Phillip C. Desrochers¹, Daniel Duggan¹, Howard Rafal¹, Erin Williams², Valerie Yunis², Michael Hoffer²

Poster presented at the 15th Annual Traumatic Brain Injury Conference, Boston, MA (5-6 May 2024)

Background: Over the last 20 years, mild Traumatic Brain Injury (mTBI) has become a significant health problem for both military personnel and civilians. mTBI is one of the most common injuries on the modern battlefield (Eskridge et al., 2012), with 365,771 incidents from 2000 through Q3 2023, accounting for 82.2% of all DOD brain injuries in that span (DOD TBI Worldwide Numbers, 2024). The seriousness of mTBI is mirrored in the civilian sector. For example, data from a sample of 950 hospitals showed a sharp increase in the weighted rates of emergency department (ED) visits from 2006 to 2010 (Marin et al., 2014). In 2006, there were 637 mTBI visits per 100,000 ED visits; by 2010, there were 822 per 100,000, with a disproportionate increase in the number of reported mTBI or concussion visits (Lagbas et al., 2013). The ability (1) to screen and diagnose mTBI, (2) predict long term consequences of injury, and (3) develop optimal methods for management of mTBI and return-to-duty (RTD) evaluation is of paramount importance (Robinson-Freeman et al., 2020). Individuals displaying symptoms of mTBI need accurate and timely assessment of their symptoms. Often, initial assessment and diagnosis must be conducted by first-level responders who attempt to assess vestibular symptoms directly following a concussive event; however, symptoms or indicators are often missed, are not adequately evaluated, or are misdiagnosed due to a lack of familiarity with the subtleties of impaired vestibular function. First responders need a reliable, easy-to-use, lightweight system for supporting simple and repeatable mTBI assessments, to assist them in making RTD decisions. ADVISOR addresses the challenges of mTBI screening to promote more appropriate RTD decisions. The ADVISOR software guides medical responders to administer assessments consistently and to correctly interpret the results.

Materials and Methods: The primary objective of this second Phase II effort is to integrate recent advancements in hardware made under related DoD- and internally-funded R&D efforts to (1) increase the number and type of assessments ADVISOR can run (2) integrate a faster frame rate eye tracking camera and capability of mounting the HMD to assess very fast eye movements that can be disrupted in mTBI (e.g., saccade kinematics and microsaccades), (3) improve the UI and report design and 4) evaluate ADVISOR’s ability to detect differences in vestibular and oculomotor function in a small-scope clinical trial. We recruited individuals presenting with mTBI in an emergency department (ED) or urgent care facility (to date, n=24); and (2) an age- and sex-matched healthy control group (to date, n=16). Exclusion criteria included severe TBI, previous head injury besides current injury, neuropsychiatric disorders, neurodegenerative disorders, pregnancy, and prior history of balance or hearing disorders. All individuals in both groups underwent an assessment using the ADVISOR system and a standard set of concussion metrics to include symptom questionnaires, IMPACT testing, and VOMs testing. mTBI patients were tested within <14 days post injury, 6-8 days after the first assessment, and >31 days since the first assessment. Healthy control participants were tested in a single session. These activities have allowed us to rapidly refine and develop ADVISOR to a TRL of 6-7.

Results: To achieve our objectives, we have made significant advancements to hardware and software developed under prior R&D efforts and integrated them into the full-scope ADVISOR project. We have continued to broaden ADVISOR’s Patient Assessment Suite with new assessments to target a wide array of vestibular and oculomotor functions. This has resulted in 16 assessments covering vestibular, oculomotor, sensorimotor domains thus far, and we are working to add more. We have transitioned our VR software from the Unity Engine to the more powerful and adaptable Unreal Engine, resulting in more refined VR experience. In collaboration with FOVE Inc., we have also updated the camera hardware to enable new capabilities for ADVISOR’s Virtual Reality (VR) head mounted display (HMD) including eyetracking frame rates >4x faster than other eyetracking enabled VR HMDs. We have created a new full-stack web application software architecture to further harden, streamline, and optimize ADVISOR’s Patient Assessment Suite. Because of this, the application has the key benefit of being hardware agnostic, able to function on any system that can support a web browser and the Unreal Engine. Preliminary analyses suggest that performance on ADVISOR’s assessments is different between groups. For example, one way ANOVA shows that the difference in proportion of anti-saccade errors to total saccades is significantly greater for the mTBI group than the control group (F(1,29)=6.13, p=0.019). Additionally, voluntary saccades show significant differences in displacement (F(1,29)=30.58, p<0.001) and peak velocity (F(1,29)=21.98, p<0.001).

Conclusions: The assessment of vestibular and oculomotor function (VOF) provides a key target for objective mTBI screening and is highly sensitive and specific to detecting mTBI (Balaban et al., 2016; Hoffer et al., 2017). Preliminary analyses show that ADVISOR is successfully able to capture reduced inhibition of oculomotor movement. The net effect of ADVISOR as part of the medical care chain will be less expensive and more accurate triage efforts and better informed RTD decisions. We expect the full-scope ADVISOR system to have immediate and tangible benefits in civilian mTBI assessment in inpatient and outpatient settings as well as for the military in operational, training, and garrison environments.

Acknowledgments: This work was supported by United States Army Medical Research and Materiel Command under Contract Nos. W81XWH-15-C-0041, W81XWH-16-C-0070, and W81XWH21C0029. Any opinions, findings and conclusions or recommendations expressed in this material are those of the author(s) and do not necessarily reflect the views of the United States Army Medical Research and Materiel Command. In the conduct of research where humans are the participants, the investigators adhered to the policies regarding the protection of human participants as prescribed by Code of Federal Regulations (CFR) Title 45, Volume 1, Part 46; Title 32, Chapter 1, Part 219; and Title 21, Chapter 1, Part 50 (Protection of Human Participants).

¹ Charles River Analytics
² University of Miami Miller School of Medicine

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