Influence of the severity and location of bodily injuries on post-concussive and combat stress symptom reporting after military-related concurrent mild traumatic brain injuries and polytrauma.

Traumatic brain injuries (TBI) sustained in combat frequently co-occur with significant bodily injuries. Intuitively, more extensive bodily injuries might be associated with increased symptom reporting. In 2012, however, French et al. demonstrated an inverse relation between bodily injury severity and symptom reporting. This study expands on that work by examining the influence of location and severity of bodily injuries on symptom reporting after mild TBI. Participants were 579 US military service members who sustained an uncomplicated mild TBI with concurrent bodily injuries and who were evaluated at two military medical centers. Bodily injury severity was quantified using a modified Injury Severity Score (ISSmod). Participants completed the Neurobehavioral Symptom Inventory (NSI) and the Posttraumatic Stress Disorder Checklist (PCL-C), on average, 2.5 months post-injury. There was a significant negative association between ISSmod scores and NSI (r=-0.267, p<0.001) and PCL-C (r=-0.273, p<0.001) total scores. Using linear regression to examine the relation between symptom reporting and injury severity across the six ISS body regions, three body regions were significant predictors of the NSI total score (face; p<0.001; abdomen; p=0.003; extremities; p<0.001) and accounted for 9.3% of the variance (p<0.001). For the PCL-C, two body regions were significant predictors of the PCL-C total score (face; p<0.001; extremities; p<0.001) and accounted for 10.5% of the variance. There was an inverse relation between bodily injury severity and symptom reporting in this sample. Hypothesized explanations include underreporting of symptoms, increased peer support, disruption of fear conditioning because of acute morphine use, or delayed expression of symptoms.