Routinely Used Concussion Screen Less Reliable More than 10 Days after Injury

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By Sandra Basu

WASHINGTON — A new study suggests the military’s current screening and diagnostic tool for concussion lacks utility when it is used more than 10 days following an injury.

“The current study adds to the body of literature indicating that neurocognitive testing, and in particular the ANAM, does not have a role as a screening instrument for detection of concussion by approximately 10 days post-injury,” military researchers wrote in a study published last month in Military Medicine.

In 2008, the assistant secretary of defense for health affairs issued a memorandum directing all services to begin implementing baseline predeployment neurocognitive assessments using the Automated Neuropsychological Assessment Metrics (ANAM) for troops after Congress mandated that all returning troops from Iraq and Afghanistan be evaluated for concussive injury. The purpose of the test is to establish a baseline in the event the servicemember becomes injured. Injured servicemembers are retested, and those results are compared with the original baseline to help determine the treatment plan. It remains unclear, however, how useful the ANAM is after the first few days following injury. DoD researchers also are trying to understand how the ANAM compares with other tests.

Lance Cpl. Steven A. Meyer, an engineer with 3rd Combat Engineer Battalion, 1st Marine Division, takes the Automated Neuropsychological Assessment Metrics test at the Concussion Restoration Care Center at Camp Leatherneck, Afghanistan in 2010. Photo by Cpl. Kenneth Jasik.

ANAM

For this study, researchers went to Iraq in 2009 to test the validity of the ANAM for the diagnosis of concussion in the combat environment by comparing performance on all six ANAM subtests in a group of concussed soldiers compared with that of controls.

While the team found that the ANAM demonstrated utility in detecting neurocognitive dysfunction within 72 hours of a single concussive event, which they said was consistent with previous reported data, the ANAM was found to lack utility as a diagnostic or screening tool 10 days out.

“It showed very little effectiveness after seven days, in fact, but, certainly by 10 days following an injury, the ANAM did not demonstrate sufficient sensitivity or specificity to differentiate those who had a concussion and those who did not,” study author Col. Rodney Coldren told U.S. Medicine.

Coldren said that clinicians relying on the test results after the seven- to 10-day delay could create two dangers: One would be if the results appeared normal and the clinician discounted the possibility of ongoing problems due to concussion. On the other hand, the ANAM could show “abnormal results,” leading the clinician to conclude that the servicemember suffered a concussion. That finding of “abnormal results” could be misleading, however, because the ANAM does not appear to have diagnostic accuracy at seven to 10 days after injury, he explained.

Still, Coldren said “as part of an overall evaluation by a medical provider to include a thorough history, symptom review and physical exam, there may be a role for the ANAM in the evaluation of a concussed soldier, even following seven to 10 days.”

“What we don’t want is for someone to have an initial evaluation with the ANAM more than 10 days after an injury and the result of that test to be used as the sole criteria to determine whether someone may or may not have suffered a concussion or any residual symptoms resulting from that concussion,” Coldren explained.

The study authors suggested that alternative strategies “relying on questionnaires focused on medical history are more valuable for screening purposes.”

“Other modalities for screening, to include biomarkers and neuroimaging techniques, must be explored,” they wrote. “A thorough evaluation by a medical provider, including a detailed history and physical examination, must be included in any ‘diagnostic’ assessment of potential concussion or postconcussive syndrome.”

Coldren said an important finding of the study was that “most concussed servicemembers in the theater of operation recovered their neurocognitive functioning within seven to 10 days following their injury,” or, he said more specifically, they “could not detect a difference in neurocognitive functioning between those who suffered a concussion more than seven to 10 days previous and those who had not suffered a concussion.”

The study, “The ANAM Lacks Utility as a Diagnostic or Screening Tool for Concussion More than 10 Days Following Injury,” was published in the February issue of Military Medicine.

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