Selection of stimulus parameters for deep brain stimulation

Kuncel, Alexis M.; Grill, Warren M.

doi:10.1016/j.clinph.2004.05.031

Cited by 406 publications

(339 citation statements)

References 46 publications

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“…A good worst case estimate for a practical icEEG experimental arrangement may be represented by a conducting loop placed 1m from the magnet isocentre, and gradients of strength 69.3mT/m (40mT/m summed over xyz) that can be switched in impedance, 500Ω, [28] the corresponding rms current is 12mA. In practice such a low-impedance closed loop at gradient switching frequencies (~1kHz) will only be formed if a fault occurs at the amplifier, the electrode leads (termed tails) have a short-circuit, or the tail terminations are in electrical contact.…”

Section: Theoretical Estimation Of the Maximum Effect Size Due To Gramentioning

confidence: 99%

“…The induced surface charge density can be calculated by dividing the product of the voltage and pulse width by the product of the impedance and electrode surface area [28]. As an assessment of risk, using the estimated worst case induced voltage of 17V and assuming an approximately square pulse-shape, gradient switching time of 200μs, electrode contact-area 0.07cm 2 , and tissue impedance 500Ω, the estimated surface-charge density is 97μC/cm 2 , exceeding the limit (30μC/cm 2 ) necessary to cause stimulation and tissue damage.…”

Section: Theoretical Estimation Of the Maximum Effect Size Due To Gramentioning

confidence: 99%

“…This can be placed in the context of the recommended charge density limit for chronic therapeutic neuronal stimulation [28,[50][51] of 30 μC/cm 2 (where non-continuous this is the average over a pulse width) and cortical stimulation studies for seizure provocation: the recommended initial stimulation parameters are 2V, 0.5mA, 152ms pulse duration, 40 per second, 5 seconds [52]. These parameters exceed guidelines, which deliberately lie below the level required for stimulation.…”

Section: Appendix a Safety Guidelines -Currentsmentioning

confidence: 99%

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Feasibility of simultaneous intracranial EEG-fMRI in humans: A safety study

Carmichael¹,

Thornton

Rodionov³

et al. 2010

NeuroImage

111

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In epilepsy patients who have electrodes implanted in their brains as part of their presurgical assessment, simultaneous intracranial EEG and fMRI (icEEG-fMRI) may provide important localising information and improve understanding of the underlying neuropathology. However, patient safety during icEEG-fMRI has not been addressed.Here the potential health hazards associated with icEEG-fMRI were evaluated theoretically and the main risks identified as: mechanical forces on electrodes from transient magnetic effects, tissue heating due to interaction with the pulsed RF fields and tissue stimulation due to interactions with the switched magnetic gradient fields.These potential hazards were examined experimentally in-vitro on a Siemens 3 T Trio, 1.5 T Avanto and a GE 3 T Signa Excite scanner using a Brain Products MR compatible EEG system. No electrode flexion was observed. Temperature measurements demonstrated thatheating well above guideline limits can occur. However heating could be kept within safe limits (<1.0°C) by using a head transmit RF coil, ensuring EEG cable placement to exit the RF coil along its central z-axis, using specific EEG cable lengths and limiting MRI sequence specific absorption rates (SARs). We found that the risk of tissue damage due to RF-induced heating is low provided implant and scanner specific SAR limits are observed with a safety margin used to account for uncertainties (e.g. in scanner-reported SAR). The observed scanner gradientswitching induced current (0.08mA) and charge density (0.2μC/cm 2 ) were well within safety limits (0.5mA and 30μC/cm 2 , respectively).3

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Section: Theoretical Estimation Of the Maximum Effect Size Due To Gramentioning

confidence: 99%

Section: Theoretical Estimation Of the Maximum Effect Size Due To Gramentioning

confidence: 99%

Section: Appendix a Safety Guidelines -Currentsmentioning

confidence: 99%

See 1 more Smart Citation

Feasibility of simultaneous intracranial EEG-fMRI in humans: A safety study

Carmichael¹,

Thornton

Rodionov³

et al. 2010

NeuroImage

111

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“…First, the tuning of DBS systems could be significantly improved if we understood the mechanisms of DBS. 6,7 Several weeks after the surgical implantation, a clinician uses a radio-frequency programmer to set the stimulation parameters. Experienced clinicians are generally successful in quickly reducing the number of potentially successful parameter settings and in tuning DBS systems to treat visible motor symptoms that respond quickly to DBS.…”

Section: Introductionmentioning

confidence: 99%

Mechanisms of Deep Brain Stimulation in Movement Disorders as Revealed by Changes in Stimulus Frequency

2008

Self Cite

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Summary: Deep brain stimulation (DBS) is an established treatment for symptoms in movement disorders and is under investigation for symptom management in persons with psychiatric disorders and epilepsy. Nevertheless, there remains disagreement regarding the physiological mechanisms responsible for the actions of DBS, and this lack of understanding impedes both the design of DBS systems for treating novel diseases and the effective tuning of current DBS systems. Currently available data indicate that effective DBS overrides pathological bursts, low frequency oscillations, synchronization, and disrupted firing patterns present in movement disorders, and replaces them with more regularized firing. Although it is likely that the specific mechanism(s) by which DBS exerts its effects varies between diseases and target nuclei, the overriding of pathological activity appears to be ubiquitous. This review provides an overview of changes in motor symptoms with changes in DBS frequency and highlights parallels between the changes in motor symptoms and the changes in cellular activity that appear to underlie the motor symptoms.

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“…Several clinical studies have been conducted to determine the differential effects of various stimulation protocols on DBS outcome measures (Benabid et al, 1991;Holsheimer et al, 2000;Rizzone et al, 2001;Moro et al, 2002;O'Suilleabhain et al, 2003;Kuncel et al, 2006). And, multiple theoretical studies have calculated the voltage field generated by DBS (McIntyre and Thakor, 2002;Kuncel and Grill, 2004;McIntyre et al, 2004a;McIntyre et al, 2004b;Hemm et al, 2005;Wei and Grill, 2005;Astrom et al, 2006;Sotiropoulos and Steinmetz, 2007). However, we recently identified discrepancies between the idealized waveforms assumed in these previous studies, and the actual waveforms produced by clinical DBS devices (Butson and McIntyre, 2005).…”

Section: Introductionmentioning

confidence: 99%

Differences among implanted pulse generator waveforms cause variations in the neural response to deep brain stimulation

Butson

McIntyre

2007

Clinical Neurophysiology

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Objective-Two different Medtronic implantable pulse generator (IPG) models are currently used in clinical applications of deep brain stimulation (DBS): Soletra and Kinetra. The goal of this study was to evaluate and compare the stimulation waveforms produced by each IPG model. Methods-We recorded waveforms from a broad range of stimulation parameter settings in each IPG model, and compared them to idealized waveforms that adhered to the parameters specified in the programming device. We then used a previously published computational model to predict the neural response to the various stimulation waveforms.Results-The stimulation waveforms produced by the IPGs differed from the idealized waveforms assumed in previous theoretical and clinical studies, and the waveforms differed among the IPG models. These differences were greater at higher frequencies and longer pulse widths, and caused variations of up to 0.4 V in activation thresholds for model axons located 3 mm from the DBS electrode contact.Conclusions-The specific details of the stimulation waveform directly affect the neural response to DBS and should be accounted for in theoretical and experimental studies of DBS.Significance-While the clinical selection of DBS parameters is individualized to each patient based on behavioral outcomes, scientific analysis of stimulation parameter settings and clinical threshold measurements are subject to a previously unrecognized source of error unless the actual waveforms produced by the IPG are accounted for.

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Selection of stimulus parameters for deep brain stimulation

Cited by 406 publications

References 46 publications

Feasibility of simultaneous intracranial EEG-fMRI in humans: A safety study

Feasibility of simultaneous intracranial EEG-fMRI in humans: A safety study

Mechanisms of Deep Brain Stimulation in Movement Disorders as Revealed by Changes in Stimulus Frequency

Differences among implanted pulse generator waveforms cause variations in the neural response to deep brain stimulation

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