A 74-year-old woman was scheduled for surgical treatment of a carpal tunnel syndrome. An intravenous (i.v.) regional anaesthetic was performed using 1% prilocaine standard technique. Three minutes after injection of the local anaesthetic mild to moderate central nervous system symptoms developed, along with tachycardia, sweating and peri-oral paraesthesia. The evolution was favourable, no convulsions or other more serious events occurred. Despite showing adequate pressure inflation the tourniquet failed to accomplish its purpose. The patient recovered well without any sequelae.