Updated: 7/22/2018

Ischemic Stroke

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  • A 60-year-old woman is immediately brought to the emergency department due to slurred speech and right arm and leg weakness. The patient was eating breakfast with her husband prior to developing these symptoms. Her husband denies his wife having any head trauma or recent surgeries. It has been one hour since her symptoms began. Medical history is significant for hypertension and type II diabetes mellitus. On physical exam, the patient can comprehend but speech is impaired. There is 0/5 strength in both right upper and lower extremities. Non-constrast computerized tomography (CT) of the head does not show any intracranial bleeds. After further evaluation, she was started on intravenous tPA.
Introduction
  • Clinical definition
    • a sudden loss of blood supply to an area of the brain leading to
      • a neurologic deficit
        • the deficit depends on which area of the brain is affected
  • Epidemiology
    • incidence
      • 3rd leading cause of death in the United States
    • risk factors
      • hypertension
      • diabetes
      • smoking
      • atrial fibrillation 
      • mechanical valves
      • valvular abnormalities
      • patent foramen ovale
      • significant decreased ejection fraction
      • hypercoagulable state
      • family history
      • prior history of
        • stroke
        • vascular disease
  • Pathogenesis
    • ↓ blood supply to a region of the brain for enough time to result in infarcted (liquefactive necrosis) cerebral tissue
      • the most vulnerable to ischemic hypoxia is the
        • hippocampus
      • after 5 minutes, irreversible neuronal damage occurs
      • causes of this ↓ blood supply include
        • embolic infarction
          • a clot (typically) from one region of the body travels in the blood stream and occludes a vessel supplying the brain
          • consider in cases of sudden neurologic deficit
            • maximal neurologic deficit occurs at onset
          • large vessel infarcts are commoly due to an embolism
        • thrombotic infarction
          • a clot is locally formed in the wall of the blood vessel usually
            • where an atherosclerotic plaque is found
          • typically has a stuttering course
 
Large vs. Small Vessel Infarcts
Type
Comments
Large vessel
  • Occlusion of the major blood vessels such as the
    • middle cerebral artery
  • Occlusion is most often caused by emboli
Small vessel
  • Occlusion of the small penetrating arteries that supply the deep cerebral structures such as
    • basal ganglia
    • thalamus
    • internal capsule
  • Sometimes called lacunar infarcts
 
Ischemic Stroke Syndromes
 
Ischemic Stroke Syndromes
Anterior Circulation Stroke
Findings
Middle cerebral artery (MCA) stroke
  • Symptoms
    • contralateral weakness and sensory loss in the
      • face and upper limb
    • hemineglect if the non-dominant hemisphere is involved
    • aphasia
      • Broca's aphasia if the superior division of the MCA is involved in the dominant hemisphere
      • Wernicke's aphasia if the inferior division of the MCA is involved in the dominant hemisphere
        • may also result in a right superior quadrant visual field defect
  • Lesion localization
    • motor and sensory cortices distributed by the
      • MCA
    • Wernicke's or Broca's area
Anterior cerebral artery (ACA) stroke
  • Symptoms
    • contralateral weakness and sensory loss in the
      • lower extremity 
  • Lesion localization
    • motor and sensory cortices supplied by the
      • ACA
Lenticulostriate artery stroke
  • Symptoms
    • contralateral weakness and sensory loss in the
      • face and body in the absence of
        • cortical signs (e.g., neglect)
  • Comments
    • a common site of lacunar infarcts
      • secondary to chronic hypertension leading to
        • lipohyalinosis
Posterior Circulation Stroke Findings
Medial medullary (Dejerine) syndrome
  • Secondary to occlusion of the
    • paramedian branches of the anterior spinal artery and/or vertebral artery
  • Symptoms
    • triad
      • ipsilateral hypoglossal palsy
      • contralateral hemiparesis
      • contralateral lemniscal sensory loss (e.g., proprioception)
  • Lesion localization
    • lateral corticospinal tract
    • caudal medulla
    • medial lemniscus
Lateral medullary (Wallenberg) syndrome
  • Secondary to occlusion of the
    • posterior inferior cerebellar artery (PICA) or
    • vertebral artery
  • Symptoms
    • dysphagia
    • hoarsness
    • ↓ gag reflex
    • vertigo
    • ↓ pain and temperature sensation of the
      • ipsilateral face
      • contralateral body
    • Horner's syndrome
    • ataxia
  • Lesion localization
    • lateral medulla involving the
      • nucleus ambiguus
      • vestibular nuclei
      • lateral spinothalamic tract
      • spinal trigeminal nucleus
      • sympathetic fibers
    • inferior cerebellar peduncle
Lateral pontine syndrome
  • Secondary to
    • anterior inferior cerebellar artery
  • Symptoms
    • facial paralysis
    • ↓ salivation, lacrimation, and taste from the anterior tongue (2/3rd)
    • vertigo
    • ↓ pain and temperature sensation of the
      • ipsilateral face
      • contralateral body
    • ipsilateral Horner's
    • ataxia
  • Lesion localization
    • Lateral pons involving the
      • facial nucleus
      • vestibular nuclei
      • spinothalamic tract
      • spinal trigeminal nucleus
      • sympathetic fibers
    • middle and inferior cerebellar peduncle
Locked-in syndrome 
  • Secondary to occlusion of the
    • basilar artery
  • Symptoms
    • quadraplegia
    • bulbar manifestations
    • able to perform vertical eye movements
    • preserved conciousness
  • Lesion localization
    • ventral pons, lower midbrain, and medulla affecting the
      • corticospinal and corticobulbar tracts
      • oculomotor nerve nuclei
      • paramedian pontine reticular formation
Posterior cerebral artery (PCA) occlusion
  • Symptoms
    • contralateral hemianopsia with macular sparing
  • Lesion localization
    • occipital lobe
 
Presentation
  • Symptoms
    • dependent on which area of the brain is involved
      • review chart above
  • Physical exam
    • dependent on which area of the brain is involved
      • review chart above
Imaging
  • Computerized tomography (CT)
    • indications
      • a non-contrast head CT should be performed in patients presenting with symptoms concerning for stroke and
        • to exclude intracerebral hemorrhage
      • CT angiography should be performed to assess for a thrombus and to evaluate the carotid and vertebral neck arteries
  • Magnetic resonance imaging (MRI)
    • indications
      • MRI/MRA can aid in assessing infarct volume for further management
Studies
  • Labs
    • complete blood count
    • basal metabolic panel
    • prothrombin time
    • partial thromboplastin time
    • cardiac enzymes
  • Histology
Histology
Time after Ischemic Event
Histologic findings
12-24 hours
  • Red neuron
    • the cytoplasm is eosinophilic
    • the nuclei is pyknotic
    • cell body shrinkage
    • loss of Nissl substance
1-3 days
  • Tissue necrosis
  • Neutrophillic infiltration
3-5 days
  • Macrophage (microglial) infiltration
1-2 weeks
  • Reactive gliosis
  • Vascular proliferation
> 2 weeks
  • Glial scar
 
Differential
  • Transient ischemic attack
  • Hemorrhagic stroke
Treatment
  • Medical
    • intravenous tPA
      • indication
        • used in patients presenting with
          • stroke symptoms, excluded to have an intracranial hemorrhage, and time since symptom onset is within the last 3-4.5 hours
  • Operative
    • mechanical thrombectomy
      • indication
        • used in patients presenting with
          • stroke symptoms, excluded to have an intracerebral hemorrhage, and a proximal large artery occlusion involving the anterior circulation whether or not the patient received tPA
        • time since symptom onset within the last 8 hours
Complications
  • Intracerebral hemorrhage
  • Seizures
  • Aspiration pneumoniae
 

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Questions (12)
Lab Values
Blood, Plasma, Serum Reference Range
ALT 8-20 U/L
Amylase, serum 25-125 U/L
AST 8-20 U/L
Bilirubin, serum (adult) Total // Direct 0.1-1.0 mg/dL // 0.0-0.3 mg/dL
Calcium, serum (Ca2+) 8.4-10.2 mg/dL
Cholesterol, serum Rec: < 200 mg/dL
Cortisol, serum 0800 h: 5-23 μg/dL //1600 h:
3-15 μg/dL
2000 h: ≤ 50% of 0800 h
Creatine kinase, serum Male: 25-90 U/L
Female: 10-70 U/L
Creatinine, serum 0.6-1.2 mg/dL
Electrolytes, serum  
Sodium (Na+) 136-145 mEq/L
Chloride (Cl-) 95-105 mEq/L
Potassium (K+) 3.5-5.0 mEq/L
Bicarbonate (HCO3-) 22-28 mEq/L
Magnesium (Mg2+) 1.5-2.0 mEq/L
Estriol, total, serum (in pregnancy)  
24-28 wks // 32-36 wks 30-170 ng/mL // 60-280 ng/mL
28-32 wk // 36-40 wks 40-220 ng/mL // 80-350 ng/mL
Ferritin, serum Male: 15-200 ng/mL
Female: 12-150 ng/mL
Follicle-stimulating hormone, serum/plasma Male: 4-25 mIU/mL
Female: premenopause: 4-30 mIU/mL
midcycle peak: 10-90 mIU/mL
postmenopause: 40-250
pH 7.35-7.45
PCO2 33-45 mmHg
PO2 75-105 mmHg
Glucose, serum Fasting: 70-110 mg/dL
2-h postprandial:<120 mg/dL
Growth hormone - arginine stimulation Fasting: <5 ng/mL
Provocative stimuli: > 7ng/mL
Immunoglobulins, serum  
IgA 76-390 mg/dL
IgE 0-380 IU/mL
IgG 650-1500 mg/dL
IgM 40-345 mg/dL
Iron 50-170 μg/dL
Lactate dehydrogenase, serum 45-90 U/L
Luteinizing hormone, serum/plasma Male: 6-23 mIU/mL
Female: follicular phase: 5-30 mIU/mL
midcycle: 75-150 mIU/mL
postmenopause 30-200 mIU/mL
Osmolality, serum 275-295 mOsmol/kd H2O
Parathyroid hormone, serume, N-terminal 230-630 pg/mL
Phosphatase (alkaline), serum (p-NPP at 30° C) 20-70 U/L
Phosphorus (inorganic), serum 3.0-4.5 mg/dL
Prolactin, serum (hPRL) < 20 ng/mL
Proteins, serum  
Total (recumbent) 6.0-7.8 g/dL
Albumin 3.5-5.5 g/dL
Globulin 2.3-3.5 g/dL
Thyroid-stimulating hormone, serum or plasma .5-5.0 μU/mL
Thyroidal iodine (123I) uptake 8%-30% of administered dose/24h
Thyroxine (T4), serum 5-12 μg/dL
Triglycerides, serum 35-160 mg/dL
Triiodothyronine (T3), serum (RIA) 115-190 ng/dL
Triiodothyronine (T3) resin uptake 25%-35%
Urea nitrogen, serum 7-18 mg/dL
Uric acid, serum 3.0-8.2 mg/dL
Hematologic Reference Range
Bleeding time 2-7 minutes
Erythrocyte count Male: 4.3-5.9 million/mm3
Female: 3.5-5.5 million mm3
Erythrocyte sedimentation rate (Westergren) Male: 0-15 mm/h
Female: 0-20 mm/h
Hematocrit Male: 41%-53%
Female: 36%-46%
Hemoglobin A1c ≤ 6 %
Hemoglobin, blood Male: 13.5-17.5 g/dL
Female: 12.0-16.0 g/dL
Hemoglobin, plasma 1-4 mg/dL
Leukocyte count and differential  
Leukocyte count 4,500-11,000/mm3
Segmented neutrophils 54%-62%
Bands 3%-5%
Eosinophils 1%-3%
Basophils 0%-0.75%
Lymphocytes 25%-33%
Monocytes 3%-7%
Mean corpuscular hemoglobin 25.4-34.6 pg/cell
Mean corpuscular hemoglobin concentration 31%-36% Hb/cell
Mean corpuscular volume 80-100 μm3
Partial thromboplastin time (activated) 25-40 seconds
Platelet count 150,000-400,000/mm3
Prothrombin time 11-15 seconds
Reticulocyte count 0.5%-1.5% of red cells
Thrombin time < 2 seconds deviation from control
Volume  
Plasma Male: 25-43 mL/kg
Female: 28-45 mL/kg
Red cell Male: 20-36 mL/kg
Female: 19-31 mL/kg
Cerebrospinal Fluid Reference Range
Cell count 0-5/mm3
Chloride 118-132 mEq/L
Gamma globulin 3%-12% total proteins
Glucose 40-70 mg/dL
Pressure 70-180 mm H2O
Proteins, total < 40 mg/dL
Sweat Reference Range
Chloride 0-35 mmol/L
Urine  
Calcium 100-300 mg/24 h
Chloride Varies with intake
Creatinine clearance Male: 97-137 mL/min
Female: 88-128 mL/min
Estriol, total (in pregnancy)  
30 wks 6-18 mg/24 h
35 wks 9-28 mg/24 h
40 wks 13-42 mg/24 h
17-Hydroxycorticosteroids Male: 3.0-10.0 mg/24 h
Female: 2.0-8.0 mg/24 h
17-Ketosteroids, total Male: 8-20 mg/24 h
Female: 6-15 mg/24 h
Osmolality 50-1400 mOsmol/kg H2O
Oxalate 8-40 μg/mL
Potassium Varies with diet
Proteins, total < 150 mg/24 h
Sodium Varies with diet
Uric acid Varies with diet
Body Mass Index (BMI) Adult: 19-25 kg/m2
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(M1.NE.4671) A 74-year-old African-American woman is brought to the emergency department by her home health aid. The patient was eating breakfast this morning when she suddenly was unable to lift her spoon with her right hand. She attempted to get up from the table, but her right leg felt weak. One hour later in the emergency department, her strength is 0/5 in the right upper and right lower extremities. Strength is normal in her left upper and lower extremities. Sensation is normal bilaterally. An emergency CT of the head does not show signs of hemorrhage. Subsequent brain MRI shows an infarct involving the internal capsule. Which of the following is true about her disease process?
Review Topic

QID: 107131
1

The most important risk factors are hypertension and diabetes

82%

(9/11)

2

The most common cause is embolism originating from the left atrium

0%

(0/11)

3

It is caused by ischemia to watershed areas

18%

(2/11)

4

IV thrombolysis cannot be used

0%

(0/11)

5

The most important risk factors are ethnicity and sex

0%

(0/11)

M1

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(M1.NE.4671) A 75-year-old woman with a history of stroke 1 year ago was found unconscious on the floor of her home by her son. The patient was brought to the emergency department by ambulance but expired prior to arrival. An autopsy was performed and showed the cause of death to be a massive ischemic stroke. The coroner also examined sections taken from the area of her prior stroke. Which histologic finding would be prominent in the area of her stroke from one year prior? Review Topic

QID: 107142
1

Red neurons

5%

(3/66)

2

Necrosis and neutrophils

2%

(1/66)

3

Macrophages

3%

(2/66)

4

Reactive gliosis and vascular proliferation

35%

(23/66)

5

Cyst formed by astrocyte processes

55%

(36/66)

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(M1.NE.33) A patient is transferred from an outside hospital by family request. The patient is a 76-year-old gentleman who developed acute onset left-sided weakness four days ago with the imaging findings seen in Figure A. Despite aggressive care, the patient dies shortly after transfer. The family requests an autopsy. What histological finding would you expect to find on evaluation of the patient's brain? Review Topic

QID: 101697
FIGURES:
1

Red neurons

9%

(9/100)

2

Neutrophilic infiltration and necrosis

19%

(19/100)

3

Macrophage infiltration and phagocytosis

54%

(54/100)

4

Reactive gliosis and vascular proliferation

10%

(10/100)

5

Glial scarring

6%

(6/100)

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(M1.NE.38) A 58-year-old man with history of diabetes and hypertension suffers a cardiac arrest at home. The family calls 911, yet no one performs CPR. Five minutes after the arrest, EMS arrives to begin resuscitation. At this point, which region of the CNS is most likely to suffer ischemic damage? Review Topic

QID: 101702
1

Thalamus

12%

(12/98)

2

Spinal cord

0%

(0/98)

3

Pons

2%

(2/98)

4

Medulla

6%

(6/98)

5

Hippocampus

78%

(76/98)

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