Repeat concussion

People with a history of multiple concussions are at risk of persisting post-concussion symptoms.³⁸⁷ People who have experienced multiple concussions, especially within a short time period such as a season of sport, should be managed more conservatively and may benefit from the involvement of a concussion interdisciplinary team.³⁷ Evaluation may reveal underlying causes or risk factors for repeated injury³⁸⁸. Advise on strategies to prevent concussion and the increased risks associated with certain activities should be given (i.e. contact sports, activities involving high speeds, equestrian show jumping). Currently, there is no evidence to support health care professionals in advising when people with multiple concussions should retire from sport. Referral to a specialist such as a sports medicine physician or concussion expert is recommended, especially where symptoms take a very long time to remit.

• People diagnosed with a repeat concussion soon after the index injury (within 3 months) or after multiple repeat episodes are at increased risk of persisting post-concussive symptoms (children and adults)

  CBR345,388,394

  7. Babl FE, Tavender E, Dalziel S. Australian and New Zealand guideline for mild to moderate head injuries in children – Full guideline. Melbourne: Paediatric Research in Emergency Departments International Collaborative; 2021.345. 345. Brooks BL, Mannix R, Maxwell B, Zafonte R, Berkner PD, Iverson GL. Multiple past concussions in high school football players: are there differences in cognitive functioning and symptom reporting? Am J Sports Med. 2016;44(12):3243-51. 388. Curry AE, Arbogast KB, Metzger KB, Kessler RS, Breiding MJ, Haarbauer-Krupa J, et al. Risk of repeat concussion among patients diagnosed at a pediatric care network. J Pediatr. 2019;210:13-9. e2. 394. Alsalaheen B, Stockdale K, Pechumer D, Giessing A, He X, Broglio SP. Cumulative effects of concussion history on baseline computerized neurocognitive test scores: systematic review and meta-analysis. Sports Health. 2017;9(4):324-32.

  Adapted7

Long-term effects

There is increasing concern about whether repetitive head injuries lead to a future increased risk of dementia and neurological problems. No source recommendations were identified on the prevalence/risk of long-term effects of mTBI, traumatic encephalopathy syndrome (TES) or chronic traumatic encephalopathy (CTE) as there is no conclusive data to support this risk or its management, the GDG were unable to develop any recommendations.

Chronic traumatic encephalopathy is a pathological syndrome with degenerative changes that can can only be diagnosed at autopsy (CTE-NC). CTE-NC is linked to repetitive head injuries. Evidence from pathological case series suggests that CTE-NC (i.e. the pathological changes) increases with increased exposure (years of play) in athletes e.g. those who have played for more that 14.5 years were 10 times as likely to have CTE pathology.³⁸⁹

The relationship between clinical symptoms and signs and the pathology CTE-NC is not clear. It is not known whether, or the extent to which, clinical signs and symptoms are caused directly or indirectly by CTE-NC. This becomes problematic for the management of people with prolonged exposure to repetitive head injury and concerns about their neurological function. The clinical syndrome that may accompany CTE-NC is referred to as traumatic encephalopathy syndrome (TES), a non-specific constellation of progressive cognitive, neurobehavioral, and motor impairments leading to loss of function and dementia. There are no clinical symptoms or signs that are specific to TES and all may be seen in other neurological or mental health conditions and community-dwelling adults.³⁹⁰

TES classification criteria have been developed in order to facilitate research helping understand how TES may or may not relate to CTE-NC and repetitive head injury.³⁴⁴ The diagnosis of TES requires (1) substantial exposure to repetitive head impacts from contact sports (e.g. 5 or more years of American football, with at least 2 years at the high school level), military service, or other causes (2); core clinical features of cognitive impairment (in episodic memory and/or executive functioning), neurobehavioral dysregulation, or both (3); a progressive course; and (4) that the clinical features are not fully accounted for by any other neurologic, psychiatric, or medical conditions.³⁹¹ Psychiatric conditions such as depression, anxiety, suicide, or intermittent explosive condition are not core features, and there is controversy about whether they should be considered supportive features or not.³⁹²

Currently, there is no evidence for an increased risk of mental health or neurological conditions in amateur athletes with repetitive head injury, although there may be an increased risk in former professional athletes.³⁹² Other factors that may increase this risk of TES symptoms and/or CTE-NC include genetic, general health factors (e.g. obstructive sleep apnoea, cardiovascular disease, diabetes), social and lifestyle factors (e.g. alcohol use and substance use). As many of these factors are modifiable, healthy lifestyle practices and good medical care may ameliorate risks of TES in athletes.³⁹³

• Practice point for children and adults:
  When returning to sport, people with repeat mTBI/concussions within the season are likely to require a more conservative approach and may require input from an interdisciplinary concussion team.

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• People who are concerned about possible long term effects of repetitive head injuries should be encouraged to seek medical assessment and advice. Symptoms that cause concern are more likely to be due to other medical conditions that can be managed effectively.

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