Initially the Pentagon said there were no injuries in the missile attack, but as more symptoms were diagnosed, the number was updated to 11, then 34 and now 50.
Officials have acknowledged that it can take time for the concussion-like symptoms to present themselves.
"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 spokesperson. "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," Campbell added.
There was no update on the eight other service members who had been transported to the United States last week for evaluation and treatment.
The increasing numbers of service members who suffered from traumatic brain injuries in the attack earlier this month has become a political controversy because of President Donald Trump's recent comments that the injuries were "headaches" and "not serious."
This past weekend, the head of the Veterans of Foreign Wars requested that the president apologize for "his misguided remarks."
"We ask that he and the White House join with us in our efforts to educate Americans of the dangers TBI has on these heroes as they protect our great nation in these trying times, said William "Doc" Schmits, the VFW's national commander. "Our warriors require our full support more than ever in this challenging environment."
Traumatic brain injuries are considered to be the signature wound and the invisible epidemic from the wars in Iraq and Afghanistan because service members who suffered explosive blasts of roadside bombs later suffered concussion-like effects.
The Pentagon and the Department of Veterans Affairs estimated that 408,000 military service members worldwide have suffered from some form of traumatic brain injuries over the last 20 years.