Diagnosis

Stroke

Etiology

Cause [mpt][rfd]

• Hemorrhage (10%)

• Subarachnoid Hemorrhage (5%): spontaneous (85%), traumatic

• Thromboembolism --> Vascular occlusion (85%)

  • Large-artery stroke: Embolization of atherosclerotic debris originating from the carotid arteries or the heart

  • Small-vessel lacunar stroke - 15%: Microatheroma or microemboli cause occlusion of the parenchymal branches

  • Cardioembolic infarction - 20%: Atrial fibrillation, myocardial infarction, mitral stenosis, endocarditis, prosthetic valve, atrial myxoma

Pathophysiology [mpt][rfd]

1. Embolus pathway: Heart -> Carotid Artery and Vertebral Artery -> Circle of Willis:

   • Anterior Cerebral Artery (medial frontal lobe)

     • Contralateral hemiparesis in the lower extremities

   • Middle Cerebral Artery (lateral frontal lobe, parietal lobe, temporal lobe)

     • Contralateral hemiparesis in the face and upper extremities

     • Facial paralysis

     • Gaze preference toward the side of the lesion

     • Dysarthria

     • Aphasia

     • Neglect

     • Visual field loss (contralateral inferior quadrantanopia)

   • Posterior Cerebral Artery (occipital lobe medial portion of the temporal lobe)

     • Visual cortex: contralateral homonymous hemianopia, cortical blindness

     • Thalamus: hypersomnolence, cognitive impairment, ocular findings, hypoesthesia, and ataxia

     • Larger infarcts --> hemisensory loss and hemiparesis

     • Anmesia

   • Vertebral artery and basilar artery

     Ataxia, vertigo, headache, vomiting, oropharyngeal dysfunction, visual field deficits, abnormal oculomotor findings

   • Cerebellar Infarction

     Ataxia, nausea, vomiting, headache, dysarthria, and vertigo

2. Insufficient blood supply --> ischemia/cell hypoxia --> irreversible damage (infarction)

3. Depletion of ATP --> unable to maintain ionic gradients across the cell membrane --> influx of sodium and calcium ions --> passive inflow of water into the cell --> cytotoxic edema

4. Ischemia --> breakdown of the blood-brain barrier occurring within 4-6 hours after infarction --> proteins and water flood into the extracellular space --> leading to vasogenic edema --> brain swelling and mass effect that peak at 3-5 days and resolve over the next several weeks with resorption of water and proteins

5. Hemorrhagic transformation occurs in 5% of ischemic strokes

6. The infarcted tissue eventually undergoes liquefaction necrosis and is removed by macrophages, with the development of parenchymal volume loss.

Risk factors [mpt]

• Age, smoking, diabetes mellitus, hypertension, migraine, transient ischemic attacks, atrial fibrillation, hypercholesterolemia, carotid stenosis, physical inactivity, obesity, hormone replacement, heredity

• Hypercoagulable states: antiphospholipid antibodies, protein C deficiency, protein S deficiency, pregnancy, polycythemia, thrombocytosis, thrombocytopenia, leukemia, Sickle cell anemia

• Fibromuscular dysplasia

• Arterial dissections

• Vasoconstriction (cocaine, amphetamines)

Complications [mpt][rfd]

• Intracranial hemorrhage after ischemic stroke

• Deep vein thrombosis

• Pulmonary embolism

• Aspiration pneumonia

• Recurrent seizures

• Cerebral edema --> increased ICP

• Hydrocephalus

Epidemiology

Incidence per 100.000 [2nt][fyp][eiz][d5a][bvq][qf8]

Approach

• Blood test: Complete blood count, electrolytes, creatinine, coagulation studies, Troponins, PT-INR, toxicology, HCG due to thrombolysis, sedimentation rate, ANA, RF

• Blood gas

• ECG

• CT caput

• MR caput

• CT angiography

• Doppler ultrasonography

• Echocardiography

• Lumbar puncture

Treatment

The goal of therapy is to preserve areas of reversible tissue damage. [mpt]

1. Vital signs: [mpt]

   • Airway

   • Breathing

   • Circulation --> Blood pressure <180/105

     • Labetalol 10 to 20 mg IV; may repeat once

     • Nicardipine 5 mg/hour IV, increase 2.5 mg/hour (max 15 mg/hour)

     • Clevidipine 1 to 2 mg/hour IV, double dose every 15 minutes (max 21 mg/hour)

     • Hydralazine and enalaprilat may be considered

   • Temperature <38 °C (acetaminophen, exclude infections)

   • Glucose: insuline to achieve normoglycemia

   • Nutrition: Early enteric feeding is encouraged (dysphagia -> nasogastric tube)

   • Thrombosis prophylaxis: heparin or low molecular weight heparin

2. Ischemic stroke recanalization strategies: Effective if performed quickly

   • Antiplatelet/anticoagulation:

     • Aspirin is recommended within 24 to 48 hours of symptom onset

     • DVT-prophylaxis: low-dose heparin or low molecular weight heparin

     • Atrial fibrillation: oral anticoagulation within 4 to 14 days

   • IV alteplase/tenecteplase (within 4.5 hours of stroke onset)

   • Mechanical thrombectomy (within 6 hours of stroke onset) if large vessel occlusion

3. Intracerebral Hemorrhage [rfd]

   • Discontinued anticoagulation immediately, rapid reversal

   • Platelet transfusion if treated with antiplatelet or indication for neurosurgery

   • Surgery:

     • Minimally invasive hematoma evacuation with endoscopic/stereotactic aspiration

     • External ventricular drain insertion

     • Craniotomy

4. Subarachnoid Hemorrhage [rfd]

   • Early (<72 hours) endovascular coiling (or clipping) of aneurysm to decrease the risk of rebleeding

   • Seizure --> antiepileptic drugs

5. Cerebellar/Cerebral edema:

   • Peaks in 3 to 5 days after an ischemic stroke

   • Correlate with the size of the stroke

   • May increase ICP/herniation/hydrocephalus --> apnea, pupillary dilatation, death

   • Treatment: ventriculostomy, decompressive craniectomy, surgical evacuation

6. Post-stroke seizure: Antiepileptic drugs for 1 month (or longer if late seizures)

7. Cardiac evaluation: Treatment of atrial fibrillation

Differential diagnoses

Amphetamine toxicity, Bell's Palsy, Benign paroxysmal positional vertigo, Brain abscess, Brain tumor, Cerebral venous sinus thrombosis, Cocaine toxicity, Drug side effects, Epilepsy, Hepatic encephalopathy, Hyperglycemic hyperosmolar nonketotic state, Hypoglycemia, Hyponatremia, Intracranial hemorrhage, Migraine, Multiple sclerosis, Myocardial infarction, Postseizure encephalopathy, Psychotropic drugs, Sepsis, Subarachnoid hemorrhage, Syncope, Transient global amnesia, Transient ischemic attack, Wernicke encephalopathy