Authors :
Presenting Author: Paul Park, MD – Yale University
Tuan Bui, BS – Yale University
Imran Quraishi, MD, PhD – Yale School of Medicine
Hal Blumenfeld, MD, PhD – Yale University
Aline Herlopian, MD – Yale
Rationale:
The Percept® deep brain stimulation (DBS) model records thalamic local field potentials (LFP) in patients with refractory epilepsy. The electrophysiological characteristic of these thalamocortical EEG signals is poorly defined. We characterize these thalamic EEG signals, thalamocorticograms, extracted from the DBS livestreamed recordings of LFP.
Methods:
24 patients (median age: 25.5 years, range 6-58 years; median follow-up 38 months, range 6 months to 5 years) with Percept® DBS between 2019-2025 were studied at Yale Comprehensive Epilepsy Center. We excluded patients with older DBS ® models lacking the capability to record and livestream thalamic LFP. We stratified our patients into those with depth electrodes targeting the anterior nucleus of thalamus (ANT; n=12) and the centromedian nucleus (CM; n=12). Livestreamed data (median duration: 5 minutes, with maximum 15 minutes) using BrainSense® technology was exported in JavaScript Object Notation (JSON) format and converted to European Data Format (EDF) using specialized code. We then analyzed these EDF files using Persyst® software to understand the epileptiform and non-epileptiform EEG activity of the thalamic nuclei and compare them with their presurgical scalp and intracranial EEG interictal and ictal findings. Of note, all 24 patients had scalp EEG monitoring, and 10 patients had intracranial EEG monitoring as part of their presurgical workup, but none of the patients had thalamic depth electrode study prior to DBS implantation.
Results:
Among the 12 ANT patients, 6 did not have any thalamic epileptiform activity; 2 had seizure onset zone (SOZ) laterality concordant with DBS-recorded interictal epileptiform findings; 4 had epileptiform discharges contralateral to the scalp/intracranial EEG-identified SOZ. For the 12 CM patients, 6 had generalized seizure pattern on scalp/intracranial EEG, of whom 4 showed generalized epileptiform patterns on thalamic EEG, one showed right lateralized epileptiform discharges, and the other did not capture any interictal abnormalities; 4 CM patients had multifocal SOZ on presurgical scalp/intracranial EEG, with one revealing no discernable pattern on thalamic EEG, another showing a left-sided epileptiform activity, and two showing bilaterally independent epileptiform discharges. Interestingly, 2 CM patients with left lateralized SOZ on scalp/intracranial EEG had bilaterally independent epileptiform discharges on thalamic EEG. In terms of ictal activity, 2 ANT patients and 4 CM patients had ictal events captured on thalamic EEG. Table 1 demonstrates the interictal and ictal thalamic EEG findings and their correlation to ictal laterality observed during presurgical scalp and intracranial EEG monitoring.
Conclusions:
The latest DBS Percept ® System allows access to thalamic interictal and ictal EEG data alongside the opportunity to compare the findings to certaint extent with scalp and intracranial EEG findings. This is a critical step towards utilizing these thalamoorticograms to tailor stimulation settings and integration of this data into longitudinal follow-up on clinical outcomes, such as response to therapy.
Funding:
No funding sources to disclose.