Direct Hits to the Head during Amateur Boxing is Associated with a Rise in Serum Biomarkers for Brain Injury

Abstract

Boxing exposes participants to the physiological response to high intensity exercise and also to direct body and brain trauma. Amateur boxing is increasing and females have also been included in the Olympics. The aim of this study is to assess the stress response and possible brain injury incurred during a match by measuring serum biomarkers associated with stress and cellular brain injury before and after combat. Sixteen male amateur boxers were studied retrospectively. The study population was divided into two groups: (a) a group that received predominantly punches to the head (PTH) and (b) a group that received predominantly punches to the body (PTB). Blood samples were taken before and five minutes after each contest. They were analysed for S-100B, neuron-specific enolase (NSE), creatine kinase (CK) and cortisol. The PTH group received direct contacts to the head (not blocked, parried or avoided) and to the body (n=8, age: 17.6 ± 5.3, years; height: 1.68 ± 0.13, meters; mass: 65.4 ± 20.3, kg). The PTB group received punches to the body including blocked and parried punches, but received no direct punches to the head, (n=8, mean ± SD, age: 19.1 ± 3.2 years; height: 1.70 ± 0.75, meters; mass: 68.5 ± 15 kg). Significant increases (P<0.05) were observed between pre-and post-combat serum concentrations in serum concentrations in PTH of S-100B (0.35 ± 0.61 vs. 0.54 ± 0.73, Jig.VI) NSE (19.7 ± 14 vs.31.1 ± 26.6, ng.ml") and cortisol (373 ± 202 vs. 756 ± 93, nmel.L"), Significant increases (P<0.05) of creatine kinase were recorded in both groups. This study demonstrates significant elevations in neurochemical biomarkers in boxers who received direct blows to the head. However, further work is required to quantify this volumetric brain damage and long term clinical sequelae.Children as young as 11 years of age are eligible to compete in boxing bouts that involve full contact blows to the head (1). Furthermore, female amateur boxing has also recently been included as an Olympic sport and is a testament to equality in sport and the assumed confidence in the safety of amateur boxing (2). The perception of safety surrounding the sport can be attributed to the lack of consensus in the scientific literature on the potential dangers involved in boxing (3-5), compounded by the assumed protection afforded by the mandatory use of headguards. This position is often assumed to be due to

Impaired cerebral haemodynamic function associated with chronic traumatic brain injury in professional boxers

“…This may prove to be the common mechanism underlying the systemic extravasation of the BBBspecific protein S100β [53], punctate micro-haemorrhages [56] and neuropathological lesions [41] that have previously been reported in more advanced cases of CTBI.…”

“…Given that clinical TBI is associated with elevated metabolic-neural activity and associated oxygen demand [51], even a subtle reduction in cerebral perfusion and oxygenation has the potential to cause intermittent cerebral hypoxia if not indeed ischaemia, resulting in secondary neuronal-parenchymal damage [14,52]. Such changes may provide an alternative (haemodynamic) mechanism to account for the chronic elevation recently observed in the blood-borne concentration of neuron specific-enolase, an ischaemia-sensitive biomarker of neuronal-parenchymal injury [53].…”

Mind the gaps—advancing research into short-term and long-term neuropsychological outcomes of youth sports-related concussions

“…Elevated serum and CSF levels of S100B have been observed in adult boxers after matches, and correlate positively with the number and severity of head impacts. 124,125 Increased serum S100B levels have also been observed in concussed professional ice hockey players, 126 with levels measured 1 h post-concussion predicting symptomatic recovery time. However, S100B levels were also raised after controlled play where no concussions occurred, indicating that this marker is not injury-specific.…”

“…[134][135][136] Neuron-specific enolase (NSE) is a marker of neuronal injury, but its usefulness as a serum or CSF biomarker remains uncertain. [133][134][135][136][137] Elevated serum NSE levels have been observed after head impacts in boxers, 124 but were also seen in ice hockey players after a match where no concussions occurred. 126 Serum NSE levels failed to predict recovery time after concussion, 126 and might not correlate with injury severity in children.…”

The Pathophysiology of Concussion

“…Similarly, serum levels of neuron-specific enolase (NSE), a marker of neuronal damage, may be elevated in boxers even persisting after a resting period, suggesting there is an effect of repetitive trauma [138]. S100B has also been shown to be elevated in boxers with direct blows to the head as opposed to those who experience blows to the body [139]. Given these changes that can be seen through different techniques even without diagnosed concussion, we must consider the potential effect that repeated blows may have on long-term outcome of athletes.…”