Thalamic Stimulation for Epilepsy Study

In this study, the investigator aims to perform cortical stereo electroencephalogram (sEEG) recordings during simultaneous anterior nucleus of the thalamus (ANT) recording and stimulation to better understand the following: 1) how the ANT is involved in various seizure types; 2) which cortical regions are modulated by established ANT stimulation patterns; and 3) how novel ANT stimulation patterns modify epileptogenic cortical activity. Together, this knowledge will advance ANT deep brain stimulation (DBS) therapy by providing a physiologic basis for patient selection for ANT DBS, while identifying brain signals and stimulation patterns that can be used to develop novel methods for ANT DBS. Up to 15 adult patients (18 and older) who present to Duke Neurosurgery for routine seizure localization using sEEG will be asked to enroll in this pilot study of ANT recording and stimulation. In the course of surgical epilepsy treatment, patients routinely undergo surgical placement of sEEG electrodes for the purposes of seizure localization. During this procedure, 2 additional leads will be placed in the ANT. These patients remain hospitalized for 7-14 days after sEEG placement, during which time their seizure medications are tapered. Concurrent video monitoring is performed while continuous neural recordings are made through the sEEG electrodes. Additionally, continuous recordings will be performed through the electrodes placed in the thalamus. Periodically, standard intermittent high-frequency stimulation (130 Hz, 90-ms pulse width, and 2 mA intensity) will be performed with a 60-s on and a 300-s off cycle after surgery. These standard ANT stimulation parameters are employed clinically. Data will include the sEEG recordings marked for ANT stimulation, any side effects, medications, past medical history (PMH), and tests/procedures during the hospital stay. Risks involved are as described for the standard depth electrode surgery with the addition of the possible side effects from the stimulation which include sensations of numbness and tingling, and possibly increased seizure activity.