Controlled cortical impact

Pigs were anesthetized, and a periosteal block (0.5% bupivacaine; 2 mg/kg; Pfizer) at the cranium was applied under aseptic technique. A craniectomy was performed, approximately 20 mm in diameter, to expose the underlying dura at the left anterior junction of the coronal and sagittal sutures. Each pig was secured in a controlled cortical impactor device (University of Georgia Instrument Design and Fabrication Shop, Athens, GA), and a 15 mm impactor tip was positioned over the intact dura to induce injury with the following parameters: velocity of 4 m/s, depth of depression of 9 mm, and dwell time of 400 ms. These parameters were based on previous studies to generate a moderate TBI^25,81,82.

Pre-operatively, TBI pigs received antibiotics (ceftiofur crystalline free acid; 5 mg/kg intramuscular (IM); Zoetis). Pre-induction sedation and analgesia for TBI surgery was achieved using buprenorphine (0.01 mg/kg IM; Covetrus), midazolam (0.2 mg/kg IM; Heritage), and xylazine (2 mg/kg IM; VetOne). Prophylactic lidocaine (0.5 mL 2% lidocaine; VetOne) was topically applied to laryngeal folds, and propofol (to effect, intravenous (IV); Zoetis) was administered to achieve intubation. Anesthesia was maintained with isoflurane (2.0%; Abbott Laboratories) in oxygen. Post-operatively, once vitals returned to normal ranges, the pigs were monitored every four hours for 24 h and then twice a day. For pain and inflammation maintenance, pigs received buprenorphine (0.01 mg/kg IM; Covetrus) every eight hours for 24 h and banamine (2.2 mg/kg IM; Merck) every 12 h for 24 h, and then every 24 h for 72 h post-operatively. TBI pigs displayed contralateral ataxia. Healthy control pigs did not receive pre-operative antibiotics or post-operative medications.