Introduction to Pediatric Stroke Management
by Miya Bernson-Leung.
Hello.
My name is Miya Bernson-Leung from the Boston Children's
Hospital Stroke and Cerebrovascular Center.
Today, I will be speaking about pediatric stroke.
Incidence of Stroke.
Stroke is unfortunately common among serious pediatric
neurologic problems.
About 1 in 1,600 to 1 in 4,000 neonates
will have a stroke around the time
of birth, defined as between the 20th week of gestation
and the 28th postnatal day.
In older children one month of age to 18 years,
the annual incidence of stroke is between 2.3 and 4.6
per 100,000 children per year.
This means that at least 1,000 neonates and 1,600 children
will have a stroke in the United States this year.
Of note, we will not talk about neonatal stroke
for the remainder of this video, as the risk factors
and treatments for neonatal stroke
and stroke in older children are completely different.
Classification.
Stroke can be divided into ischemic and hemorrhagic.
And in children, about half of strokes are ischemic,
and half are hemorrhagic.
An ischemic stroke occurs when brain tissue
is damaged due to the blockage of an artery or vein.
An arterial ischemic stroke, or AIS,
is caused by the loss of downstream blood supply
when an artery is occluded.
This can be resulting from areas of vessel lumen narrowing
or endothelial injury, an increase in clot formation,
what we call hypercoagulability, or thromboembolism,
when a clot formed elsewhere in the body, such as in the heart,
moves and becomes lodged in a cerebral artery.
Ischemic stroke resulting from the blockage of a vein
is called "venous infarction."
The loss of venous drainage leads
to pressure buildup and therefore tissue damage.
This is one possible result of a cerebral sinovenous thrombosis,
or CSVT, when a clot forms within the draining
sinuses of the brain.
Symptoms of each type of stroke will be discussed
at a later point in the video.
Transient ischemic attack, or TIA,
is defined as the symptoms of an ischemic stroke that resolve.
In adults, this has been defined as symptom resolution within 24
hours without ischemic injury being apparent on imaging.
And we now know that TIA can also occur in children.
TIA is important because it often heralds a future stroke.
And therefore, a complete workup is warranted.
Hemorrhagic strokes occur when there
is tissue damage due to bleeding within the brain,
an intraparenchymal hemorrhage, or adjacent to the surface
of the brain, a subarachnoid hemorrhage.
This produces mass effect and ischemia
of the adjacent tissues.
Risk factors.
A number of risk factors have been
identified for arterial ischemic stroke in children.
And often, these are quite different from those
for adults.
Many of these are also risk factors for CSVT.
It's important to identify these risk factors
because many of them may be of value for prognosis
or may necessitate a targeted therapy.
The major category, at 53% of arterial ischemic strokes
in children, is arteriopathy, a congenital
or acquired abnormality of the cerebral blood vessels.
Examples include dissection, vasculitis, the arteriopathy
associated with sickle cell disease, moyamoya,
and focal cerebral arteriopathy, a unique phenomenon
in children that may have an infectious trigger.
The second major category of risk factors
for arterial ischemic stroke in children is cardiac disease.
This includes congenital heart disease, particularly cyanotic
lesions, and acquired heart disease,
such as endocarditis or cardiomyopathy.
Children with cardiac disease are
at particular risk of stroke around the time of procedures
such as surgeries or cardiac catheterizations
or when requiring mechanical circulatory support,
such as with an ECMO or VAD device.
The next category, at 23% of arterial ischemic strokes,
is acute head and neck conditions,
including head trauma, intracranial surgery,
meningitis, and pharyngitis.
Following that, at 22% of arterial ischemic strokes,
is acute systemic conditions, including sepsis and shock.
A number of chronic systemic conditions
are seen in about 19% of children
with arterial ischemic stroke.
And these include sickle cell disease,
other genetic disorders, such as connective tissue disorders,
systemic malignancies, indwelling catheters,
and the use of oral contraceptives.
Similarly, a prothrombotic state is found in about 13%
of children with ischemic stroke,
including genetic or acquired thrombophilias
or hypercoagulable states.
Importantly, atherosclerosis, which
is a major contributor to stroke burden in adults,
is seen in only 2% of children with stroke.
All told, about 24% of children with stroke
will have some sort of infection around the time
of presentation.
And oftentimes, this can serve as the acute trigger for stroke
in a child who has an underlying predisposition.
In fact, about 50% of children with arterial ischemic stroke
will be found to have two or more risk factors.
And therefore, it's important to keep looking,
even after a single risk factor has been identified.
All told, 90% of children will have one or more risk factors,
leaving only 10% unexplained.
Factors associated with hemorrhagic stroke in children
include vascular anomalies, such as arteriovenous malformation,
aneurysm, and cavernous malformation, vasculopathies,
such as those associated with sickle cell disease or moyamoya
syndrome due to the fragility of those blood vessels,
coagulation disorders such as hemophilia, vitamin K
deficiency, or anticoagulant therapy--
and this is one reason that children with cardiac disease
may be at risk for both ischemic and hemorrhagic stroke
if they are using anticoagulants--
and, finally, brain tumors.
Hemorrhage can also occur secondary to CSVT
due to the buildup of venous pressure.
And finally, an ischemic stroke can undergo
hemorrhagic transformation.
Similar to ischemic stroke in children, about 90%
of children with hemorrhagic stroke
will have at least one identifiable risk factor.
Clinical Presentation.
The presentation of acute ischemic stroke in children
can be similar to that of adults.
The hallmark is the acute onset of a focal neurologic deficit.
About 85% of children with arterial ischemic stroke
will have focal signs, including hemiparesis in 60 to 80%,
a speech difficulty in 10 to 35%,
or visual field defects in 5 to 20%.
Focal symptoms of ischemic stroke
may be localizable to specific areas of brain tissue
that correspond to the vascular territory
of the occluded vessel.
I'll highlight a number of these vascular syndromes.
But it's important to recognize that children may not
manifest all of the symptoms of a given vascular syndrome
and that other combinations of symptoms
may be possible depending on the territory affected.
Strokes affecting the anterior cerebral artery
often involve weakness of the contralateral leg
and may also have behavior changes.
Strokes of the middle cerebral artery
can manifest as weakness of the contralateral face
and arm, a speech disturbance, such as aphasia or dysarthria,
a visual field deficit, or hemianopia,
inattention to stimuli on one half of the body
or in one half of space, called hemineglect,
and sensory deficits.
Stroke in the posterior cerebral artery territory
can also produce visual field deficits and sensory deficits.
Strokes in the vertebrobasilar system
can be harder to identify because they often
don't manifest with lateralized signs.
For instance, symptoms of vertebrobasilar stroke
can include dizziness, ataxia, impaired balance,
abnormalities of eye movements or pupils,
changes in speech or swallowing, and weakness
and sensory changes in various patterns,
as well as a decrease in the level of consciousness.
Finally, occlusions of the cerebral veins and sinuses,
such as CSVT, can produce decreased level
of consciousness, headache, vomiting, and papilledema,
particularly as a late sign.
Children with ischemic strokes can also
present with diffuse signs, making recognition
that a stroke has occurred challenging.
About 61 to 64% of children with arterial ischemic strokes
will have diffuse signs, such as altered mental status
in 42 to 52% or headache in 24 to 40%.
And in fact, about 10% of children with stroke
may have only diffuse signs.
Similarly, about 33% to 49% of children
with an arterial stroke will have both focal signs
and diffuse signs that are not referable to
a specific vascular territory.
There's an important relationship between stroke
and seizures for children.
About 25 to 31% of children with an arterial ischemic stroke
will have a seizure around the time of presentation.
And as many as 42% of younger children will have a seizure.
This is in comparison to only 5% of adults having a seizure
at the time of their stroke.
Oftentimes, the acute onset of focal deficits
is attributed to a postictal, or Todd's, paralysis.
But it's important to recognize that the incidence
of a new onset focal epilepsy presenting
with a Todd's paralysis is about comparable to that
of a new stroke.
And so it's important to consider stroke
for all first-time focal seizures,
regardless of the presence of paralysis.
About 37% of hemorrhagic strokes will have acute seizures.
And 20 to 48% of CSVT will have acute seizures.
Prognosis.
The prognosis of stroke in children
is unfortunately mixed.
The immediate mortality is between 10 and 40%,
making cerebrovascular disorders among the top 10
causes of child mortality.
Only 37% of children who have an ischemic stroke
will make a full recovery.
And 41% of children with arterial ischemic stroke
or CSVT will have moderate to severe deficits.
The recurrence risk of arterial stroke within five years
ranges between 7% and 41% depending on the etiology
and the population studied.
For example, perinatal strokes have only a 1 to 2%
recurrence rate, whereas strokes associated with arteriopathy
have a 66% recurrence rate within five years.
And finally, regardless of the presence
of seizure at the time of acute stroke, more than 25%
of children with stroke will go on to have epilepsy.
Differential Diagnosis.
There's a broad list of differential diagnoses
for the acute onset of neurologic deficits
in children.
But many of them, like stroke, are serious
and warrant rapid recognition.
The list of differential diagnoses
for stroke in children includes complicated migraine, seizure
or postictal symptoms not due to stroke, hemorrhage,
such as traumatic hemorrhage or a hemorrhagic stroke
being on the differential for an ischemic stroke,
intracranial infection, such as meningitis or abscess, trauma,
tumor, demyelinating diseases, such as multiple sclerosis
or acute disseminated encephalomyelitis,
or ADEM, posterior reversible encephalopathy syndrome,
or PRES, toxic exposures, metabolic derangements,
idiopathic intracranial hypertension, formerly known
as pseudotumor cerebri, post-infectious processes,
such as cerebellitis or acute cerebellar
ataxia, musculoskeletal causes of weakness, and finally,
somatoform disorders.
The literature has consistently demonstrated significant delays
in the diagnosis of pediatric stroke.
The delay from symptom onset to diagnosis
in children with arterial ischemic stroke
has consistently been shown to be greater than 24 hours.
While some of this may be attributable to a lack
of recognition by the lay public that stroke
can happen to children, diagnoses
are delayed even in strokes that occur in hospital.
This highlights the need to establish
pathways of rapid triage and definitive diagnosis
for pediatric stroke.
These pathways are often referred
to as stroke STAT, code stroke, or hyperacute stroke protocols
and are based on models from the adult stroke world.
In general, the goal is for the time of presentation
to the hospital, to diagnosis, to institution
of targeted therapies, the so-called door-to-needle time,
as being under 60 minutes.
The rationale for having hyperacute stroke
protocol for children is that time is brain.
For every minute of brain ischemia,
1.9 million neurons are lost.
14 billion synapses are lost.
And 7.5 miles of myelinated fibers are lost.
Some children, those who present within a narrow time window
and don't have other contraindications,
may be candidates for acute reperfusion therapy with tissue
plasminogen activator, TPA, or mechanical thrombectomy,
an endovascular approach with stent retrievers
or other devices.
However, even patients who are not
candidates for these acute reperfusion therapies
will benefit from the rapid institution of therapies
that aim to maximize the supply and minimize demand
to the area of ischemic brain, as well
as rapid attention to preventing or managing complications
should they arise, such as seizures or aspiration.
Imaging pathways have been developed
for the rapid diagnosis of hyperacute stroke in children.
And the preferred modality is magnetic resonance imaging,
or MRI.
The reason for this is that an MRI
can demonstrate an area of ischemic injury
within minutes after it has begun
and thereby allow a patient to be
a candidate for an acute reperfusion therapy.
The sequences that should be considered
include a diffusion weighted image,
which will show the development of ischemia,
and a susceptibility weighted image,
which will rule out hemorrhage without the need
for an additional CT scan.
Other sequences that are important
are the FLAIR, or T2, sequence to look for edema
and, if possible, perfusion weighted imaging
to assess regional blood flow.
It's very important to do an angiogram
of the head and the neck to assess
for areas of vessel occlusion and vascular abnormalities.
With magnetic resonance imaging, this
can be performed as a time of flight MRA, which
is a non-contrast study.
And it's very important to include the neck as well
as the head in order to assess the entire course
of the cervicocephalic vessels.
The alternative imaging pathway is based
on computed tomography, CT.
But it's important to recognize that CT done early after
the onset of stroke will not demonstrate any abnormalities
and so cannot be used to prove that there is ischemic injury
that has occurred.
A non-contrast head CT will rule out the presence of hemorrhage
but, again, will not show any signs of ischemia early
in the course.
CT angiography can also be used to assess for vessel occlusions
or vascular abnormalities.
And again, this should involve the head and the neck.
A CTA or a CT Angiogram, is a contrast study.
Here, we demonstrate some of the imaging
findings of an acute arterial ischemic stroke.
The first image is diffusion weighted imaging, specifically
the trace sequence.
And you can see a large area of bright signal corresponding
to an acute stroke in the left-middle cerebral artery
territory.
The magnetic resonance angiogram shows
the area where the left middle cerebral artery should be
is not opacifying, and therefore is
likely to be occluded, corresponding
to the area of left-middle cerebral artery
stroke that we saw on the diffusion weighted imaging.
Treatment.
In terms of acute stroke treatments,
for arterial ischemic strokes with a demonstrated vascular
occlusion, intravenous TPA, and intra-arterial therapy,
such as endovascular stent retrieval,
has been performed in research settings
and on a case-by-case basis.
For all children with arterial ischemic stroke,
secondary stroke prevention should
be initiated with either aspirin, three to five
milligrams per kilogram once per day
for a maximum of 81 milligrams, or with therapeutic
anti-coagulation with a heparin drip
or injection of low molecular weight heparin,
depending on the etiology or while the evaluation of stroke
etiology is ongoing.
For children with stroke due to sickle cell disease,
an emergent exchange transfusion is
indicated to reduce the fraction of sickle hemoglobin.
For CSVT, anti-coagulation is generally warranted,
even in some cases if hemorrhage is already present,
in order to prevent further propagation of the thrombus.
All children with stroke will benefit
from neuroprotective and supportive care measures
to maximize perfusion to the area of ischemic brain tissue.
This always starts with the ABCs,
maximizing oxygenation and perfusion.
The head of the bed should be laid
flat to increase forward flow to the area of ischemic brain.
Perfusion can be supported with isotonic fluids running
at maintenance with consideration
of an additional bolus.
Our blood pressure targets are usually greater
than the 50th percentile for the patient's age and height.
Fever and seizures, should they arise,
should be treated aggressively to minimize metabolic demand
on the already ischemic brain.
Sodium and glucose should be normalized.
And in cases in which severe edema develops,
such as the malignant MCA syndrome,
hyperosmolar therapy and decompressive hemicraniectomy
may be indicated.
In summary, stroke in children is not rare
and has significant mortality and morbidity.
The rapid recognition and diagnosis of pediatric stroke
can enable the delivery of time-sensitive therapies
and can minimize complications.
And finally, ischemic and hemorrhagic stroke
and cerebral sinovenous thrombosis
have many causes in children, and a detailed evaluation
is warranted.
Thank you for watching.
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