CVA

CEREBROVASCULAR ACCIDENT (CVA)

Definition

Cerebrovascular Accident (CVA), commonly known as a stroke, is defined as a sudden loss of brain function resulting from the disruption of blood supply to a part of the brain. According to Brunner and Suddarth (2010), this disruption leads to a sudden decrease in the oxygen supply to nerve cells, caused either by obstruction or rupture in one or more blood vessels supplying the brain.

Types of Stroke

There are two primary classifications of strokes:

  1. Ischemic Stroke
  2. Hemorrhagic Stroke

In both cases, the brain is deprived of blood and oxygen, leading to an infarct.

Ischemic Stroke

Definition and Incidence:
Ischemic stroke accounts for approximately 80% of all strokes. It is characterized by a blockage in a blood vessel supplying the brain.

Mechanisms of Ischemic Stroke:
There are two principal ways ischemic strokes can occur:

  • Embolic Stroke: Occurs when a clot forms in another part of the body and lodges in a brain blood vessel.
  • Thrombotic Stroke: Develops when a clot forms in a blood vessel within the brain itself.

The prognosis for ischemic strokes is generally better than for hemorrhagic strokes.

Hemorrhagic Stroke

Definition:
Hemorrhagic stroke results from the rupture of a blood vessel within the brain, which prevents blood from reaching specific brain areas. Hemorrhage can occur either within the brain substance (intracerebral) or in the membranes surrounding the brain (subarachnoid).

Prognosis:
The prognosis for hemorrhagic stroke is poorer compared to ischemic strokes.

Transient Ischemic Attack (TIA)

Definition:
TIAs are distinct from the aforementioned types of stroke as they involve only a temporary disruption of blood flow to the brain, lasting less than 24 hours. They are often caused by the same factors as ischemic strokes, such as blood clots or debris.

Causes of CVA

  1. Cerebral Thrombosis:

    • Commonly affects elderly individuals due to arteriosclerosis, where the inner lining of cerebral arteries becomes thick and rough. This condition obstructs blood flow and leads to clotting.
    • The thrombus (clot) obstructs the artery, depriving part of the brain of its blood supply.

  2. Cerebral Hemorrhage:

    • Characterized by the rupture of a blood vessel leading to bleeding within the brain, often associated with hypertension (high blood pressure). Managing hypertension is crucial for prevention.

  3. Cerebral Embolism:

    • An embolus, or a detached clot, can lodge in one of the cerebral arteries, leading to a stroke. This often occurs in cases where a clot forms on the left side of the heart and is carried through the bloodstream.
    • Common causes include:
      • Mitral Stenosis with Atrial Fibrillation
      • Myocardial Infarction
      • Subacute Bacterial Endocarditis

Risk Factors for Stroke

  • Age: 60-75% of strokes occur in individuals over the age of 65.
  • Sex: Men exhibit a slightly increased incidence of stroke.
  • Race: Studies suggest that individuals of African descent have a higher propensity for stroke.
  • Hypertension: This is considered a major risk factor, especially when combined with atherosclerosis.
  • Heart Disease: Contributes to stroke risk through mechanisms involving atherosclerosis and emboli.
  • Diabetes Mellitus: Associated with both microvascular and macrovascular changes contributing to atherosclerosis.
  • Lifestyle Factors: Cigarette smoking, oral contraceptive use (especially among smokers), alcohol consumption, and family history of stroke.

Pathophysiology

  • The brain requires a continuous supply of oxygen and glucose from the blood.
  • Vascular Supply: Blood supply is primarily maintained by the internal carotid and vertebral arteries, with a consistent blood flow rate of approximately 750 mL per minute.
  • Homeostasis Mechanism: The cerebral vessels actively regulate their dilation and constriction based on changes in blood pressure and blood gas levels.
  • Ischemia: If blood supply to any brain region is obstructed, ischemia occurs, leading to the death of cerebral cells (cerebral infarction) and the formation of necrotic tissue.
  • Secondary Effects: Certain cells may temporarily become non-functional, as seen in TIAs. Ischemia can disrupt the movement of ions such as calcium and potassium, leading to high intracellular calcium levels that activate harmful enzymes, trigger oxidative stress, and result in cellular damage.

Clinical Manifestations

The symptoms of stroke reflect the site and severity of ischemic damage:

  • Motor Effects:

    • Hemiparesis or hemiplegia affecting the side of the body opposite the ischemic event. Presentation is initially flaccid but may progress to spasticity.
    • Dysphagia may occur, impairing the swallowing reflex.
    • Dysarthria may lead to difficulties in speech articulation.

  • Bowel and Bladder Dysfunction:

    • Symptoms such as frequency and urgency, along with urinary incontinence, may appear.
    • Constipation and bowel incontinence may also be present.

  • Language Impairments:

    • Aphasia: Difficulty expressing oneself verbally or comprehending speech.
    • Alexia: Inability to understand written words.
    • Agraphia: Inability to express oneself in writing.

  • Sensory-Perceptual Problems:

    • Reduced response to superficial sensations like touch, pain, pressure, heat, and cold.
    • Diminished proprioception or awareness of body part positioning.

  • Cognitive-Emotional Problems:

    • Patients may exhibit emotional lability, depression, memory loss, and a short attention span.
    • Loss of higher cognitive functions such as reasoning, judgment, and abstract thinking abilities. As cerebral edema progresses, mental status changes may include apathy, irritability, confusion, memory impairment, withdrawal, drowsiness, stupor, or coma.

  • Other Clinical Features:

    • Signs may include numbness, weakness or paralysis on one side of the body, headaches, neck stiffness, vomiting, seizures, and dizziness.
Right and Left Brain Damage Effects

  • Right-brain damage (Right Side Stroke):

    • Results in paralyzed left side (hemiplegia), left-sided neglect, spatial-perceptual deficits, denial of problems, rapid performance, and impulsivity, potentially leading to safety issues.

  • Left-brain damage (Left Side Stroke):

    • Leads to paralyzed right side (hemiplegia), language-related impairments (aphasias), impaired right-left discrimination, cautious slow performance, awareness of deficits, and associated anxiety or depression around comprehension issues in language and math.

Management of Stroke

Medical Management

  1. Investigations:

    • CT Scan: To identify sites of infarctions, hematomas, and shifting brain structures.
    • MRI: To reveal infarction locations.
    • EEG: To assess nerve impulse transmission abnormalities.
    • Lumbar Puncture: Rarely performed when increased intracranial pressure (IICP) is a concern.
    • Cerebral Angiography: To locate ruptures or occlusions and assess collateral blood circulation.

  2. Supportive Care:

    • Maintenance of patent airway and oxygen delivery as necessary (100% may be supplied).
    • IV fluids for fluid and electrolyte balance, while being cautious of risks related to IICP.
    • Positioning the patient, especially elevating the head of the bed to 30° to facilitate venous outflow and maintain cerebral perfusion.
    • Dietary measures may include NPO status and possible gastric tube feeding if swallowing is impaired, with low sodium and low-fat diets considered.

  3. Pharmacotherapy:

    • Anticoagulants: Such as Heparin and Warfarin in patients with CVA or TIA to prevent further clotting.
    • Antihypertensive Agents: Nifedipine to manage severe hypertension possibly leading to cerebral edema.
    • Antiplatelet Medications: Aspirin with dipyridamole or Sulfinpyrazone to prevent thrombosis.
    • Glucocorticosteroids: Such as Dexamethasone, in conjunction with osmotic diuretics (Mannitol), to manage cerebral edema.
    • Others: Antacids, histamine H₂-receptor blockers for GI hemorrhage risk, anti-epileptic medications for seizure control, sedatives/tranquilizers for comfort without exacerbating neurological deficits and analgesics for headache management.
Nursing Care

  • Aims:

    • Prevention of complications and restoration of function and nutritional status to near normal.
    • Total assistance may be necessary for all daily living activities.

  • Environmental Considerations:

    • Best monitored in an intensive care unit during the critical phase.
    • Head of the bed elevated at 30° and patient positioned to prevent airway obstruction or aspiration.
    • Maintain a calm environment to reduce anxiety and agitation, monitoring for IICP and providing frequent position changes (every two hours).

  • Rehabilitation Exercises:

    • Active physical therapy and passive range of motion exercises are vital, initiated 24 hours post-stroke.
    • Encourage coughing and deep breathing exercises, assist with mobility as soon as feasible, and involve physiotherapists and speech therapists in rehabilitation endeavors.
Health Education
  • In preparing for discharge, educate the family and patient about potential residual deficits and realistic expectation of recovery.
  • Stress the importance of engaging in physiotherapy, adhering to dietary modifications, engaging in weight management strategies, and changing lifestyle habits related to smoking and alcohol use for prevention of recurrent strokes.
Complications

Potential complications following a stroke may include:

  • Contractures resulting in disabilities.
  • Paralysis, including facial limbs.
  • Pressure sores.
  • Pneumonia as a secondary infection risk.
  • Speech defects, including various forms of aphasia.
  • Altered gait and mobility challenges resulting from muscle weakness or paralysis.