Why does Cristiano Ronaldo have zigzag hair?

There have been tens of thousands of tweets about Cristiano Ronaldo's new zigzag haircut - with many of them praising him for his "tribute" to a boy who had brain surgery. But is this just a big Twitter rumour?

Portugal's Cristiano Ronaldo has been trending around the world since late on Sunday, not for his footballing prowess, but his latest haircut - a bold zigzag-y stripe on the right-hand side of his head.

When he first sported the new style in public, a few hours before the Portugal v USA game, Twitter erupted in a collective round of head-scratching and mickey-taking. Some suggested it merited a place among the World Cup's "worst haircuts". Others wondered if it was a funky-looking "7" - similar to Ghana's Asamoah Gyan, who has a yellow "3" dyed into his hair.

And there were thousands of references to a certain wizard's scar. "What's with Ronaldo's hair? Is he sponsored by Harry Potter now or something?" for example.

But the widespread mockery of his locks - admittedly mostly from Americans - soon morphed into something completely different. And it sent the Twitter rumour mill into overdrive. A single tweet from a regular football fan with 900 followers seems to have been the trigger.The tweet read: "Ronaldo cut his hair to match the scar of a young fan who had surgery to remove a brain tumor last week. #respect."

That tweet has now been shared more than 11,000 times. It was also copied word-for-word and reposted by numerous larger accounts. In all, there have been about 50,000 tweets and retweets. The problem is, there's nothing to suggest this is anything but a rumour. Ronaldo himself has not posted to his social media accounts since before Sunday's match, and neither his agent nor the Portugal team have responded to our request for clarification.

Some people who've had brain surgery started sharing images of their scars

It does appear to be the case that, some months ago, Ronaldo paid for the treatment of a young child needing surgery for a brain abnormality,cortical dysplasia, which causes epileptic fits. The story was widely reported in the media - and a screengrab from a USA Today articleabout this was included in the original tweet. But whether Ronaldo's haircut has anything to do with this, or brain tumours - or anything else - is anyone's guess.

Whether it's true or not doesn't matter to 29-year-old Nick Barrett who lives in Florida and who had brain surgery for a tumour eight months ago. He tweeted photos of his large, curved, post-surgery scar after watching the game and the discussion online. "It brought back memories," he told BBC Trending. "When you walk around with a scar like that, everybody looks at you... It would be great if it just raises awareness about it."