P275 Clinical trial: EEG alpha real-time phase-triggered TMS to modulate left vs. right DLPFC activity for the treatment of depression

• Published in: Clinical neurophysiology 2017-03, Vol.128 (3), p.e145-e145
• Main Authors: Schreitmüller, B, Müller-Dahlhaus, F, Soekadar, S, Fallgatter, A.J, Ziemann, U
• Format: Article
• Language: English
• Subjects: Neurology
• ISSN: 1388-2457; 1872-8952
• DOI: 10.1016/j.clinph.2016.10.384

TMS is an effective neuromodulatory tool in the treatment of stroke and depression. In the case of stroke, an imbalance between the affected and unaffected hemisphere in the M1-M1 interhemispheric motor network is presumed; in the case of depression, left dorsolateral prefrontal cortex (DLPF) is presumed underactive vs. right. Whereas motor network excitability can be assessed with hand muscle contractions, no such “direct” readout is available for frontal networks. Furthermore, classical rTMS protocols suffer from large variability, requiring large numbers of patients to demonstrate a (small) group effect. An ongoing clinical pilot trial addresses this conundrum using a novel brain-state triggered TMS protocol previously shown to be more effective and reliable at bi-directionally modulating cortical excitability in the motor system than classical protocols. Can we translate the basic research results from the motor network to a clinical application involving the prefrontal network? 18 patients with depression receive different interventions on different days. The main intervention consists of 200 brain-state triggered triple-pulses (inter-pulse-interval 10 ms) applied over left DLPFC triggered by the negative peak phase of local ongoing 10 Hz oscillations (to increase excitability) or on the right DLPFC during the positive peak phase (to decrease excitability), with a sham coil on the respective other side. There are two control conditions consisting of the offline replay of the same stimulus sequence and a classical TBS protocol (continuous over right DLPFC, intermittent over left). Resting-state EEG, spectral power ratio, TMS evoked EEG potentials (from both right and left DLPFC, randomized interleaved, using a two-coil set-up), before and at multiple times after the intervention are recorded, as well as a depression inventory. Neuronavigation with individual MRI anatomy is used. We demonstrate the applicability of local brain network state triggered therapeutic TMS protocols to modulate cortical excitability therapeutically and quantify suitable neurophysiological markers (interhemispheric spectral power, left vs. right prefrontal network TMS evoked EEG potentials) to track effectiveness in a network where direct readouts are not available.