A concussion or mild traumatic brain injury (mTBI) is a disruption of brain function caused traumatically by a blow to the head or an acceleration/deceleration (whiplash) event in which there are subsequent changes in awareness, thinking ability, sensation, motor control, and emotion. Loss of consciousness or a blow to the head is not necessary to cause a concussion.
Concussions disrupt cell-based electrical and chemical regulation and have both immediate and somewhat delayed effects. Radiologists cannot see a concussion on standard CT or MRI scans and we do not yet have accurate and readily available blood tests to make this determination. Concussion remains a largely clinical diagnosis, relying upon history, symptoms, and changes in function.
While concussions have received significant attention in the past 10-15 years in the context of contact sports, concussions are also very common in automobile collisions. The Centers for Disease Control (CDC) report that 17% of people in accidents suffer concussions. However, more than half of auto accident concussions are missed by ER doctors (Powell 2008) and a subsequent study (Cassidy, et. al, 2014) upgraded that estimate to 24%. The most recent research (Clionsky and Clionsky, 2017a and 2017b) finds that as many as 40% of auto accident patients suffer problems with memory and response time one to two weeks after the accident. In other words, accident concussions are much more common than has been thought and may be more common that sports concussions.
Most concussions resolve in a matter of weeks or months, but in the meantime, they impair everyday, school and work function, create significant emotional distress, and put that patient at higher risk if they have a second concussion. And, about 20% do not resolve and may become permanent. Earlier identification of at-risk patients improves medical care and may prevent diagnostic confusion and emotional distress.