A 28 year old 18-series Soldier was the driver in a vehicle which struck an improvised explosive device (IED). The vehicle was destroyed and the other occupant in the vehicle was killed instantly. The Soldier recalled hitting the roof of the vehicle a least once; however, he suffered no life-threatening injuries and was not initially evacuated to higher medical care. Immediately following the event the Soldier noticed a headache, mild dizziness, nausea, and short-term memory loss. Upon return to the forward operating base (FOB), he was evaluated by the forward surgical team physician who performed a military acute concussion exam (MACE). His score was 24 out of 30 and he was diagnosed with a mild concussion, his symptoms were treated with acetaminophen, and he was released. On day three, he participated in another combat patrol. During the operation he suffered from dizziness and headaches. He self-medicated with acetaminophen and meclizine transdermal for his symptoms. On this patrol, he was exposed to overpressure from explosions on two separate events. Each explosion was the equivalent of approximately 27 pounds of TNT (trinitrotoluene). Following this mission, he returned to his FOB and noticed increased dizziness, nausea, and memory loss. No other members of his team who were exposed to those two explosions reported any symptoms. He continued to self medicate with acetaminophen and meclizine transdermal. He did not seek follow-up medical care. Later that same day, he participated in a third mission as part of a quick reaction force which included a high altitude helicopter assault. He was not exposed to any additional blast or injuries. After returning from the third mission, the patient experienced significant fatigue. He went to sleep and later the same night experienced loss of consciousness after quickly standing from a lying position. Upon recovering consciousness, he experienced increased dizziness, nausea, and emesis. He was evaluated by the unit medical provider and evacuated to a Level III Theater Hospital. Over the next three days, his nausea and dizziness improved; however, he continued to have significant issues with short term memory loss, difficulty concentrating, short-term memory recall, and headaches. His MACE scores slowly improved to 27 out of 30 over several days. He was evacuated through Landstuhl Regional Medical Center to the United States for additional evaluation and treatment.