4 WEST - BRK. 45: EMPLOYEE WAS UNLUGGING TRACK TIES WITH A HAMMER, WHEN HE MADE A SWING WITH THE HAMMER; HE MISSED THE TIE AND FELT SOMETHING PULL IN BACK WITH BURNING/TINGLING IN LEFT LEG. THIS EMPLOYEE CONTINUED TO WORK UNTIL 5/2/00. HE STARTED MISSING WORK ON 5/3/00.