Thalamic Stimulation for Epilepsy Study
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.
The purpose of this research is to examine the physiologic underpinnings of deep brain
 stimulation of the anterior nucleus of the thalamus (ANT), a method reducing seizures in
 adults diagnosed with medically refractory epilepsy. In this study, the investigator aims to
 perform cortical stereo electroencephalogram (sEEG) recordings during simultaneous 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 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.

 Approximately 3 million people in the United States experience epilepsy. Despite medical
 therapy, up to 30% of these patients continue to experience recurrent seizures. In this
 medically refractory population, tissue resection or ablation offer a high likelihood of
 seizure freedom, if a single epileptogenic focus can be precisely identified. For patients
 who are not candidates for resection or ablation, or those who continue to have seizures
 after these treatments, neuromodulation represents an alternative therapeutic option. One
 such therapy, deep brain stimulation (DBS) has been approved for around 5 years in Europe and
 was recently approved in the United States as a treatment for medically refractory epilepsy.

 A number of potential DBS targets are being investigated, particularly, the ANT, which
 consists of the anteroventral, anterodorsal, and anteromedial nuclei. The ANT was recognized
 as a potential target because of its central connectivity to cortical regions where seizures
 often originate. Several pilot studies and recent trials have demonstrated 5-year efficacy
 and safety outcomes for ANT DBS. In a large randomized controlled study of ANT stimulation
 with long-term follow-up, there was a 56% median seizure reduction at the 2 year, and a 69%
 median and seizure reduction at the 5 year, in patients with drug-resistant focal epilepsy.
 This study also suggested that patients with temporal lobe epilepsy achieved greater benefit
 than those with extra-temporal or multifocal seizures. Since these pivotal trials, DBS of the
 ANT has emerged as a promising therapy for focal drug resistant epilepsy, however, its basic
 mechanism of action is unclear. One study which examined cortical local field potentials
 recordings during high-frequency ANT stimulation (130 Hz), has suggested that epileptic
 network desynchronization is a potential mechanism of DBS of the ANT.
All epilepsy patients admitted to Duke Hospital for surgical placement of depth electrodes
 age 18 and up are eligible.