Authors :
Presenting Author: Stacey Kim, MEng, BA – Kern Medical
Alan Salim, BS – Kern Medical
Aaron Fernandez, BS – Kern Medical
Christel Benny, BS – Kern Medical
Charles Liu, MD, PhD – University of Southern California
Brian Lee, MD, PhD – Keck School of Medicine, University of Southern California
Laura Kalayjian, MD – Keck School of Medicine, University of Southern California
Hari Veedu, MD, FACNS – Kern Medical, United Neuroscience Institute
Rationale:
Deep Brain Stimulation (DBS) is a neuromodulation therapy for patients with medically refractory epilepsy and are ineligible for resective surgery [1]. As an open-loop system delivering continuous electrical stimulation in a cycling pattern, DBS was initially FDA-approved for focal epilepsy, primarily targeting the anterior nucleus of the thalamus (ANT). Efficacy of ANT-DBS was first demonstrated in the Stimulation of the ANT for Epilepsy (SANTE) trial, with the Medtronic Registry for Epilepsy confirming its long-term safety and effectiveness [2]. We report a patient with intractable epilepsy who failed multiple antiseizure medications (ASMs) and Vagus Nerve Stimulation (VNS). Through the USC Epilepsy Care Consortium, he subsequently underwent ANT-DBS implantation and initial programming at USC Keck Medicine, with follow-up at a Kern County epilepsy clinic, bridging the gaps between advanced care and underserved communities.
Methods:
A 65-year-old right-handed male presents a 23-year history of refractory focal epilepsy following a large bilateral posterior cerebral artery infarct at age 42. Neuroimaging revealed bilateral posterior cortical atrophy (left more than right) and left hippocampal atrophy. Seizure semiologies included focal impaired awareness seizures (FIAS) and focal to bilateral tonic clonic seizures (FTBTC). The patient failed multiple ASMs and underwent VNS implantation at age 54. His present VNS parameters are 130 µs pulse width, 25 Hz frequency, 1.75 mA output current, 30 s on-time, 0.5 min off-time, and a 57% duty cycle. Due to ongoing seizures, the patient had bilateral ANT-DBS implantation. Intraoperative high-resolution MRI visualized the ANT and was further confirmed using Montreal Neurological Institute brain coordinates. Postoperative imaging verified accurate electrode placement without complications.
Results:
The patient received bilateral ANT stimulation at 90 μs, 145 Hz, and 1.5 mA, with a duty cycle of 1 min on and 3 min off. Prior to DBS, the patient experienced a median of 4 seizures per month—2 FTBTC and 2 FIAS. In the first 3 months post-DBS, seizure frequency decreased to 2 focal seizures per month, with no FTBTC events. From months 4 to 19 post-DBS, he reported 1 FIAS every 3 months, with continued absence of FTBTC, representing ~92% reduction in seizure frequency.
Conclusions:
This case of ultra-refractory focal epilepsy, unresponsive to VNS and polytherapy with 5 ASMs, showed a significant seizure reduction to ANT-DBS. This highlights DBS’s effectiveness for certain patients resistant to conventional treatments, with imaging enabling precise lead placement. Long-term care and programming were managed in an underserved community epilepsy clinic, demonstrating that complex epilepsy treatments can be maintained outside tertiary care institutions. This model shows potential to bridge specialized neurological care into community settings, expanding access to advanced therapies for underserved populations.
Funding:
N/A