This is not Percy Harvin, but use your imagination.

Here at Goal-Line Stand, we were quite involved in the Colts-Bills preseason game in Toronto yesterday. Lost in the shuffle because of that was a scary incident involving Vikings wide receiver Percy Harvin.

Harvin vomited and collapsed on the sideline at Vikings practice. The apparent culprit: another migraine.

The 22-year-old star-in-the-making from Florida dealt with chronic migraines for much of his rookie season, missing several practices and a game. Despite an offseason trip to the legendary Mayo Clinic, Harvin’s head problems aren’t going away in 2010. Before his medical emergency Thursday, Harvin had already missed pretty much all of training camp because of the chronic issue.

In what has become one of the most famous stories in NFL history, Terrell Davis scored a touchdown in Super Bowl XXXII despite not being able to see straight due to a migraine. And I’m thinking that tale has softened the average sports fan’s expectations in regard to how debilitating migraines can be.

Harvin’s been plagued by this problem since he was 10 years old, and it’s clearly hindering his ability to perform consistently as a professional athlete (not to mention his ability to perform day-to-day tasks as a human being).

So, could migraines ruin Percy Harvin’s career?

“He said he’s tried everything,” Vikings left tackle Bryant McKinnie told ESPN.com. “Hopefully he can eventually find something.”

But to actually try everything, it could take a lifetime. I had a conversation with osteosomatic therapist Dan Palma from the Toronto-based Headache and Pain Relief Centre. The majority of Palma’s patients are migraine-sufferers, most of whom get rid of their symptoms permanently once they’ve been treated.

The problem, though, according to Palma, is that it’s extremely difficult for a specialist to determine what’s triggering the migraines in patients that don’t wipe them out the first time around.

“There is a very small percentage of recurring or chronic patients that you’ll stabilize and, guess what? After a while they need to come back and do the whole program again,” Palma said.

Palma says there are dozens of potential causes that trigger migraines — deep-seated vascular problems, hormonal imbalances, benign tumours, aneurysms, teeth grinding, stress, and jaw issues to name a few — meaning it can take years to properly diagnose the underlying root, or roots, of the problem.

Palma, who interned with the 49ers in the 1980s while attending San Francisco State University, notes that we rarely hear of athletes suffering from chronic migraines because they’re less likely to encounter them.  

“I would find that we have less athletes presenting with chronic migraines,” he said, “and if we do (get them), they tend to respond better to treatment.” That make sense, because athletes are generally healthier than the average Joe.

But it’s too late for a guy like Harvin. Treatment hasn’t work for 12 years and there’s no telling when it will. What does an athlete do when migraines are interfering with his or her livelihood and there’s no cure in sight?

“You need to slow things down,” Palma said. “Of course that’s not easy when you’re being paid to perform.”