Stroke Syndromes Dr. Gerrard Uy Transient Ischemic Attack

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Stroke Syndromes

• Dr. Gerrard Uy

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Cerebrovascular Disease

• ischemic stroke
• hemorrhagic stroke
• cerebrovascular anomalies such as intracranial
  aneurysms and arteriovenous malformations (AVMs)
• Cause 200,000 deaths each year in the U.S.
• Incidence increases with age

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Stroke

• Most strokes manifest by the abrupt onset of a
  focal neurologic deficit
• Like patients were struck by the hand of God
• Definition
• abrupt onset of a neurologic deficit that is
  attributable to a focal vascular cause

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Definition of terms

• Thrombosis inappropriate clotting
• Embolism migration of clots
• Ischemia loss of blood supply in a tissue due to
  impeded arterial flow or reduced venous drainage
• Infarction cell death

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Definition of Terms

• Cerebral ischemia is caused by a reduction in
  blood flow that lasts longer than several seconds
• infarction - death of brain tissue
• transient ischemic attack (TIA) - all neurologic
  signs and symptoms resolve within 24 h regardless
  of whether there is imaging evidence of new
  permanent brain injury

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Hemorrhagic Stroke

• Bleeding into subdural and epidural spaces is
  principally produced by trauma
• SAHs are produced by trauma and rupture of
  intracranial aneurysms
• Hemorrhage are classified by location
• Often identified by CT scan

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Approach to the patient

• Rapid evaluation is essential for use of time
  sensitive treatments such as thrombolysis
• Most patients with acute stroke do not seek
  medical attention because they are rarely in pain
  and they experience anosagnosia
• Important clues pointing to stroke
• Hemiparesis
• Changes in vision
• Changes in gait
• Disturbance in the ability to speak or understand
• Sudden severe headache

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Approach to the patient

• Migraine can mimic stroke
• The sensory and motor deficit tend to migrate
  slowly across a limb over minutes rather than
  seconds as with stroke
• Once diagnosis of stroke is made, brain imaging
  study is necessary to determine the cause of the
  stroke whether ischemic or hemorrhagic
• CT imaging is the standard imaging procedure

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ISCHEMIC STROKE
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Ischemic Stroke

• Acute occlusion of an intracranial vessel causing
  reduction in blood flow to the brain region
• The magnitude of flow reduction is a function of
  collateral blood flow
• INFARCTION results when
• Cerebral blood flow of 0 (zero) in 4 10 mins
• CBF lt16-18 ml/ 100g tissue per min in 1 hour
• CBF lt20ml/100g tissue per min ischemia
• The tissue surrounding the infarction is ischemic
  and is called the ischemic penumbra

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Pathophysiology

• Ischemia produces necrosis by starving neurons of
  glucose
• No glucose means no ATP production
• No ATP, the neurons start to depolarize which in
  turn increases intracellular calcium levels to
  rise and glutamate to accumulate
• Free radicals produced in this process will
  result in cellular dysfunction and death

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Management of Acute Ischemic Stroke

• First goal is to prevent or reverse brain injury
• Check ABCs and treat hypoglycemia or
  hyperglycemia
• Brain imaging to determine whether stroke is
  ischemic or hemorrhagic

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Management of Acute Ischemic Stroke

• 6 categories to improve clinical outcome
• Medical support
• Intravenous thrombolysis
• Endovascular techniques
• Antithrombotic treatment
• Neuroprotection
• rehabilitation

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Management of Acute Ischemic Stroke

• Medical Support
• Immediate goal is to optimize cerebral perfusion
• Prevent complications such as infections, DVT,
  and bedsores
• Maintain euglycemia
• Treat fever
• Manage hypertension
• Use of IV Mannitol to raise serum osmolarity and
  prevent brain edema

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Management of Acute Ischemic Stroke

• Intravenous Thrombolysis
• NINDS rTPA stoke study showed benefit for IV
  rTPA in selected patients with acute stroke
• Golden period is within 3 hrs of the onset of
  ischemic stroke (0.9 mg/kg 10 as bolus and
  remainder over 1 hr)
• The time of onset of stroke is defined as the
  time patients symptoms began or the time the
  patient was last seen normal

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Management of Acute Ischemic Stroke

• Indications for rTPA
• Clinical diagnosis of stroke
• Onset lt 3 hrs
• CT scan shows no hemorrhage or edema of gt 1/3 of
  the MCA territory
• Age gt 18 yrs of age
• consent

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Management of Acute Ischemic Stroke

• Contraindications
• Sustained BP gt 185/110 despite treatment
• Plt lt 100,000, hct lt 25, glucose lt50 or gt400
  mg/dl
• Use of heparin within 48 hrs, prolonged PTT, or
  elevated INR
• Rapidly improving symptoms
• Prior stroke or head injury within 3 months
• Major surgery in preceding 14 days
• Minor stroke symptoms
• GI bleeding in preceding 21 days
• Recent MI
• Coma or Stupor

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Management of Acute Ischemic Stroke

• Endovascular Techniques
• Usually done in occlusions of large vessels such
  as MCA, internal carotid artery, and basilar
  artery
• Procedure is done intraarterially
• Mechanical thrombectomy is an alternative

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Management of Acute Ischemic Stroke

• Antithrombotic Treatment
• Platelet inhibition
• Aspirin is the only antiplatelet agent that has
  been proven effective for the acute treatment of
  ischemic stroke
• Usually given within 48 hrs of stroke onset
• Anticoagulation
• Has shown no benefit in the primary treatment of
  atherothrombotic cerebral ischemia

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Management of Acute Ischemic Stroke

• Neuroprotection
• To provide a treatment that prolongs the brains
  tolerance to ischemia
• Most common neuroprotective drug
• Citicoline reduces the rate of death and
  disability

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Management of Acute Ischemic Stroke

• Rehabilitation
• to improve neurologic outcomes and reduce
  mortality
• Directed towards educating the patient and family
  about the patients neurologic deficit,
  preventing complications of immobility and
  providing encouragement and instruction in
  overcoming the deficit
• Goal is to return the patient home and to
  maximize recovery

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Causes of Ischemic Stroke

• establishing a cause is essential in reducing the
  risk of recurrence
• 30 of strokes remain unexplained despite
  extensive evaluation
• Focus on atrial fibrillation and carotid
  atherosclerosis

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Causes of Ischemic Stroke
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Cardioembolic Stroke

• Responsible for 20 of all ischemic strokes
• embolism of thrombotic material forming on the
  atrial or ventricular wall or the left heart
  valves
• thrombi then detach and embolize into the
  arterial circulation
• Embolic strokes tend to be sudden in onset, with
  maximum neurologic deficit at once

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Cardioembolic Stroke

• Emboli from the heart most often lodge in the
  MCA, PCA, and infrequently ACA
• Nonrheumatic atrial fibrillation is the most
  common cause of cerebral embolism overall
• Patients with atrial fibrillation have an
  average annual risk of 5
• Left atrial enlargement and CHF are additional
  risk factors for the formation of atrial thrombi

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Cardioembolic Stroke causes

• nonrheumatic atrial fibrillation
• MI
• prosthetic valves
• rheumatic heart disease
• ischemic cardiomyopathy

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Carotid Atherosclerosis

• 10 of all ischemic strokes
• frequently within the common carotid bifurcation
  and proximal internal carotid artery
• RISK FACTORS
• Male gender, older age, smoking, hypertension,
  diabetes, and hypercholesterolemia

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Other causes of stroke

• Intracranial Atherosclerosis
• Dissection of Internal Carotid Artery
• Hypercoagulability
• Venous sinus thrombosis
• Fibromuscular dysplasia
• Vasculitis
• Drugs (amphetamines, cocaine, phenylpropanolamine)

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Transient Ischemic Attack (TIA)

• Episodes of stroke symptoms that last briefly
• Duration lt 24 hrs
• May arise from emboli to the brain or from in
  situ thrombosis
• Amaurosis fugax transient monocular blindness
  occurs from emboli to the central retinal artery
  of the eye

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Transient Ischemic Attack (TIA)

• Risk of stroke after a TIA is 10-15 in the
  first 3 months with most events occurring in the
  first 2 days
• Acute antiplatelet therapy is effective and
  recommended
• Atherosclerotic risk factors
• Old age
• Family history of thrombotic stroke
• DM
• Tobacco smoking
• dyslipidemia

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Transient Ischemic Attack (TIA)

• Other risk factors
• Prior stroke or TIA
• Certain cardiac conditions
• Oral contraceptives
• Hypertension most significant risk factor

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Transient Ischemic Attack (TIA) Treatment

• Antiplatelet agents
• Aspirin
• Can prevent platelet aggregation
• Acetylates cyclooxygenase whicg irreversibly
  inhibits the formation in platelets of
  thromboxane A2
• Effect is permament and lasts for the usual 8-day
  life of the platelet
• Also inhibits endothelial prostacyclin, and
  antiaggregating and vasodilating prostaglandin
• 50-325 mg/day is recommended for stroke prevention

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Transient Ischemic Attack (TIA) Treatment

• Antiplatelet agents
• Clopidogrel
• Blocks the ADP receptor on platelets blocking the
  platelet aggregation
• Dypiridamole
• Inhibits the uptake of adenosine by a variety of
  cells
• Adenosine inhibitor of aggregation
• Also potentiates the anti aggregatory effects of
  prostacyclin and nitric oxide by inhibiting
  platelet phosphodiesterase
• Prinicpal side effect is headache

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Transient Ischemic Attack (TIA) Treatment

• Anticoagulation therapies
• The decision to use anticoagulation for primary
  prevention is based on risk factors (rheumatic
  heart disease, atrial fibrillation, and
  prosthetic valve implantation)

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STROKE SYNDROMES
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Middle Cerebral Artery
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Middle Cerebral Artery

• entire MCA is occluded at its origin
• contralateral hemiplegia, hemianesthesia,
  homonymous hemianopia, and a day or two of gaze
  preference to the ipsilateral side
• Dysarthria is common because of facial weakness
• global aphasia
• anosognosia, constructional apraxia, and neglect