Effect on Varying the Impact Velocity in the Controlled Cortical Impact Injury Model: Injury Severity and Impact Velocity

OBJECTIVE: A study of the histopathologic and neurobehavioral correlates of cortical impact injury produced by increasing impact velocity using the controlled cortical impact(CCI) injury model is studied. METHODS: Twenty-four Sprague-Dawley rats (200~250g) were given CCI injury using a pneumatically driven piston. Effect of impact velocity on a 3mm deformation was assessed at 2.5m/sec (n=6), 3.0m/sec (n=6), 3.5m/sec (n=6), and no injury (n=6). After postoperative 24hours the rats were evaluated using several neurobehavioral tests including the rotarod test, beam-balance performance, and postural reflex test. Contusion volume and histopathologic findings were evaluated for each of the impact velocities. RESULTS: On the rotarod test, all the injured rats exhibited a significant difference compared to the sham-operated rats and increased velocity correlated with increased deficit (P<0.001). Contusion volume increased with increasing impact velocity. For the 2.5, 3.0, and 3.5m/sec groups, injured volumes were 18.8+/-2.3mm3, 26.8+/-3.1mm3, and 32.5+/-3.5mm3, respectively. In addition, neuronal loss in the hippocampal sub-region increased with increasing impact velocity. In the TUNEL staining, all the injured groups exhibited definitely positive cells at pericontusional area. However, there were no significant differences in the number of positive cells among the injured groups. CONCLUSION: Cortical impact velocity is a critical parameter in producing cortical contusion. Severity of cortical injury is proportional to increasing impact velocity of cortical injury.

Development of Upgraded Cortical Impact Model(Part I: Mechanics)

OBJECTIVE: Head trauma model is important and essential to development of new therapeutic modality. We present a upgraded head trauma model for experimental animals. METHODS: Using pneumatic cylinder, solenoid valve, linear variable differential transformer(LVDT) and load cell, we developed "Chung-Ang University Hospital Model 1.0(CAUH-1)" based on controlled cortical impact model. RESULTS: Changing pressure, impact velocity could be controlled up to 4m/sec. Using solenoid valve, we could control dwell time precisely. Real time impact force could be measured with load cell. CONCLUSION: Controlling dwell time, impact velocity, depth of deformation, this model would reproduce variable degrees of head injury. This model is so precise and versatile that it would be useful in diverse animal experimental researches.