Test–retest reliability of a stimulation‐locked evoked response to deep brain stimulation in subcallosal cingulate for treatment resistant depression

Abstract

Deep brain stimulation (DBS) to the subcallosal cingulate cortex (SCC) is an emerging therapy for treatment resistant depression. Precision targeting of specific white matter fibers is now central to the model of SCC DBS treatment efficacy. A method to confirm SCC DBS target engagement is needed to reduce procedural variance across treatment providers and to optimize DBS parameters for individual patients. We examined the reliability of a novel cortical evoked response that is time-locked to a 2 Hz DBS pulse and shows the propagation of signal from the DBS target. The evoked response was detected in four individuals as a stereotyped series of components within 150 ms of a 6 V DBS pulse, each showing coherent topography on the head surface. Test-retest reliability across four repeated measures over 14 months met or exceeded standards for valid test construction in three of four patients. Several observations in this pilot sample demonstrate the prospective utility of this method to confirm surgical target engagement and instruct parameter selection. The topography of an orbital frontal component on the head surface showed specificity for patterns of forceps minor activation, which may provide a means to confirm DBS location with respect to key white matter structures. A divergent cortical response to unilateral stimulation of left (vs. right) hemisphere underscores the need for feedback acuity on the level of a single electrode, despite bilateral presentation of therapeutic stimulation. Results demonstrate viability of this method to explore patient-specific cortical responsivity to DBS for brain-circuit pathologies.

Proceedings of the Sixth Deep Brain Stimulation Think Tank Modulation of Brain Networks and Application of Advanced Neuroimaging, Neurophysiology, and Optogenetics

“…These results indicated that it was feasible to obtain feedback on cortical responsivity by employing a stimulation evoked potential, which can be used as a signal of optimal targeting and test–retest reliability over time. This study indicated that the p40 feature may be an activation of the forceps minor, which was consistent with previous data that linked stimulation evoked response to white matter activation (Waters et al, 2018).…”

Quantifying the axonal pathways directly stimulated in therapeutic subcallosal cingulate deep brain stimulation

“…Nonetheless, indirect methods are possible. Electroencephalograms of cortical responses generated by the applied stimulus in DBS (Kibleur et al, ; Waters et al, ), and local field potentials recorded with the inactive electrodes (Smart et al, ), represent excellent opportunities for DBS biophysicists and electrophysiologists to begin to converge upon analyses that would be mutually beneficial.…”

From bed to bench side: Reverse translation to optimize neuromodulation for mood disorders

“…Interestingly, use of this implantation strategy has further allowed intraoperative and laboratory testing of behavioral and electrophysiological change with acute stimulation at the optimized target (6,(28)(29)(30). While intraoperative stimulation at the optimized target may explain the observed acute behavioral effects and postoperative improvement and carryover even in the absence of active stimulation ( Fig.…”

“…2D). One interpretation of the slow time course is that the therapeutic effects of DBS may occur in different stages with distinct mechanisms, some rapid and some slow (6,(28)(29)(30).…”