OSHA 2019 Presentation Script Slide 1 (Title Slide) Hello everyone, - PDF document

OSHA 2019 Presentation Script Slide 1 (Title Slide) Hello everyone, I’m very excited to be here with you all today. My name is Jim Wright, and I am a doctoral student at the University of Oregon. I am joined today by my esteemed advisor, Dr. McKay Sohlberg. We will spend the next few hours talking with you all about the role of the SLP in multidisciplinary concussion management for adolescents experiencing persistent concussion symptoms, or PCS for short. A quick background about myself. I am a person who stutters and clutters, so there may be instances where I’m dysfluent during the presentation. I will do my best to keep my speech rate controlled, but at any time if you need something repeated, please do not hesitate to ask me to do so. Slide 2 (Financial Disclosure) We have no financial disclosures to share with you all today. Slide 3 (Learning Objectives) Here are today’s four learning objectives for the presentation. We will discuss these in depth in their own sections of the presentation. The first objective is to describe the pathophysiology of concussion, clinical symptoms, and theories for the etiology of persistent concussion symptoms (PCS). Today’s second objective is to identify the required multidisciplinary practitioners for effective and coordinated concussion management. The third objective is to describe the models for coordinating integrated care in different contexts including school-based coordination and medical-school coordinated communication. Lastly, the fourth objective is to describe the range of available SLP-delivered treatment options to address ongoing symptoms disrupting return to learn, play, and community function. Slide 4 (What is Concussion Section Title Slide) So, in this first section, I will be going over some basic facts on concussion including how it is defined and current epidemiology rates. I will then provide a condensed description of the neurophysiology of concussion and how these physiological alterations manifest in clinical symptoms. I’ll then conclude this section discussing the theories on how PCS develops. Slide 5 (Epidemiology) Let’s begin with epidemiology. According to the authors cited on the bottom of this slide, every year there are 1.6-3.8 concussions in the United States. Concussion statistics are often very closely tied to sports, which there are an estimated 300,000 annual concussions in the United States. On the slide, SRC refers to sports-related concussion. I also want to share that the most common cause of concussion in the age 15-24 demographic is sports and motor vehicle accidents, which is abbreviated MVA. I also want to share a couple of quick points on the gender disparity for sports related concussion, which comes from the work of Marar et al. They concluded that women sustain

concussions at a higher rate than men in sports played with the same rules, such as basketball and soccer. Slide 6 (Definition) This slide provides a quick definition of concussion. ( READ SLIDE ) It is The application of biomechanical force to the head and/or neck via linear and/or rotational acceleration that leads to observable changes in cognitive, somatic, and neurobehavioral functioning . The key feature of concussion is the application of force to the individual, which I will soon provide more detail on. Slide 7 (Pathophysiology) I would now like to speak about the pathophysiology of concussion, specifically biomechanics of inducing a concussion, the neurometabolic cascade of events that occurs at the cellular level following the injury, and lastly, connecting these physiological events to clinical symptoms. Slide 8 (Keys to Biomechanics of Concussion) As I previously mentioned, the key to inducing a concussion is FORCE. We quantify force as the mass of an object times its acceleration Let’s apply that to humans whose brain, on average, weighs about 1400 grams Because this mass is fixed, the force applied to the brain will increase as the acceleration applied upon it increases Therefore, to prevent force from increasing, it’s important to prevent acceleration from increasing, which is where we bring in the second key…IMPACT DURATION If we increase the impact duration, that allows for deceleration, which therefore, will decrease the force. Let’s apply this to some real-world contexts: the impact duration of car accidents is approximately 3-7 ms and 15 ms for NFL collisions. So roughly, the impact humans experience may range from 3-15 ms. This impact duration allows humans to withstand accelerations within the range of 80 – 160g of force without sustaining a concussion. Slide 9 (Acceleration) Another key aspect of concussion biomechanics is the specify the type of acceleration (liner or rotational) the brain is experiencing when force is applied. The human head may experience both types of acceleration at the same time due to way the brain is anchored atop the brain stem like a lollipop. Rotational forces are very impactful in concussion because they allow the structures deep within the brain (white matter or axons) to receive the most stress. The trademark of concussion is alteration to axons, which is most significantly caused by rotational force.

Slide 10 (Effective Mass) I want to briefly discuss this principle of effective mass, as it may influence the amount of acceleration applied to an individual. If force is constant, an individual can reduce the rate of acceleration applied by increasing their effective mass, which is the combined mass of the head anchored to the body based upon the tension of the neck muscles. Our head, on its own without tension in the neck coupling it to the body, possesses a smaller mass that that is more prone to concussion at a constant force as the acceleration will be higher. Conversely, if we increase the effective mass for a given force, we reduce the acceleration applied. This principle provides a biomechanical rationale for the differences between concussion rates in males and females in sports. Because males have a larger effective mass than females, they are more able to withstand a constant force because the acceleration applied will be reduced compared to females. Slide 11 (Impulse Magnitude) This brings us to the final key of concussion biomechanics, impulse magnitude, which ties all of the biomechanical keys together. We calculate impulse magnitude as the force during the impact divided by the duration of the impact. As I just mentioned, we want to increase the duration of the impact to reduce the force. And this is why the use of helmets in sports like football, hockey, lacrosse, and cycling is so important. One, they prevent skull fractures, which significantly reduces medical cost compared to TBI’s with skull fractures. Second, the reduce direct energy transfer from skull to skull contact. Without a helmet, the force of head to head contact is directly applied to the skull and into the brain. A human helmet is our way of behaving like a woodpecker, whose anatomy, which contains a large beak anchored by the hyoid bone, allows for a crash zone to distribute the force through the beak instead of directly into the skull, which is the same intention of a helmet. The woodpecker anatomy and human helmet also allow for a third feature, which is to reduce the rate of acceleration by increasing the impact duration. It comes back to the idea of a “crash zone”. Overall, a helmet will not prevent concussion, but it will reduce the force applied and may reduce the severity of injury. Slide 12 (Neurometabolic Cascade) Let’s move onto the second part of concussion physiology, which is the neurometabolic cascade of events that occurs at the cellular level within the brain after force is applied. The information I will be sharing on this topic comes predominately from the work of Drs. Christopher Giza and David Hovda, who work together at UCLA to study the physiology of concussion using experiments on mice and rats. Slide 13 (Action Potential Review) I want to first establish the process of a typical action potential as the ionic changes that typically occur are involved following a concussion.