CVA Overview and Implications

OTA ADULT CLINICAL CONDITIONS: WEEK 9

LEARNING OBJECTIVES

  • Define CVA and Causes of CVA: Understand what cerebrovascular accident (CVA) is and its causes.
  • Areas Affected by CVA: Identify different brain regions affected by strokes.
  • Different Causes and Contributing Factors of CVA: Explore various causes of CVA and associated risk factors.
  • Common Deficits Experienced by Individuals with CVA: Describe the typical deficits following a CVA.
  • Differentiating Between Right and Left CVA: Understand the differences in symptoms and brain functionalities affected by right versus left-sided strokes.
  • Brain Areas and Function: Learn about the brain's areas, their functions, and clinical manifestations when affected by a CVA.

CEREBROVASCULAR ACCIDENTS: DESCRIPTION AND DEFINITIONS

  • Stroke (Brain Attack): Caused by interrupted blood flow to the brain, either due to blocked or ruptured blood vessels, leading to inadequate oxygen and nutrient supply.
  • Consequences of Stroke: Even brief interruptions can result in brain damage.
  • CVA Definition: Medical practitioners often use the term cerebrovascular accident (CVA) to refer to stroke, which can occur in various brain regions including cerebral hemispheres, cerebellum, or brainstem. The affected area’s site and extent determines the functional loss.

TYPES OF STROKES

  • Main Types: Divided into ischemic and hemorrhagic strokes.
  • Ischemic Stroke: Characterized by blockages; terms ischemia denotes lack of blood supply. Includes:
    • Atherothrombotic infarction
    • Lacunar infarction
    • Embolic infarction (in order of frequency)
  • Hemorrhagic Stroke: Includes:
    • Intracerebral hemorrhage
    • Subarachnoid hemorrhage
  • Common Cause: Most CVAs result from long-standing degeneration, less commonly from congenital vascular abnormalities.

CEREBRAL CIRCULATORY SYSTEM

  • Blood Supply Importance: The brain accounts for 2% of body weight but utilizes approximately 20% of oxygen.
  • Arterial Supply:
    • Anterior Circulation: Supplies front, top, and side portions of cerebral hemispheres.
    • Posterior Circulation: Supplies brainstem, cerebellum, and undersurface of cerebral hemispheres.
  • Categorization:
    • Extracranial Portions: Arteries arise outside the skull.
    • Intracranial Portions: Arteries arise within the skull.

EXTRACRANIAL VESSELS

  • Carotid Arteries: Two main carotid arteries travel in the front neck; originate from the aortic arch (left common carotid) and innominate artery (right common carotid).
  • Division at Cervical Vertebrae: Common carotid arteries bifurcate into:
    • External Carotid Arteries: Supply the face.
    • Internal Carotid Arteries: Supply the eyes and cerebral hemispheres.
    • Vertebral Arteries: Emerge from subclavian arteries, contributing to posterior circulation and traveling alongside the spine.

INTRACRANIAL VESSELS

  • Entry into Skull: Internal carotid arteries enter through the carotid canal, forming a curve (carotid siphon) and giving rise to branches including:
    • Ophthalmic Arteries: Supplies the eyes.
    • Anterior Cerebral Arteries (ACA): Supplies parts of the brain's frontal lobe.
    • Middle Cerebral Arteries (MCA): Supplies lateral parts of frontal, parietal, and temporal lobes.
    • Posterior Cerebral Arteries (PCA): Vascular supply to occipital lobes and medial portions of temporal lobes.
  • Collateral Circulation: Adequately supplied blood flow via significant vascular connections.

COMMUNICATING ARTERIES

  • Circle of Willis: An anatomical structure where the right and left carotid arteries connect, allowing for collateral blood flow if major carotid arteries are blocked.
  • Functionality of Communicating Arteries: These vessels can enlarge to compensate for blockages, though this system may fail, resulting in strokes.

ETIOLOGY

Ischemic Stroke

  • Description: Most common type (80% of cases), leads to cerebral infarction due to blood supply blockage.
  • Classifications:
    • Thrombotic
    • Embolic
    • Lacunar
  • Recovery: Some brain areas affected may recover over months due to neural plasticity.
  • Physiological Events:
    • Neuron membranes leak potassium and ATP.
    • Accumulation of fluid obstructs oxygen and nutrient flow, leading to cell death within minutes if deprived of blood supply.
    • Infarction zones are established, impacting functional recovery.

Thrombosis

  • Mechanism: Blood clot obstructs arteries supplying the brain. Often occurs in arteries damaged by atherosclerosis.
  • Impact of Atherosclerosis: Degenerative disease resulting in fatty deposits within blood vessel walls leading to reduced blood flow (stenosis).

Lacunar Strokes

  • Characteristics: Small infarctions in deep brain structures (e.g., basal ganglia, thalamus).
  • Symptoms: Often minimal and occasionally go undetected.
  • Risk Factor: Commonly associated with hypertension.

Embolism

  • Description: Occurs when the clot dislodges from another location and occludes a small vessel in the brain.
  • Sources: Cardiac sources account for 20% of ischemic strokes, often linked to cardiac conditions.

Hemorrhagic Stroke

  • General Info: Accounts for 20% of strokes, results from blood vessel rupture.
  • Types:
    • Intracerebral Hemorrhage: Bleeding directly into the brain.
    • Subarachnoid Hemorrhage: Bleeding into surrounding membranes. 95% caused by aneurysm leaks.
  • Symptoms: Includes severe headache, altered consciousness, and other neurological deficits.

INCIDENCE AND PREVALENCE

  • Statistics: Stroke is the third leading cause of death in the U.S. with 600,000 to 730,000 episodes annually and a prevalence of about 4.5 million survivors.
  • Recovery Rates: Approximately 50-70% regain functional independence, with 15-30% experiencing permanent disability.
  • Trends: Depressive symptoms are prevalent in survivors; however, advancements in treatment have reduced stroke occurrences.

RISK FACTORS

  • General Risk Factors: Similar to cardiovascular disease due to the role of atherosclerosis.
  • Key Factors:
    • Ethnicity: Higher stroke death rates in African-Americans.
    • Age: Increased risk after 65; notable strokes in those below 65.
    • Heredity: Family history increases risk.
    • Obesity & Lifestyle Choices: Linked to hypertension and diabetes.
    • Hypertension: Called the silent killer, most controllable risk factor.
    • Smoking: Doubles stroke risk; benefits arise from quitting.
    • Diabetes: Increases stroke risk by 2-3 times; more prevalent in men.
    • Cardiovascular Disorders: Heart conditions significantly raise stroke likelihood.

SIGNS AND SYMPTOMS

  • Common Symptoms of Stroke:
    • Sudden numbness or weakness (particularly on one side).
    • Confusion and difficulty speaking or understanding.
    • Problems with vision, walking, or coordination.
    • Severe headache without known cause.

TRANSIENT ISCHEMIC ATTACKS (TIAs)

  • Definition and Duration: Temporary blockages, symptoms last less than 24 hours, often resolving rapidly (75% within 5 minutes).
  • Risk Factor for Stroke: Individuals with TIAs are significantly more likely to experience a stroke soon after.

SMALL STROKES (RINDS)

  • Characteristics: Symptoms last more than 24 hours; if deficits resolve completely, termed reversible ischemic neurologic deficits (RIND).

DIAGNOSIS

  • Methodology: Diagnosing a stroke involves patient history, symptoms, and a range of diagnostic tools including imaging and blood analysis to pinpoint the type and location of the stroke.

MEDICAL/SURGICAL MANAGEMENT

  • Treatment Goals: Acute management focuses on minimizing damage and preventing recurrence. Priority is placed on accurately diagnosing stroke types before treatment.
  • Medications: Include antiplatelet agents (e.g., aspirin), anticoagulants (e.g., heparin, warfarin), and thrombolytics (e.g., t-PA).
  • Surgical Options: Procedures such as carotid endarterectomy for stenosis, surgical clipping of brain aneurysms, or hematoma evacuation based on the severity of the stroke case.

IMPACT ON OCCUPATIONAL PERFORMANCE

  • Considerations: Strokes affect individual occupational performance in daily activities, work, play, and social interactions due to both motor and sensory deficits, mental health issues, and the overall recovery trajectory.

SENSORY FUNCTION IMPACT

  • Concerns: Loss of protective tactile sensations increases safety risks. Individuals may neglect body parts or exhibit impaired proprioception, impacting mobility and balance.

EMOTIONAL AND MENTAL IMPACT

  • Psychological Changes: Common emotional reactions include depression, irritability, and anxiety. Emotional lability may also occur, affecting social interactions.
  • Cognitive Changes: Severe strokes may lead to significant cognitive deficits impacting mental functions necessary for daily activities.

REFERENCE

Atchison, B. J. & Dirette, D. K. (2012). Conditions in Occupational Therapy Effect on Occupational Performance (4th ed.). Baltimore, MD: Lippincott, Williams & Wilkins. ISBN 978-1-60913-507-2