WASHINGTON — It’s no longer necessary for Marines suffering from mild traumatic brain injuries to have been knocked unconscious to qualify for a Purple Heart, a retroactive change that could affect thousands of troops who have served in battle since Sept. 11, 2001.

Under a new fleetwide instruction, Marines who retain consciousness after a concussion may receive the medal if diagnosed by a medical officer as not fit for full duty “due to persistent signs, symptoms, or findings of functional impairment for a period greater than 48 hours from the time of the concussive incident.”

TBI, which has been called a “signature wound” of the wars in Afghanistan and Iraq, is often caused by blasts. In its mild form it can result in nausea, dizziness, speech problems and loss of coordination. Recent research suggests any form of TBI may cause clinical depression in 30 percent of sufferers.

The instruction notes that the damage caused by mild TBI can be serious and lasting: “In the more severe cases of [mild TBI], the level of inflammation may result in irreversible damage to brain tissue with long term impairments to brain function.”

About 29,000 Marines have been diagnosed with TBIs since the 9/11 attacks, of which more than 22,000 are classified as mild. Only 9,473 have received Purple Hearts over the same period, according to Marine statistics.

”Marines have always rated a Purple Heart for TBI or mild TBI if there was a loss of consciousness,” said Marine spokeswoman Maj. Shawn Haney. “This expands on that, and broadens the category ... to say you don’t necessarily have to be unconscious.”

Throughout the military, about 202,000 troops have been diagnosed with TBI since 2000.

According to a 2010 Defense Department report to Congress, the Marine Corps was the only service that had specified loss of consciousness as the threshold for requiring medical treatment for combat brain injuries. Only injuries that require medical treatment are eligible for a Purple Heart.

Sign Up for Daily Headlines

Sign up to receive a daily email of today's top military news stories from Stars and Stripes and top news outlets from around the world.

Sign Up Now