Blunted Cardiac Parasympathetic Activation in Student Athletes With a Remote History of Concussion: A Pilot Study

Abstract

Introduction: Blunted cardiac autonomic nervous system (ANS) responses, quantified using heart rate variability (HRV), have been reported after sport-related concussion (SRC). Research suggests this persists beyond clinical recovery. This study compared cardiac parasympathetic responses in student athletes with a remote history of SRC (> 1-year ago, Concussion History: CH) with those who reported no lifetime history of SRC (Concussion Naïve: CN). Design: Retrospective nested case-control. Setting: University laboratory. Patients or Other Participants: CH (n = 9, 18.3 ± 2 years, 44% male, median 2 years since injury) were student athletes with a remote history of concussion(s) from more than 1 year ago. CN (n = 21, 16.7 ± 3 years, 67% male) were student athletes with no lifetime history of concussion. Exclusion criteria included taking medications that could affect ANS function, history of concussion within the past year, persistent concussion symptoms, lifetime history of moderate to severe brain injury, and lifetime history of more than 3 concussions. Material and Methods: Participants performed the Face Cooling (FC) test for 3-min after 10-min of supine rest while wearing a 3-lead electrocardiogram in a controlled environment. Outcome Measures: Heart rate (HR), R-R interval (RRI), root mean square of the successive differences (RMSSD) of RRI, high frequency (HF) and low frequency to HF (LF:HF) ratios. Haider et al. Persistent ANS Dysfunction After Concussion Results: At baseline, CH had a lower resting HR than CN (62.3 ± 11 bpm vs. 72.9 ± 12, p = 0.034). CH had a different HR response to FC than CN (+8.9% change from baseline in CH vs. −7.5% in CN, p = 0.010). CH also had a smaller RMSSD increase to FC than CN (+31.8% change from baseline in CH vs. +121.8% in CN, p = 0.048). There were no significant group differences over time in RRI (p = 0.106), HF (p = 0.550) or LF:HF ratio (p = 0.053). Conclusion: Asymptomatic student athletes with a remote history of concussion had a blunted cardiac parasympathetic response to FC when compared with athletes with no lifetime history of concussion. These data suggest that an impaired autonomic response to a physiological stressor persists after clinical recovery from SRC for longer than previously reported.

Autonomic dysfunction in adults following mild traumatic brain injury: A systematic review

“…Of the included studies, twenty-one were crosssectional studies (Abaji et al, 2016;Bishop et al, 2017;Ding et al, 2020;Dobney et al, 2018;Hanna-Pladdy et al 2001;Hilz et al, 2011Hilz et al, , 2015Hilz et al, , 2016Hilz et al, , 2017Hilz et al, , 2020Howard et al, 2018;Huang et al, 2019;Johnson et al, 2018Johnson et al, , 2020Kozlowski et al, 2013;Mirow et al, 2016;Pyndiura et al, 2020;Russell et al, 2020;Solbakk et al, 2005;Tan et al, 2009;Truong & Ciuffredia, 2016), sixteen were cohort studies (Brandt et al, 2020;Clausen et al, 2016;Dobson et al, 2017;Gall et al, 2004;La Fountaine et al, 2009Leddy et al, 2010;Liao et al, 2016;Purkayastha, Williams et al, 2019;Senthinathan et al, 2017;Wright et al 2017Wright et al , 2018, while two (Haider et al, 2020;Hutchison et al, 2017) were case-control studies. All studies, with the exception of two (Leddy et al, 2010;Mirow et al, 2016), compared mTBI participants to nonhead injured control groups.…”

“…A total of 4,311 studies were identified, of which, 1,064 duplicates were removed. Two references were shared by a study author (Haider et al, 2020;Pyndiura et al, 2020). The title and abstract of 3,247 studies were screened with 3,092 not meeting inclusion criteria (see Table 2).…”

Preliminary Evidence of Orthostatic Intolerance and Altered Cerebral Vascular Control Following Sport-Related Concussion

“…Concussion-induced brainstem changes might contribute to altered autonomic control of the cardiovascular system in the concussed athletes. We (67,68) and others (4,(69)(70)(71)(72) have found that autonomic control of the heart during a physioloigcal stressor is altered following concussion and might persist wellbeyond symptom resolution (73). Thus, the association among structural brain abnormalities and autonomic function following a concussion warrant further investigation.…”

“…This approach would have allowed us to determine if CA returned to physiological function that is exhibited by healthy controls prior to their return to play. Important emerging evidence indicates that physiological dysfunction persists in concussed patients beyond symptom resolution (4,8,73).…”

The Influence of Family History of Neurodegenerative Disease on Adolescent Concussion Outcomes

“…The Vagal Tank theory assumes a relative degree of vagal withdrawal (e.g., decrease in HRV) is needed to support metabolically demanding tasks, such as physical exertion [ 42 ]. Preliminary evidence suggests that individuals may demonstrate blunted cardio-autonomic reactivity following concussion [ 65 , 66 ]. Importantly, we observed that fhNDD+ adolescents show minimal to no change in HRV in response to IHGC compared to fhNDD− adolescents during the subacute phase of recovery (<30 days of injury).…”