WASHINGTON - The Army will allow more battlefield concussions to be eligible for a Purple Heart, embracing the latest scientific findings that even brief periods of dizziness or headaches are evidence of the wound.

The decision to expand the definition for concussions will mean thousands of Purple Heart medals for soldiers denied them in the past.

For decades, Army award regulations used the term "concussion" for the injury, but left it to doctors or battlefield commanders to decide whether a blow to the head during combat warranted the medal.

Many held the view that "you've got to be bleeding to get (the medal)," says Gen. Peter Chiarelli, the Army vice chief of staff, who has pushed for the clarification on awarding a Purple Heart for concussion.

The new rules spell out precisely what constitute a concussion, with symptoms such as any momentary loss of consciousness or memory, dizziness, headache, nausea or light sensitivity. Medical treatment, also required for the medal, is defined by the rules to include merely rest and Tylenol.

More than 80,000 GIs have suffered concussions since 2001, many in combat and often from exposure to roadside bomb blasts in Iraq and Afghanistan.

The figure dwarfs the 26,000 Purple Hearts given to soldiers for other wounds in the two wars. How many concussion injuries will qualify for the award remains uncertain.

Chiarelli, who has worked to reduce a stigma in the Army about mental health problems, says he pushed for the changes in order to correct misconceptions that more subtle forms of concussions cannot be true war wounds.

"We're trying to change our culture. We're trying to get rid of the stigma. And it's hard to do," he says.

"The confusion among Army doctors," says Col. Jonathan Jaffin of the Army surgeon general's office, "was how much head injury qualified for the concussion diagnosis warranting a Purple Heart." The changes now provide clarity, he says.

Col. Tom Quinn of the Army office that oversees awards is urging soldiers who believe they were wrongly denied the award to see a review of their case. "We think that some deserving soldiers may not have been appropriately recognized," says Quinn, urging soldiers to re-apply at 888-276-9472 or hrcawards.tagd(AT)conus.army.mil.

The Army began reviewing how Purple Hearts are awarded for battlefield concussions last year in response to a story by NPR-ProPublica.

Rep. Bill Pascrell, D-N.J., co-chairman of the Congressional Brain Injury Task Force, hailed the changes as long overdue and called for similar criteria for other service branches.

"It is imperative that the Pentagon makes it crystal clear that all service members, no matter what branch they serve in, will be awarded the Purple Heart when they are wounded in any way," Pascrell says.

The Marine Corps awards a Purple Heart only for a concussion that causes a loss of consciousness, says Marine Capt. Patrick Boyce, a Marine Corps spokesman. But new standards have been proposed that could broaden the definition, much as the Army has done, Boyce says.

Apart from the prestige of earning a Purple Heart, the award also entitles the recipient to priority enrollment for VA benefits, exempting them from co-pays for hospital and outpatient care.

Some are cautious about the changes.

"Anything that can be done to erase the stigma so that (soldiers) will not be embarrassed to seek treatment I'm definitely in favor of," says Army Capt. Jonathan Entrekin, a chaplain who served in Iraq. "At the same time, the Purple Heart is one of the most sacred medals that can be received by somebody. We've got to be careful that we're not just giving them out for any reason. We don't want to cheapen that."

But Vietnam Army veteran Rua Pettybacks the new rules.