Ischemic Stroke

By: Nicole Bass, Kara Forwith, Olivia Martin

What is an Ischemic Stroke?

Ischemic Strokes occur as a result of an obstruction within a blood vessel supplying blood to the brain. The obstruction causes the brain not be able to receive any blood and can cut off oxygen supply to the brain. The underlying condition for this type of obstruction is the development of fatty deposits lining the vessel walls, a condition known as atherosclerosis. These fatty deposits can cause two types of obstructions, cerebral thrombosis and cerebral embolism.

Cerebral Thrombosis- refers to a thrombus, also known as a blood clot, that develops at the clogged part of the vessel.

Cerebral Embolism- refers generally to a blood clot that forms at another location in the circulatory system, usually the heart and large arteries of the upper chest and neck. A portion of the blood clot breaks loose, enters the bloodstream and travels through the brain's blood vessels until it reaches vessels too small to let it pass. A second important cause of embolism is an irregular heartbeat, also known as atrial fibrillation. It creates conditions where clots can form in the heart, dislodge and travel to the brain. Silent cerebral infarction, also known as a “silent stroke,” is a brain injury likely caused by a blood clot interrupting blood flow in the brain. It’s a risk factor for future strokes which could lead to progressive brain damage due to these strokes.

Ischemic Strokes are the most common types of strokes and account for 87% of all stroke cases (Mayo Clinic, 2015.)
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Pathophysiolgy of Ischemic Strokes

Stroke is defined as an acute neurologic dysfunction of vascular origin with sudden (within seconds) or at least rapid (within hours) occurrence of symptoms and signs corresponding to the involvement of focal areas in the brain. (Huether, 2012). With an ischemic stroke, a thrombus or embolus partially or completely occludes cerebral blood flow to an area of the brain; cellular hypoxia occurs and cell membrane permeability and cell depolarization are affected. As blood flow decreases, focal areas of ischemia occur, followed by infarction to the vascular territory. Changes in membrane permeability lead to an influx of sodium and calcium ions and water, leading to edema. Neurons die from lack of oxygen (Huether, 2012).

Who is at Risk for Ischemic Strokes?

Risk Factors for Ischemic Strokes include:
  • History of Transient Ischemic Stroke
  • Hypertension
  • Heart Disease
  • Smoking
  • Family History of Cerebrovascular Disease
  • Obesity
  • Alcohol Use
  • Cardiac Arrhythmias, such as Atrial Fibrillation
  • Diabetes Mellitus
  • Use of Hormonal Contraceptives in Conjunction with Smoking and Alcohol Use
  • High Red Blood Cell Count
  • High Serum Triglyceride Levels
  • Elevated Cholesterol and Triglycerides
  • Use of Illegal Drugs

Tests and Procedures for Ischemic Strokes

A doctor will diagnose an Ischemic Stroke based on a patient's signs and symptoms, medical history, a physical exam, and test results. Diagnostic Testing can include:

Laboratory:
  • Anticardiolipin Antibodies, Antiphospholipid, Factor V Mutation, Antithrombin III, Protein S, and Protein C- these lab results may show increase for thrombotic risk.
  • Coagulation Studies- to help determine eligibility for treatment.

Imaging:

  • Magnetic Resonance Imaging and Angiography- to help determine the location and size of the lesion.
  • Cerebral Angiography- helps to detail the disruption of cerebral circulation and is the test of choice for examining the entire cerebral blood flow.
  • Computed Tomography Scanning (brain)- can help detect hemorrhage or structural abnormalities.
  • Positron Emission Tomography- can provide data on cerebral metabolism and cerebral blood flow changes.
  • Carotid Duplex Scanning- helps identify the cause of the stroke and helps evaluate for carotid stenosis.

Other:

  • Lumbar Puncture- rules out meningitis and subarachnoid hemorrhage if computed tomography scanning is negative.
  • Transcranial Doppler Studies- evaluate the velocity of blood flow and identify the location and degree of arterial occlusion.
  • Carotid Artery Duplex Scanning- measures flow through the carotid arteries, identifying reduced blood flow.
  • Two-Dimensional Echocardiography- evaluates the heart for dysfunction; transthoracic and transesophageal echocardiography identify a possible cardiac origin of the stroke.
  • Cerebral Blood Flow Studies- measure blood flow to the brain.
  • Electrocardiography- evaluates electrical activity in cortical infarction.

Clinical Manifestations of Ischemic Strokes

Watch for these signs and symptoms if you think you are or a loved one are having a stroke. It is important to make a note of when the signs and symptoms started to appear because the length of the time they have been present may help guide the treatment options available. An easy way to remember when to seek medical attention is by the acronym "FAST" (Unbound Medicine, Inc. 2014). These signs and symptoms include:
  • With stroke in the left hemisphere, signs and symptoms on the right side
  • With stroke in the right hemisphere, signs and symptoms on the left side
  • With stroke that causes cranial nerve damage, signs and symptoms on the same side
  • Change in level of consciousness
  • With a conscious patient, anxiety along with communication and mobility difficulties
  • Urinary incontinence
  • Loss of voluntary muscle control
  • Hemiparesis or hemiplegia on one side of the body
  • Facial droop
  • Monocular or binocular blindness, blurred vision, or visual field deficits
  • Decreased deep-tendon reflexes
  • Hemianopsia on the affected side of the body
  • With left-sided hemiplegia, problems with visual-spatial relations
  • Sensory losses
  • Dysarthria or aphasia
  • Ataxia, vertigo, nystagmus
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Treatments of an Ischemic Stroke

In order to treat an Ischemic Stroke, doctors must act quickly in order to restore blood flow to a patient's brain (Unbound Medicine, Inc. 2014). These interventions may include medications and surgeries, such as:

Medications:
  • When the cause isn't hemorrhagic, Tissue Plasminogen Activator (Activase)- emergency care within 3 to 4½ hours of symptom onset
  • Enteric-coated aspirin- with careful monitoring of patient
  • Anticonvulsants- such as diazepam (Valium) and lorazepam (Ativan)
  • Mannitol (Aridol)- to reduce increased ICP
  • Stool softener- such as docusate sodium (Colace); to help a patient not become constipated
  • Anticoagulants- such as heparin for deep vein prophylaxis, warfarin (Coumadin) or dabigatran etexilate mesylate (Pradaxa) to reduce the risk of atrial fibrillation (a major risk factor for stroke)
  • Analgesics
  • Antidepressants
  • Antiplatelets- such as aspirin or dipyridamole (Persantine)
  • Lipid-lowering agents- such as atorvastatin (Lipitor) or pravastatin (Pravachol)- to help maintain cholesterol and triglycerides
  • Antihypertensives- such as labetalol hydrochloride (Normodyne), enalapril (Vasotec), niCARdipine hydrochloride (Cardene), and sodium nitroprusside (Nipride)- to help maintain blood pressure.
  • Insulin to maintain blood sugar between 80 and 140 mg/dL

Surgery:

  • Craniotomy
  • Endarterectomy
  • Extracranial-intracranial bypass
  • Ventricular shunts


Medications and Surgery can be an immediate fix but patients may need more long term care such as controlling diet, physical therapy, and occupational therapy.

Works Cited

Huether, S. (2012). Chapter 15: Disorders of the Central and Peripheral Nervous Systems. In Understanding Pathophysiology (5th ed., pp. 389-390). St. Louis, Missouri: Elsevier Mosby.
Swanson, J. (2015).

Ischemic Strokes. Retrieved November 30, 2015, from http://www.mayoclinic.org/diseases-conditions/stroke/home/ovc-20117264

Unbound Medicine, Inc. (2014). Nursing Central (1.22.) [Mobile application software]. Retrieved from < https://itunes.apple.com/us/app/nursing-central/id300420397?mt=8>