Abstract
Purpose: There is an increase in mild traumatic brain injury (mTBI) in US Warfighters resulting from exposure to explosive devices. However, there is a lack of objective biomarkers to accurately identify mTBI in order to make a return-to-duty (RTD) determination in the battlefield. The present study examined pupillary light reflex (PLR) as a potential objective biomarker for early identification of mTBI. Methods: The PLR-200™ monocular infrared pupillometer was used to quantify PLR under mesopic conditions in 20 U.S. military personnel with blast induced-mTBI and 20 age-matched non-TBI military personnel. Eight PLR parameters were assessed: maximum diameter; minimum diameter; percent of constriction; constriction latency; average constriction velocity; maximum constriction velocity; 75% recovery time; average dilation velocity. Results: Four of the eight PLR parameters were statistically different between the groups: constriction latency, average constriction velocity, dilation velocity, and 75% recovery time. Conclusions: This study demonstrates the potential application of PLR as an objective index of autonomic nervous system activity and the value of using PLR, in conjunction with other biomarkers, to optimize the diagnosis of mTBI in the battlefield and to facilitate the RTD decisions by deployed healthcare providers.
Highlights
During the last decade, the US military has experienced an increase in the incidence of traumatic brain injury (TBI) resulting from the use of explosive devices by enemy forces [1,2]
The diagnosis of mild TBI (mTBI) has been a challenge for the military primarily because of the lack of objective assessment tools [4,5], the overlap of symptoms with co-morbid conditions such as post-traumatic stress disorder (PTSD) [6], and the interpretation of the signs and symptoms by healthcare providers relies on self-reported symptoms from injured Warfighters [4,7]
The data for the right and left eye were combined for further between-group comparison of pupillary light reflex (PLR) parameters
Summary
The US military has experienced an increase in the incidence of traumatic brain injury (TBI) resulting from the use of explosive devices by enemy forces [1,2]. The diagnosis of mTBI has been a challenge for the military primarily because of the lack of objective assessment tools [4,5], the overlap of symptoms with co-morbid conditions such as post-traumatic stress disorder (PTSD) [6], and the interpretation of the signs and symptoms by healthcare providers relies on self-reported symptoms from injured Warfighters [4,7]. Prompt and accurate diagnosis and management of mTBI generally increases an individual’s prognosis for neurological recovery [8,9,10] and safe return-to-duty (RTD) [1113]. There is a quest for objective biomarkers (e.g., protein, imaging, cognitive, neurosensory) to accurately diagnose Warfighters with mTBI [5,15]. Valid objective biomarkers are important in the combat zone to assist deployed clinicians in making an accurate determination of fit-for-duty (FFD) and RTD or evacuation from theater [4]
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