Prospectively Assessed Clinical Outcomes in Concussive Blast vs Nonblast Traumatic Brain Injury Among Evacuated US Military Personnel

Abstract

IMPORTANCE Blast injury has been identified as the signature injury in the conflicts in Iraq and Afghanistan. However it remains to be determined whether fundamental differences may exist between blast-related traumatic brain injury (TBI) and TBI due to other mechanisms.OBJECTIVES To determine similarities and differences between clinical outcomes in US military personnel with blast-related vs. non-blast-related concussive TBI and to identify the specific domains of impairment that best correlate with overall disability. DESIGN, SETTING, AND PARTICIPANTSProspective cohort study involving active duty US Military personnel evacuated from Iraq or Afghanistan to Landstuhl Regional Medical Center, in Landstuhl, Germany. Four groups of participants were enrolled from 2010 to 2013: (1) blast plus impact complex TBI (n=53), (2) non-blast related TBI with injury due to other mechanisms (n=29), (3) blast-exposed controls evacuated for other medical reasons (n=27) (4) non-blastexposed controls evacuated for other medical reasons (n=69). All patients with TBI met Department of Defense criteria for concussive (mild) TBI. The study participants were evaluated 6-12 months after injury at Washington University in St Louis. In total, 255 subjects were enrolled in the study, and 183 participated in follow-up evaluations, 5 of whom were disqualified. MAIN OUTCOMES AND MEASURESIn-person clinical examinations included evaluation for overall disability, a standardized neurological exam, headache questionnaires, neuropsychological test battery, combat exposure and alcohol use surveys, and structured interview evaluations for post-traumatic stress disorder (PTSD) and depression.RESULTS Global outcomes, headache severity, neuropsychological performance, and surprisingly even PTSD severity and depression were indistinguishable between the two TBI groups, independent of mechanism of injury. Both TBI groups had higher rates of moderate to severe overall disability than the respective control groups: 41/53 (77%) of blast plus impact TBI and 23/29 (79%) of nonblast TBI vs. 16/27 (59%) of blast-exposed controls and 28/69 (41%) of non-blast-exposed controls. In addition, blast-exposed controls had worse headaches and more severe PTSD than non-blast-exposed controls. Self-reported combat exposure intensity was higher in the blast plus impact TBI group than in nonblast TBI group and was higher in blast-exposed controls than in non-blast-exposed controls. However, combat exposure intensity did not correlate with PTSD severity in the TBI groups, but a modest positive correlation was observed in the controls. Overall outcomes were most strongly correlated with depression, headache severity, and number of abnormalities on neuropsychological testing. However a substantial fraction of the variance in overall outcome was not explained by any of the assessed measures. CONCLUSIONS AND RELEVANCEOne potential interpretation of these results is that TBI itself, independent of injury mechanism and combat exposure intensity, is a primary driver of adverse outc...

The Impact of Multiple Concussions on Emotional Distress, Post-Concussive Symptoms, and Neurocognitive Functioning in Active Duty United States Marines Independent of Combat Exposure or Emotional Distress

“…Indeed, a recent study of active duty soldiers showed that recent concussion, independent of injury mechanism or combat exposure, is predictive of persistent post-concussive complaints. 54 Thus, although these findings are consistent with research that failed to find independent evidence for the presence or absence of previous concussion, the evidence of recent and multiple concussion across a range of emotional distress, post-concussive symptom, and neurocognitive functioning is in contrast with other studies that failed to find a unique contribution for concussion across a wide range of persistent post-concussive symptoms. 18,55 Possible reasons for this may include the failure of other studies to include both objective and subjective assessments of functioning, assessment of a wide range of PPCS including neurocognitive, selfreport emotional and somatic symptoms, and, most importantly, the distinction between single and multiple concussion, and its recency.…”

Chronic Neurodegeneration After Traumatic Brain Injury: Alzheimer Disease, Chronic Traumatic Encephalopathy, or Persistent Neuroinflammation?

“…Similar symptoms and brain pathology have been reported following multiple mTBI in other contact sports, particularly American football, and termed chronic traumatic encephalopathy (CTE) [9][10][11][12]. Delayed chronic neuropsychiatric alterations following repeated concussions have also been increasingly recognized in military personnel exposed to improvised explosive devices [13][14][15].…”

Abnormal White Matter Blood-Oxygen-Level–Dependent Signals in Chronic Mild Traumatic Brain Injury

“…93 Our chronic mTBI patients showed some affective problems (higher depression and PTSD scores) and cognitive problems (slower reaction time, poorer memory performance, reduced verbal fluency) in the neuropsychological tests, consistent with previously published studies. 32,51,75 Analysis of the scatter plots of the neuropsychological scores, however, indicated that the distributions for chronic mTBI patients and matched controls showed considerable overlap, even on tests that revealed significant group differences between patients and controls. Further, there was no correlation (except for WTAR scores) between neuropsychological measures or affective disorders and BOLD signal magnitudes.…”