Authors :
Presenting Author: Thomas Foutz, MD, PhD – Washington University School of Medicine
Murphy Liu, B.S. – Neurosurgery – Washington University School of Medicine; Markus Adamek, B.S. – Neurosurgery – Washington University School of Medicine; Tao Xie, B.S. – Neurosurgery – Washington University School of Medicine; David Camacho, n/a – Brigham Young University; R. Edward Hogan, M.D. – Neurology – Washington University School of Medicine; Peter Brunner, Ph.D. – Neurosurgery – Washington University School of Medicine; Willie Jon, M.D.,Ph.D. – Neurosurgery – Washington University School of Medicine
Rationale:
Drug-resistant epilepsy affects approximately 1 million people in the United States. While deep brain stimulation (DBS) presents a promising treatment option for refractory seizures, optimizing its effectiveness has proven challenging due to factors such as inter-patient variability, electrode placement, and the wide range of available stimulation parameters. The centromedian nucleus (CMN) has emerged as a potential therapeutic target for refractory epilepsy, but the optimal implantation target and stimulation settings remain unclear. Therefore, the primary objective of this study is to investigate the effects of CMN-DBS on surface and intra-thalamic EEG through external time-synced, intra-thalamic stimulation, with the aim of gaining valuable insights into optimal programming strategies.
Methods:
In the anesthetized state during the operating room implantation procedure, high-frequency stimulation (40-50 Hz) was administered pairwise to each of eight contact pairs. This stimulation was delivered in five trains of five stimulation periods, using amplitude intensities ranging from two to six mA and a pulse width of 250 microseconds. Simultaneous recordings were obtained from the scalp and intrathalamic regions and subsequently analyzed. Interpolation over the stimulation artifacts was used, and the frequency band activity during stimulation was compared to the non-stimulated baseline.
Results:
Six patients (ages 16 to 29) with medically refractory epilepsy, including four individuals with Lennox-Gastaut syndrome, underwent comprehensive surgical evaluation at our institution. Following a multidisciplinary conference, DBS implantation was recommended. Pooled analysis of all stimulation settings revealed a significant reduction of beta-frequency activity by -38% (SD 27%) and theta-frequency activity by -50% (SD 19%) with high-frequency stimulation. Additionally, individual patients exhibited a spatial dependence in the reduction of beta frequency power, suggesting potential therapeutic significance. Furthermore, when evaluating relative frequency-band power in relation to total bandpower, the widest separation of active electrodes (contacts 0 and 3, bilaterally) yielded the greatest changes in alpha, beta, and theta power.
Conclusions:
Our findings indicate that evoked EEG responses to high-frequency stimulation can be reliably detected through CMN-DBS stimulation in the anesthetized state. This approach holds promise as a valuable biomarker for improving implantation and optimizing stimulation settings in DBS treatment.
Funding:
This work was supported by AES Research and Training Fellowship for Clinicians, AES #980019, and NIH #
5T32GM139799-02.