HISTOPATHOLOGIC CONSEQUENCES OF MODERATE CONCUSSION IN AN ANIMAL-MODEL - CORRELATIONS WITH DURATION OF UNCONSCIOUSNESS

Although duration of unconsciousness is commonly used as a prognostic index following traumatic brain injury (TBI), few controlled studies h ave statistically evaluated the relationship between unconsciousness a nd histologic pathology, particularly after moderate head injury, Usin g a pendulum-striker concussive device, a reproducible model of TBI in rats was developed. This model is uncomplicated by skull fractures, c ontusions, or experimenter-induced craniotomies. In the present study, the severity of the histopathology observed in this model of moderate closed-head injury at 48 h posttrauma is linearly related to the dura tion of unconsciousness (p < 0.0001), The pathology, assessed with a s ilver stain for neurodegeneration, is particularly striking if unconsc iousness persists for 4 minutes or more, These data suggest that the i nitial period of unconsciousness may be a useful predictor of clinical brain histopathology associated with moderate closed-head injury, pre dicting either the degree of pathology and/or the rate it progresses i f left untreated.