Concussive Blast Mild TBI Symptoms May Worsen Over Time

Megan Brooks

May 05, 2017

Many military service members with concussive blast mild traumatic brain (mTBI) experience evolution, rather than resolution, of symptoms from 1 to 5 years, a new study suggests, and the process may be driven more by psychiatric symptoms than by cognitive deficits.

"It was surprising to us to see a substantial number of patients significantly decline from 1-year to 5-year outcome when these injuries were presumed to be the mildest form of head injury, ie, concussion," Christine Mac Donald, PhD, associate professor, Department of Neurological Surgery University of Washington School of Medicine in Seattle, told Medscape Medical News.

"The historic mantra in medicine regarding general 'stability at 6 to 12 months' postinjury appears to be challenged in this population with progression of postconcussive symptoms well after this time frame," said Dr Mac Donald.

The study was published online May 1 in JAMA Neurology.  

Evolving Disease Process

In a longitudinal case-control study, the researchers examined 1- and 5-year outcomes of 50 active-duty US military serving in Afghanistan who sustained concussive blast mTBI, as well as 44 combat-deployed control military with no TBI. "This allowed us to investigate functional trajectories over time to gain a better appreciation of the impact of these exposures on long-term outcome," said Dr Mac Donald. 

All concussive blast injuries met the Department of Defense definition of mild, uncomplicated TBI.  

Overall, 36 of 50 patients (72%) with blast mTBI experienced a decline on the Extended Glasgow Outcome Scale, a measure of overall disability, from the 1-year to 5-year assessment, compared with only 5 of 44 controls (11%).

At 5 years, satisfaction with life, global disability, neurobehavioral symptom severity, psychiatric symptom severity, and sleep impairment were worse in patients with concussive blast mTBI than in  combat-deployed military without TBI. There were no between-group differences in performance on cognitive measures at 5 years. 

Brain injury diagnosis, preinjury intelligence, motor strength, verbal fluency, and neurobehavioral symptom severity at 1 year were risk factors for poor outcome at 5 years, with an area under the curve of 0.92 "indicating excellent prediction strength," the researchers say.

Psychiatric issues appeared to be most troubling for military with concussive blast mTBI. 

Between the 1- and 5-year evaluations, 40 patients with concussive blast TBI (80%) reported seeking help from a licensed mental health professional compared with 18 controls. Yet, 9 patients with concussive blast TBI (18%) and 9 combat-deployed controls (20%) reported that mental health programs helped.

"The second important finding is focused on the very high rate of severe comorbid mental health symptoms in our combat concussion patients and their attempts at seeking treatment," Dr Mac Donald told Medscape Medical News. 

"While 80% of service members sought treatment and help, only 18% reported sustained resolution from the programs and therapies they completed. It's not to say there's nothing to do to help these patients but it's saying that we are likely giving a lot of people the wrong treatment and this study emphasizes the need for targeted therapy approaches and precision medicine strategies," said Dr Mac Donald. 

"This is not a one size fits all. No two brain injuries are alike and no two brain injury patients will respond the same way to the same treatment," she added. 

The authors of an editorial in JAMA Neurology  note that as many as 20% of service members from the Iraq and Afghanistan conflicts had at least one mTBI and many sustained multiple TBIs. 

The findings in this study indicating deterioration in functional status from 1 to 5 years "suggests that, for some individuals, concussive blast injury may be associated with a progressive, evolving disease process," write Kristen Dams-O'Connor, PhD, from the Icahn School of Medicine at Mount Sinai in New York, New York, and Jack Tsao, MD, from the University of Tennessee Health Science Center in Memphis. 

"To some extent these findings are consistent with a growing body of literature that suggests TBI is most appropriately conceptualized not as an isolated event but as a disease process that may cause and/or accelerate medical and mental health morbidity long after the initial injury," they add. 

The study was supported by the Department of Defense and the National Institute of Neurological Disorders and Stroke. The authors and editorial writers have disclosed no relevant financial relationships. 

JAMA Neurol. Published online May 1, 2017. Abstract, Editorial

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