title: The progression of electrophysiologic abnormalities during epileptogenesis after experimental traumatic brain injury.
abstract: OBJECTIVE
  Posttraumatic epilepsy (PTE) accounts for 20% of acquired epilepsies. Experimental models are important for studying epileptogenesis. We previously reported that repetitive high-frequency oscillations with spikes (rHFOSs) occur early after lateral fluid percussion injury (FPI) and may be a biomarker for PTE. The objective of this study was to use multiple electrodes in rat hippocampal and neocortical regions to describe the long-term electroencephalographic and behavioral evolution of rHFOSs and epileptic seizures after traumatic brain injury (TBI).
  
  
  METHODS
  Adult male rats underwent mild, moderate, or severe FPI or sham injury followed by video-electroencephalography (EEG) recordings with a combination of 16 neocortical and hippocampal electrodes at an early, intermediate, or late time-point after injury, up to 52 weeks. Recordings were analyzed for the presence of rHFOSs and seizures.
  
  
  RESULTS
  Analysis was done on 28 rats with FPI and 7 shams. Perilesional rHFOSs were recorded in significantly more rats after severe (70.3%) than mild (20%) injury or shams (14.3%). Frequency of occurrence was significantly highest in the early (10.8/h) versus late group (3.2/h). Late focal seizures originating from the same electrodes were recorded in significantly more rats in the late (87.5%) versus early period (22.2%), occurring almost exclusively in injured rats. Seizure duration increased significantly over time, averaging 19 s at the beginning of the early period and 27 s at the end of the late period. Seizure frequency also increased significantly over time, from 4.4 per week in the early group to 26.4 per week in the late group. Rarely, rats displayed early seizures or generalized seizures.
  
  
  CONCLUSIONS
  FPI results in early rHFOSs and later spontaneous focal seizures arising from peri-lesional neocortex, supporting its use as a model for PTE. Epilepsy severity increased over time and was related to injury severity. The association between early rHFOSs and later focal seizures suggests that rHFOSs may be a potential noninvasive biomarker of PTE.
authors: Department of Neurology, University of California Los Angeles, Los Angeles, California, U.S.A.. aylin.reid@utoronto.ca.
authors: Aylin Y
authors: AY
authors: Reid
authors: Department of Neurology, University of California Los Angeles, Los Angeles, California, U.S.A.
authors: Anatol
authors: A
authors: Bragin
authors: Department of Neurosurgery and Pediatric Neurology, University of California Los Angeles, Los Angeles, California, U.S.A.|Brain Research Institute, University of California Los Angeles, Los Angeles, California, U.S.A.|Mattel Children's Hospital - UCLA, University of California Los Angeles, Los Angeles, California, U.S.A.
authors: Christopher C
authors: CC
authors: Giza
authors: Department of Neurology, University of California Los Angeles, Los Angeles, California, U.S.A.
authors: Richard J
authors: RJ
authors: Staba
authors: Department of Neurology, University of California Los Angeles, Los Angeles, California, U.S.A.|Brain Research Institute, University of California Los Angeles, Los Angeles, California, U.S.A.|Department of Neurobiology, University of California Los Angeles, Los Angeles, California, U.S.A.|Department of Psychiatry and Biobehavioral Sciences, University of California Los Angeles, Los Angeles, California, U.S.A.
authors: Jerome
authors: J
authors: Engel
mesh_terms: D000818:Animals; D000070642:Brain Injuries, Traumatic / Q000150:complications* / Q000209:etiology; D001931:Brain Mapping; D058256:Brain Waves / Q000502:physiology*; D004195:Disease Models, Animal; D018450:Disease Progression; D004567:Electrodes, Implanted; D004569:Electroencephalography; D004834:Epilepsy, Post-Traumatic / Q000209:etiology*; D007839:Functional Laterality; D008297:Male; D010474:Percussion / Q000009:adverse effects; D051381:Rats; D017207:Rats, Sprague-Dawley; D014741:Video Recording
keywords: Biomarker; Electroencephalography; Lateral fluid percussion injury; Posttraumatic epilepsy; Seizure