Fast Ripple-Delta Coupling as Early Biomarker for Post-Traumatic Epileptogenesis in Repetitive Brain Injury

Area of Science:

• Neuroscience
• Epileptology
• Trauma Research

Background:

• Traumatic brain injury (TBI) is a known cause of post-traumatic epilepsy (PTE).
• Early detection of epileptogenesis following TBI is crucial for timely intervention, but reliable biomarkers are lacking.
• Current understanding of electrophysiological changes preceding PTE is limited.

Purpose of the Study:

• To identify early electrographic biomarkers for epileptogenesis after repetitive diffuse TBI (rdTBI) in a mouse model.
• To investigate the temporal dynamics of EEG signatures before and during seizure development.
• To assess the predictive value of identified biomarkers for post-traumatic seizure susceptibility.

Main Methods:

• Utilized a mouse model of repetitive diffuse TBI (rdTBI).
• Implemented continuous video-electroencephalography (EEG) monitoring for up to 4.5 months post-injury.
• Analyzed EEG data for power spectrum changes, oscillation patterns (fast ripples, delta, theta, alpha, beta, gamma), and spike activity.

Main Results:

• 25% of rdTBI mice developed seizures with variable latency.
• Fast ripple-delta DOWN state coupling was identified as an early biomarker, present at 4 days post-TBI and preceding seizure onset in all affected mice.
• EEG analysis revealed network hyperexcitability in seizure-prone animals, characterized by elevated delta/theta power, reduced physiological oscillations, and increased pathological fast ripples.
• TBI increased cortical excitability, with seizure onset causing a further significant escalation in interictal activity.

Conclusions:

• Fast ripple-delta DOWN state coupling is a promising, specific early biomarker for post-traumatic epilepsy, detectable before clinical seizure onset.
• This biomarker effectively identified all seizure-prone animals, irrespective of seizure frequency (single or recurrent), suggesting common underlying mechanisms.
• Temporal EEG analysis is valuable for detecting early epileptogenic changes post-TBI, potentially guiding future therapeutic strategies.