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Stroke

Overview

Stroke is a medical condition characterized by loss of blood supply to a part of the brain resulting in neurological deficits such as loss of consciousness, loss of control of limbs’ movement, etc. Loss of blood supply is due to a blood clot constricting blood supply in brain vessels or the rupture of an already formed clot resulting in hemorrhage in that part of the brain. When uncontrolled for a prolonged time, certain medical conditions such as diabetes and hypertension can increase the prevalence of stroke.

Causes

There are two main causes of stroke:
Blockage of a blood vessel (blood clot) that takes blood to the brain due to fatty deposits in arteries that can break off and travel to the brain (embolus).
Due to bursting or leakage of a blood vessel in the brain due to uncontrolled high blood pressure.

Types

Stroke can be classified into two types depending upon the causes of stroke:

  • Ischemic stroke: caused due to formation of a clot in blood vessels supplying the brain or maybe dislodged in the brain from other vessels such as carotid vessels.
  • Hemorrhagic stroke: caused by rupture of an already formed clot that causes blood spill in the affected areas of the brain.
    Ischemic stroke is the most common type, with more than 80 percent of stroke cases being ischemic. Sometimes ischemic type can be converted into hemorrhagic type as the blood clot dislodges and ruptures due to fibrinolytic therapy. 

Risk Factors And Epidemiology

Stroke is one of the leading causes of death worldwide. According to WHO, 15 million people suffer from stroke each year, 5 million people die, and 5 million suffer permanent disability. In the United States alone, stroke is the fifth leading cause of death. It is more prevalent in blacks than in whites.
Men are at higher risk for stroke than compared to women. With increasing age, the incidence also increases.
Risk factors for stroke include:

  • Female gender
  • Advanced age
  • Hypertension
  • Diabetes
  • Obesity
  • History of migraine
  • Oral contraceptives
  • Excessive alcohol intake
  • Smoking
  • Hypercholesterolemia
  • Sickle cell disease
  • Pregnancy

Signs And Symptoms

Following are the signs and symptoms of stroke:

  • Altered level of consciousness
  • Loss of movement in one or two limbs
  • Sensory deficits such as loss of touch, temperature, or vibratory sense
  • Sudden abrupt movement of eyeballs called nystagmus
  • Vision loss
  • Dizziness and loss of balance
  • Double vision
  • Loss of speech
  • Drooping of face
  • Abnormal and uncoordinated movements of the body
  • Varying degrees of muscle weakness
  • Urinary incontinence

Diagnosis

 Following labs are used for the diagnosis of stroke:

  • Imaging is the mainstay of diagnosis. Non-contrast CT imaging is used to diagnose ischemic stroke.
  • Magnetic resonance angiography (MRA) is used to detect cerebral edema early and diagnose hemorrhagic stroke.
  • Carotid scanning is used for at-risk individuals to see carotid stenosis due to carotid artery clots.
  • A lumbar puncture is done to rule out meningitis.
  • Complete blood count to distinguish between the causes of stroke (such as polycythemia, thrombocytosis, or leukemia)
  • Basic chemistry panel including liver function test and renal function tests
  • Coagulation studies such as prothrombin time and APTT
  • Cardiac enzymes and other biomarkers
  • Fasting lipid profile
  • Erythrocyte sedimentation rate
  • Antinuclear antibodies

Differential Diagnosis

It is essential to differentiate between ischemic and hemorrhagic stroke to manage and contain stroke effectively. Clinical features such as coma, neck stiffness, headache, vomiting, etc., are generally associated with hemorrhagic stroke.
Other differential diagnoses for stroke include:

  • Bell’s palsy
  • Tumors of brain
  • Seizures
  • Migraine
  • Hypoglycemic attack
  • Syncope
  • Subarachnoid hemorrhage (SAH)
  • Conversion disorder
  • Global amnesia

Treatment

  • Treatment for acute stroke focuses on restoring the blood supply of involved brain tissue. This is done by administering intravenous fibrinolytic therapy that causes revascularization and prevents irreversible damage of ischemic brain tissue.
  • Antiplatelet therapy is started within 48 hours of a stroke to reduce stroke recurrence.
  • For acute management patient’s airway, breathing, and circulation (ABCs) are assessed, followed by imaging and lab studies within the first 60 minutes.
  • Where the patient’s oxygen saturation is less than 95%, supplemental oxygen is provided with IV fluids and vasopressor therapy.
  • Hyperglycemia is treated with IV insulin to maintain serum glucose levels between 70 to 130mg/d,l as extreme hyperglycemia can be dangerous in the setting of acute stroke. Hypoglycemia is also managed accordingly to achieve ideal blood glucose levels.
  • Optimal blood pressure control
  • Prevention oh hyperthermia

Medications

Following medicines are used to treat stroke:

  • Fibrinolytics that include alteplase or streptokinase
  • Anticonvulsants such as diazepam and lorazepam
  • Antiplatelet agents such as aspirin and clopidogrel
  • Anticoagulants such as warfarin for secondary stroke prevention
  • Analgesics
  • Beta-blockers to decrease blood pressure without inducing reflex tachycardia
  • Vasodilators
  • Mannitol and other therapies that reduce intracranial pressure are used to prevent/treat cerebral edema

Prognosis

The prognosis of stroke depends upon many factors such as the severity of the stroke, patient’s age, comorbidities, and post-stroke complications. Mortality can be predicted using various clinical assessment criteria such as the stroke score, which considers factors like preexisting diabetes, hypertension, severity, and extent of stroke, etc., where a score of 10 or higher is associated with a higher death rate.

Prevention

  • Preventive measures against stroke include using antiplatelet agents, statins, smoking cessation, and exercise for at-risk individuals. (At-risk individuals include people with uncontrolled high blood pressure, uncontrolled diabetes, hypercholesterolemia, previous history of transient ischemic attack, and pregnancy). They should be educated about the importance of these lifestyle modifications.
  • Patients who have already had a stroke are advised to use antiplatelet agents, anticoagulants, antihypertensives, statins, and lifestyle modifications such as smoking cessation, blood pressure control, low fat, low salt diet, weight loss, and regular exercise. They are also screened for diabetes, obesity, sleep apnea, atrial fibrillation and undergo a nutritional assessment.

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