with TMS; (c) painful infusion of hypertonic saline in the FDI muscle; and (d) pain combined with dual stimulation. There were no significant changes in FDI MEPs following the control paradigm, and dual stimulation induced an increase in the FDI MEPs only inconsistently. In contrast, the painful stimulation and the combined pain and dual stimulation paradigms were followed by significant suppression of the FDI MEPs at higher stimulus intensities. No changes were observed in the FCU MEPs following the four paradigms. In two additional subjects...

Afferent stimulation facilitates performance on a novel motor task

McDonnell, M.; Ridding, M.
Fonte: Springer Publicador: Springer
Tipo: Artigo de Revista Científica
Publicado em //2006 EN
Relevância na Pesquisa
36.34%
Training on a motor task results in performance improvements that are accompanied by increases in motor cortex excitability. Moreover, periods of afferent stimulation result in increased motor cortex excitability. There is increasing evidence to suggest that raised motor cortical excitability may facilitate movement and learning. Here we examined whether a period of electrical stimulation of hand afferents (“associative stimulation”), known to increase motor cortex excitability, facilitated the performance of a complex sensorimotor task. Three groups of nine normal subjects participated in these studies. All subjects were trained on the grooved pegboard test (GPT). Training consisted of three blocks, each of five trials, of placing pegs as quickly as possible. The time to complete each block was recorded. One group of subjects had a 1-h period of associative stimulation prior to training on the GPT. A second group received non-associative stimulation (which does not change cortical excitability) of the same hand afferents while a third group received no stimulation prior to training. Motor evoked potentials (MEPs) were recorded from the first dorsal interosseous (FDI) and abductor digiti minimus (ADM) muscles both prior to and following stimulation and performance of the GPT. In contrast to non-associative stimulation...

Simultaneous application of slow-oscillation transcranial direct current stimulation and theta burst stimulation prolongs continuous theta burst stimulation-induced suppression of corticomotor excitability in humans

Doeltgen, S.; McAllister, S.; Ridding, M.
Fonte: Blackwell Science Ltd Publicador: Blackwell Science Ltd
Tipo: Artigo de Revista Científica
Publicado em //2012 EN
Relevância na Pesquisa
36.37%
The objective of this study was to assess whether the simultaneous application of slow-oscillation transcranial direct current stimulation enhances the neuroplastic response to transcranial magnetic theta burst stimulation. Motor evoked potential amplitude was assessed at baseline and at regular intervals up to 60 min following continuous theta burst stimulation, slow-oscillation transcranial direct current stimulation, and the simultaneous application of these paradigms. In addition, the electroencephalographic power spectra of slow and fast delta, and theta frequency bands recorded over the motor cortex were analyzed prior to and up to 5 min following each intervention. There was longer-lasting motor evoked potential suppression following the simultaneous application of continuous theta burst stimulation and slow-oscillation transcranial direct current stimulation compared with when continuous theta burst stimulation was applied alone. Slow-oscillation transcranial direct current stimulation applied alone did not modulate the motor evoked potential amplitude. No significant changes in spectral power were observed following slow-oscillation transcranial direct current stimulation. Simultaneous application of continuous theta burst stimulation and slow-oscillation transcranial direct current stimulation may provide an approach to prolong the induction of neuroplastic changes in motor cortical circuits by repetitive transcranial magnetic brain stimulation.; Sebastian H. Doeltgen...

Selbstregulation langsamer Hirnpotentiale (SCP) nach transkranieller Magnetstimulation (TMS); Modulation of slow cortical potentials by transcranial magnetic stimulation in humans

Schmidt, Konrad-Friedrich Reinhart
Fonte: Universidade de Tubinga Publicador: Universidade de Tubinga
Tipo: Dissertação
DE_DE
Relevância na Pesquisa
36.36%
Die Arbeiten von Birbaumer et al. haben in Vergangenheit hinreichend gezeigt, daß die langsamen Komponenten (SCPs) des Elektroenzephalogrammes bewußt kontrolliert werden können. Auf Grundlage dieses Effektes konnte eine Kommunikationshilfe für schwerstgelähmte Patienten konstruiert werden. Die transkranielle Magnetstimulation (TMS) ermöglicht eine schmerzlose und nichtinvasive Induktion von elektrischer Spannung in das menschliche Gehirn. Für wenige Millisekunden können durch ein starkes Magnetfeld ausgedehnte Kortexareale depolarisiert werden. Thema der vorliegenden Arbeit ist die Wechselwirkung von TMS mit der Selbstregulation langsamer Hirnpotentiale. Dreizehn gesunde Probanden und ein gelähmter Patient mit amyotropher Lateralsklerose (ALS) wurden durch visuelle Rückkoppelung trainiert, ihre SCPs selbst zu kontrollieren. Ihre Aufgabe bestand darin, auf ein Signal hin positive oder negative SCPs zu generieren. Ein Durchgang dauerte dabei 5 Sekunden und wurde bei Erfolg mit einer Bildschirmanzeige belohnt. Eine Sitzung bestand aus 70 Durchgängen, pro Proband wurden 27 Sitzungen durchgeführt. Die Potentiale wurden unipolar und zentral von der Elektrodenposition Cz abgeleitet. Neun der dreizehn Probanden erlernten die Selbstkontrolle über ihre langsamen Hirnpotentiale...

Towards closed-loop stimulation for stroke rehabilitation; Über die Umsetzung von adaptiver Stimulation zur Schlaganfallrehabilitation

Walter, Armin
Fonte: Universidade de Tubinga Publicador: Universidade de Tubinga
Tipo: Dissertação
EN
Relevância na Pesquisa
36.42%
The restoration of motor function to chronic stroke patients with a severe hand impairment is challenging, because no effective rehabilitation option exists. In recent years, brain-computer interfaces (BCIs) have shown potential to remedy this problem by decoding the patient’s movement intention from the brain signal and translating it into movements of an orthosis. In addition, brain stimulation has been investigated for the treatment of a variety of neurological conditions, including stroke. Combining both approaches into a closed-loop stimulation system has been proposed to increase the effectiveness of this treatment approach. However, this has not been put into practice before, therefore it is unknown, if closed-loop paradigms can be realized for stroke patients. In this thesis, closed-loop stimulation for stroke rehabilitation is studied for the first time. Two approaches for a closed-loop system are investigated: (i) Stimulation coupled to the movement intention of the patient and (ii) adaptation of stimulation parameters to control the shape of the evoked activity. The focus lies on 3 chronic stroke patients with a paralyzed left hand that had been implanted with epidural electrodes for electrocorticogram (ECoG) recording and electrical stimulation. To implement intention-dependent stimulation for the first approach...

Pathways involved in thalamic ventrobasal stimulation for pain relief: evidence against the hypothesis VB stimulation -> rostroventral medulla excitation -> dorsal horn inhibition

Vilela Filho,Osvaldo; Tasker,Ronald. R.
Fonte: Academia Brasileira de Neurologia - ABNEURO Publicador: Academia Brasileira de Neurologia - ABNEURO
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/09/1994 EN
Relevância na Pesquisa
36.35%
Despite its use for a long time, the way thalamic ventrobasal (VB) stimulation acts to produce pain relief is still unknown. One of the most accepted hypotheses, sponsored by Tsubokawa among others, proposes that VB stimulation excites raphespinal and reticulospinal neurons of the rostroventral medulla which in turn send respectively inhibitory serotonergic and noradrenergic axons through both dorsolateral funiculi (DLF) to the dorsal horn ( DH) nociceptive neurons; this pathway would be the same as is involved in periventricular-periaqueductal gray (PVG-PAG) stimulation induced inhibition of DH nociceptive neurons. This hypothesis implicates the necessity of DLF intactness; in fact, it was showed that section of bilateral DLF inhibits the response of DH nociceptive neurons to VB stimulation. If the above mentioned hypothesis is correct, one could expect that unilateral VB stimulation would produce bilateral pain relief, VB and PVG stimulation would be useful for treating the same modalities of pain and that in patients with central cord-based pain harboring complete cord transection, VB stimulation would not work at all. In order to check these possibilities, the patiens with central cord-based pain admitted to the Division of Neurosurgery...

Design of Electrodes for Efficient and Selective Electrical Stimulation of Nervous Tissue

Howell, Bryan
Fonte: Universidade Duke Publicador: Universidade Duke
Tipo: Dissertação
Publicado em //2015
Relevância na Pesquisa
36.35%

Modulation of neural activity with electrical stimulation is a widespread therapy for treating neurological disorders and diseases. Two notable applications that have had striking clinical success are deep brain stimulation (DBS) for the treatment of movement disorders (e.g., Parkinson's disease) and spinal cord stimulation (SCS) for the treatment of chronic low back and limb pain. In these therapies, the battery life of the stimulators is much less than the required duration of treatment, requiring patients to undergo repeated battery replacement surgeries, which are costly and obligate them to incur repeatedly the risks associated with surgery. Further, deviations in lead position of 2-3 mm can preclude some or all potential clinical benefits, and in some cases, generate side-effects by stimulation of non-target regions. Therefore, despite the success of DBS and SCS, their efficiency and ability to activate target neural elements over non-target elements, termed selectivity, are inadequate and need improvement.

We combined computational models of volume conduction in the brain and spine with cable models of neurons to design novel electrode configurations for efficient and selective electrical stimulation of nervous tissue. We measured the efficiency and selectivity of prototype electrode designs in vitro and in vivo. Stimulation efficiency was increased by increasing electrode area and/or perimeter...

Improved Efficacy and Efficiency of Non-Regular Temporal Patterns of Deep Brain Stimulation for Parkinson's Disease

Brocker, David
Fonte: Universidade Duke Publicador: Universidade Duke
Tipo: Dissertação
Publicado em //2015
Relevância na Pesquisa
36.39%

Deep brain stimulation (DBS) is an effective therapy for motor symptoms in Parkinson's disease (PD). DBS efficacy depends on the stimulation parameters, and the current gold standard therapy is high-frequency stimulation (>100 Hz) with constant interpulse intervals and short pulse widths (<210 μs). However, the temporal pattern of stimulation is a novel parameter dimension that has not been thoroughly explored. We used non-regular temporal patterns of DBS to pursue two goals: to better understand the mechanisms of DBS, and to increase the efficacy and efficiency of DBS for PD.

First, we designed high frequency patterns of non-regular stimulation with distinct features proposed to be important for efficacy and evaluated these patterns in human subjects with PD. Unexpectedly, some non-regular patterns of stimulation improved performance of an alternating finger-tapping task-a proxy for bradykinesia-compared to high frequency regular stimulation. Performance in the motor task was correlated with suppression of beta band power in a computational model of the basal ganglia suggesting a possible mechanism for effective stimulation patterns.

Inspired by the increased clinical efficacy of non-regular patterns of stimulation with high average frequencies...

Control of Bladder Function by Electrical Stimulation of Pudendal Afferents

Woock, John
Fonte: Universidade Duke Publicador: Universidade Duke
Tipo: Dissertação Formato: 6204937 bytes; application/pdf
Publicado em //2010 EN_US
Relevância na Pesquisa
36.38%

Spinal cord injury (SCI) and other neurological diseases and disorders can cause urinary dysfunction that can cause serious health problems and reduce an individual's quality of life. Current methods for treating urinary dysfunction have major limitations or provide inadequate improvement in urinary symptoms. Pudendal nerve stimulation is a potential means of restoring control of bladder function in persons with neurological disease or spinal cord injury. Bladder contraction and relaxation can be evoked by pudendal afferent stimulation, and peripheral pudendal afferent branches may be ideal targets for a bladder control neural prosthesis. This dissertation investigates control of bladder function by selective activation of pudendal afferents.

This study investigated the ability to improve both urinary continence and micturition by both direct and minimally-invasive electrical stimulation of selected pudendal afferents in α-chloralose anesthetized male cats. Direct stimulation of the pudendal afferents in the dorsal nerve of the penis (DNP), percutaneous DNP stimulation, and intraurethral stimulation were used to investigate the bladder response to selective activation of pudendal afferents. Finite element modeling of the cat lower urinary tract was used to investigate the impact of intraurethral stimulation location and intraurethral electrode configuration on activation of pudendal afferents. Also...