Ischemic Stroke Flashcards

1
Q

What is a stroke?

A

An injury to the brain caused by interruption of its blood flow (ischemic), or by bleeding (hemorrhagic) into or around the brain.

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2
Q

What does a stroke produce?

A

Abrupt onset of focal neurologic deficits that frequently result in permanent disability or death.

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3
Q

What is a transient ischemic attack (TIA)?

A

The abrupt onset of focal neurological deficits that resolve within less than 1 hour.

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4
Q

Do TIAs warn for future stroke?

A

Yes

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5
Q

What are silent strokes?

A

Acute focal neurologic symptoms and signs that resolve completely but take longer than 1 hour do so.

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6
Q

Are silent strokes associated with detectable injury on MRI?

A

Yes

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7
Q

What is another name for a silent stroke?

A

Resolving ischemic neurologic deficits (RINDs)

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8
Q

Percentage of strokes that are hemorrhagic? Ischemic?

A

~20%

~80%

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9
Q

Types of hemorrhagic strokes?

A

Intracerebral - bleeding into the parenchyma of the brain

Subarachnoid - bleeding around the surface of the brain

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10
Q

Causes of ischemic stroke?

A

Athersclerotic occlusion of an intra- or extracerebral blood vessel
Embolus traveling to the brain from either the heart of a cerebral blood vessel
Disease of the lumen of small arterioles (Lacunar infarcts)
Cryptogenic - unknown cause

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11
Q

Non-modifiable stroke risk factors?

A

Age (doubles each decade > 55)
Gender (male 1.5 x risk of female)
Race (AA 2 x risk of EAs)
Family Hx (other genetic factors)

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12
Q

Modifiable stroke risk factors?

A
HTN
DM
Hyperlipidemia
Smoking
Carotid artery stenosis
A-Fib
Obesity
Physical inactivity
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13
Q

What is the number one risk factor for stroke?

A

HTN

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14
Q

How does the stores of energy in the brain compare to the utilization of energy in the brain?

A

The stores of energy in the brain are very meager compared to the use of energy and thus ischemia and infarction occur rapidly with loss of blood supply to the brain.

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15
Q

What will accelerate and worsen brain injury?

A

Hyperthermia and hyperglycemia

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16
Q

How does hyperglycemia worsen brain injury?

A

The brain will continue to metabolize glucose via glycolytic pathways. This will lead to a high accumulation of lactic acid.

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17
Q

During an ischemic stroke, what is the central area with severe blood flow reduction called?

A

Ischemic Core

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18
Q

During an ischemic stroke, what is the peripheral areas with less severe ischemia called?

A

Ischemic penumbra

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19
Q

How long does it take tissue to die in the ischemic core? Ischemic penumbra?

A

< 1 hrs

~4-6 hrs

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20
Q

The cerebral blood flow (CBF) is proportionally related to what?

A

Mean arterial pressure (MAP) / cerebral vascular resistance (CVR)

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21
Q

At what levels in a normal individual are MAP and CBF virtually independent of each other? Chronic HTN pt?

A

55 mmHg - 155 mmHg

75 mmHg - 175 mmHg

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22
Q

What does severe hypotension lead to?

A

Reduced CBF and syncope

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23
Q

What does severe acute HTN lead to?

A

Raised CBF and hypertensive encephalopathy

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24
Q

What must you be careful of doing in a person with chronic HTN?

A

Lowering the blood pressure too fast leading to syncope.

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25
Q

Neurologic signs and symptoms produced by a stroke?

A
Weakness or paralysis
Loss of sensation
Loss of vision in one eye of field
Difficulty in talking or in understanding what is being said
Clumsiness of lack of balance
26
Q

What is loss of vision in one eye called?

A

Amaurosis fugax

27
Q

If a stroke is in which vessels is it considered an anterior circulation stroke?

A
Internal carotid (ICA)
Middle cerebral (MCA)
Anterior cerebral (ACA) 
Any of their branches
28
Q

If a stroke is in which vessels is it considered a posterior circulation stroke?

A
Posterior cerebral (PCA)
Vertebral (VA)
Superior cerebellar (SCA)
Anterior inferior cerebellar (AICA)
Posterior inferior cerebellar (PICA)
Any of their branches
29
Q

A stroke is considered large vessel if?

A

It occurs in any of the main branches

30
Q

A stroke is considered small vessel if?

A

It occurs in any of the penetrating branches off of the main arteries

31
Q

A disruption of what blood supply will result in Lateral medullary syndrome (Wallenberg syndrome)?

A

Vertebral Artery

Posterior inferior Cerebellar Artery

32
Q

Major symptoms of Wallenberg syndrome?

A

Loss of pain and temperature from the face - ipsilaterally and the body - contralaterally

33
Q

What causes the ipsilateral loss of pain and temperature of the face in Wallenberg syndrome?

A

Lesion of the spinal trigeminal tract and nucleus

34
Q

What causes the contralateral loss of pain and temp of the body in Wallenberg syndrome?

A

Lesion of the spinothamalic tract

35
Q

What are some other symptoms in which a Wallenberg syndrome patient might present with?

A

Ptosis (drooping eyelid), miosis (small pupil), anhidrosis (loss of sweating), dysarthria (trouble speaking), dysphagia (trouble swallowing), and gait ataxia –> all ipsilateral

36
Q

What is the cause of the ptosis in Wallenberg syndrome?

A

Loss of sympathetic innervation to the superior tarsal muscle

37
Q

What is the cause of the miosis in Wallenberg syndrome?

A

Loss of sympathetic innervation to the pupillodilator muscle in the eye

38
Q

What is the cause of the anhidrosis in Wallenberg syndrome?

A

Loss of sympathetic innervation to sweat glands

39
Q

What is the cause of the dysarthria and dysphagia in Wallenberg syndrome?

A

Lesion to the nucleus ambiguus

40
Q

Occlusion of what vessels will lead to Medial Pontine syndrome?

A

Paramedian branches of the basilar artery.

41
Q

Symptoms associated with Medial Pontine Syndrome?

A

Contralateral - hemiparesis, ataxia, discriminative touch, vibration, and conscious proprioception, may include pain/temp
Both - horizontal gaze palsy, internal strabismus of the affected eye ( deviation toward the nose)
Ipsilateral - (depends on the level of the lesion) facial weakness

42
Q

What causes the contralateral hemiparesis in MPS?

A

Lesion to the corticospinal tract rostral to the pyramidal decusation

43
Q

What causes the contralateral ataxia in MPS?

A

Lesion of the pontine nuclei and transverse fibers in the basal pons that arise from the pontine nuclei and cross to enter the contralateral cerebellum

44
Q

What causes the contralateral loss of discriminative touch, vibration, and proprioception in MPS?

A

Lesion of the medial lemiscus

45
Q

What causes the gaze palsies seen in MPS?

A

Damage to the paramedian pontine reticular formation, the medial longitudinal fasciculus, and abducens nerve

46
Q

Occlusion of what vessels will cause Central Midbrain Syndrome (Benedikt Syndrome)?

A

Posterior cerebral artery

47
Q

How does a patient present in Benedikt Syndrome?

A

Ipsilateral - Eye is abducted and rotated down, and dilated

Contralateral - Tremor and ataxia, loss of discriminative touch, vibration, and proprioception

48
Q

What causes the ipsilateral eye problems in Benedikt syndrome?

A

CN III palsy as well as an affected Edinger-Westphal Nucleus

49
Q

What causes the contralateral tremor and ataxia in Benedikt Syndrome?

A

Lesion to the red nucleus

50
Q

What causes the contralateral loss of discriminative vibration, and proprioception in Bendikt syndrome?

A

Lesion to the medial lemniscus

51
Q

What are possible signs and symptoms of an anterior circulation stroke?

A

Ipsilateral blindness or contralateral inferior quadrantanopsia (anopia affecting a quarter of the field of vision)
Contralateral gaze paresis
Contralateral mono/hemiparesis and/or mono/hemisensory deficit
Aphasia in the dominant hemisphere or neglect in the nondominant hemisphere

52
Q

What are possible signs and symptoms of a posterior circulation stroke?

A

Unilateral, bilateral, or crossed (face/body) weakness or sensory deficits
Contralateral homonymous hemianopsia or superior quadrantanopsia
Vertigo, nausea/vomiting, gait ataxia, diplopia, dysphagia, Horner’s syndrome
Altered consciousness and amnesia

53
Q

What are lacunar strokes?

A

Small areas of ischemic necrosis caused by occlusion of small, penetrating arteries

54
Q

Lacunar Syndromes?

A

Pure hemiparesis
Pure hemisensory deficit
Ataxia hemiparesis
Dysarthria-clumsy hand syndrome

55
Q

Common sites of atherothrombosis/atheroemboli?

A

Origins of carotid and vertebral arteris
Bifurcations of common carotid arteries
Internal carotid arteries at the carotid siphon and at branch points of middle and anterior cerebral arteries
M1 segment of the middle cerebral arteries
Basilar artery

56
Q

Pathogenesis of lacunar stroke?

A

Microatheroma
Microemboli
Lipohyalinosis
Fibrinoid necrosis

57
Q

What is lipohyalinosis and fibrinoid necrosis?

A

Histological transformation that occurs in the smooth muscle and intima of small penetrating cerebral vessels as a consequence of chronic HTN.

58
Q

Common causes of cardiogenic emboli?

A
Arrhythmia (A-Fib)
Valvular Heart Dz (Mitral stenosis, bacterial endocarditis, prosthetic heart valves)
Mural Thrombus (MI)
59
Q

Uncommon causes of cardigenic emboli?

A
Atrial myxoma
Valvular Heart DZ (Mitral Valve prolapse, marantic endocarditis)
Mural Thrombus (cardimyopathy)
60
Q

Pts with CNS vasculitis present how?

A

Multifocally reflecting multiple small and medium-sized vessel occlusions

61
Q

Causes of CNS vasculitis?

A

Collagen Vascular Dzs (Lupus - most common)
Giant Cell Arteritis ( >55 yrs) [responds well to corticosteroids]
Infectious vasculitis