Neural and Behavioral Sequelae of Blast-Related Traumatic Brain Injury
Condition: TBI
MeSH terms: Brain Injuries; Brain Injuries, Traumatic
Study type: Observational

Summary: 
      Hypothesis 1: On fMRI scanning, frontoparietal activation during performance of executive
      function tasks of working memory, inhibitory control processes, and stimulus-response
      interference will exhibit greater signal intensity, a wider spatial extent, and more
      bilateral activation in chronic MTBI than chronic OI participants.

      Hypothesis 2: DTI changes, characterized by lower FA and higher MD at the gray-white
      junction, corpus callosum, central semiovale, and internal capsule, will be seen in MTBI but
      not in OI subjects.

      Hypothesis 3: Increased fMRI activation in chronic MTBI will be correlated with location and
      severity of disrupted fiber tracks that subserve neural networks associated with each fMRI
      activation task.

      Hypothesis 4: Performance on computerized neuropsychological testing (ANAM) and reaction time
      measures on fMRI tasks will better discriminate MTBI from OI than standard paper-and pencil
      tests.

      Hypothesis 5: The combination of fMRI, DTI, and ANAM will better discriminate MTBI from OI
      than each individual method.

      Hypothesis 6: More severe brain pathology in MTBI, as measured by neuroimaging (fMRI, DTI)
      and ANAM test scores, will be associated with less severe PTSD and symptoms.
    

Detailed description: 
      Traumatic brain injuries (TBI) are a common occurrence from roadside blasts of improvised
      explosive devices (IEDs). Like civilian TBI, blast-related TBI can result from mechanical
      forces in which objects in motion strike the head or the head is forcefully put into motion
      and strikes an object. TBI from exposure to an explosive blast may also result from a third
      cause: barotrauma. Blasts produce wave-induced changes in atmospheric pressure, which in turn
      produce characteristic injuries to vulnerable bodily regions at air-fluid interfaces, such as
      the middle ear. It is unknown whether the neural and cognitive sequelae of blast-related TBI
      differ from those resulting from mechanically-induced TBI commonly observed in civilian
      accidents. Understanding the potentially unique sequelae of blast-related TBI is critical for
      accurate diagnosis and designing effective pharamacological and neurorehabilitation
      interventions.

      In the proposed cross-sectional study, we aim to apply neurobehavioral testing and advanced
      MRI techniques [task-activated functional MRI (fMRI) and diffusion tensor imaging (DTI)] to
      gain a comprehensive understanding of the neural changes underlying blast-related MTBI. This
      will be accomplished by comparing neurobehavioral and neuroimaging findings obtained from
      military personnel who have experienced a blast injury with those obtained from civilians who
      have experienced TBI from motor vehicle accidents and from military and civilian control
      participants with orthopedic injuries. We will accomplish this goal by conducting advanced
      neuroimaging (task-activated fMRI and DTI fiber tracking) and neurobehavioral testing
      (computerized assessment and standard neuropsychological testing) on 120 chronic trauma
      patients: 30 military MTBI patients who have experienced blast injuries, 30 civilian MTBI
      patients with mechanical closed head injuries, and 30 military and 30 civilian patients with
      orthopedic injuries.
    

Observational model: Case-Control
Time perspective: Other
Sampling method: Probability Sample
Study population: 
        This is a prospective, observational study using a cross-sectional design to compare brain
        imaging and neuropsychological findings at 12 to 72 months post-injury in four groups of at
        least 30 patients each: two groups of military patients who have sustained mild to moderate
        TBI (milMTBI) or orthopedic injury or uninjured veterans, reservists, or service members
        (milControl) and two groups of civilian patients who had MTBI (civMTBI) or OI (civOI).