MANKATO -- Vikings wide receiver Percy Harvin has been dealing with migraine headaches after the death of his grandmother, according to coach Brad Childress. Harvin has not practiced since July 31 and it remains uncertain when he will return to the team. There appears a real chance he might not return to Mankato, considering that training camp practices end Thursday.

Childress confirmed that Harvin has "had some" migraines, a problem he dealt with on several occasions last season. Harvin, who missed one game last season because of the issue, was sent to the Mayo Clinic in Rochester last winter and the Vikings came away from that visit confident that Harvin had found a better treatment plan.

However, migraines can be triggered by stress and Harvin has certainly had that with the passing of his grandma in late July. "God willing he is going to work through this," Childress said, confirming that Harvin remains in the Twin Cities.

Agent Joel Segal would only say the Vikings were handling the situation.

"It's ongoing," Childress said of how the team and Harvin are dealing with his migraine issues. "From the people at Mayo that are extremely qualified, there is a Mayo down in Jacksonville. He's seen neurologists. It's just something that continues on. The only thing that would be wrong is if we quit trying to find things and throw our hands up in the air. It's kind of an inexact science if you will."

Asked when Harvin would return, Childress said: "I'm not sure. If I knew I would tell you."

Meanwhile, the Vikings signed wide receiver Freddie Brown from Utah on Monday to add a fresh body to a depth chart that is missing Harvin and Sidney Rice. Brown, according to NFL.com, had been with Cincinnati. The Vikings released strong safety Terrell Skinner to make room for Brown. Childress said the Vikings worked out two wide receivers on Tuesday morning before signing Brown.

Other notes from Tuesday:

  • The Vikings had planned to conduct a practice in full pads outside Tuesday but after stretching and starting special teams drills the rumble of thunder and lightning moved in and the team quickly got off the field. The Vikings then conducted a special teams practice inside Myers Field House and is hoping to get in a full practice starting at 2:45 p.m. this afternoon. The plan had been for the afternoon session to be special teams only.
  • Darius Reynaud, who suffered a sprained ankle last week, returned to practice. Meanwhile, tight end Jim Kleinsasser was set to miss a second consecutive practice with an undisclosed injury.
  • Also missing from Tuesday's practice (when it looked as if it would be outside) were Harvin, Rice (hip), cornerback Cedric Griffin (knee), long snapper Cullen Loeffler (family related), linebacker J Leman (toe), guard Anthony Herrera (back), center John Sullivan (calf) and tight end Visanthe Shiancoe (unknown injury).