Physician Assistant Exam: Transient Ischemic Attack and Stroke
The Physician Assistant Exam (PANCE) will want you to be aware of the vascular system. Two of the most common vascular problems are transient ischemic attack, so stroke and you can count on them being covered on the PANCE.
The transient ischemic attack
Welcome to the world of the mini-stroke, the transient ischemic attack. Picture this: A 60-year-old man comes to your office for an urgent visit, demanding to be seen. He states he was sitting home reading when he noticed vision in his left eye became dark. He says it’s as if someone pulled a window shade over my left eye.
It lasted for a few minutes but then suddenly went away. He denies feeling weak in any one area of the body or talking funny. What happened? This person had one version of a transient ischemic attack (TIA).
The changes to the man’s eye are termed amaurosis fugax, which is the acute onset of blindness in one eye. Another common scenario suggesting a transient ischemic attack is the person who presents to the emergency room with weakness on one side of her face, starts to talk funny and arms and legs that went away. This usually refers to an acute episode of aphasia that occurs and then resolves.
What do these transient ischemic attack variants have in common? They occur and then spontaneously resolve. By definition, the symptoms of a transient ischemic attack don’t persist for more than 24 hours. If they do, you then need to think about something else — the ever-popular stroke, for example.
Here are some other key points concerning the transient ischemic attack:
The risk factors include hypertension, diabetes mellitus, tobacco use, hyperlipidemia, chronic inflammation, and peripheral vascular disease present elsewhere.
Part of the initial evaluation involves a carotid ultrasound to evaluate the patency of the carotid arteries and an echocardiogram to evaluate for a possible embolic source.
Other studies can include a magnetic resonance angiography (MRA) and/or angiogram.
The treatment involves the use of antiplatelet agents, including aspirin, and clopidogrel (Plavix). Also, identifying and reducing the risk factors is essential.
A brain attack isn’t an incursion of zombies. We’re referring to an acute cerebrovascular accident (CVA), commonly called a stroke. If a transient ischemic attack is like an anginal episode, then an acute stroke is like an acute heart attack. Both require immediate intervention for survival and a good outcome.
The transient ischemic attack sufferer usually recovers spontaneously, but the stroke sufferer doesn’t. The time course in treating a stroke is especially important.
Types of stroke
Strokes may be ischemic or hemorrhagic. Furthermore, the acute ischemic stroke may be embolic or thrombotic:
Embolic strokes: These strokes most commonly occur in the setting of a heart issue, such as underlying atrial fibrillation. Another possible cause of an embolic stroke is infective endocarditis with valvular vegetation. In someone with a very low ejection fraction or a very hypokinetic left ventricle, a ventricular thrombus can be present. Of course, this increases the risk of an embolic stroke.
Thrombotic strokes: A thrombotic stroke most commonly occurs in the setting of significant atherosclerosis. The carotid arteries are most commonly affected. Other risk factors for a thrombotic stroke include vasculitis and/or the presence of a hypercoagulable state.
Stroke symptoms depend on the area of the brain affected. In a hospital setting and on the PANCE, you’ll likely deal with the acute ischemic embolic presentation — someone who presents with a weakness of the right arm and right leg, with or without aphasia (impairment of language ability).
Stroke symptoms aren’t always a right arm/right leg thing. When the presentation is different, you must have some idea of the vascular territory involved:
A stroke involving the right anterior cerebral artery produces weakness in the left leg compared to the left arm. There are sensory disturbances as well.
A stroke involving the right middle cerebral artery produces weakness in the left arm compared to the left leg. Understand that a stroke affecting this area of the brain is a biggie because it affects the blood supply to more than 60 percent of the anterior circulation of the brain. Additional symptoms can include aphasia and increased reflexes.
Hypoglycemia is an example of a disease that mimics a stroke. In someone who has a history of a prior cerebrovascular accident, if the blood sugar is low, the patient can present like he or she is having an acute stroke. Normalize the blood glucose level, and the symptoms go away.
How to treat acute stroke
For the PANCE, be very, very familiar with the time course in treating an acute ischemic stroke. We’re specifically talking about the use of thrombolytics, also known as clot-busters. Here are some key points about treating an acute ischemic stroke:
The time course for treating an acute ischemic stroke is within 4–1/2 hours from the onset of symptoms, especially when you’re considering thrombolysis. If the time is more than 4–1/2 hours, for testing purposes, no thrombolytics can be used.
If the time course of the acute stroke is within the 4–1/2-hour window, then you first need to make sure that hemorrhagic stroke isn’t present. A CT scan of the brain without contrast is a really good and quick way to check for hemorrhagic stroke.
Before giving thrombolytics, you have to ask certain questions because of contraindications to using thrombolytics. Contraindications include any bleeding, the use of blood thinners like warfarin (Coumadin), significant thrombocytopenia, and any recent traumatic events or surgeries.
In anyone presenting with hypertensive urgency and an acute stroke, be careful not to lower the blood pressure too quickly. Maintain the cerebral perfusion pressure (CPP) by keeping a higher mean arterial pressure (MAP).