Structural Integrity of Hippocampus Correlates with Distinct Seizure Cessation Patterns
Abstract number :
2.055
Submission category :
3. Neurophysiology / 3F. Animal Studies
Year :
2022
Submission ID :
2204311
Source :
www.aesnet.org
Presentation date :
12/4/2022 12:00:00 PM
Published date :
Nov 22, 2022, 05:24 AM
Authors :
Daniel Valdivia, MS – Rutgers University; David Agyapong, BS – Neurosurgery – Rutgers University; Ojas Chinchwadkar, BS – Neurosurgery – Rutgers University; Christopher Talbot, MD – Neurosurgery – Rutgers University; John-Sebastian Mueller, MBS, BS – Neurosurgery – Rutgers University; Fabio Tescarollo, PhD – Research Associate, Neurosurgery, Rutgers University; Spencer Chen, PhD – Senior Research Associate, Neurosurgery, Rutgers University; Hai Sun, MD, PhD – Associate Professor & Assistant Director of Research, Neurosurgery, Rutgers University
Rationale: Although much effort has gone into the analysis of electroencephalogram (EEG) patterns during generalized epileptic seizures of the temporal lobe, research on seizure termination patterns is sparse. EEG recordings from the kainic acid model of epileptogenesis in mice display distinct seizure ending patterns which have yet to be well characterized and studied. Seizure ending patterns could represent significant differences in brain sclerosis which in turn may suggest best approaches for the pharmacological and surgical treatment of epilepsy.
Methods: We examined chronic intracranial recordings of 139 spontaneous seizures in 8 homozygous PV-Cre mice in which status epilepticus was induced with intrahippocampal kainic acid. Kainic acid (20 mM, 50 nL) was stereotaxically injected into the hippocampal CA1 layer and a 6-channel head stage was implanted bilaterally, targeting the CA1 (-2.06 AP, ±1.6 ML, -1.4 DV) and dentate gyrus (-2.06 AP, ±1.6 ML, -1.9 mm DV). EEG recordings were conducted over a period of 24 hours over multiple sessions. Additionally, we examined the brain slices histologically using a Nissl stain and searched for associations between seizure termination patterns and histological findings.
Results: EEG recordings demonstrated three distinct seizure ending patterns (Figure 1), which were characterized as abrupt (instantaneous termination of seizure activity), elongated spike (multiple isolated bursts of activity preceding termination), and foxtail (significant waveform attenuation followed by a crescendo-decrescendo spike train). These EEG ending patterns are corroborated by spectrograms which display observable differences of power in distinct frequency bands. Histological examination of the brain slices at the site of the EEG electrode revealed two key morphological patterns (Figure 2A): a visually intact hippocampus (Visually Intact Group, VIG), and a sclerotic hippocampus (Sclerosis Group, SG). Comparison of seizure ending patterns between the morphological groups demonstrates a unique distribution. In total, 139 seizures were analyzed (SG = 66, VIG = 73). In the Sclerosis Group, 77% of seizures exhibited an abrupt ending pattern, 23% exhibited an elongated pattern, and 0% exhibited a foxtail pattern. In the Visually Intact Group, 21% of seizures exhibited an abrupt ending pattern, 3% exhibited an elongated pattern, and most interestingly, 77% exhibited a foxtail pattern (Figure 2B).
Conclusions: Our study supports the notion presented by Salami et al. (Neurobiol Dis. 2022) that there are a limited number of seizure termination patterns. Preliminary data suggest a relationship between distinct seizure termination patterns and hippocampal morphology which merits further investigation. Specifically, we found the foxtail seizure termination exclusively in mice with visually intact hippocampus at the recording site. Seizure termination patterns may provide insight into structural changes occurring within the brain and may help direct clinical treatment and care.
Funding: None
Neurophysiology