"You always want to try and be positive, but I think losing Malcolm is a huge loss for us and depending upon how long that is," McVay said, via the Los Angeles Times. "But it's a big deal for those guys to have to step up, and they've got large shoes to fill, that's for sure."
Brown has rushed 43 times for 212 yards and added five receptions for 52 yards and a touchdown for the Rams (11-1), who visit the Chicago Bears (8-4) on Sunday night (8:20 p.m. ET).
Justin Davis and sixth-round pick John Kelly will be called upon to play behind Gurley, who is the 2017 NFL Offensive Player of the Year.
"It would be a huge loss because of what Malcolm means to our football team -- not only for our offense, but for our special teams," McVay said. "And if that's the case, then it would probably be something where both Justin and John would have to end up stepping up in a role where they'd both maybe potentially would be asked if they need to sub for Todd and then get some different work."
Brown has played 36.4 percent of the Rams' special teams snaps this season.
"I mean if Malc's out for a while, it's a huge loss," left tackle Andrew Whitworth said. "He's a heck of a football player, a guy that does nothing but step in and rise to the occasion every time we need him and Todd needs a blow. He's somebody that I think everybody in the locker room has an appreciation for -- just the physically he plays with, and just the guy he is."