Fifty American military service members suffered traumatic brain injuries following Iran’s Jan. 8 missile strike on a base in western Iraq that was housing U.S. military personnel, the Pentagon announced on Tuesday, Jan. 28.

This is the third time the number of injuries has been increased since the first time the military informed that the number service members—11—were injured. Last week, the Pentagon said that 34 U.S. service members were hurt.

“Of these 50, 31 total service members were treated in Iraq and returned to duty, including 15 of the additional service members who have been diagnosed since the previous report,” said Lt. Col. Thomas Campbell, a Pentagon spokesman. “Eighteen service members have been transported to Germany for further evaluation and treatment.”

“This is an increase of one service member from the previous report, who had been transported to Germany for other health reasons and has since been diagnosed with a TBI [traumatic brain injury),” Campbell added.

For the eight other service members who had been transported to the United States last week for evaluation and treatment, no update has been made.

The military said symptoms of concussion or traumatic brain injury were not immediately reported after the strike and in some cases became known days later.

Traumatic brain injuries are considered to be the signature wound and the invisible epidemic from the wars in Iraq and Afghanistan and became a bigger concern for the military in recent years. Service members who suffered explosive blasts of roadside bombs later suffered concussion-like effects. The severity and duration of the injury can vary widely.

The Defense Department has said more than 375,000 incidents of TBI occurred in the military between the years 2000 and 2018. The Centers for Disease Control and Prevention said a severe TBI may lead to death or result in an extended period of coma or amnesia, according to TIME