Download Stroke

Pathophysiology of Stroke
Wanda Lovitz, APRN
Objectives: Stroke
 Describe the risk factors, early identification and treatment associated
with acute brain attack.
 Differentiate the pathologies of ischemic stroke, hemorrhagic stroke,
lacunar stroke, and transient ischemic attack.

Compare the arrhythmias atrial fibrillation and ventricular
fibrillation.

Cite the most common causes of hemorrhagic stroke.
 Describe the clinical manifestations associated with subarachnoid
hemorrhage.

State the progression of sensory and motor deficits, and speech and
language problems that occur as a result of stroke
Stroke (Brain Attack)
Definition
An acute focal neurologic deficit from a vascular
disorder that injures brain tissue and results in
deficits as well as causing motor & sensory, and
language and speech problems
Also known as a cerebral vascular accident (CVA)
or“ brain attack”
 About
600 people admitted to UK yearly with stroke, 25% under
the age of 55
 3rd leading cause of death
 #1 cause of nursing home admission
Primary Injury vs Secondary Injury
 Primary Injury =
SUDDEN cessation of
blood flow to an area of
brain tissue resulting in
IRREVERSIBLE ISCHEMIA
to some cells
 Secondary Injury =
development of further
neurologic damage, may
progress over days or weeks
TIME IS TISSUE!
Risk Factors Associated with Stroke
Age:
Increases with age (increases 1%/year between 65-74)
Also can see stroke in infants
& children
Gender: males > females
Race: African-Americans > Caucasians (60% greater risk) Also
Asians have increased risk
Hx: Heart disease, HTN,
smoking, high cholesterol levels, DM
What is a thrombus?
 Is NORMAL in cases of injury
 ABNORMAL :
 a blood clot that forms in a blood vessel
 may be arterial or venous
 Pathological thrombus = THROMBOSIS

May be caused by fatty deposits that build up in arteries
 Damage to the endotheilum (often r/t poorly controlled HTN) fosters buildup
of fatty deposits and cholesterol
 Body responds to the vessel wall injury by forming plaque which can
rupture and form clots
Atherosclerosis:
Hyperlipidemia/High cholesterol
Common areas in the brain for stroke
 Middle Cerebral Artery
(MCA)
 2. Basilar Artery
 3. Posterior Cerebral
Artery
The deficits the person
experiences is determined
by the LOCATION of the
infarct
RIGHT sided stroke vs LEFT sided stroke
Hemiparesis vs Hemiplegia
weakness
paralysis
Cerebral INFARCTION
Infarcted tissue is “DEAD” and the function of the organ is altered.
The tissue is not responsive to any treatment to restore its function.
Cerebral ISCHEMIA
 Ischemic tissue is
POTENTIALLY
‘salvageable’
 Current treatment is
directed toward
restoring blood flow to
injured tissue
 “TIME IS TISSUE”
Angiogram showing a
blocked cerebral artery
Main types of Stroke
ISCHEMIC –
caused by an
INTERRUPTION in blood
flow
HEMORRHAGIC –
caused BY BLEEDING into
brain tissue from a ruptured
cerebral vessel
Stroke Categories
1. Ischemic (slow event)
(70-80% of all strokes)
 Thrombotic

Embolic
2.Hemorrhagic (fast, sudden event)
Usually occurs as result of rupture of blood vessel from
HTN, aneurysm, or head injury
Think Supply and Demand Crisis!
ISCHEMIA – results in greatly reduced or interrupted
blood flow in a vessel
 A THROMBUS OR EMBOLUS is PARTIALLY blocking
the blood supply.
Ischemic Penumbra
 “Bull’s Eye
 Central core of dead or infarcted
tissue
 Ischemic Penumbra
 Small blood flow
 Cells maintain some integrity


?? Salvageable
Thrombolytics

Clot busting drugs may be
effective during penumbra window

TIME IS TISSUE!

Coronary (heart) = 6H

Stroke (brain)= 3H
Ischemic Penumbra
70-80% of all strokes are
ISCHEMIC strokes. And the
majority of ischemic strokes
are d/t a thrombus.
Ischemic zone = greatly
reduced blood flow
POTENTIAL to salvage tissue
Ischemic Penumbra
 Cells in the penumbra receive a
SMALL amount of blood flow
allowing some metabolic
function
 The injured cells undergo
ELECTRICAL FAILURE
 Goal of tx
– MINIMIZE damage to
penumbra

Support cells –
– Oxygen
– Improved circulation with “clot
busting” thrombolytics drugs
What is the Penumbra device?
 The Penumbra is a
recently approved device
(2008) that can be used to
“vacuum” out the cerebral
blood clot
 A tiny vacuum cleaner for the
brain
 Can be tried up to 8 hours
after a stroke strikes or
after failure of
thrombolytic therapy
 FDA approved 12/08
Infarction/Penumbra
If thrombus is large enough to completely occlude vessel
then INFARCTION occurs distal to the occlusion.
A partial occlusion would result in ISCHEMIA.
Alexa Eleanor Ehlers
•
•
•
•
•
•
Went to school in Argyle, TX (North
Texas)
Born in Glenwood Springs, CO (October
2, 1994) & my family lives there again
now.
I live on and manage my family’s farm,
Clear View Equestrian Center, behind
Keeneland.
I have one dog, three cats, and 5 horses
of my own.
I have represented the U.S. in
international team competitions here in
the States four times, winning team gold
and bronze, and have represented the
U.S. in international team competition
once in Australia, winning team bronze.
Last, but not least, I’m blessed with an
amazing family that loves to travel.
• My mom, Stacy; father, Jeff; older
sister, Kelsey (25); older brother,
Robbie (24)
Types of Ischemic Stroke
Small Vessel (Lacunar)
small vessels deep in the brain affected
Large Vessel (Thrombotic)
 r/t hyperlipidemia with unstable plaque
Cardiogenic (Embolic)
Clot moves from the heart and lodges in a vessel in
the brain
Small Vessel (LACUNAR) Stroke
(20% of strokes)
 KEY CONCEPTS
 TINY and in DEEP brain structures
 basal ganglia or pons
 Cause: occlusion of small branches of cerebral
arteries

Form small cavities “lacunae”

Specific manifestations based on location of injury
Generally less deficits

 Diagnosed: by symptomatology

Usually too small to be seen on CT scan
Large Vessel (THROMBOTIC) Stroke
 Key Concepts:
– Most common type of ischemic stroke
– Location: arterial bifurcations
– Affected part of brain: cortex
– Common deficits:



Aphasia
Neglect
Visual problems
– Event is NOT associated with activity
– Effects: localized (focal) distal to blockage.
Cardiogenic (Embolic) Stroke
 Key Concepts
– Most common location: middle cerebral artery
(MCA)
– A MOVING blood clot travels from its origin
(heart/cardiogenic) to the brain
– Usual location

Lodge -- larger proximal cerebral vessels often at
bifurcations
– RAPID onset of symptoms.
Cardiogenic Embolic Stroke:
Predisposing Conditions
 Atrial Fibrillation (AF)
 Rheumatic Heart
Disease (RHD)
 Recent Myocardial
Infarction (MI)
 Bacterial Endocarditis
Normal heart complex on EKG
What is Atrial Fibrillation?
 Irregular heart rate
 Atria are “quivering” instead of contracting regularly
 fibrillation waves instead of a single “P” wave before each QRS
 Results in IRREGULAR ventricular contraction
 Is the most common cause of irregular heart beat
What is Ventricular Fibrillation?
 The MOST SERIOUS cardiac arrhythmia
 Ventricles are not contracting in a coordinated fashion, just
‘fibrillating’ rapidly
 No cardiac output
 The patient is clinically dead!
 Must be ‘DEFIBRILLATED’ in order to restore cardiac rhythm

Atrial fibrillation rhythm strip
Fibrillation waves
Normal “P” wave
Note irregularity and absence of “P” waves. Instead have
“fibrillation” waves.
1. No “p” wave
2. Fibrillation waves
3. Irregular R – R interval
Normal sinus rhtthm
Atrial fibrillation vs ventricular fibrillation
What does the person LOOK LIKE?
Atrial fibrillation
is NOT life threatening
when controlled (HR less than 100)
• Will see CO, palpitations
• risk CHF,CVA
• Generally is
treatable and not
deadly.
Ventricular fibrillation is
a LETHAL arrhythmia = cardiac arrest
•Will see unresponsiveness
•No pulse, no B/P
•Person will die if
a normal rhythm is not
quickly restored
What is a TIA?
TRANSIENT ischemic attack
Key concepts
 Focal event, due to ischemia
 TRANSIENT - Sx relieved by 24 hours post onset!

Think of it as “angina of the brain!”
A WARNING SIGN OF IMPENDING STROKE
 Is A TEMPORARY disturbance and IS REVERSIBLE

Is a “mini-stroke”
 Area of penumbra, but no infarcted tissue
What is a Hemorrhagic Stroke?
 Key Concepts
 Most common cause of
FATAL STROKE, why?

Causes cerebral edema

Causes compression of brain contents

Causes spasm of adjacent blood vessels
 Usually occurs with ACTIVITY
  BP and pressure in cerebral vessels
Hemorrhagic Stroke
Worst headache of my life!!!
Most of the brain is
affected here.
Would see death or severe brain
dysfunction and have a sudden
onset
Underlying Causes of Hemorrhagic Stroke
 Cerebral Aneurysms
 Subarachnoid hemorrhage (SAH)
 Trauma
 Tumor-related erosions
 Arteriovenous malformations (AVM)
(2%)
 Poorly controlled HTN (systolic  200)
Hemorrhagic stroke: Cerebral Aneurysms
 BERRY aneurysms
 Tend to enlarge over time,
weakening vessel wall
increasing chance of
rupture
 Rupture causes
hemorrhagic stroke
 If > 10 mm in size have
Primary site is the
Circle of Willis
50% chance of bleeding
per year.
Cerebral Aneurysms
Rupture is associated with
acute increase in ICP
e.g., straining, sexual
activity, etc.
Aneurysmal Subarachnoid Hemorrhage
(SAH) – a common cause of hemorrhagic stroke
What is it?
 Bleeding into the subarachnoid space caused by a cerebral
aneurysm
 An aneurysm is a bulge at the site of a localized weakness in the
wall of an arterial vessel
SAH Factoids
Usual age: 30-60 years
Mortality/morbidity = high
About 50% die within 3 months
½ of survivors have serious disabilities
Bleeding follows along CSF channels, so SAH extends
rapidly over a large area
“Classic” Manifestations of SAH
 Sudden onset of SEVERE headache
 “Worse headache ever!”
 Deteriorating LOC – Rapid
 Meningeal irritation
 Nuchal rigidity
 Photophobia
 Cranial nerve deficits (CN II & III most often –optic& oculomotor)
 Visual disturbances, photophobia, cardinal fields of gage affected
 Increased ICP
Complications of SAH
 Rebleeding
 Watch 1st 24 hours!
Seizures
Vasospasm
 Watch for in 3 to 10 days post bleed
Intracranial hemorrhage
Vasospasm with ischemia
Diagnositic tests: SAH
 Lumbar Puncture shows:
 Blood in the CSF
Other causes of hemorrhagic stroke
Brain tumor
AV Malformation
Arteriovenous malformations (AVM)
 AVM
– A tangle of abnormal arteries and veins linked by
one or more fistulas
– Lack a capillary bed and have a deficient muscular
layer
– Predisposed to rupture and hemorrhage
You Tube Video
 ACT “FAST”
Diagnosis of Stroke
CT scan
 Hx, PE
 Lumbar Puncture
 Imaging
 CT


MRI
Shows hemorrhage or large infarct
Does not pick up new ischemic damage
 MRI
 Best for new ischemic problems or small infarcts
 Angiography
 Locates exact site of abnormality – involves use of contrast dye
CT is less sensitive than an MRI in
detecting stroke
Key Concepts: Clinical Manifestations of
Acute Stroke (most common with ischemic)
 Symptoms depend on affected cerebral artery
 Symptoms occur:
– Relatively rapidly, and are usually focal and unilateral
 Most common Sx:
– Weakness of face, arm & possibly one leg
(hemiparesis) = motor deficits
– Weakness may be replaced by hyperflexion &
spasticity
Clinical Manifestations
Common with Stroke
 Watch the You Tube Video “ Effects of Stroke”
Functional effect of stroke
Stroke
Presentation
Affected Artery
Signs
Internal carotid artery
Unilateral blindness
Contralateral hemiplegia, hemianopia
Aphasia with left hemisphere
Middle cerebral artery
Communication, cognition difficulties
Contralateral hemiplegia or hemiparesis
Anterior cerebral artery
Emotional lability, confusion, amnesia,
personality changes
Urinary incontinence
Posterior cerebral artery
Cortical blindness
Memory deficts
Effects of Stroke: Movement Issues
(motor impairment)
 Movement Problems
 Hemiparesis/hemiplegia



Mild-profound weakness on CONTRALATERAL side
Clumsiness in fine motor skills
Facial droop
 Apraxia (inability to carry out learned activity)

Verbal apraxia….person cannot say words they intend to say

Foot drop

Outward rotation of leg

Initial flaccidity followed by spasticity
Effects of Stroke: PERCEPTION issues
 Perception Problems
– Unilateral neglect (d/t inability to analyze/interpret incoming
sensory information
–
May deny illness or deny one half of body and environment on
affected side)
– Flat affect
– Hemianopsia/visual problems
–  awareness of one side of the body
– Inability to distinguish directional concepts (up/down)
Effects of Stroke: SENSATION issues
Sensation Problems
–  awareness of touch/temperature
–  proprioception
– Balance problems
– Vertigo
Effects of Stroke: LANGUAGE problems
 Language Problems
– Aphasia/dysphasia (some degree of inability to speak or to
comprehend)
– Dysphasia (impairment of speech)
– Dysarthria (imperfect speech sounds)
– Word finding problems
– Incorrect use of verbs or nouns
– Expressive aphasia (comprehension intact but cannot
express)
– Receptive aphasia (can communicate but cannot comprehend
what is being said ”can’t receive”
Consequences
 Aphasia
Effects of Stroke: VISUAL problems
 Visual disturbances
Contralateral
field blindness
Homonymous
Hemianopsia
Effects of Stroke: Movement Issues
 Flaccidity – contralateral side
 Spasticity – within 6 weeks
Effects of Stroke: MEMORY and
BEHAVIORAL Issues
 Memory problems
– Most memory problems
are with remembering
names, words, objects
 Behavioral problems
–  emotional response
– Judgment is usually intact
– May underestimate own
abilities
– Slow reaction times
– Hesitant and cautious
– May be apathetic, confused,
disoriented
FAST……. Recognizing the
symptoms of a stroke
Treatment
Be a good nurse…. Know how to
recognize a stroke
 Act FAST….Know how to assess for stroke
 80% of strokes are preventable
 500 thousand Americans will have their first stroke
this year
 There is a 4 times greater risk of stroke for women who
smoke and take the Pill
The End