Repetitive blast concussion mild traumatic brain injury (mTBI) is recognized as the "signature injury" of OIF/OEF deployment. However, controversy regarding the etiology, course, and treatment of persistent somatic, cognitive and behavioral symptoms remains. This symposium addresses whether these chronic symptoms in OIF/OEF Veterans and warriors reflect persistent structural and/or functional brain changes.
Dr. Peskind (VISN-20 MIRECC) used multi-modal structural and functional neuroimaging in OIF/OEF Veterans: 35 with mTBI and 13 controls. Findings in mTBI include: 1) decreased white matter integrity in optic radiations, inferior longitudinal fasciculus, brainstem, and cerebellar peduncles by diffusion tensor imaging (DTI); 2) decreased macromolecular proton-bound fraction in white and gray matter by cross-relaxation imaging; and 3) glucose hypometabolism in posterior cingulate and biparietal lobes by FDG-PET supported by default state fMRI (all p<0.05, corrected). Findings in mTBI were unassociated with PTSD.
Dr. Morey (VISN-6 MIRECC) examined whole brain white matter integrity in 30 Service Members and Veterans with mTBI and 42 controls. High direction DTI revealed widely distributed disruption of white matter integrity in mTBI (corpus callosum, forceps minor and major, superior and posterior corona radiata, internal capsule, superior longitudinal fasciculus (p<0.05; corrected) predicted by severity of acute mTBI symptoms but not current PTSD and depression.
Dr. Wilkinson (VISN-20 GRECC). While civilian impact mTBI is associated with 30-70% incidence of hypopituitarism, blast-related pituitary dysfunction has not been investigated. Findings of screening for pituitary and target-organ hormone abnormalities in mTBI Veterans who have complementary neuroimaging data will be presented.
Dr. Cook (VISN-20 GRECC) is addressing a mouse model of repetitive mTBI to understand pathophysiologic and genetic underpinnings of blast mTBI brain changes. A novel shock-tube based on blast exposures in OIF/OEF Veterans has been constructed. The design and operational properties of the shock tube and preliminary findings from mice with repetitive mild blast exposures will be presented.