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Results for “Deep Brain Stimulation”

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PubMed2000

The influence of pallidal deep brain stimulation on striatal dopaminergic metabolism in the rat.

Deep brain stimulation of the globus pallidus internus has been recently shown to alleviate parkinsonian symptoms and levodopa-induced dyskinesias. However, its exact mechanisms of action are unclear. Pallidal neurones are connected via various pathways to the dopaminergic nigrostriatal system. In the present study we investigated the hypothesis that deep brain stimulation of the entopeduncular nucleus (corresponds to the human internal pallidum) affects striatal dopaminergic metabolism in naive and 6-hydroxydopamine (6-OHDA) lesioned rats using microdialysis. Our results show that stimulation of the entopeduncular nucleus does not significantly affect striatal dopamine metabolism (of dopamine, 3, 4-dihdroxyphenylacetic acid and homovanillic acid) in naive and 6-OHDA-lesioned animals. They contrast with our previous observations that deep brain stimulation of the subthalamic nucleus increases striatal dopamine metabolism suggesting differential effects of these nuclei on striatal dopamine metabolism.

3,4-Dihydroxyphenylacetic Acid↗

PubMed2006

Patient-specific analysis of the volume of tissue activated during deep brain stimulation.

Despite the clinical success of deep brain stimulation (DBS) for the treatment of movement disorders, many questions remain about its effects on the nervous system. This study presents a methodology to predict the volume of tissue activated (VTA) by DBS on a patient-specific basis. Our goals were to identify the intersection between the VTA and surrounding anatomical structures and to compare activation of these structures with clinical outcomes. The model system consisted of three fundamental components: (1) a 3D anatomical model of the subcortical nuclei and DBS electrode position in the brain, each derived from magnetic resonance imaging (MRI); (2) a finite element model of the DBS electrode and electric field transmitted to the brain, with tissue conductivity properties derived from diffusion tensor MRI; (3) VTA prediction derived from the response of myelinated axons to the applied electric field, which is a function of the stimulation parameters (contact, impedance, voltage, pulse width, frequency). We used this model system to analyze the effects of subthalamic nucleus (STN) DBS in a patient with Parkinson's disease. Quantitative measurements of bradykinesia, rigidity, and corticospinal tract (CST) motor thresholds were evaluated over a range of stimulation parameter settings. Our model predictions showed good agreement with CST thresholds. Additionally, stimulation through electrode contacts that improved bradykinesia and rigidity generated VTAs that overlapped the zona incerta/fields of Forel (ZI/H2). Application of DBS technology to various neurological disorders has preceded scientific characterization of the volume of tissue directly affected by the stimulation. Synergistic integration of clinical analysis, neuroimaging, neuroanatomy, and neurostimulation modeling provides an opportunity to address wide ranging questions on the factors linked with the therapeutic benefits and side effects of DBS.

Deep Brain Stimulation↗

PubMed2005

Target-specific catecholamine elevation induced by anticonvulsant thalamic deep brain stimulation.

PURPOSE: Anterior thalamic nucleus (AN) deep brain stimulation (DBS) is effective in raising EEG and clonic seizure threshold in experimental models. Little is known about the specific properties of DBS that afford its anticonvulsant effect. We sought to test the hypothesis that experimental seizures and the anticonvulsant action of AN DBS alter the underlying regional neurochemistry of AN, specifically with facilitation of the serotonergic system to local electrical stimulation. METHODS: Halothane-anesthetized adult Sprague-Dawley male rats underwent stereotactically guided bilateral placement of bipolar stimulating steel electrodes and dialysis probes-guide cannulae in AN and posterior thalamus (PT), and placement of four epidural EEG screw electrodes 48 h before experiments. Both stimulated (AN DBS) and nonstimulated (NO DBS) animals (n=7 per group) were infused with i.v. pentylenetetrazol (PTZ, 5.5 mg/kg/min). Simultaneous thalamic and cortical EEG were recorded, and microdialysis samples were collected from AN and PT in 20-min epochs. AN stimulation was delivered (150 microA; 0.1-ms pulse duration) 40 min before and continued during PTZ infusion. RESULTS: Bilateral AN stimulation delayed the onset of EEG seizures compared with controls: 82+/-8 vs. 58+/-5 min (p=0.02). PTZ infusion alone, or together with stimulation, resulted in a steady increase in norepinephrine (NE), but not dopamine, at AN and PT sites (p<0.001). Although extracellular serotonin was measured at very low levels, the metabolite, 5-hydroxyindoleacetic acid (5-HIAA) increased selectively in AN after stimulation and during preconvulsant infusion of PTZ (p<0.001), returning to baseline after the first generalized seizure. CONCLUSIONS: These data suggest that PTZ and DBS together enhance the nonselective release of NE in thalamic nuclei while specifically stimulating AN-localized serotonin. Low serotonin levels at baseline and during STIM alone or PTZ infusion may indicate efficient reuptake systems for serotonin, with 5-HIAA serving as a surrogate marker for serotonergic activity. Modulation of the AN-specific serotonergic activity may be critical in altering PTZ seizure threshold and be an important neurotransmitter system underlying the efficacy of AN DBS.

Animals↗

PubMed2006

Fulfilment of patients' goals after thalamic deep brain stimulation: a follow-up study.

Deep brain stimulation (DBS) in the ventrolateral thalamus (VIM) is shown to reduce tremor in essential tremor (ET) and Parkinson's disease (PD). Our aim was to evaluate the results of VIM DBS from the patients' perspective. Sixteen consecutively included patients (8 ET and 8 PD) described their own outcome goals preoperatively and evaluated the fulfillment 1, 6 and 12 months postoperatively. We conclude that the patients could do specific activities that are of importance to them such as eating, drinking and socializing, and perceived either partial or total fulfillment of their goals.

Adult↗

PubMed2005

Deep brain stimulation for movement disorders and pain.

Deep brain stimulation (DBS) is an expanding field within neurosurgery. With many neurosurgeons performing relatively small numbers of these procedures, detailed descriptions of the technical aspects and nuances of DBS may be worthwhile. We describe our technique for DBS, based on over 300 procedures. This methodology continues to evolve and is refined according to our own experience, our observations of others, technological innovations, and information derived from the neurosurgical literature. The indications for DBS in our service are outlined, the anatomical targets described, and the anaesthetic and surgical aspects detailed.

Deep Brain Stimulation↗

PubMed2005

Cross validation of experts versus registration methods for target localization in deep brain stimulation.

In the last five years, Deep Brain Stimulation (DBS) has become the most popular and effective surgical technique for the treatent of Parkinson's disease (PD). The Subthalamic Nucleus (STN) is the usual target involved when applying DBS. Unfortunately, the STN is in general not visible in common medical imaging modalities. Therefore, atlas-based segmentation is commonly considered to locate it in the images. In this paper, we propose a scheme that allows both, to perform a comparison between different registration algorithms and to evaluate their ability to locate the STN automatically. Using this scheme we can evaluate the expert variability against the error of the algorithms and we demonstrate that automatic STN location is possible and as accurate as the methods currently used.

Deep Brain Stimulation↗

PubMed2006

Computerized posturography balance assessment of patients with bilateral ventralis intermedius nuclei deep brain stimulation.

Bilateral ventralis intermedius nuclei (Vim) deep brain stimulation (DBS) improves tremor in patients with both essential tremor (ET) and Parkinson's disease (PD). In each condition, patients have individually noted both subjective improvement and worsening in balance. Computerized posturography (CP) is able to quantify some aspects of balance. Twenty-one patients (8 with PD and 13 with ET) with bilateral Vim DBS were recruited to undergo randomized-order identical CP testing (EquiTest system) while their DBS devices were both activated and deactivated. One PD patient could not complete any OFF assessment and is not included. Three PD patients could not tolerate portions of the OFF testing. Overall, sensory organization testing was improved by DBS activation in conditions that involved quiet standing with eyes open with no motion of the support surface, or with sway-referenced support surface motion, but worsened during quiet standing with eyes closed only in ET patients. Falls lessened with activation in ET patients. Motor control testing was not changed. Bilateral Vim DBS activation mostly improved balance, but may modestly worsen other specific features.

Aged↗

PubMed2006

Posttraumatic peripherally-induced dystonia and multifocal deep brain stimulation: case report.

OBJECTIVE: We report on the effect of multifocal deep brain stimulation for the treatment of posttraumatic peripherally-induced dystonia. CLINICAL PRESENTATION: A 34-year-old woman presented with an 8-year history of painful tonic dystonia starting in her left leg after injury of the third metatarsal bone. She did not benefit from right-sided pallidal stimulation by an electrode misplaced in the globus pallidus externus in another hospital. INTERVENTION: Quadripolar deep brain stimulation electrodes were placed in the globus pallidus internus and the ventrolateral thalamus by computed tomographic-guided stereotactic surgery and microelectrode recording contralateral to the side of dystonia. The Burke-Fahn-Marsden motor score of 34 did not improve with chronic pallidal or thalamic stimulation. CONCLUSION: Although deep brain stimulation is received with great enthusiasm, it is important to identify its limitations in certain subtypes of dystonia.

Adult↗

PubMed2002

Deep brain stimulation for dystonia: patient selection and evaluation.

Deep brain stimulation (DBS) for dystonia still needs to be considered investigational, because there are no controlled studies for this indication, the optimal target point is uncertain, and long-term effects are unknown. The striking improvement of levodopa-induced dyskinesias in Parkinson's disease by deep brain stimulation of the internal pallidum has encouraged the use of this therapy for generalized and severe segmental dystonia in children and adults. Single case and small cohort studies have reported impressive efficacy of pallidal DBS in patients with primary dystonia, especially DYT1 mutation carriers, but results in secondary dystonia are less conclusive. This article discusses the different factors influencing patient selection for surgical treatment and describes standardized methods and the caveats for clinical documentation of treatment results in dystonia.

Clinical Protocols↗

PubMed2005

Deep brain stimulation for pain relief: a meta-analysis.

Deep brain stimulation (DBS) has been used to treat intractable pain for over 50 years. Variations in targets and surgical technique complicate the interpretation of many studies. To better understand its efficacy, we performed a meta-analysis of DBS for pain relief. MEDLINE (1966 to February 2003) and EMBASE (1980 to January 2003) databases were searched using key words deep brain stimulation, sensory thalamus, periventricular gray and pain. Inclusion criteria were based on patient characteristics and protocol clarity. Six studies (between 1977-1997) fitting the criteria were identified. Stimulation sites included the periventricular/periaqueductal grey matter (PVG/PAG), internal capsule (IC), and sensory thalamus (ST). The long-term pain alleviation rate was highest with DBS of the PVG/PAG (79%), or the PVG/PAG plus sensory thalamus/internal capsule (87%). Stimulation of the sensory thalamus alone was less effective (58% long-term success) (p < 0.05). DBS was more effective for nociceptive than deafferentation pain (63% vs 47% long-term success; p < 0.01). Long-term success was attained in over 80% of patients with intractable low back pain (failed back surgery) following successful trial stimulation. Trial stimulation was successful in approximately 50% of those with post-stroke pain, and 58% of patients permanently implanted achieved ongoing pain relief. Higher rates of success were seen with phantom limb pain and neuropathies. We conclude that DBS is frequently effective when used in well-selected patients. Neuroimaging and neuromodulation technology advances complicate the application of these results to modern practice. Ongoing investigations should shed further light on this complex clinical conundrum.

Animals↗

PubMed2000

Intraoperative test stimulation with a modified implantable pulse generator in deep brain stimulation.

A modified implantable pulse generator (MIPG) for intraoperative test stimulation in chronic deep brain stimulation is described. The MIPG can be used for bipolar stimulation with quadripolar electrodes. The device is programmed and controlled with a standard console programmer. It can also be used for postoperative test stimulation with externalized electrodes. In our experience, the MIPG has several advantages as compared to the screener that is usually used.

Brain↗

PubMed2004

Selection of stimulus parameters for deep brain stimulation.

OBJECTIVE: To provide an analysis of stimulation parameters for deep brain stimulation (DBS). METHODS: Synthesis of theoretical and empirical findings is used to provide guidance for the selection of stimulus parameters. Finite element modeling is used to investigate the effects of contact location and electrode geometry on the electric field, and to estimate the effects of current density distribution on the limit for non-damaging stimulation. RESULTS: Anatomical targeting of DBS electrodes is complicated by the uncertainty of which neural elements are targeted and differences in the electric field distribution in fiber tracts and nuclei. Electrical targeting by selection of electrode geometry and stimulus waveform can alter the distribution of the electric field and control neural activation. The recommended charge density limit for DBS represents a liberal estimate for non-damaging stimulation. Short duration stimulus pulses reduce charge injection and increase the therapeutic window between therapeutic effects and side effects. CONCLUSIONS: There are several challenges to developing rational methods of selecting stimulus parameters including a large number of degrees of freedom, the unknown effects of stimulation, and the complexity of the responses. SIGNIFICANCE: Understanding the fundamentals of electrical stimulation of the nervous system enables rational selection of stimulus parameters.

Brain↗

PubMedDate not supplied

Deep brain stimulation for psychiatric disorders.

Over the last decade, deep brain stimulation (DBS) has revolutionized the practice of neurosurgery, particularly in the realm of movement disorders. It is no surprise that DBS is now being studied in the treatment of refractory psychiatric disease. Deep brain stimulation has inherent advantages over previous lesioning procedures. It is fully reversible, and stimulation can be adjusted according to a patient's changing symptoms and disease progression. Coupled with the fact that the stimulation can generally be turned on or off without the patient's awareness, DBS provides a unique opportunity for double-blinding studies. To undertake DBS for psychiatric conditions, appropriate surgical targets must be chosen. What is most strongly supported is the role of cortico-striato-thalamocortical (CSTC) loops in the pathophysiology of psychiatric symptoms. Recent functional imaging studies have consistently found evidence that corroborate this model of psychiatric symptom pathogenesis. Based on the psychiatric and cognitive effects seen in recent movement disorder surgery, it is apparent that modulation of neural systems subserving psychiatric phenomenon can be accomplished by DBS. The few published studies on DBS for obsessive-compulsive disorder (OCD) suggest that this can be done safely. While efficacy data are still uncertain, initial data are promising.

Bipolar Disorder↗

PubMedDate not supplied

Deep brain stimulation for the treatment of Parkinson's disease.

Deep brain stimulation (DBS) is increasingly accepted as an adjunct therapy for Parkinson's disease (PD). It is considered a surgical treatment alternative for patients with intractable tremor or for those patients who are affected by long-term complications of levodopa therapy such as motor fluctuations and severe dyskinesias. Thalamic stimulation in the ventral intermediate nucleus (Vim) leads to a marked reduction of contralateral tremor but has no beneficial effect on other symptoms of Parkinson's disease. The subthalamic nucleus (STN) and the internal segment of the globus pallidus (GPi) are targeted for the treatment of advanced Parkinson's disease. Several studies have proven the efficacy of STN-DBS and GPi-DBS in alleviating off motor symptoms and dyskinesias. Sub-thalamic nucleus deep brain stimulation is currently considered superior to GPi-DBS because the antiakinetic effect seems to be more pronounced, allows a more marked reduction of antiparkinsonian medication, and requires less stimulation energy. More recently, however, a number of reports on possible psychiatric and behavioral side effects of STN-DBS have been a matter of concern. Given the chronic nature of PD and the noncurative approach of DBS, both targets will need to be reevaluated on the basis of their long-term efficacy and their impact on quality of life. Despite the rapidly increasing numbers of DBS procedures, surprisingly few controlled clinical trials are available that address important clinical issues such as: When should DBS be applied during the course of disease? Which patients should be selected? Which target should be considered? Which guidelines should be followed during postoperative care? Here is summarized the available evidence on DBS as a therapeutic tool for the treatment of Parkinson's disease and the current state of debate on open issues.

Antiparkinson Agents↗

PubMed2002

Results of deep brain stimulation for dystonia: a critical reappraisal.

Deep brain stimulation for severe dystonia is still in the very first stage of development. Only single case reports or small case series have been reported to date. Best results have been obtained with pallidal stimulation in patients with primary generalised dystonia, especially in DYT1 mutation carriers. In secondary dystonia, conflicting results were reported. However, there is today enough promising evidence for a striking efficacy of pallidal stimulation in dystonia, supporting the need for further investigations in the field, with collaborative projects (regarding to the limited number of eligible patients); double-blind studies, including a consensus about surgical method; and a precise anatomic analysis of the position of the electrode. A careful assessment of the efficacy by using improved clinical scale is also warranted.

Dystonia↗

PubMed2003

Is the target for thalamic deep brain stimulation the same as for thalamotomy?

Deep brain stimulation (DBS) has virtually replaced thalamotomy for the treatment of essential tremor. It is thought that the site for DBS is the same as the optimal lesion site; however, this match has not been investigated previously. We sought to determine whether the location of thalamic DBS matched the site at which thalamotomy would be performed. Eleven patients who had detailed microelectrode recording and stimulation for placement of DBS electrodes and subsequent successful tremor control were analysed. An experienced surgeon, blinded to outcome and final electrode position, selected the ideal thalamotomy site based on the reconstructed maps obtained intraoperatively. When the site of long-term clinically used DBS and theoretical thalamotomy location was calculated in three-dimensional space and compared for each of the x, y, and z axes in stereotactic space, there was no significant difference in the mediolateral location of DBS and theoretical lesion site. There was also no difference between the theoretical lesion site and the placement of the tip of the electrode; however, the active electrodes used for chronic stimulation were significantly more anterior (P = 0.005) and dorsal (P = 0.034) to the ideal thalamotomy target. This mismatch may reflect the compromise required between adverse and beneficial effects with chronic stimulation, but it also suggests different mechanisms of effect of DBS and thalamotomy.

Adult↗

PubMed1997

Deep brain stimulation and thalamotomy for tremor compared.

Deep brain stimulation (DBS) and thalamotomy are both capable of abolishing tremor. However, no technique is perfect and if thalamotomy proves inadequate so that tremor recurs, presumably because of suboptimal lesion location, the only option is to repeat the thalamotomy. With DBS all that has been necessary to date is to change the parameters of stimulation. Similarly with complications such as the "cerebellar" ones and paraesthesiae. If these occur after thalamotomy one can only wait and hope that they will subside and they do not always do so. With DBS, changing the parameters in the authors' patients has so far been successful in eliminating them. DBS, like thalamotomy is very effective for controlling tremor in Parkinson's disease (PD) and essential tremor (ET) and for improving dexterity in ET, but both techniques are less useful for the control of dopa dyskinesia, Parkinsonian rigidity, or impaired dexterity in PD, though DBS may be better than thalamotomy for the latter condition. On the other hand, both DBS and thalamotomy are very effective in improving dexterity in PD and ET may depend upon the fact that in PD bradykinesia is a major component, whereas in ET only the tremor is. The advantages of DBS over thalamotomy have to be weighed against the peculiar risks of DBS and of course, its cost.

Adult↗

PubMed2004

Uncovering the mechanism(s) of action of deep brain stimulation: activation, inhibition, or both.

High-frequency deep brain stimulation (DBS) of the thalamus or basal ganglia represents an effective clinical technique for the treatment of several medically refractory movement disorders. However, understanding of the mechanisms responsible for the therapeutic action of DBS remains elusive. The goal of this review is to address our present knowledge of the effects of high-frequency stimulation within the central nervous system and comment on the functional implications of this knowledge for uncovering the mechanism(s) of DBS. Four general hypotheses have been developed to explain the mechanism(s) of DBS: depolarization blockade, synaptic inhibition, synaptic depression, and stimulation-induced modulation of pathological network activity. Using the results from functional imaging, neurochemistry, neural recording, and neural modeling experiments we address the general hypotheses and attempt to reconcile what have been considered conflicting results from these different research modalities. Our analysis suggests stimulation-induced modulation of pathological network activity represents the most likely mechanism of DBS; however, several open questions remain to explicitly link the effects of DBS with therapeutic outcomes.

Animals↗