Acute changes in regional cerebral metabolite values following experimental blunt head trauma.

A Remington humane stunner was used to deliver a blow to the left side of the surgically-exposed skull in ketamine-anesthetized cats. At 15 minutes after the trauma, brain tissue was frozen in situ. In animals without visible tissue hemorrhage (Grade 0) and in those with unilateral cerebral contusions involving the cerebral cortex and white matter (Grade 2), regional cerebral metabolite concentrations were measured by enzymatic-fluorometric techniques and edema was tested with an organic gradient. No substantial changes in cerebral metabolite concentrations were observed in head-injured animals without cerebral contusions. In animals with unilateral contusions, the white matter neighboring the tissue hemorrhage had an increase in lactic acid and a decrease in phosphocreatine as compared to values from corresponding areas on the contralateral side, and in control and Grade 0 animals. The cerebral cortex adjacent to tissue hemorrhage had a variable response that ranged from metabolite concentrations within normal ranges to marked decreases in high-energy phosphates and increases in lactic acid. Metabolites of the cortex and white matter contralateral as well as distant to contusion were not statistically different from values of control animals. Changes in several metabolites correlated well with the magnitude of edema. It is concluded that focal metabolic alterations can occur shortly after severe blunt head injury, and that these events may contribute to acute traumatic cerebral edema.