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Types of Stroke and Risk Factors
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There are two types of stroke, both of which result in a reduction in oxygen reaching the brain.
- Ischemic Stroke – Occurs when blood supply to part of the brain is blocked by a thrombus (blood clot) or by narrowing of the artery from atherosclerosis. Major causes include arterial thrombus, venous emboli that migrate, atrial fibrillation, arteritis, and patent foramen ovale. Less commonly, ischemic stroke can occur from severe hypotension caused by left ventricular dysfunction, large loss of blood, and refractory septic shock.
- Hemorrhagic Stroke – Occurs when there is bleeding into the brain tissue (intracerebral hemorrhage) or bleeding between the inner and outer layers of tissue covering the brain (subarachnoid hemorrhage). Intracerebral hemorrhages (ICH) are typically caused by a rupture of the vessels due to long-term atherosclerotic damage and arterial hypertension. Other mechanisms include bleeding diatheses, iatrogenic anticoagulation, cerebral amyloidosis, and cocaine abuse.
Transient Ischemic Attack (TIA) or “mini-stroke” occurs when there is a temporary disruption of blood flow to the brain that causes a brief episode of neurologic dysfunction. The symptoms typically last less than one hour and mimic those of a stroke, including slurred speech, visual changes, extremity weakness, or changes in level of consciousness (LOC).
Common Risk Factors for Stroke (National Institute for Health, 2020)
- High blood pressure
- Diabetes
- Coronary artery disease, atrial fibrillation, heart valve disease, and carotid artery disease
- High low-density lipoprotein (LDL) cholesterol levels
- History of TIA, previous stroke or myocardial infarction
- Smoking
- Brain aneurysm or arteriovenous malformations (AVMs)
- Infections or conditions that cause inflammation such as lupus or rheumatoid arthritis
- Age – risk increases with age
- Ethnicity (Black, Hispanic, Alaska Native, American Indian)
- Substance abuse or alcoholism
- Gender (men more at risk at younger age, but women have higher lifetime risk)
- Family history and genetics
Signs and Symptoms of Stroke
Cardinal signs of stroke such as sudden motor and sensory deficits include:
- Facial droop
- Hemiparesis
- Unilateral extremity weakness
- Slurred speech
Additional signs and symptoms:
- Sudden-onset dizziness (vertigo)
- Loss of coordination or balance
- Gait disturbances
- Vision loss in one or both eyes
- Expressive or receptive aphasia
- Visuospatial neglect: inability to report, respond, or orient to stimuli, generally on the opposite side of the lesion
Signs of thrombosis of the basilar artery:
- Acute-onset quadriparesis (muscle weakness of all four limbs)
- Loss of consciousness
- Respiratory failure
Stroke Assessment Tools
The National Institute of Neurological Disorders and Stroke (NINDS) recommends using a specific stroke assessment tool. Examples include:
- Cincinnati Prehospital Stroke Scale (CPSS) – commonly used by emergency medical services (EMS) and paramedics. The American Hospital Association (AHA) and the NINDS promote educating the community on these symptoms and to notify emergency services (FAST).
- Facial droop: one side of the face does not move at all
- Arm drift: one arm drifts compared with the other
- Speech: the patient uses slurred or inappropriate words, or is mute
- Time to call 911
- National Institutes of Health Stroke Scale (NIHSS) – identifies the severity of ischemic stroke by assessing 11 areas including LOC, eye gaze, visual fields, facial palsy, motor arm (drift), motor leg (drift), limb ataxia, sensation, language, aphasia/dysarthria, and inattention. An NIH stroke scale should be administered and scored when stroke is suspected, 24 hours after fibrinolytic therapy, 7 days post-stroke, and 30 days post-stroke. The NIHSS is the preferred stroke scale and the total score (0 to 42) correlates to stroke outcome (Filho & Mullen, 2020b):
- Less than 5: mild
- Between 5 and 9: moderate
- Greater than or equal to 10: severe
Emergency Department (ED) Triage
Early interventions when a stroke is suspected are critical to improving outcomes.
- Ensure medical stability with airway, breathing, and circulation.
- Determine if signs and symptoms are consistent with stroke and if onset of symptoms is within the 3-hour timeframe for treatment with alteplase [intravenous tissue plasminogen activator (tPA)].
- Time of onset is defined as the time the patient was last known to be neurologically normal.
- In a select group of patients, the treatment window may be extended to 3-4.5 hours of last known neurologically normal time.
The Golden Hour
The AHA and American Stroke Association (ASA) developed the 60-minute or less stroke protocol with a goal of intervention within 60 minutes upon arrival to the ED.
THE GOLDEN HOUR |
TIME |
PLAN |
Time Zero |
Arrival to the Emergency Department (ED). |
10 Minutes |
Patient seen by ED physician for initial assessment. |
15 Minutes |
Patient seen by stroke team. |
25 Minutes |
Non-contrast computed tomography (CT) scan performed. |
45 Minutes |
CT scan results available to stroke team and decision made for treatment.
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60 Minutes |
Door-To-Needle (DTN): Fibrinolytic therapy initiated within 3 hours of time last known well, unless contraindicated (up to 4.5 hours in selected patients).
- Administer IV alteplase in eligible patients.
- Carefully lower blood pressure (BP) below 185/110 mm Hg before IV fibrinolytic therapy.
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Physical Exam
In addition to a thorough neurological assessment and use of stroke assessment tools, important components of the physical exam include:
- Inspect chest wall movement and observe the respiratory rate, respiratory effort and skin color for cyanosis.
- Inspect head and extremities for signs of trauma.
- Auscultate heart for irregular rhythm and abnormal rate and murmurs.
- Auscultate carotid arteries for bruits.
- Auscultate lungs for adventitious breath sounds.
- Inspect skin for ecchymoses and evidence of surgery or other invasive procedures.
Diagnostic Studies
Laboratory and diagnostic tests should NOT delay the initiation of fibrinolytic therapy if stroke is suspected (Powers, et al., 2018).
DIAGNOSTIC STUDIES |
TEST |
INDICATION |
Non-contrast Head CT |
- Preferred study at most centers due to widespread availability and rapid scan times
- Rule out intracranial hemorrhage or non-stroke lesions. Identify the degree of ischemic brain injury.
- Identify the vascular lesion responsible for the ischemic attack.
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CT Angiography (CTA) |
- Identifies patients with large vessel occlusion who may benefit from endovascular intervention
- Can be obtained concurrently with non-contrast CT brain
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MRI with diffusion weighted imaging |
- Superior to noncontrast CT for the very early detection of acute ischemia and the exclusion of some conditions that mimic stroke.
- MRI can be used as the only imaging method in select centers with sufficient MRI availability for the evaluation of suspected stroke patients who do not have MRI contraindications.
- Limitations: Not readily available at most centers for the acute evaluation of patients with stroke; MRI in practice is more limited by patient contraindications or intolerance than CT; MRI is a longer study and may delay the administration of alteplase.
- There are no data to show that MRI is superior to CT for selecting patients who could be treated with intravenous thrombolysis.
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Oxygen saturation (O2 sat) |
- Rule out acute ischemic stroke associated with hypoxemia.
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Fingerstick blood glucose |
- Rule out hypoglycemia and hyperglycemia.
Serum glucose is the only lab test that must be measured before IV fibrinolytic therapy is started, unless there is strong clinical suspicion for contraindication.
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Complete blood count (CBC)*
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- Check red blood cells (RBC), white blood cells (WBC), and platelets.
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Coagulation studies* |
- Check prothrombin time (PT), activated partial thromboplastin time (aPTT), international normalized ratio (INR), Ecarin clotting time, thrombin time, direct factor Xa assay.
Note: INR, aPTT, and platelets may be needed if coagulopathy is suspected, however fibrinolytic therapy should not be delayed while waiting for results.
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Cardiac biomarker* |
- Check troponin level to rule out myocardial infarction (MI).
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Electrocardiogram (ECG)* |
- Rule out acute MI and atrial fibrillation.
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Basic metabolic panel† |
- Check serum electrolytes, blood urea nitrogen (BUN), and creatinine.
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Blood alcohol & toxicology† |
- Include liver panel for patients with suspicion of alcohol intoxication.
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Arterial blood gas (ABG) † |
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Pregnancy test† |
- Assess women of child-bearing potential.
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Chest X-ray† |
- Assess for suspected lung disease or injury.
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Electroencephalogram† |
- Rule out ongoing seizures.
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Lumbar puncture† |
- Rule out suspected subarachnoid hemorrhage when brain imaging is negative (lumbar puncture will preclude IV alteplase, which should not be given if there is a suspicion for subarachnoid hemorrhage).
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Urinalysis† |
- Indicated if fever is present to check for infectious source.
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Blood cultures† |
- Indicated if fever is present to check for infectious source.
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Type and cross match† |
- Perform as needed, if transfusion of blood products is anticipated.
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*Should NOT delay fibrinolytic therapy
†May be appropriate for select patients (Filho & Mullen, 2020b)