>> Instructor: Once again, this is Lisa Klein
and I'll be going over ischemic strokes with this lecture.
So the objectives of this lecture.
At the end, you'll be able to list at least three causes
of an ischemic stroke, define what the ischemic penumbra is,
and list at least five stroke risk factors.
There are two types of stroke.
The first type that we're gonna be talking about
in this lecture is an ischemic stroke.
And this comprises when we talk about ischemic stroke
and transient ischemic attacks.
The second type is hemorrhagic stroke.
And that encompasses the non-traumatic intracerebral,
intraventricular hemorrhages,
including those caused by aneurysms,
arterial venous malformations,
intracranial venous thrombosis,
and other vascular issues.
But we're gonna be focusing on ischemic strokes here.
So when we look at the pathogenesis of ischemic stroke,
this accounts for nearly 85% of all strokes.
Of the 85%, 20% of them are caused by atherosclerosis.
So plaque buildup in your arteries.
20% of the ischemic strokes are caused by embolism,
most usually from the heart as a cardiac embolism,
due to atrial fibrillation.
25% of strokes are lacunar strokes.
And these are small vessel strokes usually caused by
high blood pressure, or uncontrolled high blood pressure.
And then about 30% of strokes
are what we used to call cryptogenic strokes,
but now are called embolic strokes of undetermined source,
or ESUS for short.
And these are strokes that following the work
of first stroke,
we don't know what actually caused the stroke.
But we believe it has some embolic source
that we just can't identify from where.
These ischemic strokes are part of a vascular disease.
It is part of what we consider the process
that's similar to acute coronary syndrome
for those patients with unstable angina and MI,
as their cholesterol and plaque are building up over time
and breaking off, it's much similar to how a patient
is suffering a heart attack from having
a clot go into their heart.
But instead, the clot goes to their brain.
Thus, it's an ischemic stroke
or what we can call a brain attack.
So ischemic strokes, accounting for 80 to 85% of strokes,
are obstructions of blood flow to the brain
that lead to ischemia, which is lack of oxygen,
and eventual infarct, which is tissue death.
This involves both ischemic and transient ischemic attacks.
And we can see here in the picture, how the blocked flow,
very much like if you have piping in your house
and you have blockage, doesn't get through.
And thus, both blood and oxygen
doesn't get to all your brain cells.
For transient ischemic attacks,
these are also known as mini strokes.
And these are warning signs that a stroke is gonna happen.
A transient ischemic attack is a transient episode
of neurological dysfunction that is caused by focal brain,
spinal cord, or retinal ischemia, without acute infarction.
And of patients presenting with an ischemic stroke,
seven to 40% of them had a TIA before their stroke.
So the patient pretty much, they look like they've had
the symptoms of a stroke, but because the symptoms resolve,
they don't seek medical attention.
They're like I'm gonna continue with my day.
Or their symptoms come, and they're like
I'm gonna sleep on it and maybe they'll resolve.
And of course, these are warning signs
that you're gonna have a stroke.
And a patient and a person who's had one or more TIAs
is actually 10 times more likely to have a stroke.
Also about a third of the people who have a TIA
go onto have a more severe stroke within a year.
For TIAs, about 41% of them last less than an hour.
But interestingly, if you actually get an MRI
and look at the diffusion rated image of these patients,
in about 30% of those, their MRI will be positive
for actually having a stroke.
And if the patient symptoms last up to 12 hours,
50% of those patients that have TIAs
will also have a positive MRI or a stroke.
So strokes will occur within 90 days
and about 10 to 20% of TIA patients.
And approximately 50% will occur within 24 to 48 hours
of a TIA.
So TIAs are not something we should take lightly.
And it's something we try to educate not only our patients,
but their family members that you have any good symptoms
of a stroke, even if they will go away,
you need to seek medical attention as soon as possible.
When patients arrive to the emergency department,
one scale that we can use is called the ABCD2 score.
And this is looking for patients that arrive
with a probable TIA and their likelihood
of having a stroke within the next few days.
So they look at starting risk factors,
including age, blood pressure, the clinical features
of the TIA, the duration of the TIA,
and whether the patient has diabetes.
And then you can see on the chart to the right,
the higher your score is, the greater likelihood
that you're gonna have a stroke within the next few days.
And so that can help decide whether a patient can get
some of the work, stroke work up as an outpatient,
or if they should be admitted to the hospital
because the risk is much higher
of having an imminent stroke.
As far as risk factors for ischemic stroke,
we have some that are within your control
and we have others that are outside of your control.
For those within your control, hypertension
is the leading cause of ischemic stroke.
Other things within your control would include smoking,
diabetes, having poorly controlled diabetes, a poor diet,
physical inactivity, obesity, high cholesterol,
or carotid artery disease, having atrial fibrillation,
another heart disease, or sickle cell anemia.
What is outside of your control is your age,
and we know that your chance of having a stroke
approximately doubles for every decade of life
after the age of 55.
We know that while stroke is common among the elderly,
we do have a lot of people under the age of 65
that also have strokes.
Family history, so if you've had a first degree relative
that has had a stroke before the age of 65,
or even a heart attack before the age of 55,
that puts you at greater risk of having a stroke.
Your race and your gender also increase risk.
Women have more strokes than men,
and strokes kill more women than men.
The use of birth controls, birth control pills,
pregnancy, history of preeclampsia or eclampsia,
or gestational diabetes, along with smoking,
post-menopausal hormone therapy, may pose
a special stroke risk for women.
As well, if you've had a prior stroke, TIA, or heart attack.
Looking at the risk factors here in the UAE,
we can see that physical activity,
both from men and women, and this is data from 2016,
we had very high rates.
With nearly 38% of the population being physically inactive.
We can see here another one that has highest rates
would be tobacco use.
We can see that is much more used by men,
with 38% of men compared to 1% of women.
And then down here at the bottom with obesity.
It probably correlates as well with physical inactivity
is that we have about a third of the population
once again, that is considered obese.
Now when a patient has had a stroke,
there's an area called the ischemic penumbra.
And where the stroke is,
that's where you've had the dead tissue.
That is the core of the infarction.
And the ischemic penumbra is the area
around that core infarct with minimally surviving cells.
And this is our target for medical
and pharmacological interventions,
and to reestablish adequate perfusion.
So you can see in the picture here
that we have the dead tissue in black.
But the penumbra that's around it in orange,
that's a much bigger size.
So when we have a patient that's had a stroke,
we'd much rather keep the stroke,
that minimal small size of the stroke
that's already happened with the dead tissue,
instead of it expanding to this penumbra.
We know that within an hour of a hypoxic ischemic event,
the core of infarction is already starts dying.
And then those minimally surviving cells,
this ischemic penumbra, these cells are at greatest risk
for neuronal death.
But they are alive and they are salvageable.
And so we really are going to focus our care
to save these, this area.
And so patients, because it has decreased perfusion,
frequently we do permissive hypertension
to keep blood flow to this area.
But these you know, this tissue is also viable.
It's not extremely happy.
So we wanna make sure we're not having
too high of blood sugars or too low of blood sugars,
because we wanna keep this tissue alive as well.
When we look at our patient's scans,
a diffusion-weighted MRI, and if we look at the diffusion
versus perfusion images, if we see a mismatch, then we know.
We can see here on the left in the white,
we have a core infarction area.
But if you look on the left, that red area,
that's the whole area that's at a risk for also dying
and becoming infarcted.
So that's the area we want to allow our patients to salvage,
so that their stroke deficits won't be as, won't be worse.
So we have some treatment options for patients
that have had an ischemic stroke.
So for acute revascularization, so opening up the vessels.
We have intravenous thrombolytic therapy.
Our go-to one is Alteplase.
We also call it tPA.
And we can give it within three to four and a half hours
of stroke onset.
That's not a lot of time.
As well, options we have include endovascular recanalization
with a mechanical thrombectomy.
So you can see here in the picture at the bottom right,
where we have stent retrievers that go in
to actually pull out the clot.
This we try to do within six to, it's up to 24 hours
since the patient was last known well.
And then we might also do a combined intravenous
or intraarterial therapy.
And this might be also followed by mechanical thrombectomy.
If we give intraarterial tPA, it usually is within
three to six hours of onset,
frequently followed by a mechanical thrombectomy.
And then the other part of you know, ischemic stroke
management is actual medical management.
'Cause if a patient doesn't come within
the early time frame, it means they're out of the window
to get any of these therapies.
So it means we're gonna medically manage them.
Time is brain.
As I said, a lot of these things have to be given
within three to four and a half,
or even up to 24 hours.
But when we look at the data of how fast patients
arrive to the hospital,
only about 36% arrive within six hours.
And only really 27% coming within zero to three hours.
Meaning that of the you know, 64% of patients
that come to the hospital for stroke,
they can't get tPA because they're outside the window.
Up next, we're gonna go over hemorrhagic strokes.