Ischemic Stroke

Aka: Ischemic Stroke, Cerebrovascular Accident, Cerebrovascular Disease, Cerebral Infarction, Ischemic CVA, CVA, Cerebral Cortex CVA, Cortical Stroke, Anterior Circulation CVA, Anterior Circulation Brain Infarction

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II. Definitions

  1. Ischemic Cerebrovascular Accident
    1. Neurologic dysfunction with evidence of infarction on brain imaging
  2. Transient Ischemic Attack
    1. Transient neurologic dysfunction without evidence of infarction on brain imaging

III. Risk Factors

  1. See Cerebrovascular Accident Risk Factors

IV. Epidemiology: Incidence (from most to least common)

  1. Overall Incidence: More than 795,000 cases in U.S. per year (2012)
    1. First Stroke: 610,000
    2. Recurrent Stroke: 185,000
  2. Ischemic Stroke: 85-88%
    1. Thrombotic Stroke (most common)
    2. Embolic Stroke
    3. Lacunar Stroke (least common of Ischemic Strokes)
  3. Hemorrhagic Stroke
    1. Intracerebral Hemorrhage: 9%
    2. Subarachnoid Hemorrhage: 3%
  4. Cerebral Venous Thrombosis
    1. Resulting in secondary Cerebral Infarction or Hemorrhage: 0.5 to 1%

V. Pathophysiology: Types

  1. Thrombotic CVA
    1. Typically in older patients
    2. May also occur over age 40 years old with risks (Hypertension, Hyperlipidemia, Diabetes Mellitus, Tobacco Abuse, Family History)
    3. Large vessel thrombosis (carotid, Vertebral arteries or Circle of Willis) cause fluctuating or recurring deficits developing over days
    4. Small vessel thrombosis involve deeper brain tissue (e.g. Internal Capsule, Basal Ganglia, pons, Thalamus)
  2. Embolic CVA
    1. More common in patients under age 50 years old
    2. Associated with new onset Atrial Fibrillation, valvular heart disease, endocarditis
    3. Cardiac or aortic source with often multiple sites affected and maximal deficit at onset
  3. Hypoperfusion
    1. May present as focal CVA due to asymmetric atherosclosis predisposing to localized injury
    2. Chronic Hypertension predisposes to Lacunar Infarctions (small focal Ischemic Strokes)

VI. History: General

  1. Prehospital Screening Tools
    1. See BE-FAST Stroke Screening Tool
    2. See Cincinnati Prehospital Stroke Scale
    3. See Los Angeles Prehospital Stroke Screen
  2. Exact time of onset (or last seen time when at baseline status)
  3. Seizure activity
    1. Before stroke-like symptoms
      1. Consider postictal paralysis (see below)
    2. After stroke-like symptoms
      1. Contraindicates Thrombolysis
  4. Migraine Headaches (recent)
  5. Trauma (esp. Head Trauma, neck injury) in preceding days
    1. High velocity injuries (e.g. MVA) may result in neck vessel injury and secondary thrombosis
  6. Recent illness (e.g. Pneumonia or urinary tract symptoms)
  7. Diabetes Mellitus

VII. History: Mnemonic ("LoST MIND")

  1. Last well or
  2. Onset (when observed)
  3. Seizure
  4. Trauma
  5. Migraine
  6. Illness
  7. Neck injury
  8. Diabetes Mellitus

VIII. Exam: Rapid Neurologic Exam

  1. See NIH Stroke Scale
  2. See Neurologic Exam
  3. Perform in addition to NIH Stroke Scale
    1. Goal is to rapidly identify classic lesion pattern, including findings suggestive of large vessel Occlusion
    2. High yield, focused testing for pathognomonic CNS signs
    3. Cortical signs are the most localizing CNS findings (specific for cerebral regions)
      1. Contrast with the broad differential of extremity motor and sensory findings
  4. Cortical Signs
    1. Aphasia
      1. Name 2 objects (e.g. "watch, pen")
      2. Repeat a phrase (e.g. "No Ifs Ands or Buts")
      3. Follow a command (e.g. "Raise your left hand and close your eyes")
    2. Visual defect
      1. Gaze deviation
      2. Homonomous Hemianopia (70% of large vessel Occlusions)
        1. One half of Visual Field lost in both eyes by confrontation
        2. Show 2 fingers on one side and one finger on the other side
    3. Hemineglect
      1. Is there a preference for one side over another?
      2. When performing the overall evaluation, switch sides of the bed midway through the exam
  5. Motor Exam
    1. Observe for lateralization (Unilateral Weakness)
    2. Pronator drift
      1. With palms up (supination), arms elevated and reaching forward and eyes closed
      2. Subtle weakness may be identified as the palms fall into pronation (pronator drift)
    3. Coordination
      1. Finger-Nose-Finger
      2. Finger roll
        1. Index fingertips touching and rotating around their axis
  6. Sensory Exam
    1. Light Touch Sensation in large swaths of the face and extremities
    2. CNS isolated sensory deficits may represent thalamic strokes
  7. References
    1. Kobner and Swaminathan in Swadron (2023) EM:Rap 23(3): 13-15

IX. Findings: Most reliable findings suggestive of Ischemic CVA

  1. Symptoms
    1. Acute onset of focal neurologic deficit (96% of patients)
    2. Subjective arm or leg weakness (63 to 54% of patients)
    3. Subjective speech disturbance (53% of patients)
    4. Subjective facial weakness (23% of patients)
  2. Signs
    1. Arm or leg paresis (61-69% of patients)
    2. Dysphagia or Dysarthria (57% of patients)
    3. Hemiparesis or Ataxia (53% of patients)
    4. Facial paresis (45% of patients)
    5. Eye movements or Visual Fields abnormal (27-24% of patients)
  3. References
    1. Hand (2006) Stroke 37(3): 776-80 [PubMed]
    2. Nor (2005) Lancet Neurol 4(11):727-34 [PubMed]

X. Signs: Vascular Distribution

  1. Anterior Circulation CVA
    1. Anterior Cerebral Artery CVA (2-3% of Ischemic Strokes)
      1. Contralateral motor weakness
      2. Contralateral sensory deficit of leg, and to lesser extent head (spares forehead) and arm
      3. May be accompanied by significant cognitive and emotional deficits
    2. Middle Cerebral Artery CVA (90% of Ischemic Strokes, most common)
      1. Contralateral motor weakness
      2. Contralateral sensory deficit of head (spares forehead) and arm, and to a lesser extent leg
      3. Aphasia occurs with left MCA lesion (dominant hemisphere)
      4. Hemineglect occurs with a right MCA lesion (non-dominant hemisphere)
      5. May be associated with eye changes
        1. Conjugate Eye Deviation towards the Brain Lesion
        2. Contralateral homonymous Hemianopsia (blindness in same Visual Field of each eye)
    3. Lacunar CVA (Lacunar Syndrome)
      1. Chronic Hypertension or Diabetes Mellitus results in small vessel infarcts in the distal MCA branches
      2. Microinfarctions occur from Occlusions in small, deep, penetrating vessels
      3. Patterns include pure motor Hemiparesis, pure sensory syndrome, ataxic Hemiparesis, clumsy hand
  2. Posterior Circulation CVA
    1. Posterior Cerebral Artery CVA (PCA CVA, 5% of Ischemic Strokes, affects occipital cortex)
      1. Contralateral homonymous Hemianopsia (Visual Field cut)
      2. Contralateral Visual Agnosia (cannot recognize objects)
      3. Cortical blindness may occur (e.g. CPR)
      4. Dizziness
      5. Memory and language deficits
      6. Minimal motor involvement
    2. Posterior Inferior Cerebellar Artery CVA (PICA CVA)
      1. Dysarthria, Dysphagia, Dysphonia, Vertigo, Nystagmus, and Ataxia
      2. May also be associated with crossed findings of Medullary CVA
        1. Ipsilateral facial deficit
        2. Contralateral extremity deficit
    3. Vertebro-Basilar CVA (1% of Ischemic Strokes, affects Brainstem, Cerebellum, visual cortex)
      1. Similar Posterior Circulation findings to either PCA CVA or PICA CVA described above
      2. Ipsilateral Cranial Nerve deficit and contralateral motor and sensory deficits
      3. Often presents with Vertigo, Nystagmus, and Vomiting
      4. Other associations
        1. Syncope
        2. Coma
        3. Quadriplegia
        4. Diplopia or Visual Field Deficits
        5. Dysphagia
        6. Dysarthria
      5. Associated syndromes
        1. Wallenberg's Syndrome (Vertebral ArteryOcclusion)
        2. Locked-In Syndrome (Basilar ArteryOcclusion at pons)

XI. Signs: Anatomic Distribution

  1. Cerebral Cortex CVA
    1. Motor and sensory deficits of contralateral face (Cranial Nerve deficits) and extremities
  2. Cerebellar CVA
    1. High risk for rapid decompensation and respiratory arrest due to Hemorrhage or infarct edema
      1. Consult neurosurgery early
    2. Severe Nausea and Vomiting (may be only presenting symptom)
    3. Vertigo with Nystagmus
    4. Ataxia
    5. Drop attacks (sudden inability to walk or stand)
    6. Headache
  3. Pons CVA
    1. Abnormal breathing pattern
    2. Coma
    3. Miosis
    4. Gaze Paralysis
  4. Brainstem CVA
    1. Ipsilateral facial weakness (from uncrossed Cranial NerveBrainstem nuclei)
    2. Contralateral extremity weakness (crossed Corticospinal tract)

XII. Exam: Distinguishing CVA etiology

  1. Embolic stroke-related findings
    1. Most severe at onset
    2. Concurrent embolic phenomenon (e.g. sudden pale, cold extremity)
    3. Irregularly irregular heart rhythm (Atrial Fibrillation)
    4. Heart Murmur (especially mitral valve or aortic valve)
    5. Mechanical heart sounds (Heart Valve Replacement)
    6. Fever (risk of Subacute Bacterial Endocarditis)
  2. Hypoperfusion stroke-related findings
    1. Chronic Hypertension
    2. Focal, pure deficits (pure motor or sensory deficit)
  3. Thrombotic stroke-related findings (Peripheral Arterial Disease)
    1. Decreased extremity pulses
    2. Carotid Bruits

XIII. Evaluation

  1. See CVA Evaluation
  2. See NIH Stroke Scale
  3. Bedside Glucose is an initial Vital Sign in CVA
  4. Presentations with other specific evaluation
    1. Acute Vestibular Syndrome
      1. HiNTs Exam may differentiate central Vertigo from peripheral Vertigo
    2. Thunderclap Headache (Subarachnoid Hemorrhage)
      1. Consider Lumbar Puncture if presenting >6 hours after onset
  5. Code Stroke
    1. Code stroke in most U.S. hospitals activates emergent imaging and stroke neurology Consultation
    2. Code stroke Indications (both criteria met)
      1. Reasonable likelihood presenting complaint could be explained by an acute Brain Lesion AND
      2. Patient qualifies for urgent intervention based on stroke guidelines given time and contraindications

XIV. Differential Diagnosis: Most Common (stroke mimics)

  1. Complicated Migraine such as hemiplegic Migraine (especially younger women)
  2. Hemorrhagic Stroke (Intracerebral Hemorrhage)
  3. Hypoglycemia
  4. Hypertensive Encephalopathy (PRES or Posterior Reversible Encephalopathy Syndrome)
  5. Seizure (post-ictal paralysis or Todd's Paralysis)
    1. Seizures may also secondary to Ischemic Stroke in up to 13% of cases

XV. Differential Diagnosis: Less Common (stroke mimics)

  1. Head Trauma or Spinal Trauma (Closed Head Injury)
    1. Subdural Hematoma
    2. Epidural Hematoma
    3. Spinal Epidural Hematoma
  2. CNS Infection
    1. Meningitis
    2. Encephalitis
    3. Headache and Neurologic Deficits with Cerebrospinal Fluid Lymphocytosis (HaNDL Syndrome)
  3. Metabolic Encephalopathy
    1. Nonketotic hyperosmolar coma (Hyperglycemia)
    2. Hyponatremia
    3. Postcardiac Arrest Ischemia
    4. Toxin Ingestion
    5. Myxedema (Severe Hypothyroidism)
    6. Uremia
    7. Wernicke Encephalopathy
  4. Systemic Infection
    1. Respiratory infection
    2. Urosepsis
  5. Miscellaneous
    1. Psychiatric symptoms (e.g. Somatoform Disorder, Conversion Disorder)
    2. Hypotension, shock state or Syncope
    3. Intracranial Mass (e.g. Intracranial Tumor)
    4. Acute confusional state
    5. Multiple Sclerosis
    6. Alcohol Intoxication (or other drug Intoxication)
    7. Moyamoya Disease

XVI. Precautions

  1. Stroke mimic (15-30% of stroke-like presentations) is a diagnosis of exclusion
    1. Err on the side of "Code Stroke" evaluations in first 24 hours despite increased negative work-ups
    2. Consult stroke neurology in acute presentations
    3. Be alert for stroke chameleons (neurologic deficits due to CVA but not appearing consistent with CVA)
      1. Cerebellar Strokes and Medulla Strokes (PICA CVA) may have atypical presentations
  2. Acute stroke presentation requires rapid assessment and management ("time is brain")
    1. Thrombolytics are only indicated within first 3 to 4.5 hours) from CVA onset
    2. Intervention for large vessel Occlusion is also very time sensitive
    3. Discuss with patient and family when interventions are contraindicated or not recommended
  3. ABC Management is critical
    1. Especially important in Hemorrhagic Stroke, where patients typically present obtunded
  4. Posterior Circulation CVA
    1. NIH Stroke Scale significantly underestimates posterior strokes despite disabling strokes
    2. Posterior CVA symptoms (e.g. Vertigo) are often confused with peripheral causes (e.g. Vestibular Neuronitis)
    3. Posterior strokes are not typically visualized on CT (only visualized on MRI Brain)
    4. Vertebral Artery Dissection causes 25% of Posterior Circulation strokes

XVII. Diagnosis

  1. Stroke is overdiagnosed in as many as a third of patients
    1. See differential diagnosis above for stroke mimics
    2. Stroke mimics represent up to 16% of cases in which Thrombolytics were given
    3. Predictors of misdiagnosis (stroke mimic)
      1. Known history of cognitive deficit (underlying Dementia)
      2. Non-neurologic abnormal physical findings
      3. Decreased Level of Consciousness
      4. Younger age
      5. Lower baseline NIHSS Score
      6. Global Aphasia without Hemiparesis
    4. References
      1. Guillan (2012) Cerebrovasc Dis 34(2): 115-20 [PubMed]
      2. Hand (2006) Stroke 37(3): 769-75 [PubMed]
      3. Mehta (2014) J Stroke Cerebrovasc Dis 23(5): 844-9 [PubMed]
  2. Dizziness is poorly corelated with Cerebrovascular Accident
    1. Isolated Dizziness is caused by Cerebrovascular Accident in only 0.7% of cases
      1. However stroke presenting as Dizziness is missed by the examiner in almost half of cases
    2. Factors predictive of Dizziness due to stroke
      1. See Central Causes of Vertigo
      2. Acute vestribular syndrome (Posterior Circulation in 25% of cases)
        1. Rapid onset (<1 hour) of acute, persistent, continuous Vertigo or Dizziness
        2. Associated with Nystagmus, Nausea or Vomiting, head motion intolerance, gait unsteadiness
    3. References
      1. Kerber (2006) Stroke 37(10): 2484-7 [PubMed]
      2. Tarnutzer (2011) CMAJ 183(9): E571-92 [PubMed]

XVIII. Associated Conditions: Disorders that may present concurrently or as causative factor

  1. Acute Coronary Syndrome
  2. Congestive Heart Failure
  3. Atrial Fibrillation
  4. Atrial Flutter
  5. Carotid Dissection
  6. Vertebrobasilar Dissection
  7. Thoracic Aortic Dissection (less common)

XIX. Labs

  1. See CVA Evaluation
  2. Obtain bedside Serum Glucose (fingerstick Blood Sugar)
    1. Hypoglycemia (<63 mg/dl): Administer D50W (do not over-correct)
    2. Hyperglycemia (>300 mg/dl): Administer Insulin
  3. Labs to obtain in all patients
    1. Complete Blood Count (CBC) with Platelet Count
    2. Basic metabolic profile (e.g. Chem8)
    3. INR/ProTime (PT)
    4. Partial Thromboplastin Time (PTT)
    5. Serum Troponin (or other Serum Cardiac Marker)
    6. Electrocardiogram
    7. Oxygen Saturation
  4. Labs and other diagnostics to obtain in selected patients
    1. Liver Function Tests
    2. Urine toxicology screen
    3. Blood Alcohol Level
    4. Pregnancy Test
    5. Arterial Blood Gas or Venous Blood Gas
    6. Chest XRay
    7. Hemoglobin A1C
    8. Thrombin Time (or Ecarin clotting time) Indications
      1. Direct Thrombin Inhibitor use
      2. Direct Factor Xa Inhibitor use
    9. Lumbar Puncture indications
      1. Subarachnoid Hemorrhage is suspected despite negative Head CT
      2. Meningitis or Encephalitis suspected
    10. Electroencephalogram (EEG) indications
      1. Seizure suspected
  5. Labs to consider in cryptogenic stroke
    1. Connective Tissue Disorders (e.g. Antiphospholipid Antibody Test)
    2. Hypercoagulable State (e.g. Factor V Leiden)

XX. Imaging: Initial

  1. See CVA Evaluation
  2. CT Head (non-contrast)
    1. Performed immediately in the code stroke algorithm (followed by CTA if negative)
    2. Single most important imaging test that in combination with history drives emergent management
    3. Adequate sensitivity to exclude CNS mass lesions as well as acute Hemorrhage (with caveats)
    4. Negative Head CT does not exclude CVA (especially in first few hours and in posterior CVA)
      1. More than one third of strokes are missed on initial Head CT
  3. MRI Brain with and without contrast
    1. Preferred initial study if delayed presentation (esp. >24 hours)
    2. Consider rapid MRI protocol with Diffusion Weighted Imaging (DWI) as alternative to CT Head
      1. Appears to be better imaging for initial CVA Evaluation (if not so slow)
      2. However too slow for current stroke protocols
      3. Similar efficacy to CT Head for identifying Hemorrhagic CVA
      4. Chalela (2007) Lancet 369:293-8 [PubMed]
    3. Higher Test Sensitivity for Ischemic CVA (especially posterior CVA)
      1. Overall MRI Test Sensitivity 99%
      2. Consider in patients with higher risk of stroke mimic (e.g. age <55 years old)
      3. Ferro (2010) Lancet Neurol 9(11): 1085-96 [PubMed]
      4. Bhattacharya (2013) J Neurol Sci 324(1):62-4 [PubMed]
    4. Preferred imaging to define CNS Injury after CVA
      1. After initial stabilization, MRI should be considered as part of CVA Evaluation
      2. Consider repeating MRI at 3-7 days if posterior CVA is suspected but negative on initial MRI
        1. Initial MRI in first 48 hours misses 15% of posterior strokes
    5. MRI Brain does NOT have a perfect Test Sensitivity in first few days
      1. MRI Brain may miss up to 7% of acute Ischemic Strokes in first 72 hours
      2. Missed Posterior Circulation strokes are more common than Anterior Circulation on MRI

XXI. Imaging: Vascular

  1. Performed simultaneously with initial imaging as above
    1. Identifies large vessel Occlusion
      1. Consider for endovascular intervention (onset <24 hours, large prenumbra on perfusion imaging)
      2. CTA and MRA have Test Sensitivity 87 to 100% and Test Specificity 95% for large vessel Occlusion
        1. CTA has greater accuracy than MRA for large vessel Occlusion
    2. Identifies severe stenosis (esp. Carotid Stenosis)
  2. Preferred vascular imaging modalities
    1. CT Angiogram head and neck
    2. MR Angiogram Circle of Willis and MR Angiogram neck vessels
  3. Other vascular imaging modalities
    1. Digital Subtraction Angiography
      1. Gold standard for Carotid Artery Stenosis (but largely replaced by CTA and MRA in practice)
    2. Transcranial Doppler Ultrasound
      1. Used to monitor large vessel Occlusion after tPA
    3. Carotid Doppler Ultrasound
      1. Largely replaced by CTA and MRA imaging

XXII. Imaging: Perfusion

  1. Indications: Evaluation for Endovascular Intervention in Large Vessel Occlusion
    1. Identifies regional perfusion hemodynamics
    2. Identifies ischemic infarct prenumbra with potentially reversible injury
  2. Perfusion Studies
    1. CT Perfusion
    2. MR Perfusion (esp. with diffusion weighted imaging or DWI)

XXIII. Imaging: Secondary Cause Evaluation

  1. Echocardiogram
    1. Evaluate for cardiac anomaly (esp. Patent Foramen Ovale)

XXIV. Management

  1. See CVA Management

XXV. Prevention

  1. See Prevention of Ischemic Stroke
  2. See Cerebrovascular Accident Risk Factors
  3. Evaluate for secondary causes after cryptogenic Ischemic Stroke or TIA
    1. See CVA Causes
    2. See Transient Ischemic Attack
    3. Evaluate for Carotid Stenosis
    4. Evaluate for paroxysmal Atrial Fibrillation (Event Monitor, implantable loop recorder)
  4. Educate patients and their families
    1. Urgent evaluation for possible CVA (face drooping, arm weakness, speech difficulty)
    2. American Stroke Association (F.A.S.T campaign)
      1. http://www.strokeassociation.org/STROKEORG/WarningSigns/Stroke-Warning-Signs-and-Symptoms_UCM_308528_SubHomePage.jsp

XXVI. Prognosis: Outcomes (based on U.S. 2011-2012 data)

  1. Total strokes: 795,000 per year in U.S.
  2. Recurrent CVA (highest risk in the next week): 25% of all CVAs
  3. Recovery to baseline: 15% (119,000 in U.S/year)
  4. Persistent Aphasia (at 6 months): 15% (119,000 in U.S/year)
  5. Persistent Hemiparesis (at 6 months): 50% (398,000 in U.S/year)
  6. Mortality: 16% (130,000 in U.S./year)
    1. Fifth leading cause of death in the United States (accounts for 5% of U.S. deaths)

XXVII. Resources

  1. CDC Stroke
    1. http://www.cdc.gov/stroke/facts.htm

XXVIII. References

  1. (2019) Neuro-Psych, CCME National Board Review Course, accessed 6/7/2019
  2. Burgess and Stowens (2014) Crit Dec Emerg Med 28(5): 2-13
  3. (2000) Circulation 102(suppl I):I-204 to I-216 [PubMed]
  4. Adams (2007) Stroke 38(5): 1655-711 [PubMed]
  5. Bath (2000) West J Med 173:209 [PubMed]
  6. Choi (2022) Am Fam Physician 105(6): 616-24 [PubMed]
  7. Larson (2023) Am Fam Physician 108(1): 70-7 [PubMed]
  8. Yew (2015) Am Fam Physician 91(8): 528-36 [PubMed]
  9. Yew (2009) Am Fam Physician 80(1):33-40 [PubMed]

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