Concussion can have life-changing consequences, but Dana Johannsen and Dylan Cleaver report that a 'she'll be right' attitude means the dangers are often ignored.
It had the potential to be one of sports medicine's great "Eureka!" moments, but when an American neuro-pathologist discovered large accumulations of tau proteins in the brain of a legendary American footballer Mike Webster, he instead kicked open a hornet's nest of scorn and recriminations.
The issue of concussion in contact sport was nothing new, but as Dr Bennet Omalu pored over the brain matter of Webster - who had gone from winning four Super Bowls to dying penniless at 50, having spent his final days with rotten teeth that had been glued together, and able to sleep only by tasering himself - he discovered a connection between head injuries and degenerative brain disease.
He coined the disease chronic traumatic encephalopathy (CTE); those three letters had the effect of a large stick of gelignite being placed under the offices of the US National Football League, with a lit fuse.
Medicos on the NFL's payroll went to extraordinary lengths to discredit Omalu's work, by now published in a prestigious medical journal, but evidence that he was on to something kept mounting.
Omalu received the brains of other NFL players who had lived difficult, sometimes bizarre lives and suffered untimely deaths and he found the same accumulation of tau proteins.
Concussion suddenly became the most emotive topic in contact sport. Everyone knew about the short-term and even some medium-term effects of concussion - nausea, dizziness and migraines - but here was a tangible link to long-term disorders. It is a fear now stalking rugby, all contact sports for that matter, but the 15-man code is our national sport and the sensitivity in this sport is only heightened.
It is not a New Zealand problem alone. In Northern Ireland, an inquest continues into the death of Ben Robinson, 14, a Carrickfergus schoolboy who died last year after carrying on playing following a heavy tackle.
While rugby bodies have played down the research coming out of the US and its relevance here, there is a big push on to quantify the long-term risks of playing the sport.
The International Rugby Board and NZ Rugby Union have commissioned research into the long-term health impacts of rugby on elite and amateur players - the results of which aren't expected to be published until November next year.
Auckland neurologist Dr Rosamund Hill says the cases in the US are significant and need to be used as a springboard for more thorough, wider research. "I think that is really important research to be done, and until it's done I think everyone has to err on the side of raising awareness and say, 'Look, there could be a serious long-term problem if you ignore this'."
The fact that new pitchside concussion assessments have been put in place this year points to a sporting body that realises it can no longer view concussion as just the unfortunate by-product of a contact sport.
There is a long way to go. Concussion is common in rugby, whether it be on Eden Park or a club ground in Ashburton. The only difference is that players at Eden Park have immediate access to quality medical care.
If you listen to former Taranaki player Paul Tito, who recently retired after a particularly severe concussion while playing in Italy, "95 per cent" of players don't report their injuries, or at least play down the severity.
Stuart East hasn't had a proper sleep in 10 years after suffering as many as 13 concussions in a career that never progressed beyond the lower grades.
An Auckland rugby source, who does not want to be named for fear he will be reprimanded, says hundreds of people are playing each week around Auckland who shouldn't be. Dr Hill, who has treated players at all levels of the game, says: "I've seen players who should have been retired earlier."
Rob Allen, brother of All Black Nicky Allen - who died after suffering a catastrophic head injury - accuses the NZRU of a long-term "cover-up" of the seriousness of concussion.
Dr Steve Marshall, a NZ academic working at the University of North Carolina, says that while rugby has made giant strides, there is still so much more that can be done in terms of research to make the game safer.
Mike Sabin, National MP and the father of Darryl - brain-damaged after multiple concussive injuries, despite his father's efforts to prevent him playing - says "the issues are really at club level or schoolboy level, where there is no real medical oversight".
Alone, none of these things defines or quantifies the scale of the problem - Marshall was at pains to point out what an inexact science medicine is - but together, they paint a picture of a sport undergoing a treacherous balancing act, trying to get to grips with the issue while casting the game in a positive light.
That might be a reason there is still scepticism about the veracity of some of the research around long-term effects, even if it appears to be swimming against a tide of compelling evidence.
Writing this year in the Clinical Journal of Sports Medicine, Australian Professor Paul McCrory - chairman of the organising committee for the fourth international consensus conference on concussion in sport, to be held in Zurich in November - said: "At this time, scientific evidence to support the link between concussion and long-term cognitive deterioration, mental health issues and CTE is limited, with only a handful of cases... recorded."
Which begs the question: do rugby, league or any other sport in which head injuries can be a factor need them to reach epidemic levels before they're accepted as fact? Would it not be better to treat the research as incontrovertible and work backwards from there?
Over the next four days, the Herald will take a close look at the issue of concussion in sport, with a heavy emphasis on rugby. We will speak to some who are afflicted, and those who are trying to ensure the next generation of players are safer. We will look at the science behind the stories. We will look at the past and what the future might hold.
This is a problem for rugby, but it is not exclusively a rugby problem.
What is Tau?
Tau is a microtubule-associated protein that stabilises and regulates nerve cells.
* What is CTE?
Chronic traumatic encephalopathy is a neuro-degenerative disorder.
* How are the two linked?
As the brain starts to deteriorate, it builds up huge amounts of tau in the form of neuro-fibrillary tangles.
* Where else is tau found?
Tau build-up is also found in diseases such as Alzheimer's, but not in the unique pattern seen in CTE.
CTE-related NFL deaths
* Terry Long
Steelers guard, dead at 45 after drinking antifreeze.
* Andre Waters
Eagles safety, dead at 44 after shooting himself in the mouth.
* Justin Strzelczyk
Steelers lineman, dead at 36 after driving his car into the path of a tanker carrying corrosive acid.
* Junior Seau*
Star linebacker for the San Diego Chargers, dead at 43 after shooting himself in the chest on May 2 this year. (* Not confirmed as CTE. Brain specimens have been sent to a lab for further analysis.)
We look at the dangers at the community level of the game and talk to Rob Allen - older brother of the late All Black Nicky Allen - who is adamant the NZ Rugby Union is not doing enough to protect its players.