Abstracts

Rationale:
Post-traumatic epilepsy (PTE) is one of the most debilitating consequences of traumatic brain injury (TBI). Hence, there is a need for the development of biomarkers, which would help in early intervention and a cure for PTE. In the current study, electrographic-based abnormalities were reviewed in a rat TBI model, to detect biomarkers for PTE.
Method:
Experiments were conducted on 2 months-old male Sprague-Dawley rats (Sham group: n=8; TBI group: n=21). Immediately after the fluid percussion injury, microelectrodes were implanted in to the neocortex, and other brain areas and wideband local field potentials (LFP) were continuously recorded for 6 months. Based on visual- electroencephalography (EEG) data, the animals were separated into ones that became epileptic (E+; n=9) and ones that did not (E-; n=12). [Rate of high-frequency oscillations (HFO) 90-500hz], [high amplitude HFO (peak amplitude: 9 standard deviation)], [very high frequency oscillations (VHFO) 1000-1500hz], sleep spindles (8-20hz), and spike-wave discharges (7-12hz) were studied in all the groups in sleep stage EEG, from day 1 till week 4 of TBI.
Results:
EEG revealed, 40% (n=9) of TBI rats became epileptic showing generalized or focal seizures between week 2 and week 21 of TBI. The rate of; HFO, high amplitude HFO, VHFO, spike-wave discharges increased in the 1st week of TBI in the E+ group, but not in the E- nor sham group. TBI decreased sleep spindle rate only in the E+ group in the 1st week of TBI.
Conclusion:
The increased rate of HFOs is a stable biomarker of post-traumatic epileptogenesis. An increase in 1) HFO, 2) high amplitude HFO, 3) VHFO, 4) spike-wave discharges and 5) decrease in sleep spindle rate, in the 1st week of TBI could also be biomarkers of post-traumatic epileptogenesis.
Funding:
:This study was supported by research grants R01NS033310 and R01NS065877 from the National Institutes of Health.