A compound of methylcellulose-silicone expanding progressively over a 1-week period by moisture absorption was implanted in the midthoracic epidural space of 17 Sprague Dawley adult rats. When the animals became paraplegic 6.3 +/- 1.6 days later, they were randomized into three groups: untreated control (n = 5), high dose dexamethasone (HD, 1.25 mg/kg intramuscularly, twice daily, n = 5), and low dose dexamethasone (LD, 0.125 mg/kg intramuscularly, twice daily, n = 7). Motor strength was evaluated daily by an observer unaware of the treatment given to the rats. Animals treated with dexamethasone (HD or LD) improved faster than untreated control animals. No significant difference in the rate of recovery or degree of motor improvement was noted between the HD and LD groups. Mortality was higher in the HD group because of infections and gastrointestinal perforation/bleeding.