A landmark concussion lawsuit by a former National Rugby League player has rocked Australia's sporting community and could have far-reaching consequences for how the condition is diagnosed and treated.
While sport often dominates headlines in Australia, experts want more focus on head knocks -- an "invisible injury" sometimes dismissed as a badge of honour in a macho culture -- and their long-term impact.
A driver of change could be James McManus's legal action against the Newcastle Knights, in which he claims his former club breached their duty of care to him over several years.
The ex-winger alleges he was encouraged or allowed to keep playing after sustaining concussions, Fairfax Media reported. A brain injury prematurely ended his career.
"It's one of those things where I know players are suffering with things and are probably unaware that concussions are the cause of it," the 31-year-old said in February after launching his case.
"You don't want to be in the position where you are the first to do something, but I think things have to change in the game, there's no doubt about that."
Concussion campaigner and veteran Australian Football League (Aussie Rules) player agent Peter Jess has launched a website urging former athletes to come forward, which could spark class actions or individual lawsuits.
"I've worked for over 1,000 players and they were young, healthy men when they first started," Jess told AFP.
"I'm now seeing them as a range of damaged individuals in their 40s and 50s."
- Blue card trial -
Awareness about concussion in sport has grown since America's National Football League agreed to a US$1 billion settlement in 2015 to resolve thousands of lawsuits by former players suffering from neurological problems.
In sports-mad Australia, various codes including rugby union, rugby league and cricket have sought to boost their protocols on the issue.
Recent measures include the NRL fining three clubs a total of Aus$350,000 (US$268,000) -- the heaviest ever issued -- for failing to follow concussion rules in games this season.
The Australian Rugby Union is trialling a system where players showing signs of concussion are shown a blue card and sent off for the remainder of the match. They cannot play again until given a medical all-clear.
Meanwhile, Cricket Australia is pushing for concussion substitutes in international games, a rule they introduced for domestic matches following the death of batsman Phillip Hughes after he was hit by a bouncer in 2014.
But experts say codes need to go further, such as using an independent doctor to assess on-field injuries alongside a club's medical officer, who could be biased or busy tending to others when a head knock occurs.
The issue was highlighted recently when English NRL star Sam Burgess played for some minutes with suspected concussion before he was withdrawn, as the team doctor was reportedly checking on one of his South Sydney team-mates.
"I think the New Zealand protocol with rugby union where they have an independent concussion assessment by a second doctor who is available at the field is a good one," Sydney-based neurosurgeon Richard Parkinson told AFP.
"That avoids any potential bias and makes sure that every player from each team is assessed in the same way."
Concussion occurs when blow to the head or body causes the brain to move in different directions quickly.
Most concussions do not result in a loss of consciousness, and the injury often doesn't show up on brain scans.
As a result, current sideline tests rely on feedback from a patient through simple cognitive tasks such as reciting numbers backwards, making their results subjective.
Biological tests, viewed as more objective, have yet to be formally introduced, although researchers are exploring the viability of procedures such as brain stimulation, eye movement tests and impact sensors.
- More research needed -
A lot is still unknown about concussion, and there are growing calls for independent research, particularly when the link between the traumatic brain injury and long-term health woes is still contentious.
Last year, US lawmakers found the NFL attempted improperly to influence a major study into links between the sport and brain disease, raising impartiality questions about research funded by sporting bodies.
Neurophysiologist Alan Pearce, who advocates independent research, recently put 25 retired NRL players through cognitive tests and found their brains more damaged than a control group with no history of concussion or playing contact sport.
"We are also trying to look at the acute aspects... when is someone ready to come back to training and playing competitively," Pearce told AFP.
"If we are able to manage that part properly, then the long-terms risks are reduced noticeably."
Pearce is part of an athlete-driven concussion working group set up by major Australian sporting codes last year to change cultural attitudes and push for an independent national study.
"It's not about bringing sport to its knees," Australian Athletes' Alliance chief Ian Prendergast told the Herald Sun this month.
"In my view we protect sport more than we currently are if we can find out additional information about the impact of concussions... it's something we should be all embracing."