From Bumps to Breakthroughs: Advances in Understanding Concussions and Mild Traumatic Brain Injuries

Concussion and Mild Traumatic Brain Injury (mTBI) are high-visibility topics in public health, military, athletics, and healthcare. Traumatic Brain Injury (TBI)  is, in fact, the leading cause of death and disability worldwide (2). While the growing awareness of TBI emphasizes the seriousness of even a mild TBI,  the average person still can view the treatment of this injury as similar to many other "mild" acute injuries: it may require short-term activity restrictions while symptoms dissipate, but with enough rest, the injury will heal itself. Today, we know this to be inaccurate.

Given the influx of interest (and funding) on this topic, our understanding of the brain and mTBI is improving at a rapid pace. Besides learning that rest isn't the best treatment, researchers are starting to uncover the potential long-term effects of head injuries on overall health and wellness. To be clear, this research isn't only relevant to "high-risk" professional American football players that are often the focus of the media but across all populations (e.g., veterans, athletes, and the general population). In reality, most mTBIs occur in nonathletes through traumatic events like falls and car accidents.

• Early childhood concussions are associated with lower global cognition, visual memory, and motor-visual scores compared to later childhood concussions (9).
• Service members with concussion, mTBI, and TBI have higher rates of PTSD, depressive disorder, substance use disorder, and anxiety disorder than those without (3).
• A history of a single prior head injury was associated with a 1.25x increased risk of dementia, and two or more prior head injuries were associated with over 2x increased risk of dementia compared to individuals without a history of head injury (10).
• Veterans with a history of mTBI are 1.62 times as likely to die by suicide as those without such a diagnosis (5).

In most cases, the common symptoms related to mTBI resolve in three to four weeks, but we are now beginning to assess the potential long-term effects of even a single, mild traumatic brain injury. Most doctors and medical resources will confidently explain that the majority of patients that sustain a mTBI will have no long-term effects. It is important to note that this is accepted as the norm, not because a large body of evidence supports this conclusion but because there is a lack of high-quality evidence supporting the alternative. But the news isn't all grim. Experts involved in ongoing studies and treatments today continue to support the notion that these long-term effects can be avoided, with one critical caveat:

"I firmly believe, and we've published a lot of papers on this, that concussion is a treatable injury. –that if you manage the injury effectively and treat it fully, we don't see repetitive, chronic, accumulative problems."

- Dr. Michael "Micky" Collins, clinical and executive director, UPMC Sports Medicine Concussion Program

Given the historical lack of data (a 2017 study suggests that 50-90% of mTBIs go undiagnosed) and awareness, it is difficult to draw precise conclusions about the proportion of effectively managed mTBIs (1). An emphasis on better understanding and improving awareness of mTBI and its effects will no doubt result in better managing this injury in the long run. But beyond continuing to fund research and supporting education and destigmatization of mTBI and mental health, how can we more effectively manage mTBI to improve outcomes today?

mTBI Complexity

As a mTBI is, by definition, an injury to the primary component of the Central Nervous System (CNS), the brain, the potential effects are widespread and can be detected across different physiological systems. Like many other complex pathologies, there is no globally accepted biomarker or assessment to diagnose a mTBI objectively. As a result, a battery of tools and assessments, both objective and subjective, are leveraged to provide clinicians and patients with data and information to guide care. One simple framework to understand how mTBI is assessed is by defining three distinct domains in which the potential effects of mTBI can be evaluated:

• Cognitive: For example, effects on memory, language, functional communication, and activities of daily living (ADL).
• Behavioral: For example, effects on mood, sleep, social function, interpersonal communications, and substance use.
• Physical: For example, effects on balance, motor control, and vision, as well as headaches and neck pain.

This is undoubtedly an oversimplification, as these domains (as with all physiological systems) do not operate independently. mTBI experts will quickly point out that different combined and interconnected subsystems more accurately describe the mechanisms for how mTBI affects individual patients. More recently, experts have been classifying concussions related to their effect on pathways within the brain (11). These frameworks identify different impairments and treatment paths related to the Vestibular system (balance), Ocular system (vision), Post-Traumatic Migraines (headache), Cognitive function (fatigue/fogginess), and Anxiety (mood).

These different classifications appear not to be mutually exclusive. Instead, these symptoms often coexist and have complex interactions with one another. For example, the same pathways in the brain that control the vestibular system mediate the sympathetic nervous system (SNS). When the vestibular or balance system is affected, this can trigger massive SNS arousal or our "fight or flight" response. Because all these systems are interconnected, this can then cause increases in symptoms represented by other classifications, such as anxiety and headaches. In the literature relating to the long-term impacts of mTBI, recent research has shown significant differences in balance capabilities, or postural sway, when comparing athletes and soldiers with and without a history of mTBI and even sub-concussive head impacts years after the injuries occurred and reported symptoms have subsided (7, 8).

mTBI Assessment

Various tools and assessments are utilized based on the resources and information available to the patient and caregiver. Using these classification frameworks, a comprehensive evaluation will leverage multiple tools to provide coverage of these different pathways. Some examples are provided below, not including some more commonly used subjective assessments that aggregate components below in an attempt to address these different domains using a single tool (e.g., variations of the Sport Concussions Assessment Tool or SCAT):

• Vestibular
  • Balance Error Scoring System (BESS)
  • Force Plate Based Posturagrapy (e.g., CDP)
  • Vestibular Ocular Motor Screening (VOMS)
• Ocular
  • Vestibular Ocular Motor Screening (VOMS)
  • Wearable Computerized Eye-Tracking
• Post-Traumatic Headache
  • Post-Concussion Symptom Scale (PCSS)
• Cognitive/Fatigue
  • Post-Concussion Symptom Scale (PCSS)
  • Neurocognitive Assessment Tools (NCAT)
• Anxiety/Mood
  • Post-Concussion Symptom Scale (PCSS)
  • Psychological Assessment (e.g., PHQ-9)

Additional tools exist for the more immediate assessment and triaging of mTBI at the time of injury. For example, the Glasgow Coma Scale (GCS) is used by first responders, the Military Acute Concussion Evaluation (MACE) is used in military environments, and the modified BESS test (mBESS) and King-Devick Test (K-D Test) are often used in athletic settings.

As you can see, the complexity of mTBI itself lends itself to a complex and multifaceted diagnostic process. To further complicate this, most existing tests used in practice are subjective by nature, requiring both highly skilled clinicians and cooperative patients. Given that there are no objective biomarkers to diagnose mTBI, many of these subjective tools will remain the best practice for the foreseeable future. However, what can be instrumented, objectively assessed, or digitized, should be. Not necessarily because digital is always better, but because technology can help to support and scale highly trained personnel. This does not diminish their role but extends their reach and impact to help more people more efficiently.

Innovation Begins with Data

Today's existing technology can more easily and objectively assess balance capabilities in other contexts. This can help reduce the burden and subjectivity of tests like the Balance Error Scoring System (BESS) often utilized in mTBI management. This objective measurement technology also provides much more granular data by evaluating a patient's balance 1000 times per second and providing a much larger scale of balance metrics than subjective tests that only result in a singular pass/fail score. These tools are particularly advantageous for innovation in mTBI assessment as they can support advanced nonlinear balance biometrics, such as entropy, that are more sensitive to mTBI and related impairments (6).

Technological advances continue to make high-quality sensors, data storage, and analysis ubiquitous and affordable. Clinicians can utilize hardware devices like wearables, mobile devices, and portable force plates to assess vestibular and ocular mTBI-related impairment more objectively and scalably. Clinical scales and questionnaires are also a large part of mTBI diagnoses and impairment identification. Patients can interact with software applications run on standard consumer products (e.g., mobile devices) to improve the efficacy and frequency of collecting this information and enable more extensive data aggregation and analysis. Like any single assessment, computerized Neurocognitive Assessment Tools such as the imPACT and ANAM are not to be utilized in isolation. Still, they provide essential information for clinicians, and if leveraged appropriately, data can be mined and analyzed to enable continued learning and innovation in mTBI assessment and treatment.

Adopting Best Practices at Scale

Aggregate and simplified tools, such as variations of the Sport Concussion Assessment Tool (SCAT), are commonly used as subjective catch-all assessments to identify mTBI-related impairment. Historically, the standard practice recommends reactively referring to more specific and objective tools only if symptoms do not dissipate. However, some of these technology-enabled tools are utilized proactively as a standard of care in concussion-focused specialty clinics that drive much of the innovation and recommendations around mTBI treatment. These clinics are the few places actively leveraging technology and the latest available evidence that ultimately need to be adopted on a much broader scale to reach the masses. For this adoption, change will need to occur to drive proactive, objective, data-rich assessment to become a standard of care. While this change will not be easy, technology, as it always has been, will need to be the foundation that enables large-scale adoption, alleviating the existing burdens for clinicians to provide the best patient outcomes.

Take Home:

• mTBIs are incredibly complex and can affect many physiological systems and human functions.
• Our understanding of mTBI and mTBI treatment is advancing rapidly, yet most of these learnings have yet to become standard practice.
• Technology can help to close this gap and support clinicians by extending their reach and providing the best available evidence to serve their patients.

REFERENCES:

1. Prince, C., and M. E. Bruhns. 2017. 'Evaluation and Treatment of Mild Traumatic Brain Injury: The Role of Neuropsychology', Brain Sci, 7.
2. Graham, Neil SN, and David J. Sharp. "Understanding neurodegeneration after traumatic brain injury: from mechanisms to clinical trials in dementia." Journal of Neurology, Neurosurgery & Psychiatry 90.11 (2019): 1221-1233.
3. Greer, Nancy, et al. "Prevalence and severity of psychiatric disorders and suicidal behavior in service members and veterans with and without traumatic brain injury: systematic review." The Journal of Head Trauma Rehabilitation 35.1 (2020): 1-13.
4. Barnes, Deborah E., et al. "Association of mild traumatic brain injury with and without loss of consciousness with dementia in US military veterans." JAMA neurology 75.9 (2018): 1055-1061.
5. Hostetter, Trisha A., et al. "Suicide and traumatic brain injury among individuals seeking Veterans Health Administration services between fiscal years 2006 and 2015." The Journal of Head Trauma Rehabilitation 34.5 (2019): E1-E9.
6. Purkayastha, Sushmita, et al. "Balance Testing Following Concussion: Postural Sway versus Complexity Index." PM&R 11.11 (2019): 1184-1192.
7. Schmidt, Julianne D., et al. "Balance regularity among former high school football players with or without a history of concussion." Journal of athletic training 53.2 (2018): 109-114.
8. Wright, W. Geoffrey, et al. "History of mild traumatic brain injury affects static balance under complex multisensory manipulations." Journal of neurotrauma 39.11-12 (2022): 821-828.
9. Taylor, Kathryn M., et al. "Concussion history and cognitive function in a large cohort of adolescent athletes." The American journal of sports medicine 46.13 (2018): 3262-3270.
10. Schneider, Andrea LC, et al. "Head injury and 25‐year risk of dementia." Alzheimer's & Dementia 17.9 (2021): 1432-1441.
11. Lumba-Brown, Angela, et al. "Concussion guidelines step 2: evidence for subtype classification." Neurosurgery 86.1 (2020): 2.