Harvin's health a growing concern/Erin Henderson update included

Percy Harvin was not on the practice field Wednesday for the portion that is open to the media and it's clear there are growing concerns about the wide receiver's continuing issues with migraine headaches.

Brad Childress said this morning that Harvin is at Winter Park and was on the field for a walk-through, but the Vikings coach did not hide the fact that the team is exhausting all avenues in trying to find out exactly what is wrong and why the standout rookie continues to suffer from debilitating headaches.

In his most extensive comments about Harvin's situation to date, Childress said the rookie saw another doctor on Monday and indicated that he went through a variety of tests to make sure the problem doesn't go beyond migraines. Harvin has suffered from the problem since he was 10 years old and has missed several practices this season because of the issue. But last week, marked the first time he had missed an entire week of practice and a game in the NFL. He missed two games as a sophomore at the University of Florida. However, the episodes seem to becoming more and more frequent of late.

"You know I think [the doctors] attempt to alley their fears in terms of other things, worse things, by asking questions," Childress said at his mid-week news conference. "But not being a doctor, they've got a whole set of kind of protocols that they are taking him through."

Asked if those protocols were continuing, Childress said, "It's still part of the process." Childress added that Harvin wil be seeing "somebody whose expertise lies in the area," of migraines.

The Vikings knew about Harvin's issues with migraines when they took him with the 22nd pick in the first round of the draft last April but at that point the headaches were not as frequent as they've become in Minnesota.

Harvin, for instance, missed two days of practice leading up to the Vikings victory over San Francisco in Week 3. However, he was able to play in that game and caught four passes for 51 yards and returned a kickoff 101 yards for a touchdown. He missed a practice the week before the Vikings beat the Packers on Nov. 1 but had five receptions for 84 yards and a touchdown in the victory and also averaged 35 yards on five kickoff returns. Harvin also landed on the injury report the day before the Vikings beat the Bears on Nov. 29. He had six catches for 101 yards and a touchdown that day.

"We're attempting to look into and see if there are any common denominators," Childress said of the tests Harvin is undergoing. "He's been having them for a good period of time. It's important for us to get some kind of baseline if we can, doctor-wise, and yet still know that [the migraines] are fairly unpredictable. We as coaches -- you know, the controlling types -- we would like to control those things but that's something beyond my control. So I'm maturing too in the things I can control and can't control."

Said Childress when asked if the Vikings were aware of the extent of the problem back in April: "[We] really didn't. [We] just knew that it said migraine headaches on the scouting report. ... Just so we're clear, it wouldn't have been a disqualifier or anything like that. But I think anybody that reads the scouting report, I don't know that we look into it and say, 'Oh, boy, to what extent?' Not to the point where he's missed a bunch of games or anything like that. We'll be wiser next time and, again, it's just something that we have to learn and deal with."

Harvin is the favorite to win the NFL offensive rookie of the year honor. He is second on the Vikings with 48 receptions for 681 yards and six touchdowns and has averaged 29 yards with two touchdowns on 34 kickoff returns.

Practice update: Harvin was the only player not on the field during practice. Tyrell Johnson (concussion) returned after missing last week.

Henderson serving suspension: Vikings backup linebacker Erin Henderson must spend the next four weeks away from Winter Park as he serves his four-game suspension for violating the NFL's policy on performance-enhancing substances.

Henderson, the younger brother of injured Vikings linebacker E.J. Henderson, only had been active for two games this season and played on special teams. Childress said seen four players now face suspensions for violating the league's policy on performance-enhancing substances. This includes defensive end Ray Edwards and defensive tackles Kevin and Pat Williams, who have yet to serve four-game suspensions because their case remains tied up in the legal system.