Brian Austin Green -- Spousal Support Necessary ... Vertigo Derails Work

Brian Austin Green will almost certainly get spousal support from Megan Fox in their divorce, and the reason appears to stem from a terrible car accident.

TMZ broke the story, Megan filed for divorce Friday. As we said, our sources say it's likely she'll end up paying Brian spousal support, because of the large disparity in income and income potential.

We're told Brian has worked very little since last December, when he was in a head-on collision. As we reported, Brian and Megan were driving when they were hit by a drunk driver who was arrested. Brian says the guy was going around 50 MPH and it was severe enough for the airbags to deploy.

At the time of the accident TMZ was told Brian and Megan were not injured. But now we're told the accident triggered a serious medical condition ... vertigo, which affects balance.

Our sources say Brian's vertigo is so bad he can't get out of bed. We're told he hasn't worked since the accident.

As we reported, Brian and Megan -- who is working steadily on huge movies -- are still living in the same home.