Returning to play: What brain imaging can teach us about concussion

Returning to play: What brain imaging can teach us about concussion

March 13, 2020 0 By Stanley Isaacs


In Canada, hockey concussions account for
roughly half of all sports-related concussions. Most of the people who get
these tend to be young players and this is a problem because young players
brains are still developing. This means that they’re actually still forming
connections between different areas of the brain and this makes them particularly
vulnerable to damage from injuries such as concussions. And the problem with
concussions is while we can recognize the symptoms of concussion, we don’t
actually know what’s happening in the brain and what gives rise to these
symptoms. My laboratory uses some of the most sophisticated magnetic resonance
imaging machines in the world to study the human brain. This allows us to look
at the brain immediately after a concussion as well as in the weeks
months and years following that concussion – a nice non-invasive tool for
actually trying to figure out this problem. We use MRI to study brain
structure – actually microstructure – and brain function. We use a technique called
diffusion tensor imaging which allows us to map out the white matter tracts in
the brain. These are the wires in the brain that connect the different areas,
and we use something called functional magnetic resonance imaging to actually
look at the communication between the different areas. So this is analogous – DTI
essentially maps out the roadways, and functional MRI tells you something about
the traffic that’s going on along the roadways. So, using these techniques we were able
to study concussion in players such as a Bantam hockey team that we studied,
immediately after their concussion as well as up to three months later. And
what we found was particularly interesting. Immediately after concussion
what we found was that the white matter tracts – the wiring – particularly the long
tracts that run from the front of the brain to the back of the brain, or from
the left side to the right side, were subtly damaged. And the resting state
networks – so, what we get the communication between the different
areas – was also disrupted as you might expect. This is very much like
encountering a traffic jam and you can no longer get the information along that
route and so traffic gets disrupted. But, when we looked at them three months
later, we found something rather disturbing. These long fibers were still damaged and
the concerning thing was that every single one of these players had been
returned to play, not arbitrarily, but because we follow standard clinical
guidelines. So why is it that our MRI is showing brain damage but the kids seem
to be alright when you use standard assessment tools? So, the resting state
functional MRI gives us clues about this. What it shows is that the brain has
learned to adapt to the structural damage this is very much like your GPS
seeing construction somewhere along the roadway, so damage along the white matter
tract, and giving you an alternate route. Your brain figures that out. It can use
other pieces of the network to actually convey the information between different
areas. This is called plasticity and plasticity is a good thing, it allows us
to learn, and it allows us to deal with life. The brain it’s constantly adapting.
Plasticity takes time though, so when you get a concussion
you have these early symptoms as your brain learns to deal with them the
symptoms go away. But, the damage is still there. How long does this damage last? We
don’t actually know the answer to this. We do know that in a five-year study of
Western’s women’s rugby team, the damage appears to last for many years. Not only
that, but even in the women who did not have concussions, who just got a lot of
hits, their brains also showed similar damage, just not as severe. But, all of
these people recover. They don’t have symptoms and this is because their
brains are continually adapting. They’re continually finding new ways to move
information around in the brain. So, what does this mean? The brain is constantly
adapting to changes, those changes may come from concussion, they may come from
a brain tumor, they may come from Parkinson’s, they may come from
Alzheimer’s. A lot of these things are hidden because we find new ways to deal
with them. The problem with the brain trying to adapt to all of this
particularly in the case of concussion is as you get older and maybe you have a
stroke or maybe you have normal age-related memory loss,
if your brain has maxed out its ability to compensate because it’s exhausted all
the other possible routes, this makes you particularly vulnerable to things like
the development of Alzheimer’s, for example. And so, to do studies like that
it’s actually very hard and it’s very expensive. You can imagine following a
cohort of people from their teenage years to their 90s. Well for one thing
that takes 80 years, and I’m not gonna be around to do that. But the other thing is,
it’s really expensive. So, where does this leave us? What we do know is that
concussions do cause damage in the brain. It’s subtle, but it’s there.
We also know that the vast majority of people who have concussions will live
full, healthy, normal lives. But for those few people who encounter problems later
in life,such as a stroke, they are going to have trouble trying to compensate – at
least that’s the theory. And so those people are now at risk for the
development of further issues such as dementia. So, we know the brain is
constantly adapting, that’s how we learn after all, and this is a good thing. We
know concussion is scary, but scary part of life. And we should go out and we
should live life and not just hide under the sheets. Thank you.