The adverse effects of concussive traumatic brain injury are similar whether the injury was sustained in a blast-related incident such as a bomb or improvised explosive device detonation or a nonblast incident such as a fall or car crash, a report published online June 16 in JAMA Neurology shows.
Researchers studied this issue by prospectively assessing the clinical outcomes of the two types of traumatic brain injury (TBI) in 178 patients injured while serving in Iraq and Afghanistan during a 3-year period. Study participants were enrolled immediately after evacuation from combat theaters, when they were medically assessed at Landstuhl Regional Medical Center in Germany, and were followed up at 6 and 12 months afterward, said Christine L. MacDonald, Ph.D., of the department of neurology, Washington University, St. Louis, and her associates.
A total of 53 patients sustained blast-plus-impact TBI; 29 sustained nonblast TBI from falls, crashes, or being struck in the head by a blunt object; and 96 who had no head injuries served as control subjects. In the control group, 27 had been exposed to blasts, and 69 had not been exposed to blasts; most required medical evaluation for gastrointestinal, dermatologic, gynecologic, or orthopedic indications.
Global outcomes as measured by the Glasgow Outcome Scale-Extended were "essentially indistinguishable" between blast-related and nonblast TBI, as were numerous neuropsychological abnormalities; neurobehavioral impairments; focal neurological deficits such as those affecting olfaction, gait, and limb ataxia; headache-related disability; PTSD and its components; depression; alcohol misuse; and sleep disturbances. This suggests that TBI itself, independent of the mechanism of injury and of the intensity of combat exposure, is the primary driver of adverse outcomes, Dr. MacDonald and her colleagues said (JAMA Neurol. 2014 June 16 [doi:10.1001/jamaneurol.2014.1114]).
Another important finding was that control subjects who had been exposed to blasts showed significantly worse outcomes than controls who had not been exposed to blasts on measures of neurobehavioral, psychiatric, and headache-related impairment. It is possible that subconcussive blast exposure might cause direct structural damage to the brain or that other factors associated with blast exposure might play a role, the investigators added.
The relatively modest sample size and potential selection bias were cited by Dr. MacDonald and her associates as possible study limitations.
This study was funded by the Congressionally Directed Medical Research Programs. Dr. MacDonald and her associates reported no financial conflicts of interest.