Setting: emergency department (ED)
CC: “My arm is weak.”
VS: BP: 188/115 mm Hg; P: 90 beats/minute; T: 100.1°F; R: 14 breaths/minute
HPI: A 58-year-old man with half an hour of right arm and leg weakness was sent to the ED in an ambulance by his family. His family noticed the arm and leg weakness immediately because it happened while at dinner when it looked like he got up and tripped. On lifting him up, they found the whole right side of his body weak and his speech had become garbled.
PMHX:
Hypertension
Tobacco smoking
Medications:
Nifedipine
Lisinopril
PE:
Neurological: clear weakness on right side 2/5 power, right facial droop
Cardiovascular: normal
Abdominal: normal
Grading of Power on Neurological Examination
0/5: Flaccid, completely paralyzed.
1/5: Muscle twitch, no movement.
2/5: If examiner lifts extremity, patient can move it side to side.
3/5: Patient can hold up extremity against gravity only. No load bearing.
4/5: Weak.
5/5: Normal.
What is the most urgent step?
a. Control blood pressure (BP).
b. Order computed tomography (CT) of head.
c. Give aspirin.
d. Give thrombolytics.
Answer a. Control blood pressure (BP).
All of these are important in a stroke, but the point of this question is that you cannot give any form of anticoagulation without first excluding hemorrhage. You must not send someone off to a CT without giving the first dose of antihypertensive medication.
Initial Orders:
Labetalol intravenously (IV)
Head CT without contrast
Complete blood count (CBC), prothrombin time (PT), activated partial thromboplastin time (aPTT), electrocardiogram (ECG)
Neurology or stroke team evaluation
CT with contrast is used to look for cancer or infection.
Blood does not need contrast to be visible.
You move the clock forward 5 minutes. It is expected that the stroke team evaluation will occur within 5 minutes after the initial physician evaluation. More than any other disease, stroke evaluation is on a precise expectation of time frame. The head CT or magnetic resonance imaging (MRI) is expected to occur within 15 minutes of the initial physician evaluation with a reading by an expert in 20 minutes.
Why is stroke more sensitive to time than any other tissue or organ damage?
a. Brain tissue has no glycogen stores.
b. Carbon dioxide accumulation is more damaging to central nervous system (CNS) tissue.
c. Acid (hydrogen ion [H+]) accumulation is more damaging to CNS tissue.
d. Ketones cannot supply energy to cerebral tissue.
Answer a. Brain tissue has no glycogen stores.
Your brain wants 100% glucose. Because there is no glycogen storage in the brain, it needs all its food to be brought in continuously by blood flow. This is perhaps the single most important “basic science fundamental” to know for a stroke: The brain has no glycogen stores. Brain tissue uses glucose as a fuel almost exclusively. Ketones can be used, but it takes time for them to be produced and for the brain to switch the biochemistry to be able to consume them. Carbon dioxide and acid dilate cerebral vasculature to increase flow to hypoxic brain tissue, but they are not damaging.
Cerebral tissue lives mostly on glucose.
Move the clock forward 5 minutes and recheck the patient’s BP. Acute BP control with labetalol, nitroprusside, enalaprilat, or nimodipine will start to have an effect instantly if the drug is working. You cannot give thrombolytics if the BP is >180/110 mm Hg, so controlling BP is indispensable to proper management.
You must practice the computer-based case simulation (CCS) cases before entering the examination.
Orders:
Vital signs (under the “Physical Examination” tab on top)
Two to five minutes later, the repeat BP level is 180/112 mm Hg.
Give another dose of IV labetalol. The most important thing to remember about using acute BP-lowering medications on CCS is that the route of administration be IV. The specific agent is not as important. However, you cannot order medications by class on CCS; you must write orders by name of medication. You cannot order “BP drug” or “beta-blocker.” You have to order “labetalol.”
The onset of action for IV labetalol is 2 to 5 minutes.
Two to five minutes later, the repeat BP level is 170/104 mm Hg.
What is the mechanism of action of labetalol?
a. Beta-1, central alpha-1
b. Beta-1, peripheral alpha-1
c. Beta-1 and 2, peripheral alpha-1
d. Beta-1 and 2, central alpha-2
Answer c. Beta-1 and 2, peripheral alpha-1
Labetalol and carvedilol are the two combined alpha/beta-blockers. They are nonspecific beta-blockers and also block peripheral alpha-1-receptors. Peripheral alpha-1-receptors are the mechanism of how norepinephrine raises BP. Alpha-1-constriction is a rapid and powerful way to alter BP.
Do not lower BP more than 25% on first day.
Move the clock forward 10 to 15 minutes until the CT report is available. Because hemorrhages cause 15% of strokes, you have to exclude bleeding before any anticoagulation medications can be given.
Head CT: no blood, no masses
Repeat BP 158/98 mm Hg
ECG: left ventricular hypertrophy, unchanged from previous ECG
CBC, PT/aPTT: normal
What should you do next?
a. Lower BP further.
b. Give aspirin.
c. Give thrombolytics.
d. Give clopidogrel.
e. Give heparin.
Answer c. Give thrombolytics.
Thrombolytics are the standard of care for acute nonhemorrhagic stroke within the first 3 to 4.5 hours after the onset of symptoms. Most clinicians would use it up to 4.5 hours after onset, but the Step 3 examination will avoid all potential controversy and will make it either clearly less than 3 hours or more than 4.5 hours from the time of onset.
Repeat the neurological examination to confirm the findings.
Which of the following is most likely to be found?
a. Unilateral blindness
b. Bitemporal hemianopsia
c. Homonymous hemianopsia
d. None
Answer c. Homonymous hemianopsia
When you have a patient with a stroke causing loss of motor strength on one half of the body, you should expect the visual field to be lost on the same side. Half of each eye’s visual field will be lost.
Right side weakness: right visual field loss
When are the other choices correct?
• Aspirin: Use if presenting after 4.5 hours.
• Clopidogrel: If the patient is already on aspirin, switch from aspirin after 4.5 hours.
• Heparin: Never give for stroke.
• Dipyridamole: If the patient is already on aspirin at the time of a stroke, add to aspirin.
Never combine aspirin with clopidogrel for stroke!
Combining aspirin with dipyridamole is good.
Combining aspirin with clopidogrel is bad.
Thrombolytics are given. Move the patient to the hospital ward. The intensive care unit (ICU) is not needed. On CCS, there is no way to physically move the patient to a place called “stroke unit.” The stroke unit is not one of the five places you have to choose from on CCS locations.
• All of the previous orders will follow the patient in any location.
• Vital signs are done on CCS with each move.
• Unless you see it on your screen under “Orders,” it is not being done.
CBC, PT, and aPTT prior to thrombolytics:
• Thrombocytopenia and coagulopathy are contraindications.
Which best describes the mechanism of thrombolytics?
a. Prevents fibrinogen activation
b. Cleaves fibrin into D-dimers
c. Removes fibrin split product from fibrin
d. Increases action of plasmin on factor XIII
Answer b. Cleaves fibrin into D-dimers
Thrombolytics activate plasminogen into plasmin. Plasmin cleaves newly produced fibrin strands into their breakdown product, which is D-dimers. Fibrin split products (FSPs) are liberated from fibrinogen to activate it into fibrin. Thrombin is what cleaves off the FSPs. Factor XIII is a clot-stabilizing factor that solidifies a clot.
The patient has been moved to the hospital ward after the use of thrombolytics. His repeat BP is 156/96 mm Hg. There is a slight improvement in his right-sided weakness during the repeat neurological examination.
You will never get in trouble on the CCS by reviewing charts or examining patients too often!
Once thrombolytics are given and the follow-up neurological examination is done, you should explore reasons for the emboli going to the brain.
Orders:
Echocardiogram
Telemetry
Carotid artery duplex Doppler ultrasound
Where is the source site of the clot or stroke in this patient?
a. Anterior cerebral
b. Middle cerebral
c. Posterior cerebral
Answer b. Middle cerebral
Upper and lower extremity hemiparesis, facial droop, and expressive aphasia are classic for middle cerebral artery stroke.
Anterior Cerebral Stroke:
• Cognitive and psychiatric deficit
• Lower extremity weakness > upper extremity weakness
• Urine incontinence
Posterior Circulation (Vertebral or Basilar):
• Loss of consciousness
• Dysarthria, diplopia, dysphagia, dizziness
• Bilateral defects
Do not order carotid artery Doppler ultrasound for posterior circulation defects!
Carotid arteries do not anatomically supply the vertebral or basilar artery.
As you move the clock forward to get the results remember to order:
Physical therapy and rehabilitation evaluations
Restart aspirin 24 hours after thrombolytics
If the patient was on aspirin, switch to clopidogrel or add dipyridamole
Echocardiograms, telemetry, and carotid artery Doppler ultrasounds are often unrevealing in a stroke. If there is >70% stenosis on the affected side, refer the patient to vascular surgery for endarterectomy. We do not know what to do about asymptomatic carotid artery stenosis.