THE EFFECTS OF METHYLPREDNISOLONE ON PREVENTION OF BRAIN EDEMA AFTER EXPERIMENTAL MODERATE DIFFUSE BRAIN INJURY IN RATS - COMPARISON BETWEEN DOSAGE, INJECTION TIME, AND TREATMENT METHODS

Our study was designed to determine whether methylprednisolone exerts a beneficial effect after experimental moderate diffuse brain injury a nd whether this possible beneficial effect is affected by the dosage, the timing of administration, and the methods of treatment. A total of 200 anesthetized adult rats were injured utilizing a weight-drop devi ce through a Plexiglas guide tube. These rats were divided into eight groups: Group 1 (n=35) was assigned to receive no methylprednisolone a fter impact (control group), Group 2 (n=25) received an initial intrap eritoneal administration of methylprednisolone with a dose of 5 mg/kg at 1 hour after cranial impact, followed by administration with a main tenance dose of 5 mg/kg/4 hours. Group 3 (n=25), group 5 (n=25), and g roup 7 (n=20) received an initial 30 mg/kg at I hour, 4 hours, and 8 h ours, respectively without a maintenance dose. Group 4 (n=25), group 6 (n=25), and group 8 (n=20) received an initial 30 mg/kg at I hour, 4 hours, and 8 hours after impact, with a maintenance dose of 15 mg/kg/4 hours. Measured water content of brain tissue expressed the amount of water as the difference between fresh and dry weight. At 48 hours aft er impact, the water content in group 4 and 6 were significantly lower than group I. Mean +/- SD was 61.4 +/- 0.37% in group 4 (p < 0.03), 6 1.5 +/- 0.34% in group 6 (p < 0.001), and 63.6 +/- 0.48% in group 1. C ompared to group 1, the difference was not statistically significant i n group 2 (p > 0.1), group 3 (p > 0.5), group 5 (p > 0.6), group 7 (p > 0.1), and group 8 (p > 0.5). Groups treated with mega dose before 4 hours after head injury, including maintenance dose, showed beneficial effects. Our study suggests that the efficacy of methylprednisolone i n head injury war; related to the dosage, the timing of administration , and method of treatment.