What is the usual operating room hours for a brain surgeon in the u.s.?

Depends: This will depend on where the surgeon is in his/her training. As residents, there is an 80-hour work week limit imposed. Speaking personally as a private attending, where there is some control of the types of cases being done, i perform between 200-300 cases a year. Figure 20 cases a month, running 1-2 hours for simple cases and much longer for more complicated cases. Perhaps 12-20 hours per week.