Con-cussions and the systems devised to grade them are inexact -- hardly scientific and standardized.

The lack of certainty is likely not of much comfort to Penn State fans hoping to have an experienced, able-bodied quarterback at the helm when the Nittany Lions face Illinois on Saturday.

Last Saturday against Michigan, both starting quarterback Anthony Morelli and backup Daryll Clark were knocked out of the game with what Assistant Athletic Director for Communications Jeff Nelson termed as "mild concussions".

If this were two years ago, the pair would almost certainly be out this coming week against Illinois.

That is because, as of two years ago, Penn State Athletics adhered to the guidelines created by Dr. Robert Cantu, one of the leading experts on sports concussions.

Under Cantu's guidelines, athletes suffering their first mild concussion may resume play after one full symptom-free week. This meant that if an athlete suffered such an injury on Saturday, he would have to be symptom-free by the time he woke up on Sunday morning in order to play the following Saturday.

In 2004, quarterback Zack Mills was knocked out of the infamous 6-4 loss to Iowa when he suffered a mild concussion. He was not given the go-ahead to play in the next week's game at Ohio State.

Using Cantu's grading scale, Morelli's reported brief loss of consciousness would bump him up from a mild concussion to a moderate concussion.

Such a classification would no longer apply, though, as Penn State no longer uses the Cantu grading system.

After a 2004 international conference in Prague, medical officials at Penn State Athletics changed their grading system. The Prague conference noted that concussion severity can only be determined in retrospect after all symptoms have cleared, the neurological examination is normal and cognitive function has returned to normal as well.

"The only accurate way to diagnose is after the fact, seeing how long it takes to get over the symptoms," said Penn State's team doctor, Wayne Sebastianelli.

What all this means in the current context of the injuries to Morelli and Clark is that a weeklong sabbatical from the date of the last observed symptoms is no longer mandated by Penn State's medical philosophies.

Prague also established that the loss of consciousness should not be used as a primary measure of injury severity -- good news for Morelli's hopes at playing against Illinois.

To date, no concussion grading system is fail-proof and comprehensive, and return-to-play times accompanying these guidelines are often estimates.

"They all leave areas of overlap and areas that aren't covered so there are ways for symptoms to be either under or over-appreciated," Sebastianelli said.

With his head at stake, Morelli someday might appreciate Penn State erring on the side of caution -- no matter how much he and the Lions' faithful want him to play.