Stroke Overview and Pathophysiology

Stroke Overview

• Stroke involves abrupt onset of focal neurologic dysfunction lasting at least 24 hours.
• Strokes can be ischemic or hemorrhagic.
• Transient ischemic attacks (TIAs) are focal ischemic neurologic deficits lasting less than 24 hours, typically less than 30 minutes.
• Ischemic stroke (87% of strokes) results from occlusion of a cerebral artery.
• Ischemic strokes are caused by either local thrombus formation or emboli from distant sites.
• Atherosclerosis of large intracranial or extracranial arteries, or small artery disease can cause ischemic strokes.
• Emboli can originate from the heart in patients with atrial fibrillation, valvular heart disease, or other prothrombotic heart problems, accounting for about 25% of ischemic strokes.

Pathophysiology of Ischemic Stroke

• Insufficient oxygen supply leads to ATP depletion, lactate buildup, intracellular Na and water accumulation, cytotoxic edema, and eventually cell lysis.
• Calcium influx activates lipases and proteases.
• Release of excitatory amino acids (e.g., glutamate, aspartate) causes neuronal damage and produces damaging prostaglandins (PGs), leukotrienes, and reactive oxygen species (ROS).
• These processes occur within 2-3 hours of ischemia onset, leading to cellular apoptosis and necrosis.

Pathophysiology of Hemorrhagic Stroke

• Hemorrhagic strokes (13% of strokes) include subarachnoid hemorrhage (SAH) and intracerebral hemorrhage (ICH).
• Early hematoma expansion often occurs within 3 hours of onset.
• Early expansion contributes to worsened functional outcome and increased mortality.
• Secondary injury mechanisms include inflammatory response, cerebral edema, and damage from blood product degradation.

Clinical Presentation of Stroke

• Symptoms include unilateral weakness, inability to speak, loss of vision, vertigo, or falling.
• Ischemic stroke is not typically painful, but some patients experience headaches.
• Headaches are more common and severe in hemorrhagic strokes.
• Neurological deficits during physical exam depend on the affected brain area.
• Common neurological deficits include hemi- or monoparesis, hemisensory deficits, vertigo, and diplopia (patients with posterior circulation involvement).
• Anterior circulation strokes can cause aphasia.
• Patients may experience altered levels of consciousness.

Stroke Diagnosis

• General blood glucose, platelet count, and coagulation parameters should be checked.
• Computed tomography (CT) and magnetic resonance imaging (MRI) scans are used to detect hemorrhage and infarction areas.
• Computed tomography angiography (CTA) is recommended for patients needing endovascular treatment.
• Carotid Doppler (CD), electrocardiogram (ECG), transthoracic echocardiogram (TTE), and transcranial Doppler (TCD) studies provide additional diagnostic information.

Stroke Treatment Goals

• Reduce ongoing neurologic injury during an acute stroke to lower mortality and long-term disability.
• Prevent complications related to immobility and neurologic dysfunction.
• Prevent stroke recurrence.

Non-Pharmacologic Treatment (Ischemic Stroke)

• Endovascular intervention and thrombectomy with retrievable stents are strongly recommended within 6 hours of symptom onset for patients with anterior circulation occlusion. Consideration of 6 -24 hours may be warranted in some cases.
• The benefit of mechanical thrombectomy is less clear in posterior circulation occlusions and should be considered on a case-by-case basis.
• Decompressive hemicraniectomy, involves brain surgery to remove a portion of the skull.
• Carotid endarterectomy removes plaque buildup in stenotic carotid arteries.

Non-Pharmacologic Treatment (Hemorrhagic Stroke)

• Early intervention with either surgical clipping or endovascular coiling of the vascular abnormality reduces mortality from rebleeding in subarachnoid hemorrhage (SAH).
• Early surgical intervention plus hematoma removal is recommended for patients with cerebellar hemorrhage and neurologic deterioration, brainstem compression, or hydrocephalus from ventricular obstruction.

Temperature Management

• Fever worsens outcomes in patients with both hemorrhagic and ischemic strokes.
• Identifying the source of fever and implementing pharmacologic and/or non-pharmacologic management is crucial to maintain normothermia.

Pharmacologic Therapy (Ischemic Stroke)

• Adherence to a guideline-recommended protocol is essential.
• Activate the stroke team, obtain CT scan to rule out hemorrhage, treat as early as possible within 4.5 hours, and meet all inclusion criteria with no contraindications.
• Administer alteplase (0.9mg/kg IV). This is done in part as a bolus over 1 minute with the remainder over an hour.
• Avoid anticoagulants and antiplatelets for 24 hours following alteplase therapy..
• Monitor the patient closely for elevated blood pressure (BP), neurological status, and hemorrhage signs.
• Aspirin (160-325 mg/day) is started within 24-48 hours of symptom onset (24 hours post-alteplase).
• Elevated BP, if a patient qualifies for alteplase needs to be brought down to a goal of <185/110 mm Hg
• Elevated BP can be left as high as 220/120 for 48-72 hours for patients not requiring thrombolysis or endovascular intervention.

Pharmacologic Therapy (Hemorrhagic Stroke)

• Pharmacotherapy benefits are limited, especially in spontaneous intracerebral hemorrhage (ICH).
• Aggressive BP lowering with continuous IV infusion medications with systolic BP >220 mm Hg is generally considered.
• Patients reaching a systolic BP target of 140 mm Hg are generally safer and improve their outcome.
• Control of BP to a target of at least 160 mm Hg systolic is recommended in patients with SAH due to aneurysm rupture, during the period from symptom onset to aneurysm obliteration.
• When intracranial hemorrhage occurs in patients using anticoagulants, consider reversing the medication-induced coagulopathy.

Evaluation of Therapeutic Outcomes

• Monitor for bleeding using neurologic exam and blood pressure:

• Every 15 minutes (1 hour)

• Every 30 minutes (6 hours)

• Every hour (17 hours)

• As needed (thereafter)

• Daily monitoring of bleeding is recommended for aspirin, clopidogrel, dipyridamole, aspirin, warfarin and other oral anticoagulants

• Check PT/INR and hemoglobin/hematocrit daily for patients receiving warfarin.

This quiz covers key concepts related to strokes, focusing on the types, causes, and underlying mechanisms of ischemic stroke. Participants will explore the differences between ischemic and hemorrhagic strokes, as well as the pathophysiological processes involved in ischemic events. Enhance your understanding of how strokes affect neurological function.