First link no mention of any blackouts but he does mention the impact to the head.
Found this interesting, as it´s probably something Massa experienced after his crash,
Second link, no mention of a blackout, but mentions he felt ill.Perez told the media that Monaco accident discouraged him a lot for the remaining races of the 2011 Formula 1 season.
Perhaps it´s a combination of mental issue and physical issue. Would like to find the link where he says he nearly blacked out on the straight, that would put a nail in the coffin as far as my argument goes."I am deeply disappointed. I spoke to the team after the session and told them that I'm not a 100% fit. I only want to drive when I'm 100% well. I need some more time to recover."
BBC 5 live pit-lane reporter Jennie Gow said she had been told by team boss Peter Sauber that Perez "lacked confidence and wasn't as comfortable in the car as he felt he should be".
And commenting on Perez's withdrawal, Sauber added: "Maybe we are being overly cautious, but when it's about the health of our drivers we take zero risks."