Chapter 437: Introduction to Cerebrovascular Diseases¶
Chapter 437 | Part 13: Neurologic Disorders
KEY CLINICAL POINTS¶
- Cerebrovascular diseases include ischemic stroke (80% of cases) and hemorrhagic stroke (15%), with transient ischemic attacks (TIAs) as a precursor to stroke.
- Stroke syndromes are classified by vascular territory (anterior/posterior circulation) and mechanisms (embolism, thrombosis, low-flow ischemia).
- Imaging modalities like CT and MRI are critical for acute stroke diagnosis, with MRI superior for detecting small infarcts and posterior fossa lesions.
- Acute management includes thrombolysis (rtPA) within 4.5 hours and endovascular thrombectomy for large vessel occlusions.
- Secondary prevention strategies focus on modifiable risk factors (hypertension, diabetes, smoking) and antiplatelet/anticoagulant therapy.
1. DEFINITION & OVERVIEW¶
Cerebrovascular diseases encompass ischemic stroke (blockage of cerebral arteries), hemorrhagic stroke (bleeding into brain tissue), and transient ischemic attacks (TIAs). Stroke is the second leading cause of death globally, with 7.1 million deaths in 2020. TIAs resolve within 24 hours without infarction, while stroke involves persistent neurological deficits.
Stroke Syndromes by Vascular Territory¶
| Syndrome | Vascular Territory | Key Features |
|---|---|---|
| Middle Cerebral Artery (MCA) Syndrome | Anterior Circulation | Contralateral hemiparesis, aphasia, homonymous hemianopia |
| Posterior Cerebral Artery (PCA) Syndrome | Posterior Circulation | Homonymous hemianopia, visual field defects |
| Vertebral/Posterior Inferior Cerebellar Artery (PICA) Syndrome | Posterior Circulation | Lateral medullary syndrome (Wallenberg's syndrome) |
1.1 Stroke Classification¶
Ischemic stroke (80%): thrombosis/embolism. Hemorrhagic stroke (15%): intracerebral hemorrhage (ICH) or subarachnoid hemorrhage (SAH). TIAs are temporary neurological deficits without infarction.
1.2 Pathophysiology¶
Ischemic stroke: arterial occlusion leading to infarction. Hemorrhagic stroke: rupture of cerebral vessels causing bleeding. TIAs: temporary reduction in cerebral perfusion without infarction.
2. EPIDEMIOLOGY¶
Global stroke incidence: 15 million cases annually. Prevalence: 7 million Americans ≥ 20 years old with a history of stroke. Risk factors: age ≥ 65, hypertension, diabetes, atrial fibrillation, smoking, hyperlipidemia. Mortality: 6.2 million deaths in 2010, with age-standardized death rate reduced by 15% due to prevention/treatment advances.
Stroke Incidence and Mortality¶
| Year | Stroke Deaths (Millions) | Age-Standardized Mortality Rate (per 100,000) |
|---|---|---|
| 2020 | 7.1 | 150 |
| 2010 | 6.2 | 175 |
2.1 Demographics¶
Highest incidence in elderly ( ≥ 65 years) and young children. Age-standardized mortality rate decreased by 15% over the past decade.
2.2 Risk Factors¶
Hypertension (most significant), diabetes, smoking, atrial fibrillation, hyperlipidemia, obesity, physical inactivity, and alcohol consumption.
3. ETIOLOGY & PATHOPHYSIOLOGY¶
Ischemic stroke: atherosclerosis, embolism (cardiac sources), thrombosis. Hemorrhagic stroke: hypertension (ICH), aneurysm rupture (SAH). TIAs: transient cerebral hypoperfusion. Low-flow ischemia: carotid stenosis, subclavian steal syndrome.
Common Stroke Causes¶
| Cause | Percentage of Stroke Cases |
|---|---|
| Ischemic Stroke | 80% |
| Hemorrhagic Stroke | 15% |
| TIAs | 5% |
3.1 Ischemic Mechanisms¶
Atherosclerosis, embolism (e.g., cardiac thrombi), thrombosis, and low-flow ischemia (e.g., carotid stenosis).
3.2 Hemorrhagic Mechanisms¶
Hypertensive ICH (most common), aneurysmal SAH, arteriovenous malformations.
4. CLINICAL FEATURES¶
Acute stroke symptoms: sudden neurological deficits (hemiparesis, aphasia, visual field loss). TIA: transient deficits resolving within 24 hours. FAST acronym: Face drooping, Arm weakness, Speech difficulty, Time to call emergency services. Differential diagnoses: seizure, migraine, metabolic encephalopathy.
FAST Acronym for Stroke Recognition¶
| Feature | Description |
|---|---|
| Face | Unilateral drooping |
| Arms | Weakness in one arm |
| Speech | Slurred speech |
| Time | Call emergency services immediately |
4.1 Stroke Syndromes¶
Anterior circulation: MCA syndrome (hemiparesis, aphasia). Posterior circulation: PCA syndrome (visual field defects), vertebral artery syndrome (Wallenberg's syndrome).
4.2 TIA Features¶
Transient neurological deficits without infarction. Common symptoms: hemiparesis, aphasia, visual disturbances. Resolution within 24 hours.
5. DIFFERENTIAL DIAGNOSIS¶
Seizures (especially complex partial seizures), migraine (including acephalgic migraine), metabolic encephalopathy, intracranial tumors, and psychiatric disorders. Migraine mimics stroke with visual disturbances (scintillating scotomata) and sensory disturbances.
Differential Diagnoses for Acute Neurological Deficits¶
| Condition | Key Features |
|---|---|
| Seizure | Focal deficits without infarction, postictal confusion |
| Migraine | Visual disturbances, sensory aura, transient deficits |
| Metabolic Encephalopathy | Fluctuating mental status, no focal signs |
| Intracranial Tumor | Progressive neurological deficits, mass effect |
5.1 Seizure Mimics¶
Complex partial seizures may present with focal neurological deficits without convulsions. Postictal deficits resolve within minutes.
5.2 Migraine Mimics¶
Acephalgic migraine: sensory disturbances without headache. Scintillating scotomata and visual field defects may mimic stroke.
6. INVESTIGATIONS & DIAGNOSIS¶
Noncontrast CT for acute stroke (excludes hemorrhage). MRI (DWI/FLAIR) for early infarction detection. CTA/MRA for vascular imaging. Lab tests: CBC, coagulation profile, glucose, electrolytes. Stroke severity: NIHSS score. TIA diagnosis: no infarction on imaging within 24 hours.
Imaging Findings in Stroke¶
| Imaging Modality | Key Findings |
|---|---|
| CT | Hyperdense infarction (hemorrhage), hypodense infarct (ischemia) |
| MRI (DWI) | Bright infarct within minutes of onset |
| MRI (FLAIR) | Bright infarct days to weeks post-onset |
6.1 Imaging Modalities¶
CT: rapid for hemorrhage detection. MRI: superior for small infarcts and posterior fossa lesions. CTA/MRA: assess vascular anatomy.
6.2 Diagnostic Criteria¶
Stroke: abrupt neurological deficit with vascular cause. TIA: transient deficits without infarction. NIHSS score ≥ 3 indicates moderate stroke severity.
7. MANAGEMENT & TREATMENT¶
Acute management: thrombolysis (rtPA) within 4.5 hours, endovascular thrombectomy for large vessel occlusions. Secondary prevention: antiplatelet agents (aspirin, clopidogrel), anticoagulants (warfarin, DOACs). Lifestyle modifications: smoking cessation, diet, exercise. Surgical options: carotid endarterectomy, stenting.
Acute Stroke Treatment Algorithms¶
| Condition | Treatment |
|---|---|
| Ischemic Stroke (<4.5 hours) | rtPA IV or endovascular thrombectomy |
| Ischemic Stroke (>4.5 hours) | Mechanical thrombectomy if large vessel occlusion |
| Hemorrhagic Stroke | Avoid thrombolytics; manage intracranial pressure |
7.1 Acute Interventions¶
rtPA (0.9 mg/kg IV) within 4.5 hours. Endovascular thrombectomy for M1 segment occlusions. Thrombolysis contraindicated in hemorrhagic stroke.
7.2 Secondary Prevention¶
Antiplatelet therapy (aspirin 81-325 mg/day), statins, blood pressure control (<140/90 mmHg). Anticoagulation for atrial fibrillation (warfarin/DOACs).
8. PROGNOSIS & COMPLICATIONS¶
Mortality: 20-30% for severe strokes. Complications: stroke recrudescence, cognitive deficits, depression, recurrent TIA/stroke. Hypoxic-ischemic encephalopathy from cardiac arrest. Long-term disability: 50% of stroke survivors have moderate to severe disability.
Stroke Prognostic Indicators¶
| Factor | Impact on Outcome |
|---|---|
| NIHSS Score | Higher scores correlate with worse prognosis |
| Age ‡80 | Increased mortality risk |
| Factor | Impact on Outcome |
|---|---|
| Time to Treatment | Earlier intervention improves outcomes |
8.1 Prognostic Factors¶
NIHSS score, age, comorbidities, time to treatment. Higher NIHSS score correlates with worse outcomes.
8.2 Complications¶
Stroke recrudescence, cognitive impairment, depression, recurrent TIA, and long-term disability (50% of survivors).
9. SPECIAL CONSIDERATIONS¶
Elderly: increased risk of stroke due to hypertension and atherosclerosis. Pregnancy: risk of preeclampsia, placental abruption. Pediatrics: stroke in children often due to vasculitis, congenital anomalies. Anticoagulation in pregnancy: low molecular weight heparin preferred.
Stroke in Special Populations¶
| Population | Risk Factors |
|---|---|
| Elderly | Hypertension, atherosclerosis, anticoagulation |
| Pregnancy | Preeclampsia, placental abruption |
| Pediatrics | Vasculitis, congenital anomalies |
9.1 Elderly Patients¶
Higher incidence of stroke due to age-related vascular changes. Increased risk of hemorrhagic stroke from anticoagulation.
9.2 Pregnancy¶
Risk of preeclampsia, placental abruption, and stroke. Anticoagulation: LMWH preferred over warfarin.
10. KEY POINTS & CLINICAL PEARLS¶
- FAST acronym for stroke recognition. 2. MRI superior for detecting small infarcts. 3. rtPA within 4.5 hours for ischemic stroke. 4. Secondary prevention with antiplatelets and statins. 5. TIA diagnosis requires no infarction on imaging within 24 hours.