Changes in the electrocorticogram after implantation of intracranial electrodes in humans: The implant effect. Issue 3 (March 2018)

• Record Type: Journal Article
• Authors: Sun, Felice T.; Arcot Desai, Sharanya; Tcheng, Thomas K.; Morrell, Martha J.
• Is Part Of: Clinical neurophysiology. Volume 129:Issue 3(2018:Mar.)
• Page Start: 676
• Page End: 686
• Publication Date: 2018-03
• Subjects: Implant effect -- ECoG -- Intracranial monitoring -- Responsive stimulation -- Epilepsy; DBS deep brain stimulation -- ECoG electrocorticographic -- Hz hertz -- ms milliseconds; Neurophysiology -- Periodicals; Electroencephalography -- Periodicals; Electromyography -- Periodicals; Neurology -- Periodicals; 612.8
• DOI: 10.1016/j.clinph.2017.10.036
• Languages: English
• ISSNs: 1388-2457

Abstract

Highlights: First-of-kind 2-year ECoG data from 121 patients treated with responsive cortical stimulation. Cortical spectral power and spike rate were not stable until 5 months after electrode implantation. Duration of ECoG changes similar to transient seizure reductions seen after electrode implantation. Abstract: Objective: Subacute and long-term electrocorticographic (ECoG) changes in ambulatory patients with depth and cortical strip electrodes were evaluated in order to determine the length of the implant effect. Methods: ECoG records were assessed in patients with medically intractable epilepsy who had depth and/or strip leads implanted in order to be treated with brain-responsive stimulation. Changes in total spectral power, band-limited spectral power, and spike rate were assessed. Results: 121 patients participating in trials of the RNS® System had a total of 93994 ECoG records analyzed. Significant changes in total spectral power occurred from the first to second months after implantation, involving 55% of all ECoG channels (68% of strip and 47% of depth lead channels). Significant, but less pronounced, changes continued over the 2nd to 5th post-implant months, after which total power became more stable. Similar patterns of changes were observed within frequency bands and spike rate. Conclusions: ECoG spectral power and spike rates are not stable in the first 5 months after implantation, presumably due to neurophysiological and electrode-tissue interface changes. Significance: ECoG data collected in the first 5 months after implantation of intracranial electrodes may not be fully representative of chronic cortical electrophysiology.