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Acute Management of Mild Traumatic Brain Injury in Military Operational Settings The Defense and Veterans Brain Injury Center Working Group (page 2 of 5) Page 2 of 5

Wide consensus among experts supports the inclusion of an alteration of consciousness in the definition of mTBI, including reports of feeling “dazed and confused” after a traumatic event. Because the primary mechanism of mTBI in the current operational settings is explosion/blast, multiple mechanisms such as the over pressurized blast wave, or heat or toxic injury, some of the experts were concerned that this definition may be too conservative. There are instances, both in the sports literature and military arena, of individuals who were involved in a traumatic event without any alteration of consciousness, yet these patients have subsequently developed symptoms of concussion. We would suggest that those individuals involved in significant blast events and report subsequent symptoms be evaluated further. However, without supportive scientific evidence, we would not classify these patients as having sustained an mTBI. More inquiry is needed to explore this group before an objective conclusion can be formulated (Guskiewicz et al, 2004).

Physical and Neurocognitive Sequelae

The literature and clinical practice indicate that there often will be deficits for some period of time with respect to balance/motor functioning including postural instability or cognitive domains such as: attention/concentration, memory, cognitive processing speed, simple/complex reaction time, and/or executive function (Bleiberg et al, 2004; Warden et al , 2001). In one study by McCrea et al (2002), at least 84% of concussed athletes demonstrated neurocognitive deficits immediately after injury to include difficulties with orientation, immediate memory, concentration or delayed recall, as evidenced by their Standardized Assessment of Concussion (SAC) scores. The natural history of symptoms, balance problems and cognitive dysfunction following mTBI has been plotted in large-scale prospective studies of athletes demonstrating recovery in the majority of mTBI cases within one week (McCrea et al, 2003).

In military operational settings, the effect of concussion on function and judgment may cause risk to self and others. Alterations in attention/concentration, maneuverability/ flexibility/judgment, and impulse control, for example may adversely affect driving, handling firearms, establishing situational awareness, following rules of engagement or controlling aggression, and may result in adverse outcomes such as friendly fire incidents. These factors should be considered by medical personnel while making return to duty decisions.

Because of multiple deployments to theatres of combat, the risk for troops to sustain more than one mild brain injury or concussion is elevated. No literature is available to describe risks or sequelae of cumulative concussion sustained during combat operations; therefore, much of what is known about cumulative concussion has come from the sports literature. Parallels can be inferred between the sport and combat environments such as prolonged recovery time, costs of lifetime care, and decrease in troop strength/force readiness. Athletes with a history of concussion are more likely to suffer future concussive injuries than those without a history (Guskiewicz et al, 2003). A history of previous TBI is found to be associated with a poorer performance on neuropsychological tests as well (Collins et al, 1999). No difference exists, however, between the assessment and treatment of a service member with cumulative concussion and someone experiencing an initial concussion at this time. History of previous concussion alone should not prompt an evacuation to a higher echelon of care. Instead, evacuation decisions should be made based on assessment data for the particular service member.

Posttraumatic Stress Disorder (PTSD) and TBI overlay

There is an overlap of symptoms between TBI and Acute Stress Reaction (ASR) or Posttraumatic Stress Disorder (PTSD). This issue is most pertinent in the mTBI population as there are higher rates of ASR and PTSD seen in patients with mTBI than with more severe injuries (Glaesser et al, 2004). Sustaining any kind of physical injury in theater is known to increase a service member’s risk for PTSD (Hoge, 2004). There are several symptoms which are found in both PTSD and mTBI, such as deficits in attention and memory, irritability and sleep disturbance. However in the acute assessment of mTBI, some of the distinguishing symptoms such as headache, dizziness, balance problems and nausea/vomiting may help to differentiate TBI from ASR/PTSD.

Another distinguishing factor is the history that is obtained from the service member about the course of events before, during and after the traumatic event. Post traumatic amnesia is less common in ASR/PTSD and is diagnostic of mTBI. Fortunately, the acute treatment for both mTBI and ASR are similar.

Neurocognitive Assessment

Neurocognitive assessment in the mild TBI patient is an important part of a comprehensive approach to care. After providing evidence outlined above as to the neurocognitive sequelae after mild TBI, utilizing neurocognitive assessment procedures can be helpful in determining cognitive deficits as well as recovery from transient cognitive deficits often associated with mTBI. The Military Acute Concussion Evaluation (MACE) tool developed by the Defense and Veterans Brain Injury Center has a history and evaluation component. The history component can confirm the diagnosis of mTBI and provide further assessment data by utilizing the Standardized Assessment of Concussion (SAC) (McCrea, 2000) to preliminarily document neurocognitive deficits. This tool can be easily used by medics and corpsmen to confirm a suspected diagnosis of concussion and can be administered within 5 minutes. The four cognitive domains tested are: orientation, immediate memory, concentration and delayed recall (Appendix A).

The MACE is the recommended tool for use in theatre at Level I and II and III.

Beyond the use of the MACE, other neurocognitive measures should be used at Level III to comprehensively assess the cognitive state of the injured service member. Consensus was reached on areas to assess and the following neurocognitive domains should be assessed and documented in troops sustaining mTBI in theatre:

• Attention/concentration
• Memory
• Processing Speed
• Reaction Time
• Executive Function

There are many factors related to the applicability, utility and practicality of neurocognitive assessment procedures in the current operational environment. Some of these include:

From the Defense and Veterans Brain Injury Center Working Group. www.dvbic.org.

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