Characterization of controlled cortical impact devices by high-speed image analysis

As a consequence of their commercial availability, ease of use, and reproducibility, controlled cortical impact (CCI) devices have attained significant prevalence in preclinical traumatic brain injury research. With a CCI, the severity of injury is controlled by varying the impact depth, velocity, and duration, but the actual performance of the device is not well appreciated, partly because of the velocity and short travel distance to impact. This study used a high-speed video digital camera to investigate the performance of five electromagnetically driven CCI devices of the same model. Videography indicated that the impactor tip made a series of distinctive vertical advances and retractions before it attained the desired preset depth; this was also observed in male mouse CCI tests. The impactor tip was also observed to move in the horizontal direction by .8-1.6 mm. On the first advance, the tip extended a distance that was shorter than the preset depth and the velocity of impactor tip was slightly faster than the preset values for three of the five machines. One of the devices was evaluated on four separate occasions over a 14-month period and was found to operate consistently over time. Overall, differences in impact depth and velocity between the devices were modest, suggesting that comparisons of experimental results from different laboratories will generally be informative, particularly if reports provide relevant descriptions of neuropathology. However, the repetitive extension and retraction and horizontal movement of the tip suggests caution in modeling CCI as a single injurious event.