An Evidence-Based Objective Study Protocol for Evaluating Cardiovascular and Cerebrovascular Indices Following Concussion: The Neary Protocol

Abstract

Introduction: The prevalence and incidence of sport-related concussion have continued to increase over the past decade, and researchers from various backgrounds strive for evidenced-based clinical assessment and management. When diagnosing and managing a concussion, a battery of tests from several domains (e.g., symptom reporting, neurocognitive, physiology) must be used. In this study, we propose and develop an objective, evidence-based protocol to assess the pathophysiology of the brain by using non-invasive methods. Methods: Contact sport athletes (n = 300) will be assessed at the beginning of the season in a healthy state to establish baseline values, and then prospectively followed if a mild traumatic brain injury (mTBI) occurs on approximately days 1–2, 3–5, 7–10, 21, 30, and subsequently thereafter, depending on the severity of injury. The protocol includes spontaneous measurements at rest, during head postural change, controlled breathing maneuvers for cerebrovascular reactivity, a neurovascular coupling stimuli, and a baroreflex/autoregulation maneuver. Physiological data collection will include cerebral blood flow velocity, cerebral oxygenation, respiratory gases for end-tidal oxygen and carbon dioxide, finger photoplethysmography for blood pressure, seismocardiography for cardiac mechanics, and electrocardiography. Conclusion, Limitations, and Ethics: The protocol will provide an objective, physiological evidence-based approach in an attempt to better diagnose concussion to aid in return-to-play or -learn. Ethics approval has been granted by the University Research Ethics Board.

Neurovascular Coupling by Functional Near Infra-Red Spectroscopy and Sport-Related Concussion in Retired Rugby Players: The UK Rugby Health Project

“…The 8-channel system (OctaMon, Artinis Medical, Netherlands) monitored changes in O 2 Hb and HHb in the pre-frontal cortex, specifically covering the dorsolateral (DLPFC) and orbitofrontal (OFC) cortices in both hemispheres (Vergotte et al, 2018). Our study performed a modified Neary Protocol (Neary et al, 2019) to assess NVC using the ''Where's Wally (Waldo)'' paradigm. Previous research has confirmed this test is a valid measure of NVC (Smirl et al, 2016).…”

“…The researchers did not communicate with the participant during this baseline data collection period. The ''Where's Wally'' test (Smirl et al, 2016;Neary et al, 2019) was then implemented on a plasma screen (42" size), with the participant sitting 180 cm away. Each of the five cycles (5 min in total) consisted of 20 s of eyes closed followed by 40 s of eyes open where the participant searched the screen for ''Wally.''…”

“…The multifaceted pathophysiology of concussion varies across the acute to longer-term phases and can involve endothelial cell impairment of the blood-brain barrier, mitochondrial dysfunction which may lead to the disruption of cerebral autoregulation and cerebral blood flow velocity (Len et al, 2013;La Fountaine et al, 2016;Yang et al, 2017;Neary et al, 2019). Cerebral vasoconstriction leads to reduced arterial oxygen and consequently, there are blood pressure changes to preserve brain oxygen (Curtelin et al, 2017).…”

Pre-frontal Cortex Oxygenation Changes During Aerobic Exercise in Elite Athletes Experiencing Sport-Related Concussion

“…If the participants had baseline data collected first, a within-subject design based on this effect size will require 29 participants per group to demonstrate significance. This demonstrates the importance of including baseline testing in sport-related concussion research which has been documented previously (Len et al, 2013;Neary et al, 2019).…”

“…Most recently, exertional exercise testing protocols, such as the Buffalo Concussion Treadmill and Bike Test have proven to be safe and efficacious (Leddy et al, 2016aHaider et al, 2019;Morissette et al, 2019) in evaluating the athletes post-concussion. These laboratory testing protocols have been designed with the intent to differentiate the type of concussion injury (i.e., physiologic, vestibulo-occular, cervicogenic;Ellis et al, 2014Ellis et al, , 2015Leddy et al, 2016a), and to discern the physiological mechanisms (cerebral autoregulation, cerebrovascular reactivity, neurovascular coupling; Ellis et al, 2015Ellis et al, , 2016Ellis et al, , 2018Neary et al, 2019). This research has added to our understanding of the pathophysiological changes that occur following a concussion (Len et al, 2011(Len et al, , 2013Giza and Hovda, 2014;Bishop and Neary, 2017;Bishop et al, 2017b;Worts et al, 2019), and has also provided a greater understanding of how we can apply exercise safely as a treatment strategy.…”