Healthy Active Duty Military with Lifetime Experience of Mild Traumatic Brain Injury Exhibits Subtle Deficits in Sensory Reactivity and Sensory Integration During Static Balance

Abstract

Postural control and stress reactivity were investigated in active duty coast guard personnel to determine whether they are sensitive to lifetime effects of mild traumatic brain injury (mTBI). A custom-designed and validated virtual reality-based computerized posturography device was used to assess postural stability, whereas emotional reactivity was assessed using the acoustic startle response (ASR), and neurocognitive performance was assessed using the defense-automated neurobehavioral assessment (DANA). It was hypothesized that residual and subtle postural control imbalance and deficits in cognitive and sensory reactivity would be evident in those reporting multiple lifetime mTBI. Active duty military personnel (N = 36; 7 females and 29 males) with no Deployment Limiting Medical Condition were recruited and tested on all assessments. Medical history information provided a history of head injury. Thirty-nine percent of participants reported having a previous mTBI (nine reporting one and five reporting more than one incident). No participant had experienced a head injury within the past year and all were symptom free. A significant effect of number of mTBI was found in the postural assessment (p = 0.002). Lifetime mTBI was associated with suppressed ASR magnitude (p = 0.03) but did not affect neurocognitive performance. The current findings provide new insight into ongoing controversies concerning sensitivity to functional deficits following mTBI and when the window for treatment or restoration ends.

Chronic motor performance following different traumatic brain injury severity—A systematic review

“…The sample size for the included clinical studies was consistently low, with the majority ranging from 16 to 66 participants, with only a few moderately sized (111–453 individuals) 32 − 395 − 125 − 125 − 125 − 12 and one large study (4,007 subjects) ( 55 ). The source populations of clinical studies varied widely including rehabilitation institutes ( 22 , 23 , 59 , 67 ), professional athletes ( 25 , 26 ), college students ( 54 , 71 , 78 ), college athletes ( 19 , 60 , 61 , 63 , 68 , 73 , 76 ), military veterans ( 40 , 52 – 56 , 65 , 69 ), and the community ( 51 , 54 , 58 , 64 , 70 , 72 , 75 , 77 ).…”

Neuromotor changes in participants with a concussion history can be detected with a custom smartphone app

“…We discuss our findings in the context of previous balance control tests for concussion assessment and using the optimal movement variability hypothesis to frame our observations. Previous work has shown that neuromotor dysfunction occurs after a concussion [31,38,39]. Specifically, balance control becomes more variable due to neuromotor sensory integration challenges [32].…”

Central sensorimotor integration assessment reveals deficits in standing balance control in people with chronic mild traumatic brain injury

“…Other studies using different posturography assessments have shown people at various recovery times following mTBI with increased postural sway relative to healthy controls when exposed to visual scenes with motion or visual surrounds that moved (13,15,16,19). Balance control requires multisensory processing and it has been theorized that visual-vestibular sensory processing may be impaired acutely after mTBI (51,52).…”

“…Less common are assessments of mTBI-related balance deficits using "stimulus-evoked sway" measures derived from sway responses to stimuli applied to various sensory modalities to identify their influence on balance. For example, larger magnitude CoP sway was evoked in mTBI subjects than healthy controls (HC) when exposed to a rotating visual scene (15)(16)(17). In these studies, increased responsiveness to visual motion was interpreted as indicating abnormal visual-vestibular processing since mTBI subjects apparently had reduced ability to use vestibular orientation cues to suppress the effects of the visual stimulus.…”