Parasympathetic baroreflexes and heart rate variability during acute stage of sport concussion recovery

Abstract

This study provides preliminary evidence that autonomic function is dysregulated following mTBI within the initial 72 hours of injury.

Assessing prefrontal cortex oxygenation after sport concussion with near‐infrared spectroscopy

“…The HHb within‐subject results displayed a loss of statistically higher HHb SD after concussion, whereas D1–D3 and D4–D6 HbO 2 SD during hypercapnia was lower than resting values and statistically was different when compared to healthy controls. These haemoglobin SD results reinforce previous healthy variance research (that has utilized various measurement tools, under various physiological impairments), to show that variance in a given system is lost when one part of the system (or subsystem) no longer functions within a healthy range (Pincus, ; Coveney, ; Costa et al ., ; Papaioannou et al ., ; Cerutti et al ., ; La Fountaine et al ., ; Thayer et al ., ; Bishop & Neary, ; Bishop et al ., ).…”

“…To solve this concussion biomarker issue, some brain injury researchers have examined the frontal lobe's contribution to medullary function, which includes understanding how a loss of brain function exerts its effect on healthy variance of other physiological systems (Lang et al, 2003;Zweifel et al, 2008Zweifel et al, , 2010Ryan et al, 2011;Thayer et al, 2012;Len et al, 2013;Kontos et al, 2014;Blake et al, 2015;Urban et al, 2015;Bishop et al, 2017). This is because the frontal lobe can alter both the medulla's capacity to monitor the unconscious processes (such as cardiorespiratory status), and conscious processes such as reaction time and word recall (Goodale & Milner, 1992;Lovallo, 2005;Sakagami et al, 2006;Taylor et al, 2010).…”

Heart rate variability and implication for sport concussion

“…In a study conducted by Bishop et al . () investigating HRV and blood pressure metrics during rest and cyclical squat‐stands (0·05 Hz: 10‐s squat hold/10‐s stand – the whole cycle lasting 20 s that corresponds to the frequency of 0·05 Hz, that is on the border of LF and VLF), it was found that there were no changes between groups or within‐subject regarding the LF during the haemodynamic and autonomic challenge protocol. Further, this demonstrates that the administration of such a test is safe for concussion patients as data showed that the protocol was well‐tolerable.…”

“…Research has demonstrated that blood flow–pressure regulation can alter cerebrovascular reactivity, autoregulation and neurovascular coupling (Jünger et al ., ; Len et al ., ; Bailey et al ., ; Bishop et al ., ; Wright et al ., ). These alterations may influence or contribute to HRV changes and thus will be briefly discussed here.…”

“…Generally speaking, the application of non-invasive measures of autonomic control of the cardiovascular system such as HRV of baroreflex function shows promise as a practical and cost-effective way to index and track recovery from brain injury in concussion (Gall et al, 2004b;La Fountaine et al, 2009;Hilz et al, 2011;Senthinathan et al, 2016;Bishop et al, 2017). Furthermore, although the focus of this review was to highlight the importance and use of HRV for concussion management, the available physiological literature related to concussion suggests that multimodal assessment including blood pressure and cerebral blood flow will help to better understand the interpretation of HRV and the influence on autonomic control.…”