Concussion is a type of brain injury. It is a complex injury that is challenging to evaluate and manage. The Concussion in Sport Group (CISG) international Consensus Statement defines concussion as ‘a traumatic brain injury, induced by biomechanical forces’. It generally results from a knock to the head, face or neck - but may be anywhere on the body which transmits force to the head. Concussion involves short-lived impairment of neurological function. Concussion is an evolving injury that may change over the first few hours or over a few days. In most adult cases, symptoms are resolved within 14 days of injury.

Diagnosing concussion can be difficult - but is critical to correctly managing and preventing further injury.

Diagnosis relies on the clinical assessment of symptoms and signs. There is no specific diagnostic test which confirms the presence or otherwise of concussion.

For Adults: Medical practitioners can use the Concussion in Sport Group Sport Concussion Assessment Tool 5 (SCAT5) as part of an overall clinical assessment to assess potential concussions.

For Children: The Child Sport Concussion Assessment Tool (Child-SCAT5) can be used to assess concussion in children aged 5 – 12 years.

People without medical training can use the Concussion Recognition Tool, also developed by the Concussion in Sport Group.

Acute presentation

First-aid principles still apply for athletes suspected of having a concussion. Responders should systematically assess the airway, breathing, circulation, disability and exposure of the athlete in all situations.

Cervical spine injuries should be suspected if there is any loss of consciousness, neck pain or a mechanism that could lead to spinal injury. Until a cervical spine injury can be ruled out, undertake manual inline stabilisation and apply a hard collar.

In diagnosing concussion, medical practitioners should do a clinical history and examination that includes:

• mechanism of injury
• symptoms and signs
• cognitive functioning
• neurological assessment including balance testing
• a completed concussion assessment using the SCAT5 for adults or Child-SCAT5 for children aged 5 – 12 years

As part of the assessment medical practitioners may use:

• Computerised neurocognitive testing. Pre-season baseline neurocognitive testing is useful to compare against post-injury scores. Programs have reference ranges that can be applied in the absence of a baseline test.
• Medical imaging where there is suspicion of serious head or brain injury.

Currently, no serum biomarkers assist in the diagnosis of concussion. Blood tests and medical imaging is not indicated in the diagnosis or management of uncomplicated concussion.

Delayed presentation

Medical practitioners often have athletes present to the clinic during the week, having suffered a potential concussion over the previous weekend. This poses challenges. If there is any suspicion that a concussion occurred on the weekend, the medical practitioner should assume that a concussion did in fact occur. There is no test or series of tests which can conclude that a concussion did not occur.

Six key video review steps for the team clinician

Video technology is used by many professional sports to support identification of concussion, differentiate between mandatory and discretionary concussion signs and, in some instances, assist with return to sport decisions. The 2017 Berlin Concussion in Sport Group Consensus Statement identifies six steps for video-review focused on concussion identification.

Six key video-review steps for the team clinician

1. Look for the suspected head impact event
2. Look for the immediate response of the injured athlete (0-2 s). Does the athlete fall to the ground? If the athlete falls, is there loss of head and neck control? Does the athlete protect himself/herself when falling? If the athlete remains upright, is he/she steady on his/her feet?
3. Look for the subsequent response (2-5 s). If the athlete falls, does he/she move spontaneously? Is there evidence of purposeful voluntary movement (ie, placing the ball or completing a tackle)? Is there evidence of a concussive convulsion or tonic posturing? How does the athlete respond to the attending medical staff (this phase may extend for substantially longer than 5 s, particularly if in-line cervical immobilisation is required)? If the athlete remains standing, the distinction between the subsequent and late responses may be unclear.
4. Watch for the athlete’s late response when returning to his/her feet (if the athlete has fallen). Is the athlete unsteady when attempting to get to his/her feet and return to sport? Does the athlete need help from others to stand up? Are the athlete’s movements fluid and coordinated? Does the athlete fall to the ground?
5. Watch the athlete’s behaviour on return to sport. Are his/her actions appropriate or not? Does he/she move immediately to the correct position on the field of play?
6. Observe the responses of other athletes and match officials.

Any athlete with suspected concussion should be REMOVED FROM SPORT, medically assessed and monitored for deterioration. No athlete diagnosed with concussion should be returned to play on the day of injury.

Minimum criteria for diagnosing concussion are:

1. A thorough assessment looking at loss of consciousness, symptoms, cognition, neurobehavioural symptoms, and balance – with any abnormality being a potential sign of concussion.
2. A concussion assessment using the SCAT5 for adults or Child-SCAT5 for children aged 5 – 12 years. Note: the diagnostic utility of the SCAT decreases 3-5 days post-concussion.

Any athlete with suspected or confirmed concussion should:

• remain in the company of a responsible adult
• not be allowed to drive
• be advised to avoid alcohol
• have their medications reviewed.

Specifically, concussed athletes should avoid:

• aspirin
• anti-inflammatories (such as ibuprofen, diclofenac or naproxen),
• sleeping tablets
• sedating pain medications.

If the athlete is diagnosed with concussion, immediate management is physical and cognitive rest. This may include time off school or work, and relative rest from cognitive activity. Having rested for 24 – 48 hours after sustaining a concussion, the athlete can begin moderate intensity physical activity - as long as the activity doesn’t cause significant and sustained deterioration in symptoms. Concussive symptoms usually resolve in 10 – 14 days.

Children and adolescents

Sport-related concussions are common in children and adolescents aged 18 years or younger. For this age group, a more conservative approach to diagnosis and management is recommended. This is because this age group:

• has a slower rate of recovery from concussion
• has unique physical, cognitive and emotional differences
• is more vulnerable to concussion, due to factors including decreased myelination, poor cervical musculature, and (possibly) increased head to neck ratio
• the role of cerebral blood flow alterations in the pathophysiology of concussion may be more significant

Return to learn

‘Return to learn’ is about the athlete’s gradual return to their usual program at school or work.

‘Return to learn’ should take priority over ‘Return to sport’. School programs may need to include more regular breaks, rests and increased time to complete tasks.

Medical practitioners can use the Return to Learn Care Plan to communicate to teachers the requirements for a concussed child or adolescent.

Return to sport

‘Return to sport’ is about the athlete’s gradual return to full sporting activity.

Having rested for 24 – 48 hours after sustaining a concussion, the patient can begin moderate intensity physical activity - as long as the activity doesn’t cause significant and sustained deterioration in symptoms. Concussive symptoms usually resolve in 10 - 14 days, after which the athlete can begin a staged return to sport.

Medical practitioners can use these Return to sport protocols to inform their Return to sport patient programs.

• Return to Sport Protocol for Children and Adolescents
• Return to Sport Protocol for Adults

Predictors of clinical recovery can assist the medical practitioner in managing the concussed athlete. These predictors are associated with protracted recovery:

• high severity of acute and subacute concussive symptoms
• a high number of concussive symptoms
• prolonged loss of consciousness (longer than one minute)
• post-concussive seizure
• previous history of concussion
• age of the athlete
• female sex
• history of depression, anxiety or migraine.

There is a potential link between mental illness and concussion, although the relationship is not clear. Athletes with a history of mental illness require a more cautious approach. A conservative Return to Sport strategy is recommended.

There are a number of organisations with information on mental illness and where to go for help:

• Lifeline provides a 24 hour, 365 days per year crisis support and suicide prevention service. It is free and provides immediate support for those in need.
• Headspace is a national youth mental health support service providing mental health assistance to those aged 12–25.
• Beyond Blue supports Australians to protect their mental health through education and awareness.

Chronic traumatic encephalopathy neuropathological change (CTE-NC) is a neurodegenerative pathology associated with a history of repeated head trauma. CTE-NC can only be diagnosed by post-mortem histopathological examination.

There are a growing number of case studies and case series which document change (CTE-NC) in retired athletes with a history of RHT. There remain many uncertainties about the strength of the association between RHT, concussion, and CTE-NC.

CTE-NC is not an inevitable consequence of exposure to repeated head trauma. Further research is required to understand the prevalence of CTE-NC in athletic cohorts and the factors that predispose some athletes to the development of CTE-NC following exposure to RHT. Properly designed prospective studies, which control for potential confounding variables, are required to improve our understanding of CTE-NC and why some individuals are susceptible

CTE-NC is characterized by the build-up of hyperphosphorylated tau (p-tau) in neurofibrillary tangles (NFTs), neurites, and, sometimes, astrocytes, surrounding small blood vessels in a patchy distribution at the sulcal depths of the cerebral cortex.

Most of the reported cases of CTE-NC have been detected in sport brain banks. There are issues with significant selection bias in these studies. Research using non-sport brain banks in Australia, the US and Europe show rates of CTE-NC of less than 1%.

The potential contribution of confounders, such as genetic predisposition, psychiatric illness, alcohol and drug use or co-existing dementia, is not adequately accounted for in the current literature.

Acute cerebral oedema or ‘second impact syndrome’ has received media attention due to its catastrophic outcomes. Acute cerebral oedema refers to rapid cerebral swelling that can occur when a second concussive injury is sustained during a ‘vulnerable’ period when the brain has not recovered from an initial insult. Animal models have demonstrated that there is a period of vulnerability during which further injury can result in significant axonal injury with associated ion channel damage. It is thought that a second impact may not be needed for the swelling to develop.

The condition is rare and the only available literature consists of case studies which are inadequate to provide a good understanding of the mechanisms and risk factors. Further research is needed to better understand the pathophysiology and risk factors for ‘second impact syndrome’.