Sports vs. Military Concussions

Sports Concussion and Combat Blast Injury

Up until the early 1980s it was believed that most mild head injured patients made rapid and complete recoveries, evidence began to accumulate supporting the notion that these injuries could be problematic for a minority of patients.  Return to work was delayed, and symptoms such as fatigue, headaches, depression, irritability, cognitive slowing, and problems with attention, learning, and memory were noted in a small percentage of mild head injured patients three months post injury. These persistent symptoms were part of the post concussion syndrome (PCS) constellation.

In the mid 1980s, in a unique attempt to control for individual variability and understand mild head injury in civilian populations (motor vehicle accidents, falls, etc.), the University of Virginia began using Sports as a Laboratory Assessment Model (SLAM) to study concussion and what was being termed mild traumatic brain injury (mTBI)/concussion.  These investigations of college football players, which involved brief baseline and repeat post-concussion neurocognitive assessments, revealed that blunt trauma and/or acceleration-deceleration injury to the head, with alteration of consciousness (yet no true loss of consciousness) can result in neurocognitive deficits in attention, concentration, learning, memory, and processing speed, as well as symptoms such as headache and dizziness. They found that with rest, young, healthy, bright, motivated athletes recover within five to 10 days of injury, and sometimes much more rapidly, after a single concussion. Since these original studies, other investigators have noted similar findings across contact sports.

Multiple concussions pose a more complex problem. There is a growing literature and case examples of more severe trauma associated with multiple concussions in sports, as well as a lowering of the threshold for incurring additional concussions. Although rare, returning to play before complete recovery from concussion and sustaining a second concussion can result in a catastrophic neurological injury referred to as second impact syndrome (SIS).

An unexpected benefit of this sports concussion research was that it provided the first empirical data for the development of return to play (RTP) guidelines and decision-making for reducing poor outcome. For example, when using the American Academy of Neurology (AAN) severity and RTP guidelines, if a player were to sustain his or her first mild (grade I) concussion and all symptoms were to subside (with physical exertion) within 15 minutes, they might be allowed to return to play that day. If the symptoms lasted more than 15 minutes (grade II concussion), the player would be held out of play and practice for one week post-symptom resolution.

In the war in Iraq and Afghanistan, improvised explosive devices create blast injuries, which are the most common cause of TBI in the theater of combat. Mild and moderate TBI’s are more prevalent in this conflict due to the vast improvement in protective gear worn by our service members. Blast injuries can result in the full spectrum of closed and penetrating TBIs (mild, moderate, and severe). The mild to moderate blast related TBI’s are often over looked in the presence of more severe polytrauma. Blast injuries are defined by four potential mechanism dynamics:

1. Primary Blast: Atmospheric over-pressure followed by under-pressure or vacuum.
2. Secondary Blast: Objects placed in motion by the blast hitting the service member.
3. Tertiary Blast: Service member being placed in motion by the blast.
4. Quaternary Blast: Other injuries from the blast such as burns, crush injuries, toxic fumes.

The Defense and Veterans Brain Injury Center (DVBIC), in its efforts to assess and manage these blast injuries in theater and at all other levels of care, brought military and civilian head injury and sports medicine experts together to facilitate a dialog on mTBI /concussion, since there are clear similarities between these sports concussions and combat blast injuries. The similarities lie in the secondary and tertiary blast dynamics of blunt trauma and acceleration-deceleration injury.

The physical and neurocognitive symptoms associated with these blast injuries are also very similar to the sequelae of sports concussions and mTBI in motor vehicle accidents. Blast injury, however, is more complex than sports concussion, given the over-pressure and under-pressure atmospheric dynamics and the quaternary collateral trauma.

Nevertheless, DVBIC and its civilian partners recognized the usefulness of using a variation on the sports concussion model for use in theater with these blast injuries, and they developed Clinical Practice Guidelines for the Assessment and Management of Concussion and mTBI. These guidelines offer brief screening techniques (MACE: Military Acute Concussion Evaluation) adapted from those used to identify sports concussion on the athletic field (SAC: Standardized Assessment of Concussion). They also proposed consensus driven return to duty (RTD) guidelines, which were again similar to the RTP sports guidelines (rest and return when symptom free).

Although blast injury dynamics is more complex and often more severe than sports concussion, and it appears that multiple blast traumas are much more common than multiple sports concussions, the lessons learned from sports medicine have paved the way for a better understanding of combat TBI. There is a new awareness of the potential concussion problem associated with blast injury, brief baseline neurocognitive assessments have been initiated pre-deployment for many of our troops, and guidelines are in place to help all healthcare providers, from the medic to the surgeon, in the appropriate assessment and management of this combat injury.

Jeffrey T Barth, PhD
University of Virginia School of Medicine
DVBIC-Charlottesville Rehabilitation Programs