Motivation behind the research
Concussion, defined as a trauma-induced alteration in mental status that may or may not involve loss of consciousness, can occur during sports or other physical activities. It has been estimated that as many 1-3 million concussions occur annually in the United States. In addition, concussion incidences have steadily increased over the past decade. While the majority of athletes who sustain a concussion will no longer experience symptoms within the first month of injury, the prevalence and mechanisms responsible for a longer duration of recovery post-concussion are not well understood.
I became interested in studying the effects of concussion in youth athletes during my time as a certified athletic trainer. Particularly among adolescent athletes, it was very difficult to understand how long someone might be out of school, out of sports, or require until they were generally feeling better. As a result, our work seeks to understand how concussion affects walking patterns, one’s ability to move and think simultaneously, and how movement-based tests can provide useful clinical information. Using objective measurement techniques, we hope to create tests that reflect the demands that are placed on athletes upon returning to sport and that are assistive to inform sports medicine clinicians about projected post-injury recovery timelines.
The prerequisite knowledge needed to understand the study includes measurements pertaining to walking patterns and cognitive function.
Gait is the term that describes a person’s walking characteristics
We used variables such as gait speed (how fast a person walks over a period of time), cadence (how many steps they take over a period of time), and stride length (how far they progress forward while walking). Dual-task is a term that refers to completing two tasks at the same time. For example, in this study, we asked participants to walk and complete a cognitive task (spelling words backwards, subtracting, or saying the months in reverse order). The dual-task cost is the “cost” of adding a cognitive task while walking. In order to obtain a dual-task cost, we calculated the percent change between walking vs. walking while thinking. Thus, it theoretically reflects how well someone can adapt to an additional task and is a measure that is individualized to a person’s own walking pattern.
While many different factors may be associated with the time needed for recovery after a concussion, obtaining objective data may be a worthwhile endeavor. For example, one of the more commonly reported factors that are associated with prolonged recovery is a more severe symptom burden upon initial examination. While symptom reports are a necessary clinical tool, they can be subjective as athletes may over- or under-report both the presence and severity of their symptoms. Thus, we used an instrumented gait protocol soon after the concussion to predict whether the patient was likely to experience a prolonged recovery or not. While taking into account other factors that may influence recoveries, such as gender, age, time of the exam, and prior concussion history, we found that a higher dual-task cost of gait speed was associated with a greater risk of prolonged symptoms. In other words, if someone demonstrated more change between walking and walking while thinking, they were more likely to continue experiencing concussion symptoms.
The conclusions may be useful for clinicians who are attempting to counsel patients soon after their injury.
By objectively evaluating dual-task function within a multifaceted examination, they may be able to better inform patients whether or not they are likely to experience a protracted recovery after a concussion.
Our study had several limitations which should be considered when interpreting our findings. Although our sample size was moderate (n=59), further replication of these findings in larger samples and across multiple testing sites will be needed before any clinical adaptions can occur. In addition, the patients from our study were recruited from a somewhat small radius of institutions in the Boston area who were seen for care at a specialty care concussion clinic or within an athletic training facility. Whether or not our findings can be replicated in different geographical areas or among patients seen in other clinical care settings needs further exploration.
We are continuing with several studies to extend what we discovered in this investigation. First, we hope to identify the timeline of recovery for different physiological systems post-concussion. By combining dual-task measures with electrophysiological, eye tracking, and neurocognitive tests, we believe we will be able to better define how the brain recovers from a concussion. Furthermore, we hope to adapt these instrumented procedures to something that can be used throughout a variety of settings, not just in a hospital or laboratory setting.
Research Article: The association between dual-task gait after concussion and prolonged symptom duration. J Neurotrauma. 2017.