Response to Khokhar et al.,Re: Military Acute Concussion Evaluation: A Report on Clinical Usability,Utility,and User's Perceived Confidence (DOI: 10.1089/neu.2020.7176)

Dear Editor:

Dr. Khokhar and his colleagues evaluated the Military Acute Concussion Evaluation (MACE) in Volume 38 of the Journal of Neurotrauma. ¹ They concluded that military providers had confidence in the MACE—specifically the MACE 2—and that it was very usable. They did acknowledge that conducting the study in a non-deployed setting was a shortcoming. They also noted that the majority of those surveyed had less than 5 years of experience and there was no indication of combat experience among providers.

As a former special operations combat medic of more than 10 years with multiple combat deployments and combat casualties, I thought it prudent to advise that my colleagues and I found the usefulness of the MACE 2 in a combat setting to be extremely limited. First, the MACE 2 can take up to 15 min to complete, which is a significant amount of time in combat or situations requiring expediency. In addition, combat military operations usually last multiple days or involve multiple missions being completed many days in a row. This leads to inherently decreased cognitive capacity especially for item 6-Immediate Memory, item 15-Concentration, and item 16-Delayed Recall.

While the MACE 2 has improved the original MACE by including Vestibular Ocular Motor Screening (VOMS) and the modified Balance Error Scoring System (mBESS), the mBESS has been found to be inconsistent when tested in a military population. ² In addition, the mBESS was found to have a false-positive rate of up to 36.5%. ³

While acknowledging the efforts of the developers of the MACE 2 and the individuals who have continued to research it, its limited usability in combat settings calls for a change. While a multi-faceted approach to concussion evaluation is certainly warranted in most situations, the constraints of combat often preclude it. Given the lower rates of false negatives with VOMS ³ and the overwhelming amount of data supporting VOMS as a useful tool even when administered alone, ⁴ this author would advocate for a consideration of simplifying the MACE 2 to a VOMS by itself in combat scenarios.

Alternatively, proven Rapid Automatized Naming tests such as the King-Devick or Mobile Universal Lexicon Evaluation System, which can both be administered in 40–50 sec, could be valuable replacements. ⁵ These tests can be performed in a much timelier manner and have shown strong concussion screening sensitivity. While more research is required for these tests to be utilized as single tools in combat scenarios, they may serve as more usable and increase willingness of combat medics and other healthcare providers to perform an assessment of individuals with potential concussion when time is prohibitive. Ideally, implementing these tests, which are more user friendly, will aid in early detection of traumatic brain injuries.