Dataset Information

Electric field measurement of two commercial active/sham coils for transcranial magnetic stimulation.

ABSTRACT: OBJECTIVE:Sham TMS coils isolate the ancillary effects of their active counterparts but typically induce low-strength electric fields (E-fields) in the brain, which could be biologically active. We measured the E-fields induced by two pairs of commonly-used commercial active/sham coils. APPROACH:E-field distributions of the active and sham configurations of the Magstim 70?mm AFC and MagVenture Cool-B65 A/P coils were measured over a 7 cm-radius, hemispherical grid approximating the cortical surface. Peak E-field strength was recorded over a range of pulse amplitudes. MAIN RESULTS:The Magstim and MagVenture shams induce peak E-fields corresponding to 25.3% and 7.72% of their respective active values. The MagVenture sham has an E-field distribution shaped like its active counterpart. The Magstim sham induces nearly zero E-field under the coil's center, and its peak E-field forms a diffuse oval 3-7?cm from the center. Electrical scalp stimulation paired with the MagVenture sham is estimated to increase the sham E-field in the brain up to 10%. SIGNIFICANCE:Different commercial shams induce different E-field strengths and distributions in the brain, which should be considered in interpreting outcomes of sham stimulation.

SUBMITTER: Smith JE

PROVIDER: S-EPMC6125221 | biostudies-literature | 2018 Oct

REPOSITORIES: biostudies-literature

ACCESS DATA

Publications

Electric field measurement of two commercial active/sham coils for transcranial magnetic stimulation.

Smith J Evan JE Peterchev Angel V AV

Journal of neural engineering 20180622 5

<h4>Objective</h4>Sham TMS coils isolate the ancillary effects of their active counterparts but typically induce low-strength electric fields (E-fields) in the brain, which could be biologically active. We measured the E-fields induced by two pairs of commonly-used commercial active/sham coils.<h4>Approach</h4>E-field distributions of the active and sham configurations of the Magstim 70 mm AFC and MagVenture Cool-B65 A/P coils were measured over a 7 cm-radius, hemispherical grid approximating th ...[more]

PMID: 29932429

Similar Datasets

Project description:ImportanceMajor depressive episodes in bipolar disorder are common and debilitating. Repetitive transcranial magnetic stimulation is well established in the treatment of major depressive disorder, and the intermittent theta burst stimulation (iTBS) protocol is replacing conventional protocols because of noninferiority and reduced delivery time. However, iTBS has not been adequately studied in bipolar disorder and, therefore, its efficacy is uncertain.ObjectiveTo determine whether iTBS to the left dorsolateral prefrontal cortex (LDLPFC) is safe and efficacious in the treatment of acute bipolar depression.Design, setting, and participantsThis study was a double-blind, 4-week, randomized clinical trial of iTBS targeting the LDLPFC. Two Canadian academic centers recruited patients between 2016 and 2020. Adults with bipolar disorder type I or type II experiencing an acute major depressive episode were eligible if they had not benefited from a first-line treatment for acute bipolar depression recommended by the Canadian Network for Mood and Anxiety Treatments and were currently treated with a mood stabilizer, an atypical antipsychotic, or their combination. Seventy-one participants were assessed for eligibility, and 37 were randomized to daily sham iTBS or active iTBS using a random number sequence, stratified according to current pharmacotherapy. Data analysis was performed from April to September 2020.InterventionsFour weeks of daily active iTBS (120% resting motor threshold) or sham iTBS to the LDLPFC. Nonresponders were eligible for 4 weeks of open-label iTBS.Main outcomes and measuresThe primary outcome was the change in score on the Montgomery-Asberg Depression Rating Scale from baseline to study end. Secondary outcomes included clinical response, remission, and treatment-emergent mania or hypomania.ResultsThe trial was terminated for futility after 37 participants (23 women [62%]; mean [SD] age, 43.86 [13.87] years; age range, 20-68 years) were randomized, 19 to sham iTBS and 18 to active iTBS. There were no significant differences in Montgomery-Asberg Depression Rating Scale score changes (least squares mean difference between groups, -1.36 [95% CI, -8.92 to 6.19; P = .91] in favor of sham iTBS), and rates of clinical response were low in both the double-blind phase (3 of 19 participants [15.8%] in the sham iTBS group and 3 of 18 participants [16.7%] in the active iTBS group) and open-label phase (5 of 21 participants [23.8%]). One active iTBS participant had a treatment emergent hypomania, and a second episode occurred during open-label treatment.Conclusions and relevanceiTBS targeting the LDLPFC is not efficacious in the treatment of acute bipolar depression in patients receiving antimanic or mood stabilizing agents. Additional research is required to understand how transcranial magnetic stimulation treatment protocols differ in efficacy between unipolar and bipolar depression.Trial registrationClinicalTrials.gov Identifier: NCT02749006.

Dataset Information

Electric field measurement of two commercial active/sham coils for transcranial magnetic stimulation.

Publications

Electric field measurement of two commercial active/sham coils for transcranial magnetic stimulation.

Similar Datasets

OmicsDI is part of the ELIXIR infrastructure

Tweets