Definition

Cerebral infarction due to cerebral artery thrombosis/thromboembolism or systemic hypoperfusion.

Etiology

Approximately 2/3 of ischemic strokes are due to thrombosis of a large or small artery (most commonly due to atherosclerosis) and 1/3 are due to embolism (most commonly from a proximal large artery or the heart).

Risk Factors

Advanced age, atrial fibrillation, hypertension, hyperlipidemia, diabetes, smoking, structural cardiac disease, endocarditis, TIA, peripheral arterial disease (PAD)

Evaluation

• Differential diagnosis: hemorrhage or hematoma, complex migraine, seizure or post-ictal (“Todd’s”) paralysis, focal brain infection/abscess, tumor, hypoglycemia
• History:
  • When was the patient last seen normal? Not the same as when deficits were first noticed and critical for determining eligibility for acute stroke therapy with tPA and embolectomy
  • Risk factors for stroke (see above)
  • Presence of contraindications to tPA (history of intracerebral hemorrhage, recent stroke, recent surgery), and stroke mimics (e.g. seizure)
  • Anticoagulation
  • Symptoms: unilateral weakness or sensory disturbance, facial droop, visual field defect, difficulty speaking/understanding, diplopia, dysarthria, dysphagia, vertigo, incoordination
• Physical exam:
  • Vital signs (BP < 185 to give tPA)
  • Cardiac exam (check for atrial fibrillation)
  • NIH Stroke Scale (level of consciousness, gaze, visual fields, facial symmetry, arm strength, leg strength, numbness, ataxia, language, dysarthria, neglect)
• Labs: glucose finger stick, chem panel, CBC, coags
• EKG: evaluate for arrhythmia, current or prior infarcts
• Imaging:
  • CT stroke protocol (CT brain without contrast, CT angiogram head and neck, CT perfusion) evaluates for hemorrhage, early signs of stroke and large vessel occlusion
  • MRI: more sensitive for acute ischemic infarcts (<12 hours) and posterior fossa strokes. Can add MRA head/neck if CTA contraindicated (significant renal disease)
  • Carotid ultrasound if unable to obtain CTA or MRA in evaluating anterior circulation stroke

Management

• IV Thrombolysis (t-PA):
  • Time is brain! Patients are eligible up to 4.5 hours after patient was last known normal but earlier is always better!
  • Several contraindications exist and must be reviewed carefully!
• Embolectomy: eligible for consideration if there is a large vessel occlusion and within 24 hours of patient’s last known normal. Patients should still be treated with IV t-PA if eligible
• BP control: 
  • SBP < 185 mmHg if t-PA is administered
  • SBP < 220 mmHg (permissive hypertension) if no t-PA is administered
  • Exceptions: concomitant aortic dissection, acute MI, or alternative indication to lower BP
• Avoid fever
• Monitor for herniation due to worsening cerebral edema or hemorrhagic conversion:
  • Cerebral edema is most dangerous in 1) large MCA territory stroke and 2) cerebellar stroke involving the PICA or SCA
  • Low threshold to obtain a stat non-contrast head CT and contact neurology/neurosurgery
  • Avoid hypoosmolar IV fluids (e.g. D5W, D51/2NS), as these may worsen edema
  • Give hyperosmolar therapy if there is herniation due to cerebral edema:
    • Mannitol: 25-100g IV and continued q6 hours as needed. Check serum osmolality with each dose. Contraindicated in acute renal failure (unless on CRRT)
    • Hypertonic saline (23.4%): 30 mL push administered over 5-10 minutes by physician. Must have central access. Contraindicated in congestive heart failure due to volume overload
    • Hyperventilation (to goal PaCO2 of 25) can lower ICP but only helpful temporarily
    • Note: glucocorticoids do not improve outcome and may increase infection rates and mortality
• Urgent carotid revascularization if >70% ICA stenosis on the side of the stroke
• Prevention of complications: many stroke-related deaths are due to medical complications
  • DVT prophylaxis
  • Early mobilization with PT (within 24-48 hours)
  • Aspiration precautions: NPO until evaluated by Speech Pathology, manage nausea/vomiting with a non-sedating anti-emetic (e.g. ondansetron)
  • Careful monitoring for UTI, pneumonia, decubitus ulcers
  • Normoglycemia
• Secondary stroke prevention:
  • Anti-platelet therapy if no indication for anticoagulation
    • Small stroke/TIA: dual antiplatelet therapy with aspirin 81mg and plavix 75mg daily for 3 weeks and then aspirin or plavix monotherapy going forward
    • Large stroke: start aspirin 325mg daily while in the hospital and then aspirin or plavix monotherapy going forward 
  • High intensity statin (atorvastatin or rosuvastatin, dose based on fasting LDL)
  • Anticoagulation: should be started for patients with atrial fibrillation (timing of initiation determined by size of stroke and corresponding risk of hemorrhage); rare other indications
  • BP control, blood glucose control, smoking cessation

Choosing Wisely

• Don’t perform imaging of the carotid arteries for simple syncope without other neurologic symptoms. Occlusive carotid artery disease does not cause fainting but rather causes focal neurologic deficits such as unilateral weakness.
• Carotid endarterectomy is not indicated for asymptomatic carotid stenosis.

Key points

• Time is brain! Earlier treatment with t-PA and embolectomy leads to better outcomes.
• Many deaths in patients with stroke are from medical complications. Take great care to prevent DVTs, infection, aspiration, and decubitus ulcers. Encourage mobilization early in the hospital stay.
• Secondary prevention is extremely important. All patients should go home on maximal medical management and should be urged to quit smoking.

Jauch et al, Guidelines for the Early Management of Patients with Acute Ischemic Stroke, Stroke 2013;44

Kernan et al, Guidelines for the prevention of stroke in patients with stroke and transient ischemic attack, Stroke 2014; 45

van der Worp HB, van Gijn J. Acute Ischemic Stroke. N Engl J Med 2007;357:572-9.

Hacke, W. N Engl J Med. 2008 Sep 25;359(13):1317-29.

Schellinger, PD. Neurology. 2010;75(2):177.

Wijdicks, EF. Stroke. 2014 Apr;45(4):1222-38