How to Diagnose Large Artery Atherosclerotic Stroke

When diagnosing large artery atherosclerotic cerebral infarction, a comprehensive evaluation is essential to confirm the condition and rule out other potential causes. The diagnostic process typically involves a combination of laboratory testing, imaging studies, and clinical assessments.

Laboratory Testing

For patients suspected of having a stroke, routine blood tests are crucial in identifying underlying conditions or excluding stroke mimics. Essential tests include blood glucose, lipid profile, cardiac enzymes, liver and kidney function, and electrolyte levels. An electrocardiogram (ECG) is also performed to detect any signs of myocardial ischemia. Additional tests such as complete blood count (CBC), including platelet count, prothrombin time (PT)/international normalized ratio (INR), and activated partial thromboplastin time (aPTT) help assess clotting function and overall health status.

Imaging Studies

Non-Contrast CT Scan

In most cases, a non-contrast computed tomography (CT) scan can reveal hypodense areas indicative of cerebral infarction within 24 hours of symptom onset. Between 2 to 15 days post-stroke, the affected regions often appear as clearly defined wedge-shaped or patchy hypodense areas. In the case of large infarcts, cerebral edema may be visible, accompanied by mass effect. Hemorrhagic transformation can result in mixed density images on CT scans.

Multimodal CT Imaging

Multimodal CT techniques, including CT perfusion, can differentiate between reversible and irreversible ischemic tissue, offering valuable guidance for treatment decisions, especially in acute stroke management.

Magnetic Resonance Imaging (MRI)

MRI is highly sensitive in detecting early ischemic changes, particularly using diffusion-weighted imaging (DWI), which can identify infarcted tissue within minutes of onset.

Carotid Ultrasound and Transcranial Doppler (TCD)

Carotid ultrasound is a non-invasive method to assess extracranial carotid artery disease, such as stenosis or plaque formation. Transcranial Doppler (TCD) complements this by evaluating blood flow velocity in intracranial vessels, helping to detect stenosis or occlusion.

CT Angiography (CTA) and MR Angiography (MRA)

CTA and MRA are advanced imaging techniques that provide detailed visualization of the cerebral vasculature. These modalities are effective in identifying arterial stenosis, occlusions, or other vascular abnormalities associated with large artery atherosclerosis.

Digital Subtraction Angiography (DSA)

Although invasive, digital subtraction angiography (DSA) remains the gold standard for evaluating cerebrovascular pathology. It provides high-resolution images of blood vessels but carries a small risk of complications due to its invasive nature.

Clinical and Neurological Assessment

General Physical Examination

During the physical examination, the physician observes the patient's level of consciousness, skin color, lips, and nail beds to assess for signs of shock or systemic illness. Vital signs are closely monitored to detect any instability.

Neurological Examination

A detailed neurological exam is essential to determine the location and extent of brain injury. This includes evaluating cognitive function, spatial awareness, language skills, and responsiveness. The 12 cranial nerves are systematically tested, focusing on symmetry of facial features, tongue position, swallowing function, uvula position, and hearing. Motor and sensory functions in the limbs are assessed, along with coordination and reflexes. Deep sensation, such as proprioception and vibration, is also tested. These findings help localize the area of the brain affected by the infarction.