Stroke is the commonest cause of death in developed countries. Hypertension is the most treatable...
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- Stroke is the commonest cause of death in developed countries.
Hypertension is the most treatable risk factor. Thromboembolic
infarction (80%), cerebral and cerebellar haemorrhage (10%) and
subarachnoid haemorrhage (about 5%) are the major cerebrovascular
problems.
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- Ischemic stroke usually results when an artery to the brain is
blocked, often by a blood clot or a fatty deposit due to
atherosclerosis
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- Stroke is defined as the clinical syndrome of rapid onset of
cerebral deficit (usually focal) lasting more than 24 hours or
leading to death, with no apparent cause other than a vascular one.
Completed stroke means the deficit has become maximal, usually
within 6 hours. Stroke-in-evolution describes progression during
the first 24 hours. Minor stroke. Patients recover without
significant deficit, usually within a week. Transient ischemic
attack (TIA). This means a focal deficit, such as a weak limb,
aphasia or loss of vision lasting from a few seconds to 24 hours.
There is complete recovery. The attack is usually sudden.
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- An ischemic stroke is death of an area of brain tissue
(cerebral infarction) resulting from an inadequate supply of blood
and oxygen to the brain due to blockage of an artery
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- Causes By forming in and blocking an artery:An atheroma in the
wall of an artery may continue to accumulate fatty material and
become large enough to block the artery By traveling from another
artery to an artery in the brain: A piece of an atheroma or a blood
clot in the wall of an artery can break off and travel through (the
bloodstream (becoming an embolus
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- By traveling from the heart to the brain: Blood clots may form
in the heart or on a heart valve, particularly artificial valves
and valves that have been damaged by infection of the heart's
lining (endocarditis).
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- Several conditions besides rupture of an atheroma can trigger
or promote the formation of blood clots, increasing the risk of
blockage by a blood clot. They include the following Blood
disorders: Some disorders, such as an excess of red blood cells
(polycythemia), antiphospholipid syndrome, and a high homocysteine
level in the blood (hyperhomocysteinemia), make blood more likely
to clot. In children, sickle cell disease can cause ischemic
stroke
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- Oral contraceptives: Taking oral contraceptives, particularly
those with a high estrogen dose, increases the risk of blood
clots
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- Lacunar infarction is another cause of ischemic stroke. In
lacunar infarction, one of the small arteries deep in the brain
becomes blocked when part of its wall deteriorates and is replaced
by a mixture of fat and connective tissuea disorder called
lipohyalinosis.
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- Blood clots in a brain artery do not always cause a stroke. If
the clot breaks up spontaneously within less than 15 to 30 minutes,
brain cells do not die and people's symptoms resolve. Such cases
are called a transient ischemic attack
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- Risk factors: The major risk factors for ischemic stroke
Atherosclerosis (narrowing or blockage of arteries by patchy
deposits of fatty material in the walls of arteries) High
cholesterol levels High blood pressure Diabetes Smoking
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- Other risk factors include Having relatives who have had a
stroke Consuming too much alcohol Using cocaine or amphetamines
Having an abnormal heart rhythm called atrial fibrillation Having
another heart disorder, such as a heart attack or infective
endocarditis (infection of the heart's lining) Having inflamed
blood vessels (vasculitis) Being overweight, particularly if the
excess weight is around the abdomen Getting too little physical
activity Eating an unhealthy diet (such as one high in saturated
fats, trans fats, and calories) Having a clotting disorder
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- Determining the Location Large Vessel: Look for cortical signs
Small Vessel: No cortical signs on exam Posterior Circulation:
Crossed signs Cranial nerve findings Watershed: Look at watershed
and borderzone areas Hypo-perfusion
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- Stroke Symptoms Sudden numbness or weakness of face, arm or
leg, especially on one side of the body Sudden confusion, trouble
understanding or speaking Sudden trouble seeing in one or both eyes
Sudden trouble walking, dizziness, loss of balance or coordination
Sudden severe headache with no known cause
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- Other Symptoms Sudden nausea, fever and vomiting, distinguished
from a viral illness by rapid onset (minutes or hours vs. days)
Brief loss of consciousness or period of decreased consciousness
(fainting, confusion, convulsions or coma)
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- Lacunar Stroke Syndromes Well-defined syndromes Pure motor
hemiparesis (with dysarthria) Pure sensory stroke (loss or
paresthesias) Dysarthria-clumsy hand (with contralateral face and
tongue weakness) Ataxia-hemiparesis (contralateral face and leg
weakness) Isolated motor-sensory stroke
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- Large Vessel Stroke Syndromes MCA: Arm>leg weakness LMCA
cognitive: Aphasia RMCA cognitive: Neglect,, topographical
difficulty, apraxia, constructional impairment ACA: Leg>arm
weakness, grasp Cognitive: muteness, perseveration, abulia,
disinhibition PCA: Hemianopia Cognitive: memory loss/confusion,
alexia Cerebellum: Ipsilateral ataxia
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- Brainstem Stroke Syndromes Usually a combination of cranial
nerve abnormalities, and crossed motor/sensory findings such as:
Double vision Facial numbness and/or weakness Slurred speech
Difficulty swallowing Ataxia Vertigo Nausea and vomiting
Hoarseness
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- Watershed: Look for the watershed pattern Think about reasons
of hypo-perfusion Hypotension Stenosed vessel, etc
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- Diagnosis Doctors can usually diagnose an ischemic stroke based
on the history of events and results of a physical examination
Computed tomography (CT) is usually done first CT helps distinguish
an ischemic stroke from a hemorrhagic stroke, a brain tumor, an
abscess, and other structural abnormalities
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- Imaging CT scan Non- contrast CTH remains the gold standard as
it is superior for showing IVH and ICH CT with contrast may help
identify aneurysms, AVMs, or tumors but is not required to
determine whether or not the patient is a tPa candidate
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- MRI Superior for showing underlying structural lesion
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- If available, diffusion-weighted magnetic resonance imaging
(MRI), which can detect ischemic strokes within minutes of their
start, may be done next Electrocardiography (ECG) to look for
abnormal heart rhythms Imaging testscolor Doppler ultrasonography,
magnetic resonance angiography, CT angiography, or cerebral
(standard) angiographyto determine whether arteries, especially the
internal carotid arteries, are blocked or narrowed
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- Blood tests to check for anemia, polycythemia, blood clotting
disorders, vasculitis, and some infections (such as heart valve
infections and syphilis) and for risk factors such as high
cholesterol levels or diabetes
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- Treatment The first priority is to restore the person's
breathing, heart rate, blood pressure (if low), and temperature to
normal. An intravenous line is inserted to provide drugs and fluids
when needed doctors do not immediately treat high blood pressure
unless it is very high (over 220/120 mm Hg) because when arteries
are narrowed, blood pressure must be higher than normal to push
enough blood through them to the brain.
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- Management Most likely related to decreased level of
consciousness (LOC), dysarthria, dysphagia GCS < 8 - INTUBATE
Avoid Hyperventilation or Hypoventilation NPO until swallow
assessment completed- high aspiration risk Begin mobilization as
soon as clinically safe
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- very high blood pressure can injure the heart, kidneys, and
eyes and must be lowered If a stroke is very severe, drugs such as
mannitol may be given to reduce swelling and the increased pressure
in the brain
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- Hyperthermia Treat fevers! Evidence shows that fevers > 37.5
C that persists for > 24 hrs correlates with ventricular
extension and is found in 83% of patients with poor outcomes
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- BP Management The goal is to maintain cerebral perfusion!! CPP
= MAP ICP (needs to be at least 70) Higher BP goals with Ischemic
stroke Lower BP goals with Hemorrhagic stroke (avoid hemorrhagic
expansion, especially in AVMs and aneurysms)
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- BP increase is due to arterial occlusion (i.e., an effort to
perfuse penumbra) Failure to recanalize (w/ or w/o thrombolytic
therapy) results in high BP and poor neuro outcomes Lowering BP
starves penumbra, worsens outcomes
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- Supportive Therapy Glucose Management Infarction size and edema
increase with acute and chronic hyperglycemia Hyperglycemia is an
independent risk factor for hemorrhage when stroke is treated with
t-PA Antiepileptic Drugs Seizures are common after hemorrhagic CVAs
ICH related seizures are generally non-convulsive and are
associated to with higher NIHSS scores, a midline shift, and tend
to predict poorer outcomes
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- Thrombolytic (fibrinolytic) drugs In certain circumstances, a
drug called tissue plasminogen activator (tPA) is given
intravenously to break up clots and help restore blood flow to the
brain Before tPA is given, CT is done to rule out bleeding in the
brain To be effective and safe, tPA, given intravenously, must be
started within 3 hours of the beginning of an ischemic stroke
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- Intravenous rTPA IV thrombolytic therapy remains the
cornerstone of evidence-based acute ischemic stroke therapy (Class
I; level A) IV rt-PA is efficacious and cost-effective for patients
with acute ischemic stroke treated within 3 hours of symptom onset
6.6% complication of symptomatic intracranial hemorrhage
(sICH)
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- In patients with acute ischemic stroke in whom treatment can be
initiated within 3 h of symptom onset, we recommend IV recombinant
tissue plasminogen activator (r-tPA) over no IV r-tPA (Grade
1A).
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- In patients with acute ischemic stroke in whom treatment can be
initiated within 4.5 h but not within 3 h of symptom onset, we
suggest IV r-tPA over no IV r-tPA (Grade 2C).
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- Inclusion criteria Diagnosis of AIS causing measurable
neurological deficit Onset of symptoms < 3hours before beginning
treatment Age >18 or older
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- Exclusion Criteria Significant head trauma or prior stroke in
the last 3 months Symptoms suggest SAH Arterial puncture in non
compressible site 185 or DBP> 110 mm Hg) Active internal
bleeding Platelet count 15 secs Current use of Direct Thrombin
inhibitors or factor Xa inhibitors Blood glucose concentration 1/3
of cerebral hemisphere)
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- RELATIVE EXCLUSION CRITERIA CONSIDER RISK TO BENEFIT OF IVrTPA
ADMINSTRATION CAREFULLY IF ANY OF THESE RELATIVE CONTRAINDICATIONS
EXISTS: MINOR OR RAPIDLY IMPROVING SYMPTOMS SEIZURE AT ONSET WITH
POST ICTAL IMPAIRMENTS MAJOR SURGERY OR SERIOUS TRAUMA