Tailored Thalamic Stimulation During sEEG to Guide Neuromodulation
Abstract number :
2.202
Submission category :
3. Neurophysiology / 3E. Brain Stimulation
Year :
2025
Submission ID :
205
Source :
www.aesnet.org
Presentation date :
12/7/2025 12:00:00 AM
Published date :
Authors :
Presenting Author: Kishore Vedala, MD – Children's Healthcare of Atlanta
Jenny Lin, MD – Children's Healthcare of Atlanta
Nealen Laxpati, MD – Children's Healthcare of Atlanta
Rationale:
We present a case of a 9 year old female with right-sided porencephaly, intractable focal epilepsy, and epileptic encephalopathy with spike-wave activation in sleep (EE-SWAS) who was admitted to the EMU for stereo-EEG (SEEG). Presurgical evaluation suggested a wide but primarily unilateral epileptogenic network in the right hemisphere. In anticipation of considering neuromodulation modalities due to her epileptogenic network, thalamic electrodes were implanted in the right anterior (ANT) and centromedian (CM) nuclei. Her SEEG monitoring showed frequent electrographic seizures during wakefulness and continuous spike-wave discharges during sleep. We therefore developed a tailored protocol of thalamic stimulation with the goal of aborting seizures to determine the optimal nucleus and stimulation paradigm.Methods:
We used two neurostimulation strategies: (1) an “open-loop” high frequency (50 Hz) stimulation during the periods of continuous spike-wave discharges in sleep (i.e. SWAS), and (2) a “closed-loop” high frequency responsive stimulation to electrographic seizures or runs of prolonged diffuse discharges, where stimulation was delivered at bedside immediately upon onset. Though there are no set guidelines for thalamic stimulation during SEEG, we used available literature to guide stimulation parameters [1, 2]. The “open-loop” strategy utilized stimulation for 1 min intervals followed by an interceding 1 min “off” period in increasing amplitudes from 1 mA to 5 mA as tolerated. The “closed-loop” strategy utilized stimulation at 5 mA. Pulse width for both was 0.3 ms. Stimulation was attempted with each strategy on each thalamic nucleus.Results:
The “open-loop” stimulation was attempted during sleep and did not result in a significant reduction of epileptiform discharges. In contrast, the “closed-loop” responsive stimulation resulted in near-immediate abortion of electrographic seizures in 67% (4/6) of the stimulations in the CM nucleus but only 20% (2/10) of the stimulations in the ANT (Figure 1). This data was used to guide the placement of responsive neurostimulation (RNS) electrodes in the right CM nucleus along with an additional electrode in the right SMA. Following implantation and initiation of stimulation, the patient experienced significant improvement, from a reported pre-implantation frequency of daily to weekly seizures improved to no definite seizures in 3 months since RNS implantation. Moreover, the number of “long episodes” detected by the RNS improved from 606 per month prior to turning on stimulation to 8.6 per month afterward (Figure 2a). Events of epileptiform activity detected consistently in the SMA in sleep resolved after neuromodulation was initiated, and ECoGs reviewed afterwards only contained interrogation noise (Figure 2b).
Conclusions:
This case study supports the utilization of thalamic stimulation during SEEG to guide neuromodulation modality and thalamic nuclei selection for electrode implantation. Further responsive stimulation studies in a systematic approach would help validate the findings in this case.
References:
1. Chaitanya G, et al. Clin Neurophysiol. 2020 Sep;131(9):2158-2167
2. Damiani, Arianna, et al. medRxiv (2024): 2024-10Funding: None
Neurophysiology