Acute IschemIc stroke

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Tintinalli, J., Stapczynski, J. S., Ma, O. J., Cline, D., Cydulka, R. K., & Meckler, ..... Arkansas Nurses Association 1123 S. University, Suite 1015, Little Rock, AR ...

Acute Ischemic Stroke CE

1.0 Contact hours Objectives:

Upon Completion of this CNE activity, the learner will: 1. Define stroke and stroke types. 2. Describe risk factors for stroke. 3. Correlate the signs and symptoms of stroke with the major vessels affected. 4. Describe the acute management of patients with stroke.

Stroke is the third leading cause of death in Arkansas after heart disease and cancer. In fact, Arkansas has the highest death rate related to stroke in the U.S. (Arkansas Department of Health, 2011). It is also the leading cause of disability in the country ((McCance, Heuther, Brashears, & Rote, 2010). The “Time Lost is Brain Lost” campaign from the American Heart Association/American Stroke Association reflects the urgency of this condition due to the risk of permanent injury. Although all types of stroke share the common element of altered perfusion, the focus of this article will be the acute ischemic stroke. Stroke is defined as the sudden onset of a neurologic deficit lasting for more than 24 hours caused by a focal vascular cause (Longo et al., 2012; Tintinalli et al., 2011). Because the brain has a very high metabolic rate receiving 15% to 20% of cardiac output (McCance et al., 2010), any 12

disruption in blood flow causes potential injury. Ischemic stroke represents 87% of all strokes and is subdivided into thrombotic, embolic, and hypoperfusion related (Tintinalli et al., 2011). While ischemic stroke is caused by a reduction in blood flow, infarction is caused by the cessation of blood flow over several minutes resulting in the death of brain tissue. The tissue surrounding an area of infarction is generally ischemic and viable for a short time. This area, called the ischemic prenumbra, is the focus of revascularization therapies (Longo et al., 2012). A quick spontaneous restoration of blood flow causes a transient ischemic attack (TIA) in which the symptoms resolve within 24 hours. Most TIAs last less than one hour; however, infarcts of

the brain do occur in 15-50% of patients even when the symptoms have resolved (Longo et al., 2012). Because a TIA may be a predictor of a future stroke, the American Heart Association’s definition acknowledges that the duration of symptoms may not reflect a person’s risk of having a stroke (Tintinalli et al., 2011). Factors which increase the risk of stroke after a TIA include age >60, diabetes mellitus, symptom duration > 10 minutes, weakness and speech impairment (Tintinalli et al., 2011). Johnston et al. developed a scoring system (Table 1) which positively correlates with stroke risk after TIA; it was hoped that it would provide evidence based criteria to determine those patients who required admission vs. those who could be discharged from the ED for outpatient

Table 1 — Johnston et al. ABCD score to predict stroke after TIA Criteria


Age > 60

0 = absent; 1 = present

Blood pressure > 140/90

0 = absent; 1 = present

Clinical features

0 = absent 1 = speech impairment without unilateral weakness 2 = unilateral weakness with or without speech impairment


0 = absent 1 = 10-59 minutes 2 = > 60 minutes


0 = absent; 1 = present

Tintinalli, J., Stapczynski, J. S., Ma, O. J., Cline, D., Cydulka, R. K., & Meckler, G. (2011). Tintinalli’s emergency medicine: a comprehensive study guide (7th ed.). New York, NY: McGraw-Hill. Adapted from Johnston S.C., Rothwell, P.M., Ngyugen-Huynh M.N. et al. (2007).

Arkansas Nursing News

workup; however, those thresholds have yet to be determined. “Low risk” has been defined as 0-2 or 0-3, but research is ongoing to further validate this definition (Tintinalli et al., 2011). Risk Factors Risk factors can be divided into nonmodifiable and modifiable factors (See Table 2 for modifiable risk factors). When a patient presents with signs and symptoms of acute stroke, the ultimate goal is for rapid assessment and intervention to prevent further injury. It is very important to determine the time of onset of symptoms to assess the appropriateness of thrombolysis (clot busting) treatment. If a patient awakens with symptoms of stroke, the time of onset is considered to be the last known time that the patient was at baseline, not the time of discovery of symptoms (Tintinalli et al., 2011). It is also important to rule out other conditions which may mimic stroke (Table 3). Non-modifiable factors include age, family history, race, gender and previous history of TIA/CVA. The chance of stroke almost doubles for each decade of life after 55. African Americans have a much higher risk of death from stroke related to the increased prevalence of co-morbidities such as hypertension, diabetes and obesity. Also, African American and Hispanic populations have an increased prevalence of sickle cell disease which increases stroke risk. Although men have a higher incidence of stroke in a year, more stroke deaths occur in women. A history of prior stroke, TIA, coronary heart disease, heart failure or heart attack (myocardial infarction) also increase the risk (American Heart Association & American Stroke Association, 2012). Signs and Symptoms Signs and symptoms of stroke vary depending on the type of stroke, the vessel occluded, hemisphere dominance, and the side of the brain affected. The following list describes the most common signs: • Sudden numbness or weakness on face, arm or leg (usually affecting one side) • Sudden vision changes especially in one eye • Sudden gait disturbance, loss of balance or dizziness • Sudden confusion and/or speech difficulty • Sudden headache without a known cause (Arkansas Department of Health, 2010) Arkansas Nursing News

Brain Function Illustration

Arkansas Department of Health. (2010). Stroke awareness and education toolkit for healthcare providers, from

Types of Ischemic Strokes Thrombotic strokes result from the damage and narrowing of the vessel lumen which ultimately becomes completely blocked by a clot. Conditions associated with this type of stroke include atherosclerosis, hypercoagulable states, vasculitis, arterial dissection, infection, and polycythemia. They are typically more gradual with episodes of transient symptoms. Embolic strokes are caused by the movement of intravascular material such as a blood clot or fat through the vascular system eventually causes an obstructed blood vessel. They typically are associated with more sudden onset and related to conditions such as atrial fibrillation. Other conditions which can cause embolic strokes include myocardial infarction, prosthetic valves, rheumatic heart disease, lesions/vegetations, septic emboli, myxomas, dilated cardiomyopathy and particulate emboli such as in IV drug use (Longo et al., 2012; Tintinalli et al., 2011). Hypoperfusion strokes are related to low cerebral perfusion pressure either related to high intracranial pressure or low systemic blood pressure (Tintinalli et al., 2011). Anatomy and Pathophysiology Physical symptoms depend on the vessel occluded. The location of the occlusion produces specific stroke syndromes which

can be classified according to anterior, posterior or small vessel disease (McCance et al., 2010). The middle cerebral artery or one of its branches is most commonly involved in stroke and produces variable symptoms depending on the location of the occlusion and the dominant hemisphere. Dominant hemisphere refers to the side of the brain which is more involved in certain body functions, such as the preference for handedness (The American Heritage Stedman’s Medical Dictionary, n.d.). In right handed patients and up to 80% of left handed patients, the left hemisphere is dominant (Tintinalli et al., 2011). Table 4 lists the general functions of the left and right hemisphere in a left hemisphere dominant patient. Anterior Circulation The internal carotid artery arises from the common carotid artery and branches into the anterior cerebral artery and the middle cerebral artery. The anterior cerebral artery (ACA) serves the basal ganglia, corpus collosum, medial surfaces of the cerebral hemispheres and the superior surface of the frontal and parietal lobes. Occlusion of the ACA is the least common cause of ischemic stroke, causing hemiplegia (total paralysis of one side of the body) on the continued on page 14