stroke

Cerebrovascular Injury: Stroke and Transient Ischemic Attack

Learning Objectives

  • Define cerebrovascular accident (CVA)
  • Differentiate between ischemic stroke, transient ischemic attack (TIA), and hemorrhagic stroke
  • Identify risk factors and symptoms of ischemic stroke/TIA
  • Summarize diagnostic principles for CVA
  • Review basic considerations for thrombolytic therapy
  • Understand the stroke timeline and essentials for initial CVA management
  • Review the management of hemorrhagic stroke

Cerebrovascular Physiology

  • Blood Flow Pathway
    • Blood from the heart travels to the aortic arch, then branches to the thoracic aorta, and the common carotids.
    • Supplies blood to the brain via the internal and external carotids.
    • Additional supply involves vertebral arteries for the brain stem and spinal cord.

Cerebral Arteries

  • Key Vessels
    • Orbitofrontal artery (ACA)
    • Frontobasal (MCA)
    • Anterior cerebral artery (ACA)
    • Internal carotid artery (ICA)
    • Posterior cerebral artery (PCA)
    • Lateral branch (PCA)
    • Anterior temporal artery
    • Posterior temporal artery
    • Occipitotemporal artery
    • Medial branch (PCA)
    • Callosal artery
    • Calcarine artery

Stroke Definitions

  • Stroke: Interruption in blood flow to the brain due to a block or rupture in a blood vessel resulting in acute loss of function.
    • Ischemic Stroke: Caused by blockage.
    • Hemorrhagic Stroke: Caused by a ruptured vessel leading to intracranial bleeding.

Stroke vs Transient Ischemic Attack (TIA)

  • Symptoms and Presentation
    • Both demonstrate abrupt onset of focal neurologic deficit with an assumption of vascular origin.
    • Stroke: More than 24 hours duration.
    • TIA: 30 minutes to less than 24 hours duration; often due to smaller clots or vasospasms that naturally resolve.
    • If TIA exceeds 1 hour, it is generally indistinguishable on imaging tests.

Epidemiology

  • Stroke Prevalence
    • Leading cause of disability among adults and the 4th leading cause of death.
    • Approximately 800,000 strokes occur per year in the U.S.
    • Stroke mortality decreased by 30% from 1995 to 2005.
    • Breakdown: 87% ischemic (stroke and TIA); 13% hemorrhagic.

Ischemic Stroke

Pathophysiology
  • Mechanism
    • Blockage stops blood supply to a brain area, leading to ischemia (lack of oxygen) and eventually necrosis (death of tissue).
    • Atherosclerotic plaque and blood clots play significant roles.
Blood Flow Obstruction
  • Consequences of Blockage
    • Location of the blockage determines the severity and type of symptoms.
    • Right-side brain obstructions produce left-sided symptoms; brainstem obstructions affect vital signs.
    • Loss of blood flow, whether totally or partially, causes ischemia distal to the blockage.
    • Time-related neuron loss: Each minute without treatment results in the loss of approximately 1.9 million neurons; each hour equals 3.6 years of aging.

Risk Factors

Non-Modifiable Factors
  • Age: Risk doubles every decade post-55.
  • Sex: Men > Women.
  • Genetic predisposition: Low birth weight and family history of stroke or TIA.
Modifiable Factors
  • Hypertension
  • Smoking
  • Oral contraceptive use
  • Postmenopausal hormone therapy
  • Atrial fibrillation
  • Coronary artery disease (CAD)
  • Peripheral artery disease
  • Carotid stenosis
  • Dyslipidemia
  • Obesity/physical inactivity
  • Sickle cell disease
  • Migraines
  • Pregnancy
  • Depression
  • Hypercoagulability

Signs and Symptoms

  • Common Symptoms
    • Facial drooping
    • Arm weakness
    • Speech difficulty
    • Severe headache
    • Vision difficulty
    • Loss of coordination
    • Ataxia
    • One-sided weakness
Effects of Brain Injury

  • Right Brain Injury:

    • Results in paralysis on the left side
    • Associated with special perceptual deficits and a quick, impulsive behavioral style.

  • Left Brain Injury:

    • Results in paralysis on the right side
    • Associated with speech-language deficits, slow and cautious behavioral style, and memory deficits.

Acute Management

  • Importance of Early Recognition
    • Public education is essential for stroke awareness.
    • Utilize FAST protocol:
    • FACE: Ask the person to smile. Look for droop on one side.
    • ARMS: Ask the person to raise both arms. Observe for arm drift.
    • SPEECH: Ask the person to repeat a simple phrase; listen for slurred or strange speech.
    • TIME: If any signs are observed, call 9-1-1 immediately.

Pre-Hospital Management

  • EMS should provide dispatch with the highest alert.
  • Prioritize reaching the highest level of care quickly; a certified primary stroke center or comprehensive stroke center preferred.
  • Telemedicine is becoming increasingly utilized.
  • EMS should inform the hospital with a ‘Stroke Alert’ during transportation, comparable to acute trauma or myocardial infarction timelines.

Screening Criteria

Los Angeles Prehospital Stroke Screen (LAPSS)
  1. Age over 45 years
  2. No prior history of seizure disorder
  3. New onset of neurologic symptoms within the last 24 hours
  4. Patient was ambulatory at baseline prior to the event
  5. Blood glucose between 60 and 400
  6. Exam for unilateral weakness: Assess facial smile/grimace, grip strength, and arm weakness.
Cincinnati Prehospital Stroke Scale
  • Facial Droop:
    • Normal: Both sides of the face move equally
    • Abnormal: One side of the face does not move.
  • Arm Drift:
    • Normal: Both arms move equally or remain still.
    • Abnormal: One arm drifts compared to the other.
  • Speech:
    • Normal: Patient uses correct words without slurring
    • Abnormal: Slurred or inappropriate speech.

Initial Inpatient Management

  • Arrival Timing:
    • ED arrival to initial assessment: <10 min
    • Line started and labs drawn: <10 min
    • Imaging & neurologic assessment by stroke team: <25 min
    • Interpretation of results: <45 min
    • Administer fibrinolytic treatment if appropriate: <60 minutes from arrival, assuming onset within 3-4.5 hours.
    • Admission to stroke unit or neurology ICU: <3 hours of arrival.

Imaging

  • CT Scan:
    • Non-contrast CT recommended initially to identify bleeding.
    • Initial ischemia usually not visible but can be repeated with contrast for further intervention.
    • MRI may be utilized.
Perfusion Imaging
  • CT and/or MR Perfusion Scanning:
    • Identification of infarct core and ischemic penumbra.
    • Assessing the core-penumbra mismatch; it is beneficial for determining severity and assessing surgical intervention earlier while potentially extending the reperfusion window.

NIH Stroke Scale

  • Scoring System Categories:
    1. Level of Consciousness, Gaze, Visual Fields
    2. Facial Paresis
    3. Motor Arm (left and right)
    4. Motor Leg (left and right)
    5. Limb Ataxia
    6. Sensory
    7. Best Language
    8. Dysarthria
    9. Extinction and Inattention
    • Total Scale Score Range: 1 - 42
    • Interpretation:
    • 1 – 7: Mild impairment
    • 8 – 15: Moderate impairment
    • >15: Severe impairment
    • NIHSS Score >12 denotes worse outcomes and is significantly predictive of a major vessel stroke.

Initial Results

  • Lab Considerations:
    • Minimal initial lab focus on coagulation and bleeding risk including INR, platelets, and blood glucose levels
    • Vital signs are critical, especially blood pressure control; aim for a permissive hypertension target of <180/105 in the first 24 hours.
    • Medication history of the patient is important for pending treatments.

Supportive Care

  • Management Aspects:
    • Oxygen/airway support
    • Continuous cardiac monitoring
    • Frequent neurological examinations, especially after tPA administration
    • Monitoring vital signs
    • Administer IV fluids if needed.

Hemorrhagic Stroke

Pathophysiology
  • Mechanism
    • Associated with blood vessel rupture, often due to aneurysms leading to decreased blood flow distally and increased intracranial pressure.
  • Classifications:
    • Subarachnoid hemorrhage (SAH)
    • Intracranial hemorrhage (ICH)
    • Subdural hemorrhage
Risk Factors
  • Implications
    • Not well-studied; weakened blood vessel walls are implicated.
    • Age, hypertension, and anticoagulant/antiplatelet use increase the risk.
Diagnosis and Initial Evaluation
  • Imaging
    • Non-contrast CT utilized (similar to ischemic). Symptoms may be similar; the location could present more somnolent if brain stem is involved.
    • Assessment of medication list, lab values, and blood pressure management is critical.
Management
  • Management Goals
    • Control blood pressure and manage intracranial pressure.
    • Medications for managing ICP and reversal of anticoagulation if required.
    • Possible usage of blood products and recombinant products.
    • Address cerebral vasospasms as necessary.
Surgical Interventions
  • Types
    • Coil Procedure for cerebral aneurysm.
    • Clipping Treatment for cerebral aneurysm, often involving ruptured aneurysms.

Take Home Points

  • CVA constitutes a medical emergency demanding immediate medical attention.
  • Distinction between ischemic stroke, TIA, and hemorrhagic stroke is vital for appropriate treatment.
  • Diagnosis of ischemic stroke relies on symptoms, NIH stroke scale, imaging, and lab values.
  • Understanding the stroke timeline is paramount for delivering optimal care and ensuring positive patient outcomes.
  • Management of hemorrhagic stroke focuses on regulating blood pressure, managing intracranial pressure, reversing anticoagulation, and potential surgical intervention.