Authors :
Presenting Author: Jaysingh Singh, MD – The Ohio State University Wexner Medical Center
Jacob Miller, Biomedical Engineering – The Ohio State University; Timothy Lucas, Neurosurgeon – The Ohio State University; Jimmy Yang, Neurosurgeon – The Ohio State University; Caleb Sollars, EEG tech – The Ohio State University; Dawn Eliashiv, MD – University of California
Rationale:
Adaptive deep brain stimulation (DBS) uses local field potentials (LFPs) as feedback to guide DBS programming in Parkinson's disease. However, ANT-DBS neuromodulation in patients with focal DRE remains an open-loop system. There is limited data taking LFP patterns in patients with focal DRE. This work aims to analyze the LFPs in patient with DRE focal temporal lobe epilepsy from ANT stereo EEG intracranial recording during inter-ictal and ictal state (electrographic vs clinical seizures)
Methods:
We studied ANT-Stereo EEG (SEEG) recordings in patients with focal temporal lobe epilepsy. We classified SEEG data as inter-ictal and ictal state, which was sub-categorized into electrographic (ESz), Focal aware seizure (FAS), Focal with impaired awareness (FIA), or focal to bilateral tonic-clonic seizure (FBTC). LFP was analyzed at 4, 8, 15, 32 Hz, and higher frequencies which include high gamma (32-150 Hz) and ripples band (80-250 Hz) using visual analysis and linear regression model where LFP frequencies during different seizure types were compared to inter-ictal or baseline segment.
Results:
Fifty-two seizures (23 ESz, 17 FA, 6 FIA, and 6 FBTC) were analyzed for LFP measurement. Consistent broad activity at 4 Hz and thin-band activity at 8 Hz on the frequency spectrogram was seen during the inter-ictal state, and significant gain in activity at these frequencies was seen during the FIA and FBTC seizures. We also observed a frequency band pattern alteration, such as the discontinued activity at 32 Hz before FIA and FBTC seizure onset. The linear regression model showed a significant correlation between LFP at 8 ±2 Hz for FIA (p< 0.001, R2 0.93) and at higher frequencies for FBTC (p< 0.001, R2 >0.95). In contrast, no significant change in LFP activity was seen for ESz and FAS between the inter-ictal and seizure state.
Conclusions:
Our observations confirm that the ANT- LFP at a slower frequency band (8 ±2 Hz) for FIA seizures and at a higher frequency for FBTC seizures is a significant neurophysiological biomarker of focal epileptic seizures. This represents a first step toward understanding ANT thalamic LFP patterns during focal seizures and developing adaptive DBS strategies.
Funding: N/A