creation date: 2026-02-09 18:46
tags: Pathologies
Ischemic Stroke
Background
Definitions
Ischemic stroke is the most common type of stroke, accounting for 80% of all stroke (the other 20% being hemorrhagic stroke, consisting of subarachnoid hemorrhage and intracerebral hemorrhage).
Ischemic stroke refers to neurological deficits occurring due to ischemia to the brain.
Etiology
Among ischemic strokes, the Trial of Org 10172 in Acute Stroke Treatment (TOAST) classification system further subcategorizes ischemic stroke based on etiology.
Cardioembolism
Emboli can form in the heart and occlude a cerebral artery. Clot material travels from the heart and lodges in the distal vessels resulting in ischemia.
In these cases, the sudden blockage often results in abrupt and maximal onset of symptoms. Multiple sites may be affected at once depending on the nature of the emboli.
Small vessel occlusion
This category typically involves lacunar infarcts (small vessels) and is not associated with cerebral cortical dysfunction.
These strokes are associated with a history of hypertension and/or diabetes mellitus.
Large artery atherosclerosis
Stenosis or complete occlusion of a major cerebral artery or branch cortical artery. This occurs due to atherosclerosis in which the plaque formed narrows the artery.
In these cases, symptoms often fluctuate, remit, or progress in a stuttering fashion.
Stroke of undetermined etiology
In cases where multiple etiologies are possible, a definitive diagnosis of etiology may not be possible. For example, in patients with risk of cardiac source of emboli (eg. history of atrial fibrillation) and significant carotid stenosis, categorization would be undetermined.
Stroke of other determined etiology
This category is the umbrella for less common causes of ischemic stroke which includes:
- Nonatherosclerotic vasculopathies
- Hypercoagulable states
- Hematological disorders
Pathophysiology
Regardless of the underlying process, ischemic stroke involves reduced blood flow to regions of the brain.
Autoregulation dysfunction and ischemic penumbra
Under normal conditions, cerebral blood flow is maintained to a relatively stable flow. In cases of reduction in blood flow, compensatory mechanisms attempt to maintain perfusion. This includes:
- Vasodilation
- Increased oxygen extraction fraction
- Inhibition of protein synthesis and glucose utilization
In brain tissue that relies on one artery for blood supply, infarction begins. Surrounding the infarct core is the ischemic penumbra, which is an area of tissue that maintains partial blood flow through collateral circulation. As the ischemia progresses, the infarct core grows and penumbra decreases.
It should be noted that brain cells can survive with 30% of normal cerebral perfusion but infarction will begin once perfusion falls below this.
Ischemic stroke syndromes
Clinical manifestations will vary based on the area of brain affected.
For example, infarction of the most commonly affected artery, the middle cerebral artery, typically results in contralateral hemiparesis, facial paralysis, and sensory loss affecting the face and upper extremities.
Ischemia of the posterior circulation may result in ataxia, cranial nerve deficits, visual field loss, and vertigo.
Clinical Presentation
Signs & Symptoms
The core feature of ischemic stroke is sudden onset of focal neurological deficits. The exact focal deficit depends on the region of the brain affected.
The most common presentation includes sudden onset of:
- Numbness or weakness of the face, arm, or leg; especially unilaterally
- Sudden confusion
- Difficulty speaking or understanding speech
- Difficulty seeing in one or both eyes
- Difficulty walking, loss of balance or coordination
Specific syndromes may be observed based on artery affected (see above).
A posterior cerebral artery (cerebellar) stroke can be ascertained by the presence of the D’s:
- Dizziness
- Diplopia (double vision)
- Dysarthria (slurred speech)
- Dysphagia
- Dyspraxia/ataxia
Left hemisphere strokes commonly are associated with language, reading, and writing problems, including aphasia. Right hemisphere strokes are associated with spatial/attention problems including left-sided spatial neglect.
History & Physical Exam
Initial assessment should alway assess vitals and ABCs.
As a complete history is likely not possible, important points to attempt to ascertain are:
- Time of symptom onset
- Course of symptoms over time
- Possible embolic sources (eg. PMHx AFib)
- Possible recent trauma
- Insulin use/diabetes status and other causes that may cause symptoms
A rapid neurological exam should be performed to confirm findings. Additionally, signs of cerebellar stroke should be ascertained.
The National Institutes of Health Stroke Scale (NIHSS) is a standardized tool for assessing the severity of stroke.
Risk Factors
Risk factors for cardioembolic strokes include:
- Atrial fibrillation and other arrhythmia
- Rheumatic valve disease
- Recent MI
- Dilated CM
- Infective endocarditis
Additional risk factors include those for atherosclerosis. Blood disorders are an uncommon cause of stroke but increases risk.
Diagnosis
Criteria
A presumptive diagnosis of stroke can be made clinically following ruling out of hemorrhagic stroke.
A confirmatory diagnosis is made following therapy via assessment of risk factors, characteristics of stroke course, and vascular testing.
Work-up
Initial diagnostic approach
Immediate noncontrast head CT is indicated to rule out hemorrhagic stroke. This is sufficient to guide treatment.
Additional investigations
Beyond initial CT, additional evaluation can be performed if they do not delay treatment:
- Finger stick blood glucose
- Oxygen saturation
- ECG and troponin
- CBC
- PT and INR
ECG is particularly important for detecting concomitant cardiac ischemia as well as potential source of emboli.
If available, an MRI with diffusion-weighted imaging (DWI) can be used for identifying ischemic strokes (cytotoxic edema (intracellular shift) results in hyperintense signal on DWI within minutes of onset).
Differential
The diagnoses to consider is hemorrhagic stroke as that alters management.
Other conditions that may present like stroke include:
- Reversible cerebral vasoconstriction syndromes
- Cerebral infections
- Cerebral venous thrombosis
- Cervical artery dissection
- Acute hypertensive crisis
- Spontaneous intracranial hypotension
- Hypo/hyperglycemia
- Seizure
- Syncope
Red Flags / Complications
Time until reperfusion and severity of ischemia determines stroke prognosis.
Complications include:
- DVT and PE
- Aspiration pneumonia
- Seizures
- Depression
- Cerebral edema and increased ICP
Management
Stroke management occurs in the ICU or stroke unit. Admission should be done promptly.
Prognostication and care limits are typically delayed until following the first 1-2 days and aggressive care performed unless the patient has a preexisting DNR.
Blood Pressure Management
Management of BP consist of a balance of maintaining adequate perfusion and reducing the risk of recurrent ischemic stroke.
If a patient will be treated with with thrombolytic therapy, blood pressure should be lowered to SBP ≤185 and DBP ≤110. Blood pressure should be maintained below 180/105 for at least 24 hours after thrombolytic treatment.
If a patient will not be treated with thrombolytic therapy, BP should not be treated unless hypertension is extreme (SBP >220 or DBP >120).
Options for antihypertensives include reversible and titratable IV agents:
- IV labetalol, nicardipine, clevidipine (first-line)
- IV nitroprusside (second-line)
Acute Therapy
For adult patients with ischemic stroke and onset <4.5 hours prior, and without high risk for bleeding (eg. PMHx, possible SAH, anticoagulant use), intravenous thrombolysis with tPA or r-tPA (alteplase) is indicated.
If patient is not eligible for thrombolytic therapy, administer aspirin.
In patients with large artery occlusion in the anterior circulation, mechanical thrombectomy may be indicated. This can be done within 24 hours of onset whether IVT was administered or not.
Secondary Prevention of Recurrence
The management of risk factors and common mechanisms of brain ischemia is indicated for patients who have a history of transient ischemic attacks or ischemic stroke.
Antithrombotic therapy
For noncardioembolic stroke or TIA, antiplatelets are effective. Options include:
- Aspirin 81 mg PO daily
- Clopidogrel 75 mg PO daily
- Aspirin ER plus dipyridamole 25/200 mg BID
For high risk patients, short-term dual antiplatelet therapy (aspirin + clopidogrel) may be beneficial.
For cardioembolic stroke, long-term anticoagulation is indicated. Options include:
- DOAC (dabigatran, apixaban, rivaroxaban, edoxaban)
- Warfarin
Modification of major risk factors
Treatment of the following conditions reduce risk of stroke:
- Hypertension
- Dyslipidemia
- Diabetes mellitus
It should be noted that statins have demonstrated benefit even for patients with normal serum lipid levels.
Lifestyle modification
The following should be recommended:
- Smoking cessation
- Increased physical activity
- Cardiovascular benefiting diet (eg. Mediterranean diet)
- Elimination or reduction of alcohol consumption
- Weight loss (if obese)