In this prospective randomized trial , 1000 patients with facial spasm undergoing microvascular decompression ( MVD ) were randomly assigned to receive normal sodium ( Dex-0 group , n = 333 ) , dexamethasone 0.1 mg/kg ( Dex-1 group , n = 333 ) , or dexamethasone 0.2 mg/kg ( Dex-2 group , n = 334 ) .