Blast-related Brain Injury: Imaging for Clinical and Research Applications Report of the 2008 St. Louis Workshop

Abstract

Blast-related traumatic brain injury (bTBI) and post-traumatic stress disorder (PTSD) have been of particular relevance to the military and civilian health care sectors since the onset of the Global War on Terror, and TBI has been called the "signature injury" of this war. Currently there are many questions about the fundamental nature, diagnosis, and long-term consequences of bTBI and its relationship to PTSD. This workshop was organized to consider these questions and focus on how brain imaging techniques may be used to enhance current diagnosis, research, and treatment of bTBI. The general conclusion was that although the study of blast physics in non-biological systems is mature, few data are presently available on key topics such as blast exposure in combat scenarios, the pathological characteristics of human bTBI, and imaging signatures of bTBI. Addressing these gaps is critical to the success of bTBI research. Foremost among our recommendations is that human autopsy and pathoanatomical data from bTBI patients need to be obtained and disseminated to the military and civilian research communities, and advanced neuroimaging used in studies of acute, subacute, and chronic cases, to determine whether there is a distinct pathoanatomical signature that correlates with long-term functional impairment, including PTSD. These data are also critical for the development of animal models to illuminate fundamental mechanisms of bTBI and provide leads for new treatment approaches. Brain imaging will need to play an increasingly important role as gaps in the scientific knowledge of bTBI and PTSD are addressed through increased coordination, cooperation, and data sharing among the academic and military biomedical research communities.

Animal models of traumatic brain injury

“…Many military personnel exposed to a blast but without external injuries have been diagnosed with TBI 130,131 . To elucidate the effects of primary blast waves on the central nervous system, various animal models of blast TBI have been established, mainly in rodents 52,74,132-134 and swine 72,135 .…”

Blast Overpressure Waves Induce Transient Anxiety and Regional Changes in Cerebral Glucose Metabolism and Delayed Hyperarousal in Rats

“…The factor most unique to blast TBI compared to non-blast closed head TBI (such as sports injuries and car accidents) is the presence of an overpressure wave component. Blast-induced TBI is the most common injury of modern warfare, and has been titled as its “signature wound” (4). The nature of modern warfare and the frequent use of improvised explosive devices (IEDs) have led to increases in mild to moderate TBIs, but the availability of advanced protective gear and medical care at the battlefield have enabled military personnel to survive from otherwise lethal blast injuries (Defense and Veterans Brain Injury Center’s website: ).…”

Reduced Amygdala Volume Is Associated with Deficits in Inhibitory Control: A Voxel- and Surface-Based Morphometric Analysis of Comorbid PTSD/Mild TBI

“…That is the ventromedial prefrontal cortex (vmPFC) and the subgenual anterior cingulate cortex (sgACC) [8, 9]. Likewise, individuals with TBI that experience direct impact or blast wave trauma exhibit damage to the brain in these same regions, most significantly the vmPFC/sgACC [10–12]. The localization of injury associated with TBI may result from inner-cranial wave physics [13] and the presence of boney protuberances on the inner surface of the skull near the orbital and anterior temporal lobes [14, 15] makes the vmPFC/sgACC and amygdalar complex vulnerable.…”