Thalamic interictal epileptiform discharges in deep brain stimulated epilepsy patients
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The relationships between interictal epileptiform discharges (IEDs) in the anterior (ANT) and dorsomedial nuclei (DMNT) of the thalamus and electro-clinical parameters in pharmacoresistant focal epilepsy patients receiving intrathalamic electrodes for deep brain stimulation (DBS) were investigated. Thalamus-localized IEDs (LIEDs) and surface EEG (sEEG)-IEDs were evaluated in eight patients who underwent ANT-DBS. Occurrence and frequency of ANT- and DMNT-LIEDs and pre-operative sEEG-IEDs were examined with respect to seizure onset location and seizure outcome following ANT-DBS. LIEDs were identified in all eight patients, in the ANT, DMNT, or both. ANT-LIEDs were observed in all patients with an unequivocal temporal seizure onset zone. The ANT-LIED frequency correlated with pre-surgical sEEG-IED frequency (ρ = 0.76, p = 0.033) and predicted ANT-DBS responsiveness (T = −2.6; p = 0.0428). Of the five patients with bilateral sEEG-IEDs, all had ANT-LIEDs, but only one patient had DMNT-LIEDs. All patients with no or unilateral sEEG-IEDs had DMNT-LIEDs. Observation of LIEDS in the ANT and DMNT supports the hypothesis that these nuclei are involved in propagation of focal epileptic activity. Their correspondence with differing electro-clinical features suggests that these nuclei are functionally distinguishable nodes within the epileptic networks of individual patients.
KeywordsAnterior nucleus of the thalamus Dorsomedial nucleus of the thalamus Refractory epilepsy Deep brain stimulation Interictal epileptiform discharges
H.-B. Straub, K. Bohlmann (Epilepsy-Center Berlin-Brandenburg, Germany), A. Kowski (Department of Neurology, Charité-Universitätsmedizin Berlin, Germany), and T. Mayer (Saxon Epilepsy-Center, Germany) supported patient recruitment.
Compliance with ethical standards
Conflicts of interest
The study was funded by departmental funding from the University Clinic for Neurology, Magdeburg. Prof. Voges served as consultant for Medtronic and Sapiens Inc.; Prof. Holtkamp holds the “Friedrich-von-Bodelschwingh endowed Professorship for Clinical and Experimental Epileptology” at the ChariteUniversitaetsmedizin Berlin funded by von Bodelschwingh Foundation, Dr. Schmitt and Prof. Voges have received reimbursement for traveling expenses and/or speaker honoraria from Medtronic Inc. The remaining authors have no conflicts of interest.
Data collection was approved by the Local Ethics Committee of the Otto von Guericke University, Magdeburg and has therefore been performed in accordance with the ethical standards laid down in the 1964 Declaration of Helsinki and its later amendments. All patients provided prior informed written consent.
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