Individualized and stereotypical seizure semiology in a porcine model of post-traumatic epilepsy

Large-animal models of traumatic brain injury may yield translatable data on epileptogenesis, given their similarities in anatomy, brain size, and immune systems to humans. Adult male and female swine received bilateral cortical impact (N=16) or sham surgery (N=6) and were screened for convulsions via video-EEG for up to one year. Post-traumatic epilepsy (PTE) was defined as 2 seizures after 1-week post-injury. Nine out of sixteen pigs (56%) receiving bilateral cortical impact developed PTE, with an average 4.6 months (±3.4,SD) latent period. Seizures (N = 199) began focally, sometimes with motor onset including automatisms, before becoming generalized, with tonic-clonic or tonic convulsions. We defined a library differentiating peri-ictal behaviors (N = 31) from rhythmic/odd behaviors typical in healthy pigs (N = 12). Seizures had an average of 7.3 behaviors per seizure (max 26) lasting an average of 1.8 minutes (max 7.9). For seizures comprised of multiple convulsive episodes, the first convulsion had a greater number of peri-ictal behaviors than subsequent convulsions (P < 0.001). The array of peri-ictal behaviors displayed was pig-specific, with many behaviors consistently observed across seizures. The seizure frequency detected was 0.38/day. This large-brain model of PTE exhibits a variable period of epileptogenesis, a substantial rate of PTE, and an expansive repertoire of ictal behaviors. This first description of semiology in this species will serve as a guide for other porcine epilepsy models. Biofidelic models of PTE are expected to increase our understanding of the pathophysiology, enabling the identification and testing of therapeutics that translate into human patients.