Exerimental head injury in the rat. Part 2: Regional brain energy metabolism in concussive trauma.

A standardized model of acceleration concussion in the rat was used for the study of cerebral energy metabolism during the acute concussive reaction. Impact velocities of 7 and 9 m/sec were used, and the cerebral metabolic state was determined 1, 4, and 15 minutes after the impact. A concussive response could be sustained with a normal energy state in the tissue, but with the more intense reaction to a 9 m/sec impact, energy depletion usually occurred. At 1 minute these changes were most pronounced in the brain-stem regions. At 4 minutes the reactions were more varied but a progression usually occurred during this time, while at 15 minutes restitution was indicated. Hypoxia due to neurogenic pulmonary edema aggravated the state. The findings are compatible with a high metabolic rate during concussion, but progressive changes indicate the rapid appearance of complicating factors, including hypoxemia and probably also ischemia.