Steve Smith has been ruled out of the third Ashes Test due to a concussion suffered at Lord's last week.

The Australia batsman was struck on the neck by a fierce bouncer from England debutant Jofra Archer on day four.

Although Smith returned to resume his innings on Saturday, Cricket Australia (CA) announced the 30-year-old would not play any part on the final day of the second Test.

And following that draw, Smith will also now miss the third Test at Headingley.

Before his absence was confirmed, Omnisport spoke to expert Dr Sam Barke, medical director of Return2Play, about Smith's concussion, the delayed symptoms and the protocol for returning to action.

 

CA said Smith "passed the CogSport and SCAT5 assessments" when he came off the pitch at Lord's, so why was the concussion not spotted then?

The key to those tests is there is not really a pass-fail situation, it's just evidence building. Along with how the player is responding, how they're feeling and their symptoms, we do these tests to gather as much evidence as possible to try and work out whether the concussion has happened.

Unfortunately, there is not a 100 per cent test at the moment for concussion. It's adding all those pieces of evidence together to try and be as sure as we can.

Not infrequently we end up with situations like we had with Steve Smith where all the evidence from those tests has said, 'No, we don't think a concussion has happened'. Then further down the line symptoms start to come on.

It was later revealed that Smith suffered a "delayed concussion response" – what is that?

The concussion itself hasn't been delayed. He had concussion from moment one. It's that he wasn't showing any signs or symptoms that concern that until now.

In my experience, the vast majority of time players do have some symptoms at the immediate point of injury and then they go away very, very quickly. It may have been by the time they got out there he was feeling absolutely fine.

So it looks like the Australia medical staff followed all the procedures correctly?

We reckon that probably about 10-to-20 per cent of concussions have that delay in onset.

As an outsider, it looks like everything's been done correctly and the right decisions have been made at every point, and he unfortunately fits into that small category of players that look fine at the time and then go on to develop symptoms further down the line.

The third Test begins on Thursday and, per CA's concussion policy, Smith must not play or train until at least 24 hours after he has been cleared by the doctor. What is the process for a player returning to their sport and why do medics have to be careful?

You shouldn't be doing any activity until your symptoms have settled. In professional rugby they say you have to be 24 hours symptom-free before you start doing any sort of exercise. The theory is most people start to feel well when they do absolutely nothing and we want to see whether any symptoms come back with exertion and mental strain, so you gradually start to introduce exercise.

The big thing about concussion and the way you manage it, is the risk comes from further injury, not the initial injury. The risks from a one-off knock that's treated well are almost non-existent, but while the brain's still recovering, if it takes further knocks, that's when risks happen.