The Science Behind Second Impact Syndrome and Chronic Traumatic Encephalopathy
Second Impact Syndrome involves two mild head injuries
or concussions, mild traumatic brain injuries
are also referred to, in close proximity to each other.
Typically, the literature suggests that
Second Impact Syndrome happens when
an athlete has been injured early in a game
and then maybe later in the game.
We did not see that the person had that
injury originally and they get an injury on top of it.
It also can happen, though, within days of the first injury.
So if you've had one injury and then 4 days later
have another mild concussion,
you may end up with Second Impact Syndrome.
Second Impact Syndrome is a catastrophic
reaction in the second exposure.
What that really means is we have
a massive intracranial
pressure, and that involves
in the vascular system.
When that happens, a player, in fact,
can die or have a very, very
catastrophic outcome due to this intracranial pressure.
So it looks like a very severe head injury,
even though it's been only two mild head injuries.
This is different, though, than what
we talk about with regard to the cumulative effects in the brain.
The cumulative effects, we believe at this point,
can relate to
a degenerative neurologic condition,
which is called Chronic Traumatic Encephalopathy.
In this, there is a
change in brain tissue
that is not related to intracranial pressure
or bleeding or any autoregulatory problem,
but it is, rather, a degeneration of
tissue over time based on the fact
that the person has had multiple
concussive or subconcussive events.
The difficulty, of course, with
studying this is you
can't do an experimental design to give
some group of athletes
a lot of concussions
and have other players that don't
get concussions and compare them 30 years down the line
as to what their brain looks like.
The interesting research that's going on with
Dr. McKee and others
shows us, though, that some professional athletes
that have died at early ages
of unrelated causes,
their brains, in fact,
look like they have
a severe degenerative neurologic
condition, much like Alzheimer's disease,
but it is different histologically in some respects.
Show transcript | Print transcript
Second impact syndrome (SIS) can have in-an-instant, tragic consequences. Chronic traumatic encephalopathy (CTE), on the other hand, can have slow and heartbreaking consequences.
Produced by Victoria Tilney McDonough and Brian King, BrainLine.
Jeffrey Barth, PhD, is a professor and co-director, Neurocognitive Assessment Laboratory; section head, Neurocognitive Studies in the Department of Psychiatry and Neurobehavioral Sciences, with a joint appointment in the Department of Neurological Surgery, University of Virginia School of Medicine.
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