Factors influencing cognitive functioning following mild traumatic brain injury in OIF/OEF burn patients.

OBJECTIVE To examine the relationship between mild traumatic brain injury (mTBI), psychiatric conditions, pain medications, and injury severity on cognitive functioning in service members admitted to a burn unit. We hypothesize that psychiatric co-morbidity and pain medications will have a stronger relationship with cognitive dysfunction than mTBI diagnosis in this population. METHOD Retrospective review of clinical evaluations (n=194) completed between September 2005 - October 2007 on service members with burn injuries secondary to explosive munitions. Evaluations were completed during the acute stage of recovery (mean=7.87 weeks). mTBI diagnosis (n=50) was made through a clinical interview using ACRM criteria. Exclusion criteria included duration of posttraumatic amnesia > 24 hours (n=10); and inability to complete neurocognitive measures due to severe bimanual burns and/or amputations (n=17). Cognitive functioning was evaluated using the Repeatable Battery for the Assessment of Neuropsychological Status (RBANS). RESULTS Subjects who sustained mTBI demonstrated significantly greater difficulty on the RBANS visuospatial and attention/processing speed indices. A hierarchical linear regression, using mTBI diagnosis, psychiatric diagnosis, time since injury, presence of pain medications, and measures of trauma severity as predictive factors, found that mTBI diagnosis had a significant, but small unique effect on cognitive functioning. Contrary to our hypothesis, psychiatric co-morbidity was not shown to have a significant effect on this population of acutely injured service members. CONCLUSIONS While the relationship between severe TBI and cognitive functioning is well established, the relationship between mTBI and its effects on cognitive and behavioral abilities is less clear. The current study demonstrates that mTBI and analgesic medications have a small effect neurocognitive functioning in this population. Continued examination of this relationship is warranted.