Student Notes - Stroke

Question 1

What is the definition of stroke?

Answer 1

A neurological deficit that presents acutely, due to vascular disease. Signs and symptoms depend on the site of the lesion and the vessels involved

Question 2

What are the two umbrella categories for types of stroke? What are types of ischemic stroke? What are types of hemorrhagic stroke?

Answer 2

1) Ischemic (85%) and hemorrhagic stroke (15%)
2) Ischemic - Thrombotic, embolic, lacunar, venous, “other”
3) Hemorrhagic - Intracerebral hemorrhage (ICH), Subarachnoid (SAH)

Question 3

Do TIAs precede an ischemic stroke or hemorrhagic stroke?

Answer 3

Ischemic stroke. They can occur in all types of ischemic stroke mechanisms, but they do not precede an ICH or SAH

Question 4

What vessels near and within the brain can be affected to cause cerebral thrombosis? What are the most common areas of plaque buildup within arteries that can cause a cerebral thrombosis? What are two dangerous consequences of atherosclerotic plaques?

Answer 4

1) Atherosclerotic disease can affect both large and small vessels in the brain, as well as in the cervical vessels
2) The most common areas of plaque buildup are at major arterial branch points, such as the bifurcation of the carotid artery in the neck, or at the branch points in the Circle of Willis
3) Plaques can build up to cause a severe stenosis, or, regardless of severity of the stenosis, may rupture, activating the clotting cascade and thrombus formation. This can cause occlusion of the vessel, or the thrombus can break off and embolize to more distant arteries in the brain

Question 5

What are the common risk factors for cerebral thrombosis?

Answer 5

1) Hypertension
2) Diabetes mellitus
3) Hypercholesterolemia
4) Smoking

Question 6

What is the definition of a cerebral embolism? Where does the embolus lodge itself?

Answer 6

1) An embolus is any detached, traveling, intravascular mass (solid, liquid, or gaseous) carried by the circulation, which is capable of creating an arterial occlusion at a site distant from its origin
2) The embolus lodges in an artery of limiting diameter, and therefore can result in occlusion or a large vessel or a small distal end-artery

Question 7

What are the types of emboli?

Answer 7

1) Arterial
2) Cardiac
3) Venous

Question 8

Where do arterial emboli arise from?

Answer 8

Arteries, such as the aorta, carotid, or vertebral arteries

Question 9

Where do cardiac emboli arise from?

Answer 9

The most common cause of emboli of cardiac origin is clots that form in the left atrium or left atrial appendage in atrial fibrillation. Other intracardiac sources include valvular defects (endocarditis, valve replacement), or rarely, cardiac tumor

Question 10

Where do venous emboli arise from?

Answer 10

Paradoxical emboli - originate in the systemic veins and cross directly into the cerebral circulation via a patent foramen ovale or other form of right to left shunting. Possibilities include deep vein thrombosis, and rarely fat emboli, air emboli, amniotic fluid emboli, and tumor emboli

Question 11

In what arteries does a lacunar stroke occur? How are these arteries hemodynamically distinct from small diameter end-arteries of the major vessels of the brain? How do these deep penetrators generally become occluded?

Answer 11

1) Small arteries originating in the main arteries of the Circle of Willis penetrate into the deep structures of the brain
2) They are hemodynamically distinct from the small diameter end-arteries of the major vessels of the brain, in that they are subject to a high pressure head from the parent arteries. Another distinction is that they usually have little to no collateral supply
3) The penetrators vary somewhat in diameter, and they can be occluded by atherosclerosis of the parent vessel, by lipohyalinosis (a poorly understood denegerative thickening of these vessels), or probably uncommon, cerebral microembolism

Question 12

What arteries arise from the middle cerebral arteries to feed the basal ganglia and internal capsule and what can an occlusion of these arteries cause? What arteries arise from the top of the basilar and the proximal posterior cerebral arteries to feed the thalamus and can an occlusion of these arteries cause?

Answer 12

1) Lenticulostriate arteries - for example, a small infarct in the internal capsule may result from weakness of the contralateral face, arm, and leg
2) Thalamogeniculate and thalamoperforate arteries from the top of the basilar and the proximal posterior cerebral arteries feed the thalamus, and occlusion of one of these can lead to contralateral sensory loss due to a thalamic lacunar infarct. Perforators originating from the basilar artery can lead to brainstem lacunes

Question 13

Are lacunar infarcts frequently silent? If there is a significant number of lacunar infarcts, what can they lead to in a patient? What are the most common risk factors for lacunar strokes?

Answer 13

1) Yes
2) Progressive dementia
3) Hypertension and diabetes mellitus

Question 14

What are some other causes of ischemic strokes?

Answer 14

1) Arterial dissection
2) Hypercoagulable states: Antiphospholipid antibody syndrome, hyperhomocysteinemia
3) Drug related: cocaine (vasospastic), heroin (nonsterile injections and endocarditis)
4) Vasculitis: systemic (Temporal Arteritis, SLE) vs. primary CNS
5) Infectious: Syphilis, Herpes Simplex
6) Migraine, CADASIL
7) Vasospasm in subarachnoid hemorrhage
8) Non-inflammatory vasculopathies: fibromuscular dysplasia (FMD), Moya-moya

Question 15

What does a venous infarction occlude?

Answer 15

Occlusions of the cerebral veins and sinuses - impeding the drainage of blood from the brain. This can also lead to hemorrhages

Question 16

How does the Circle of Willis allow for collateral circulation in the brain? Are most areas of the brain supplied by overlapping arteries?

Answer 16

1) The Circle of Willis is an anastomosing network of arteries at the base of the brain, interconnecting the arteries of the anterior and posterior circulation, and the right and left sides. Therefore if there is an occlusion in one of these arteries, flow can change direction to supply the ischemic portion of the brain
2) Yes. If there is an occlusion of one artery, there is likely to be an infarction in the “core” of that territory, with more distal areas receiving enough blood flow, at least in the short term, to allow tissue survival

Question 17

What are the most common types of intracerebral hemorrhage due to?

Answer 17

The most common types of intraparenchymal hemorrhages are due to rupture at or near the bifurcations of the small penetrating vessels of the brain, usually secondary to hypertension

Question 18

What are common areas for intracerebral hemorrhage to occur?

Answer 18

Basal ganglia, thalami, pons, and cerebellum

Question 19

What can lobar hemorrhages be caused by in elderly people?

Answer 19

Lobar hemorrhages, as opposed to deep hemorrhages, can be caused by amyloid angiopathy in elderly people

Question 20

What are other causes of intracerebral hemorrhages?

Answer 20

Other causes of intracerebral hemorrhage include coagulopathies, arteriovenous malformations, hemorrhagic tumors, and trauma

Question 21

What are arteriovenous malformations?

Answer 21

Arteriovenous malformations are abnormal communications between and artery and vein, without an intervening capillary bed

Question 22

What is the most common cause of subarachnoid hemorrhage? What is the most common cause of nontraumatic subarachnoid hemorrhage? How do berry aneurysms form and where are they typically located? What does a typical CT scan show? How can a subarachnoid hemorrhage be ruled out in a patient with a negative CT scan?

Answer 22

1) The most common cause of SAH is trauma
2) The most common cause of nontraumatic SAH are berry aneurysms and AVMs
3) Berry aneurysms can be congenital or acquired, and are typically located at branch points of major intracerebral vessels, commonly in the Circle of Willis
4) The typical appearance of an SAH on CT scan is hyperdense blood seen in the subarachnoid spaces. However, occasionally, a CT scan may not reveal the blood
5) If a patient presents with symptoms of the worst headache of their life, especially with a stiff neck, and a CT scan is negative, an SAH must be ruled out with a lumbar puncture

Question 23

How does an ischemic stroke of the middle cerebral artery, dominant hemisphere present?

Answer 23

Combination of contralateral motor weakness, sensory loss, possible homonymous hemianopsia, left gaze preference, and aphasia

Question 24

How does an ischemic stroke of the middle cerebral artery, non-dominant hemisphere present?

Answer 24

Combination of contralateral motor weakness, sensory
loss, possible homonymous hemianopsia, right gaze
preference, no aphasia, and contralateral hemineglect

Question 25

How does an ischemic stroke of the anterior cerebral artery present?

Answer 25

Contralateral leg weakness

Question 26

How does an ischemic stroke of the posterior cerebral artery present?

Answer 26

Contralateral homonymous hemianopsia

Question 27

How does an ischemic stroke of the basilar artery present?

Answer 27

Ipsilateral cranial nerve signs, contralateral motor weakness and/or sensory loss, and impaired consciousness possible

Question 28

How does an ischemic stroke of the posterior inferior cerebellar artery present?

Answer 28

Possible lateral medullary syndrome or cerebellar signs, such as ipsilateral dysmetria

Question 29

What does the workup depend on for ICH? If the hemorrhage is typical for a hypertensive deep ICH, is workup required? What tests are part of the workup?

Answer 29

1) The etiology of the hemorrhage
2) No workup may be required
3) CTA, MRA, or cerebral angiogram may assist in the diagnosis

Question 30

For an ischemic stroke, what is the classic workup?

Answer 30

1) CT head and/or MRI brain
2) Vascular imaging: CTA or MRA and/or carotid duplex, cerebral angiogram
3) Echocardiogram
4) Bloodwork: HbA1C, Lipid Profile, CBC, PT/INR/PTT, as needed for hypercoagulable state, toxicology screen, platelet function tests

Question 31

What is the treatment for ICH?

Answer 31

1) Blood pressure control
2) Management of high intracranial pressure (if needed): this may include external ventricular drainage, mannitol, hypertonic saline

Question 32

What is the treatment for aneurysmal SAH?

Answer 32

1) Clipping or coiling of the aneurysm
2) Monitoring for vasospasm (a risk highest in days 2-11) with transcranial Doppler
3) Nimodipine (calcium channel blocker to prevent of vasospasm)
4) Fluids, volume expanders as needed
5) Anticonvulsants as needed
6) Management of high intracranial pressure (if needed): this may include external ventricular drainage, mannitol, hypertonic saline

Question 33

What is the treatment for arteriovenous malformation?

Answer 33

Embolization (endovascular procedure) and/or surgical resection

Question 34

What is the treatment for ischemic stroke?

Answer 34

Acute treatment varies according to the pathophysiology of the stroke, the size of the infarct, and the anticipated risks of extension (enlargement) of the infarct, recurrence (second stroke), and risks of herniation. Generally:

1) Thrombolytic therapy if patient presents in the first 4.5 hours and has no contraindications. Endovascular removal of clot can also be performed in selected patients with large vessel occlusions. If tPA given, no aspirin or anticoagulants until 24-hour CT shows no hemorrhagic conversion.
2) Antiplatelet agent (aspirin, clopidogrel [Plavix], aspirin/persantine [Aggrenox]
3) In patients with atrial fibrillation, after 2-3 days to rule out hemorrhagic conversion, anticoagulation (heparin or lovenox) and be used and bridged to warfarin. More recently, newer agents, such direct thrombin inhibitors have been used
4) IV fluids to ensure at least euvolemia and enhance cerebral perfusion (avoiding hypotonic fluids, which can lead to cerebral edema)
5) Blood pressure is generally not controlled for the first day or so, as evidence has not shown control of blood pressure to <200/110 to improve outcomes. Blood pressure can then be judiciously lowered over subsequent days