The Predictive Capacity of the Buffalo Concussion Treadmill Test After Sport-Related Concussion in Adolescents.

Mohammad N Haider,Kaitlin B Viera,Itai Bezherano,Barry S Willer,Jeffrey C Miecznikowski,Kimberly J Wilkins,John J Leddy,Charles G Wilber

doi:10.3389/fneur.2019.00395

Abstract

The Buffalo Concussion Treadmill Test (BCTT) identifies the heart rate threshold (HRt) of exercise tolerance in concussed patients. A previous study found that an absolute HRt of < 135 bpm was associated with prolonged recovery (>30 days) from sport-related concussion (SRC). In this study, we assessed the relationship of ΔHR (difference between resting HR and HRt) and recovery from SRC. Using a retrospective cohort design, we compared acutely (<10 days since injury) concussed adolescents who were prescribed either (1) relative rest (RG, n = 27, 15.2 ± 1 years, 33% female, median 17 days to recovery, ΔHR = 69.6 ± 28 bpm), (2) a placebo-stretching program (PG, n = 51, 15.4 ± 2 years, 49% female, median 17 days to recovery, ΔHR = 60.9 ± 22 bpm), or (3) sub-threshold aerobic exercise (AG, n = 52, 15.3 ± 2 years, 46% female, median 13 days to recovery, ΔHR = 62.4 ± 26 bpm). Linear regression showed that ΔHR significantly correlated with duration of clinical recovery for RG (p = 0.012, R2 = 0.228) and PG (p = 0.011, R2 = 0.126) but not for AG (p = 0.084, R2 = 0.059). ΔHR values were significantly lower in participants with prolonged recovery (>30 days) in RG (p = 0.01) and PG (p = 0.04). A ΔHR of ≤50 bpm on the BCTT is 73% sensitive and 78% specific for predicting prolonged recovery in concussed adolescents who were prescribed the current standard of care (i.e., cognitive and physical rest).

Highlights

Sport-related concussion (SRC), a type of mild traumatic brain injury, is a significant public health concern [1, 2]
27 participants made up Rest Group (RG), participants made up Placebo Group (PG) and participants made up Aerobic Group (AG)
We found that the heart rate (HR) correlated with duration of clinical recovery in participants who were prescribed relative rest or a placebo-stretching program but not in participants who were prescribed sub-threshold aerobic exercise

Summary

Introduction

Sport-related concussion (SRC), a type of mild traumatic brain injury (mTBI), is a significant public health concern [1, 2]. Concussion is defined as reversible neurological dysfunction in the absence of gross brain lesions, caused by either by a direct blow to the head, neck, or elsewhere on the body with an impulsive force transmitted to the head [3, 4]. Symptom-limited exercise intolerance, i.e., the inability to exercise to the level predicted for one’s age and fitness because of symptom exacerbation, helps. The cause for exercise intolerance after concussion is not fully understood but may be related to damage to the brainstem that uncouples the autonomic nervous system (ANS) from the cardiovascular system [9, 10]. It is theorized that abnormal ANS function alters cerebral blood flow (CBF) regulation during exercise that produces symptoms of headache and dizziness to limit exercise duration [11, 12]. If symptoms persist for more than 2 weeks in adults and for more than 1 month in adolescents, they are described as having Persistent Post-concussive symptoms (PPCS) [15]

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