Thalamic stimulation induced changes in network connectivity and excitability in epilepsy

Area of Science:

• Neuroscience
• Neurology
• Biomedical Engineering

Background:

• Deep brain stimulation (DBS) effects in neurological conditions occur over various timescales.
• Optimizing DBS for epilepsy is challenging due to delayed effects on seizures.
• Single pulse electrical stimulation and evoked potentials can measure network connectivity and excitability.

Purpose of the Study:

• To assess seizure network engagement using single pulse and high-frequency thalamic stimulation during stereotactic electroencephalography (SEEG).
• To modulate network activity and track changes in excitability and epileptiform abnormalities.
• To evaluate the potential of pulse evoked potentials and thalamic stimulation as biomarkers for DBS optimization in epilepsy.

Main Methods:

• Retrospective cohort study of ten individuals with drug-resistant epilepsy undergoing SEEG.
• High-frequency (145 Hz) thalamic stimulation was applied, with pulse evoked potentials recorded before and after.
• Interictal epileptiform discharge rates were measured using an automated classifier.

Main Results:

• Thalamic stimulation (>1.5 hours) significantly reduced pulse evoked potential amplitudes, correlated with baseline connectivity.
• High-frequency stimulation immediately suppressed interictal epileptiform discharge rates in networks with strong thalamocortical connectivity.
• Pulse evoked potentials revealed distinct patterns of network engagement across thalamic subfields.

Conclusions:

• Pulse evoked potentials and thalamic stimulation during SEEG provide novel biomarkers for evaluating target engagement and network modulation.
• This approach shows potential for efficient, data-driven neuromodulation optimization.
• It establishes a new paradigm for personalized deep brain stimulation in epilepsy.