Implication of surgical procedure in the induction of headache and generalized painful sensation in a fluid percussion injury model in rats

Background: This study demonstrated the effects of traumatic brain injury (TBI) and each step of the surgical procedure for a fluid percussion injury (FPI) model on periorbital allodynia.

New method: Adult male Wistar rats were divided in naive, incision, scraping, sham-TBI and TBI groups. Periorbital allodynia was evaluated using von Frey filaments, and heat hyperalgesia of the hindpaws was evaluated by a Plantar Test Apparatus.

Results: The statistical analyses revealed that the surgical procedure decreased von Frey filaments thresholds twenty-four hours after the surgery in all groups when compared to the naive group (p < 0.0001). Scraping, sham-TBI and TBI groups showed a decrease in the periorbital mechanical threshold for 35 days compared with the naive and incision groups (p < 0.0001). Only the TBI group demonstrated a significant difference in periorbital allodynia at 45 and 60 days after the injury (p < 0.01). A significant decrease in the thermal withdrawal latency of the hindpaw contralateral to the lesion was observed in the TBI group compared with the naive group at 7 days and 28 days after the lesion (p < 0.05).

Comparison with existing methods: This study presented in detail the effects of each stage of the surgical procedure for a FPI model on periorbital allodynia over time and characterized the TBI model for this evaluation.

Conclusion: The FPI model is relevant for the study of headache and generalized pain in both acute and chronic phases after an injury.