The effect of concussion on the vestibular and musculoskeletal systems in adolescent rugby union players

Abstract

Concussion in sports is a growing problem worldwide. The consequences of concussion on the long-term mental and physical health of athletes has generated concern among healthcare professionals. There is added concern in adolescents due to the uncertainty surrounding the effects of concussion on the developing brain, and the associated risk of developing persistent problems after concussion. Persistent problems may affect participation in sport and daily activities and have long-term impact on the health and wellbeing of athletes. There is a wide range of clinical signs and symptoms of concussion, and it involves a number of clinical domains such as neurocognition, postural control/balance, headaches, emotion, and sleep disturbances. The symptoms of concussion are not specific and often indicate associated injury to the cervical spine and vestibular system. Management of concussion requires a multidisciplinary and multimodal approach, and physiotherapy plays a key role in assessment and treatment of the underlying impairments. There is limited evidence of the effect of concussion on the sensorimotor system during the normal clinical recovery period following concussion. Physiotherapy intervention may be indicated, however, it is important to establish the deficits in the sensorimotor system that are amenable to physiotherapy. Comprehensive assessment of the sensorimotor system, in particular, the vestibular and musculoskeletal systems using established physiotherapy protocols is necessary to identify the underlying impairments that warrant intervention. Therefore, the aim of this thesis was to identify the effect of concussion on the vestibular and musculoskeletal systems. This thesis was conducted on a cohort of adolescent rugby union players due to the high risk of concussion injuries in the sport. While previous studies have reported high rates of concussion in rugby union, no recent studies have investigated concussions in Australian school level rugby union, and as such, this thesis also aimed to establish the epidemiology of injuries in Australian school level rugby union. The aim of studies 1 and 2 was to investigate the epidemiology of injuries in Australian school level rugby union. These studies found that there was a high incidence of concussion injuries in school level rugby union. Study 2 provided a thorough insight into the incidence and nature of injuries across different ages, and found a spike in injuries to the head, face, and upper and lower limbs in players between the ages of 14 and 16 years. The aim of study 3 was to examine whether a history of concussion affected the vestibular and musculoskeletal systems. The results indicated that there was a relatively high prevalence of vestibulo-ocular dysfunction in adolescent rugby union players, regardless of whether or not they had a history of concussion. Study 3 also found changes in the musculoskeletal system, in that players with a history of concussion had altered size and function of the lumbopelvic muscles. As there is variation in sensorimotor function among adolescents and residual deficits may occur after concussion, study 4 aimed to investigate the changes in sensorimotor function due to concussion using a prospective study design. The results provided evidence of vestibuloocular dysfunction after concussion, and that these deficits do not resolve spontaneously despite resolution of symptoms and after returning to sport. Changes in lumbopelvic muscle size and thickness, and cervical muscle endurance were found in the acute period after concussion, with some persisting after return to sport. No significant changes in balance were demonstrated after concussion. This thesis is the first to investigate the incidence and impact of concussion in Australian school level rugby union players. Concussion was found to be a common injury in school level rugby union in Australia. A spike in rugby union injuries was also found in players in the adolescent age group. Findings from this thesis indicated changes in the vestibular and musculoskeletal systems in adolescent rugby union players after concussion, with some of these changes persisting after return to sport despite the resolution of selfreported symptoms. Deficits in vestibulo-ocular function were common in our cohort of adolescent rugby union players and ideally should be compared with pre-concussion function where possible or considered carefully when interpreting positive findings after concussion. Assessment of the vestibular and musculoskeletal systems should be conducted in the normal clinical recovery period after concussion and prior to return to sport to identify deficits amenable to physiotherapy intervention. Although balance deficits were not identified, changes in lumbopelvic muscle size and thickness, and cervical muscle endurance may represent an altered movement strategy as a protective response after concussion. Physiotherapy management may be indicated after concussion, however, intervention should be individualised to address the specific underlying impairments.