I've been out since June. Not workman's comp. I have short term disability through my employer. They aren't required to provide that though.
I was advised to look into SSDI by a few people, but that doesn't work unless you're out for at least a year, and even then they want to fight you if you're younger(because you'll potentially be paid out until you're eligible to collect SS). If your brother ends up being out long term then that's something to look into. If that's the case, get a law firm involved. They'll take a cut but it's worth it. If he has a 401k there are some plans that let you withdraw without penalty due to these types of circumstances, but even then I still think you've gotta be out longer.
FMLA isn't gonna help anything in this case, except maybe allowing him to keep his job.