A tool used for evaluating mild traumatic brain injury in service members may not be sensitive enough in the absence of further evaluation, according to study results.

HONOLULU—One of the Department of Defense’s (DoD’s) tests for evaluating traumatic brain injury (TBI) in service members may be insufficiently sensitive when used by itself, according to study results presented at the 63rd Annual Meeting of the American Academy of Neurology.
“The bottom line is that there is no one test for determining who is able or unable to return to the fight after a concussion that is reliable, free of confounding factors, reproducible, and possible for a combat medic to administer on the battlefield,” COL Richard Young, MD, of the University of Connecticut School of Medicine, told Neurology Reviews.
Dr. Young and Kevin Scott, MD, Associate Professor of Neurology at the Pennsylvania State College of Medicine in Hershey, compared the effects of combat TBI and noncombat TBI by evaluating a cohort of 42 service members, 28 of whom had combat TBI exposure and 14 of whom had noncombat TBI exposure. One of the tests used in their evaluations was the Military Acute Concussion Evaluation (MACE), which the DoD has used as a TBI screening tool since 2006. The researchers found that while there was a trend toward worse MACE scores in patients with combat TBI compared with noncombat TBI (19.7 vs 27.4), the difference did not meet statistical significance.
These results suggest that “the MACE, in isolation, is likely not sensitive enough to stratify patients or differentiate between the two [types of injury] for the purposes of management in the setting of a forward unit without easy access to higher-level medical care (eg, neurologists),” said Dr. Scott. “It provides useful data for any individual soldier to follow their recovery or lack thereof, but is best used in combination” with further evaluations. He noted, however, that the study sample was not large enough to provide definitive statistical conclusions.
Challenges of Military Evaluations
The DoD’s evidence-based guidelines for evaluating nonpenetrating TBI, which has been called the signature injury of Operation Iraqi Freedom and Operation Enduring Freedom, are still a “work in progress,” said Dr. Scott. “With the focus on these types of injury, today’s soldiers have significantly better protection and better medical care that emphasizes early assessment and prevention of cumulative damage. Outcome measures often take time to be developed, and I think there will be a lot learned with respect to the value of medications, counseling, rehabilitation, and timing of imaging.”
At present, the best method of determining when a service member can return to duty is a careful neurologic examination, Dr. Young added. “The neurologic evaluation can best evaluate the nature of the injury, the results of cognitive testing, the service member’s degree of psychological stress, the MACE results, the prior educational status, and imaging results (if available). However, there is often no neurologist in theatre, or, only at one base. To obtain a neurologic assessment often necessitates sending the service member to Landstuhl Regional Medical Center [in Germany], with a turnaround time of two to three weeks.
“I know of no research regarding when soldiers are returned to duty,” he continued. “Current doctrine is to remove soldiers from action after a head injury.
Return to duty is a commander’s decision (the physician makes a recommendation to the commander; the commander decides) and is often dictated by the operational needs of the mission. In addition, some soldiers return to duty immediately without seeking medical attention, much as high school football players ‘shake off’ a TBI and return to play without informing their coaches of a concussion.”
Both MACE and the Automated Neuropsychological Assessment Metrics, a computerized assessment that the DoD uses to evaluate TBI, lack specificity and sensitivity, according to Dr. Young. He added that there are additional problems with using these assessments to evaluate deployed soldiers.
“There is a paucity of information about the MACE and its usefulness in the field,” said Dr. Young. “However, the MACE is identical to the Acute Sports Concussion Examination (ASCE), which is used by trainers to evaluate football players and others engaging in contact sports. Scores on the ASCE decline significantly following a concussion, but they may return to baseline within 24 hours. One of the major problems with mild TBI in Iraq is that it may be days before the service member can seek medical attention. By that time, the MACE results may be less reliable.”
Dr. Young said that his experience with service members deployed in Iraq suggests that preexisting cognitive issues may hinder the accuracy of TBI evaluations. “Several soldiers at the Joint Base Balad TBI clinic performed particularly poorly on the mathematics section of the ANAM or the entire test,” he said. “The psychologist at the TBI clinic referred these patients to me for neurologic evaluation. He and I agreed that the soldiers’ poor performance on the ANAM was due to pre-existing cognitive issues—in all likelihood, unrelated to their head injury.”
He added that ANAM is unavailable in Iraq outside of Joint Base Balad and that many service members do not have a baseline ANAM with which a post-TBI ANAM can be compared.
Combat TBI Versus Noncombat TBI
Drs. Young and Scott found some differences between injured service members depending on whether they had combat or noncombat TBI. All of the combat injuries were caused by improvised explosive devices, while the causes of noncombat injuries included falls, motor vehicle accidents, and sports.
Patients with combat TBI were significantly more likely than those with noncombat TBI to experience memory loss (44% vs 13%) and tinnitus (44% vs 6%). Headache, the most common symptom both in combat TBI and in noncombat TBI, was more common in the former injury (70% vs 50%), though the difference was not statistically significant. Patients with combat TBI also showed a nonsignificant trend toward concentration problems (43% vs 14%).
These differences may have been due to a greater severity of injury with combat TBI and to a greater lapse of time before evaluation in noncombat TBI, said Dr. Young. “It is possible that this lapse of time allowed the headache/concentration problems in the noncombat TBI to begin to resolve,” he said. He added that further research is needed to determine whether the circumstances surrounding a TBI play an important role in the injury, which could result in different outcomes for similar injuries depending on whether they occurred on the battlefield.

—Jack Baney

Military Test May Be Insensitive for Detecting TBI