Ischemic Stroke

Question 1

What is a stroke?

Answer 1

A stroke is classified into 2 major types:

• Ischemic secondary to thrombosis, embolism or systemic hypo perfusion
• Hemorrhage due to intracerebral hemorrhage (ICH) or subarachnoid hemorrhage (SAH)

A stroke is an acute neurologic injury that occurs as a result of one of these pathologic processes and lasting longer than 24 hours

• A stroke in evolution is an enlarging infarction manifested by deficits that worsen over 24-48 hours
• 80% of strokes are secondary to ischemic cerebral infarction
  
  • 20% of strokes are secondary to brain hemorrhage.

Question 2

What are some classic signs of a stroke?

Answer 2

F = Face Drooping

A = Arm Weakness

S = Speech Difficulty

T = Time to call 911

Question 3

What are the 3 types of ischemic stroke?

Answer 3

• Thrombosis (30%)
• Embolism (25%)
• Systemic hypoperfusion

Question 4

Can cause an ischemic stroke due to thrombosis?

Answer 4

• Generally, refers to local in situ obstruction of an artery
• May be due to disease of arterial wall, such as arteriosclerosis, dissection or fibromuscular dysplasia, may or may not be superimposed thrombosis
• Patients often have a history of TIA
• Progression of symptoms of hours to days or can be sudden
• Predisposing factors: atherosclerosis, HTN, DM, HLD, Vasculitis, Smoking, Trauma, Connective tissue disorders

Question 5

What causes an ischemic stroke due to embolism?

Answer 5

• Refers to particles of debris originating elsewhere that bock arterial access to a particular brain region
• Further events may occur if the source of the embolism is not identified and treated
• Very rapid onset
• History of TIA
• Predisposing factors: atrial fib, Mitral stenosis/regurgitation, endocarditis, mitral valve prolapse

Question 6

What labs/diagnostic tests are used to diagnose a stroke?

Answer 6

CT scan of head without contrast- performed initially (within 20 minutes of arrival to ED)

• Preferable to MRI in acute state to rule out cerebral hemorrhage
• Initial CT may be negative- infarct may take up to 24 hours to be visible on imaging

Chest x-ray

• Assess for cardiomegaly or valvular calcification
• Assess for neoplasm or metastasis
• Assess for dilated aorta

Immediate Diagnostics- All Patients

• Blood glucose level
• Oxygen saturation
• Serum electrolytes/renal function tests
• CBC, including platelet level
• Markers for cardiac ischemia
• PT/INR
• PTT
• EKG

Cerebral angiography continues to be GOLD STANDARD for complete evaluation of intracranial and extracranial vessels- if warranted

Question 7

How do you manage a patient with a stroke?

Answer 7

Treatment is dependent upon type of stroke

1. Emergent activation of stroke team: Neurology, Neurosurgery, Radiology, Emergency Department, ICU
2. IV alteplase eligibility for acute ischemic stroke OR
3. Mechanical thrombectomy

Question 8

What are the indications for giving IV alteplase to patients?

Answer 8

1. If it occurs within 3 hours of onset:

• > 18 years of age
• Severe stroke
• Mild but disabling stroke

2. If 3-4.5 hours from onset, 18-80 years of age and without:

• A history of both DM and prior stroke
• NIHSS score of < or equal to 25
• Taking any OACs
• Imaging evidence of ischemic injury involving more than 1/3 of the MCA territory

3. If BP can be lowered safely and maintained < 185/110 mmHg
4. With Blood glucose > 50 mg/dL
5. With mild to moderate early ischemic changes on NCCT
6. With antiplatelet drug monotherapy or combination therapy
7. With end stage renal disease with normal aPTT

Question 9

What are the contraindications to giving IV alteplase?

Answer 9

• Unclear time and/or unwitnessed symptom onset and in whom the time last known to be at baseline state is > 3 or 4.5 hours
• Awoke with stroke with time last known to be at baseline state > 3 or 4.5 hours
• CT reveals an acute intracranial hemorrhage
• CT brain imaging exhibits extensive regions of clear hypo attenuation
• Prior ischemic stroke within 3 months
• Recent severe head trauma within 3 months
• Posttraumatic infarction that occurs during the acute in hospital phase
• Intracranial/spinal surgery within prior 3 months
• History of intracranial hemorrhage
• Symptoms and signs most consistent with an SAH
• Structural GI malignancy
• Gastrointestinal bleeding event within 21 days
• Platelets < 100,000/mm3
• aPTT > 40s
• PT > 15 s
• Treatment dose of LMWH within previous 24 hours
• Taking direct thrombin inhibitors or direct factor Xa inhibitors appropriate coagulation activity assays are normal or the patient has not received a dose of these agents for > 48 hours (assuming normal renal metabolizing function)
• Concurrent administration of antiplatelet agents that inhibit the glycoprotein IIb/IIIa receptor outside a clinical trial
• Symptoms consistent with infective endocarditis
• Known or suspected to be associated with aortic arch dissection
• Intra-axial intracranial neoplasm

Question 10

How do you manage a patient receiving IV alteplase for a stroke?

Answer 10

• Infuse 0.9 mg/kg (maximum dose 90 mg) over 60 minutes, with 10% of the dose given as a bolus over 1 minute
• Admit patient to an ICU or stroke unit for monitoring for at least 24 hours
• If patient develops severe headache, acute HTN, nausea/vomiting, decreased neurological exam, discontinue infusion and obtain emergent CT head
• Measure BP and neuro assessment q 15 minutes during and after alteplase infusion for 2 hours, then every 30 minutes x 6 hours, then hourly x 24 hours after alteplase treatment.
• Increase frequency of BP measurements if SBP > 180 mmHg or DBP > 105 mmHg. Administer anti-hypertensive medications to maintain BP at or below these levels.
• Delay placement of NGT, Urinary catheters, intra-arterial pressure catheters if patient can be safely managed without them
• Obtain f/u CT or MRI scan at 24 hours post IV alteplase before starting anticoagulants or antiplatelet agents.

Question 11

How do you manage a patient receiving IV alteplase for a stroke?

Answer 11

• In select patients with Acute ischemic stroke within 6-16 hours of last known normal who have LVO in the anterior circulation and have favorable imaging studies, mechanical thrombectomy is recommended
• Imaging studies may indicate some patients could reasonably have mechanical thrombectomy up to 24 hours after last known normal
• If patients who undergo mechanical thrombectomy, it is reasonable to maintain BP < or equal to 180/105 during and for 24 hours after procedure.

Question 12

What is a lacunar infarct?

Answer 12

This infarct occurs in the deep penetrating branches of major cerebral arteries

• Most common – less than 5 mm in diameter
• Associated with poorly controlled HTN or diabetes
• Contralateral pure motor or sensory deficits
• Ipsilateral ataxia with crural paresis (leg or thigh)
• Dysarthria with clumsiness of hand