Comparison of the Long-Term Effect of Positioning the Cathode in tDCS in Tinnitus Patients.
Front. Aging Neurosci. 2017, July; 9(217) doi: 10.3389/fnagi.2017.00217 Download PDF: Comparing long-term effect
Sarah Rabau, Giriraj S. Shekhawat, Mohamed Aboseria, Daniel Griepp, Vincent Van Rompaey, Marom Bikson6 and Paul Van de Heyning.
Objective: Transcranial direct current stimulation (tDCS) is one of the methods described in the literature to decrease the perceived loudness and distress caused by tinnitus. However, the main effect is not clear and the number of responders to the treatment is variable. The objective of the present study was to investigate the effect of the placement of the cathode on the outcome measurements.
Methods: Patients considered for the trial were chronic non-pulsatile tinnitus patients with complaints for more than 3 months and a Tinnitus Functional Index (TFI) score that exceeded 25. The anode was placed on the right dorsolateral prefrontal cortex (DLPFC). In the first group—“bifrontal”—the cathode was placed on the left DLPFC, while in the second group—“shoulder”—the cathode was placed on the shoulder. Each patient received two sessions of tDCS weekly and eight sessions in total. Evaluations took place on the first visit for an ENT consultation, at the start of therapy, after eight sessions of tDCS and at the follow-up visit, which took place 84 days after the start of the therapy. Subjective outcome measures such as TFI, Visual Analog Scales (VAS) for loudness and percentage of consciousness of tinnitus were administered in every patient.
Results: There was no difference in the results for tinnitus loudness and the distress experienced between the placement of the cathode on the left DLPFC or on the shoulder. In addition, no statistically significant overall effect was found between the four test points. However, up to 39.1% of the patients experienced a decrease in loudness, measured by the VAS for loudness. Moreover, 72% of those in the bifrontal group, but only 46.2% of those in the shoulder group reported some improvement in distress.
Conclusion: While some improvement was noted, this was not statistically significant. Both electrode placements stimulated the right side of the hippocampus, which could be responsible for the effect found in both groups. Further research should rule out the placebo effect and investigate alternative electrode positions.
Neuromodulation: Technology at the Neural Interface, Clinical Research
Download PDF: Ezquerro_et_al-2017-Neuromodulation-_Technology_at_the_Neural_Interface
The Influence of Skin Redness on Blinding in Transcranial Direct Current Stimulation Studies: A Crossover Trial
Fernando Ezquerro, Adriano H. Moffa, Marom Bikson, Niranjan Khadka, Luana V. M. Aparicio, Bernardo de Sampaio-Junior, Felipe Fregni, Isabela M. Bensenor, Paulo A. Lotufo, Alexandre Costa Pereira, Andre R. Brunoni
To evaluate whether and to which extent skin redness (erythema) affects investigator blinding in transcranial direct current stimulation (tDCS) trials.
Material and Methods
Twenty-six volunteers received sham and active tDCS, which was applied with saline-soaked sponges of different thicknesses. High-resolution skin images, taken before and 5, 15, and 30 min after stimulation, were randomized and presented to experienced raters who evaluated erythema intensity and judged on the likelihood of stimulation condition (sham vs. active). In addition, semi-automated image processing generated probability heatmaps and surface area coverage of erythema. Adverse events were also collected.
Erythema was present, but less intense in sham compared to active groups. Erythema intensity was inversely and directly associated to correct sham and active stimulation group allocation, respectively. Our image analyses found that erythema also occurs after sham and its distribution is homogenous below electrodes. Tingling frequency was higher using thin compared to thick sponges, whereas erythema was more intense under thick sponges.
Optimal investigator blinding is achieved when erythema after tDCS is mild. Erythema distribution under the electrode is patchy, occurs after sham tDCS and varies according to sponge thickness. We discuss methods to address skin erythema-related tDCS unblinding.
Full PDF: Erythema and tDCS
Congratulation to Belen, Asif, and Natalie
Dr. Marom Bikson lectures on “The Promise and Pitfalls of tDCS” at the Department of Clinical Neuroscience, University of Calgary, Jun 30, 2017
Download the slide: 2017_Calgary
2017 Brain Stimulation and Imaging Meeting, Vancouver Canada, June 23-24
Meeting website link
June 24: 1:45 PM
Lucas Parra, Professor of Biomedical Engineering, The City College of the City University of New York Center for Discovery and Innovation, New York, NY, USA
TITLE: CELLULAR MECHANISMS OF TRANSCRANIAL ELECTRICAL STIMULATION
Watch excerpts form the talk here and here
June 24: 2:15 PM
Marom Bikson, Professor of Biomedical Engineering at The City College of New York (CCNY) of the City University of New York (CUNY) and co-Director of the Neural Engineering Group at the New York Center for Biomedical Engineering
TITLE: THE PROBLEM WITH CONCURRENT EEG AND TDCS
Download Bikson slides: BrainStim2017_final
Friday 6/23 at 3 pm in CDI 3rd floor conference room (3.352)
Laurent Koessler from CNRS and Lorraine University will be speaking
Title: Brain source detection and localization using multi-scale EEG recording.
Abstract: In drug-resistant epilepsy surgery investigations, epileptogenic zone and brain functional areas localization are required. This localization relies on scalp and intracerebral EEG recordings. In Nancy (France) I developed a program concerning simultaneous scalp and intracerebral EEG recordings. Using this methodological approach, 1) in vivo human brain tissue conductivities can be estimated, 2) relationship from brain sources to scalp EEG correlates can be studied and 3) non invasive electrical source localization can be validated.
Tomorrow June 21st at 2pm in CDI 3rd floor conference room (3.352)
Bashar Badran from the Medical Universty of South Carolina and University of New Mexico will be speaking
Title: Development, optimization, and neurophysiological effects of transcutaneous auricular vagus nerve stimulation (taVNS)
Abstract: taVNS is an emerging new form of neuromodulation involving transcutaneous electrical stimulation of the auricular branch of the vagus nerve. Still in its infancy and showing much clinical promise, the optimal human stimulation parameters and direct brain effects are undetermined. This lecture will present the findings of two important studies that aim to solve the taVNS problem of infinite parametric solutions. The first, a taVNS parametric study exploring 9 different combinations of pulse width and frequency and their activation of the vagal tone as measured by physiological recordings. The second is a novel multi-modal imaging study that establishes concurrent taVNS/fMRI and explores the direct brain effect of taVNS on the human brain’s BOLD response. These findings aim to establish an aim and direction of the optimal taVNS parameters to guide future trials.
Neuroimage. 2017 May 31;157:69-80. doi: 10.1016/j.neuroimage.2017.05.059.
Optimal use of EEG recordings to target active brain areas with transcranial electrical stimulation.
Dmochowski JP, Koessler L, Norcia AM, Bikson M, Parra LC.
Full paper: OptimalUseEEG_2016
Abstract: To demonstrate causal relationships between brain and behavior, investigators would like to guide brain stimulation using measurements of neural activity. Particularly promising in this context are electroencephalography (EEG) and transcranial electrical stimulation (TES), as they are linked by a reciprocity principle which, despite being known for decades, has not led to a formalism for relating EEG recordings to optimal stimulation parameters. Here we derive a closed-form expression for the TES configuration that optimally stimulates (i.e., targets) the sources of recorded EEG, without making assumptions about source location or distribution. We also derive a duality between TES targeting and EEG source localization, and demonstrate that in cases where source localization fails, so does the proposed targeting. Numerical simulations with multiple head models confirm these theoretical predictions and quantify the achieved stimulation in terms of focality and intensity. We show that constraining the stimulation currents automatically selects optimal montages that involve only a few (4-7) electrodes, with only incremental loss in performance when targeting focal activations. The proposed technique allows brain scientists and clinicians to rationally target the sources of observed EEG and thus overcomes a major obstacle to the realization of individualized or closed-loop brain stimulation.