Military servicemen and women who are exposed to blast shockwaves may end up with hidden scars on their brains that can’t be picked up by most brain imaging techniques, according to a new study in the journal Lancet. As a result, their injuries are likely to go undiagnosed, and quite possibly untreated as well.
In a statement, lead researcher Daniel Perl explained that “blast-related brain injuries are the signature injury of modern military conflicts.” Paradoxically, however, despite the high prevalence of cognitive impairment experienced by military personnel who are exposed to these shockwaves, “routine imaging for blast-related traumatic brain injury often shows no brain abnormalities.”
Previous research has led to several theories regarding how shockwaves cause the types of symptoms that soldiers tend to suffer after being caught up in bomb blasts. For example, one study earlier this year provided evidence that these shockwaves cause tiny bubbles to form and then burst in the cerebrospinal fluid of nearby people, damaging their neurons.
Now, a group of researchers have taken a closer look at the brains of deceased soldiers who had experienced bomb blasts at some point during their military service. Some of these died immediately after these incidents, while others lived on for up to nine years afterward, yet suffered a range of cognitive deficits such as post-traumatic stress disorder for the rest of their lives.
At the same time, the team examined the brains of other dead people who had not been exposed to blast shockwaves. Some of these people were fully healthy, while others had suffered from traumatic brain injuries (TBI) caused by sporting accidents or drug abuse.
The military brains all showed evidence of a particular form of scarring called astroglial scarring, whereby a type of brain cell called astroglia increase in number to compensate for the destruction of neurons and other tissues like white or gray matter.
Post-traumatic stress disorder is commonly reported by soldiers exposed to blast shockwaves. studio0411/Shutterstock
This scarring was particularly noticeable in certain brain regions that are associated with memory disruption and sleep disorders, such as the hypothalamus. Astroglial scarring also penetrated blood vessels in several of the military brains, which the study authors say could explain a number of symptoms reported by these soldiers, like chronic headaches.
In contrast, the researchers note that “the civilian cases, with or without history of impact traumatic brain injury or a history of opiate use, did not have any astroglial scarring in the brain regions analyzed.” As such, it seems that this particular pattern of scarring may be unique to those who have been exposed to blast shockwaves.
However, in spite of the seemingly compelling nature of this finding, the team remain cautious not to jump to any conclusions, with Perl insisting that “we need to further study these patterns, and compare them with soldiers' medical history in order to build a better understanding of the neuropathology of traumatic brain injury.”