Sensorimotor system changes in adolescent rugby players post-concussion: A prospective investigation from the subacute period through to return-to-sport
Introduction
Concussion injuries are common in contact and collision sports (Zuckerman et al., 2015). A high incidence of concussions has been reported in adolescent rugby union (Leung et al., 2017a, 2017b), and in comparison with other adolescent sports, rugby union has the highest incidence (Pfister et al., 2016). The current management of athletes following concussion involves a period of rest followed by a graduated return to activity protocol (McCrory et al., 2017). In most cases, symptoms resolve spontaneously, and full clinical recovery is achieved within 14 days in adults and four weeks in children and adolescents (McCrory et al., 2017). However, despite the resolution of symptoms in the majority of cases, there is evidence of an increased risk of subsequent concussions and musculoskeletal injury in athletes returning to sport after concussion (Herman et al., 2017), suggesting that there may be residual deficits in the sensorimotor system that may last longer than the symptomatic period.
Integration of the vestibular, visual and somatosensory systems is important in maintaining optimal balance and postural control, as well as enabling stable vision during dynamic functional activities (Ellis et al., 2015; Riemann and Lephart, 2002). Altered function in any of the sensorimotor systems after concussion may contribute to the symptoms and impairments which are commonly reported following concussion. Impairments in the vestibular and oculomotor systems have been reported in adolescent athletes post-concussion (Mucha et al., 2014). Symptoms including dizziness, nausea, vertigo, balance deficits and visual/tracking disturbances may indicate an underlying impairment in vestibular and oculomotor function (Mucha et al., 2014; Kontos et al., 2017). The mechanism of injury is similar for concussion and whiplash injuries, and comparable patterns of pain and associated deficits of the cervical spine have been demonstrated post-concussion (Schneider et al., 2018; Treleaven et al., 1994). Recent studies in adult rugby union players have also demonstrated altered sensorimotor function post-concussion, including changes in balance strategies and altered motor control of the lumbopelvic region (Hides et al., 2017a, 2017b). Muscles in the lumbopelvic region have a high concentration of muscle spindles and play an important sensory role which helps control segmental motion of the lumbar spine and maintain postural control (Kiefer et al., 1997). These findings suggest that identification of impairments in specific systems within the sensorimotor system could help inform targeted management of athletes with concussion (Schneider, 2019).
There is an evolving scope for physiotherapy in the management of athletes post-concussion, with physiotherapy-based interventions (vestibular rehabilitation and cervical spine treatment) resulting in faster return to sport and resolution of symptoms in athletes with persistent symptoms (Schneider et al., 2014; Grabowski et al., 2017). Establishing the changes in sensorimotor function post-concussion has the potential to better inform physiotherapy management of these athletes regardless of their symptom presentation. It may also be possible to reduce the risk of subsequent concussions or musculoskeletal injuries by addressing observed impairments in the sensorimotor system (Herman et al., 2017).
The aim of this study was to undertake a prospective multifaceted assessment of the sensorimotor system in adolescent rugby players to identify specific changes after concussion. This included investigation of, i) whether changes in sensorimotor function were evident in adolescent rugby players in the subacute period following a concussion, and ii) whether sensorimotor function returned to preseason (baseline) levels following return to sport.
Section snippets
Participants
Participants included 285 adolescent male rugby union players (aged 13–18 years) from six schools during the 2016 and 2017 school rugby seasons in Queensland, Australia. Players in the senior or emerging playing squads were eligible for inclusion in the study. Written informed player assent and parental consent was obtained for all participants. The study was approved by the university's ethics committee (HREC 2014-253Q).
Study Design
A prospective nested case-control study was conducted, with assessments at
Results
Twenty-three of the 285 participants (8%) sustained a concussion during either the 2016 or 2017 playing season. Preliminary analyses demonstrated that at baseline there were no significant differences between groups (players who did and did not sustain a concussion) for balance, cervical spine proprioception, vestibulo-ocular function and lumbopelvic muscle size and contraction. Twenty players who sustained a concussion and 14 age- and position-matched control players were assessed in the
Discussion
The current investigation demonstrated changes in vestibulo-ocular function and the size and thickness of lumbopelvic muscles during the subacute period post-concussion, with some changes persisting after players had returned to sport.
Following concussion, the results of the current investigation demonstrated an increase in vestibulo-ocular dysfunction in adolescent rugby players. The prevalence of vestibulo-ocular dysfunction increased during the subacute period post-concussion. These results
Conclusion
Changes in sensorimotor function were observed in the subacute period post-concussion, with some persisting after return-to-sport. Using symptom-based criteria for return-to-sport may not adequately reflect the sequelae of concussion on the sensorimotor system. A thorough and individualised assessment of the sensorimotor system and comparisons with pre-concussion measures may be required to adequately identify specific impairments post-concussion. The results of our study warrant further
Declaration of interest
The authors declare there were no conflicts of interest.
Ethical approval
The study was approved by the Australian Catholic University's ethics committee (HREC 2014-253Q).
Funding source
Felix Leung was funded through a National Health and Medical Research Committee (NHMRC) post-graduate scholarship (#1133186). The research project was funded by a Collaborative Research Network and Australian Catholic University Research Fund (Grant no. 2013000523).
Acknowledgement
The authors would like to acknowledge the principals, directors of sport and players from the 6 schools involved for their support and participation in this study. The authors would like to thank the physiotherapists that were involved as part of a larger study during data collection, in particular, Christine Sonsearay, Margot Sexton, Brittany Grantham, Juan da Cal, Jacob Johannnessen, Peter Sloss, Liam Codd, Joe Kerby and Ben Harris. The authors would also like to thank Jenny Peat and Chris
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