ALTERATIONS IN REGIONAL CEREBRAL BLOOD-FLOW FOLLOWING BRAIN INJURY IN THE RAT

To elucidate the temporal changes in regional cerebral blood flow (rCBF) after experimental traumatic brain injury, serial rCBF measurements were made during a 24-h period following fluid-percussion (F-P) traumatic brain injury in the rat. Brain injury of 2.2 atm was induced over the left parietal cortex and serial measurements of rCBF were performed using the radiolabeled microsphere method. rCBF values were obtained prior to injury and at 15 and 30 min and 1, 2, 4, and 24 h postinjury. At 15 min postinjury, there was a profound, wide-spread reduction in rCBF in all brain regions studied (p < 0.05). At 30 min and 1 h postinjury, all brain regions except pons-medulla and cerebellum showed significantly reduced rCBF compared to the preinjury values (p < 0.05). By 2 h postinjury, however, a significant focal reduction of rCBF was observed only in the cerebral tissue surrounding the trauma site (p < 0.05); rCBF in the remaining brain regions had recovered to the preinjury levels. By 4 h postinjury, rCBF had returned to normal in all brain regions studied. This recovery of rCBF was still evident at 24 h postinjury. The present study demonstrates that, following the experimental traumatic brain injury in the rat, (a) an initial global suppression of rCBF occurs up to 1 h postinjury; (b) at the trauma site, a more persistent focal reduction of rCBF occurs; and (c) these alterations in rCBF after trauma dissolve by 4 h postinjury. The result was discussed in the context of the neurological, electroencephalographic, magnetic resonance spectroscopic, and pathological findings observed in our lateral F-P brain injury rat model.