What is the most likely anatomic/pathophysiologic cause of stroke in a 55-year-old right‑hand‑dominant male smoker with hypertension and stable angina who presents with persistent mild right facial weakness, right hand weakness, and expressive aphasia, with prior transient right facial droop and hand weakness, blood pressure 170/95 mm Hg, regular pulse 90/min, no cervical bruits, an S4 gallop, borderline left ventricular hypertrophy on electrocardiogram, and normal laboratory studies?

Most Likely Anatomic/Pathophysiologic Cause: Atherosclerotic Disease of the Left Internal Carotid Artery

The most likely cause is atherosclerotic disease of the left internal carotid artery (option d), given the constellation of right-sided motor and language deficits, multiple prior transient ischemic attacks, and the patient's extensive atherosclerotic risk factor profile. 1

Clinical Localization

The neurologic findings definitively localize to the left cerebral hemisphere:

• Right hemiparesis (face and hand) indicates left motor cortex involvement 2
• Aphasia in a right-hand-dominant patient localizes to the left hemisphere language centers 2
• The pattern of cortical symptoms (motor + language) points to left middle cerebral artery territory involvement, typically supplied by the left internal carotid artery 1

Mechanism: Large Artery Atherosclerosis

This patient's presentation is classic for atherothromboembolism from left internal carotid artery disease 1:

• Stuttering progression with two prior TIAs (one week and two months ago) followed by completed stroke is the hallmark pattern of large artery atherosclerotic disease 3
• The European Society of Cardiology identifies plaque inflammation, disruption, and embolization of thrombus or debris as the predominant mechanism producing anterior-circulation cortical occlusions 1
• Approximately 18% of first-ever ischemic strokes are attributable to large vessel disease (extracranial or intracranial) 1

Why Not the Other Options?

Cardiac embolism (option a) is unlikely because:

• Regular pulse rate argues against atrial fibrillation 4
• S4 gallop and borderline LVH reflect chronic hypertensive heart disease, not acute cardioembolic sources 5
• Cardiac emboli typically cause sudden-onset maximal deficits without preceding TIAs, whereas this patient had two warning events 4
• The absence of cervical bruits does not exclude carotid disease but makes cardiac source less likely given the stuttering course 4

Intracerebral hemorrhage (option b) is excluded by:

• The clinical pattern of stuttering progression over months is incompatible with hemorrhage 2
• Hemorrhagic stroke presents with sudden onset, often with headache, vomiting, and decreased consciousness 2

Right middle cerebral artery atherosclerosis (option c) is anatomically incorrect:

• Right MCA disease would produce left-sided hemiparesis and left-sided neglect, not aphasia 6
• Aphasia in a right-hand-dominant patient requires left hemisphere pathology 2

Supporting Risk Factor Profile

This patient has the quintessential atherosclerotic risk profile 4:

• Active smoking and carotid/intracranial atherosclerosis were the only independent risk factors for abnormal cardiac stress tests in patients with cerebral ischemia 4
• Hypertension (BP 170/95 mmHg) increases stroke risk by 30-45% for each 10 mmHg increase 4
• Stable angina indicates systemic atherosclerosis 4
• Borderline LVH confers independent increased risk for cerebrovascular events (RR 1.79) in hypertensive patients 5

Clinical Pitfall to Avoid

Do not assume the absence of cervical bruits excludes significant carotid stenosis 4. Bruits have poor sensitivity for high-grade stenosis, and approximately 43% of carotid-related strokes present with internal carotid artery occlusion, which may be silent on auscultation 7. The American Heart Association recommends noninvasive vascular imaging (carotid ultrasound, CTA, or MRA) in all patients with anterior circulation stroke or TIA 4.

Immediate Next Steps

Urgent carotid imaging with duplex ultrasound, CTA, or MRA is mandatory 4:

• Patients with symptomatic high-grade cervical carotid stenosis are candidates for urgent revascularization 4
• The 2021 AHA/ASA guidelines recommend initial noninvasive testing rather than digital subtraction angiography (stroke risk 0.3-3.0%) 4
• CTA from aortic arch to vertex is the most cost-effective immediate strategy for high-risk patients 4

This patient requires evaluation within hours, as symptomatic carotid stenosis carries a 6% risk of recurrent stroke within the first year, with highest risk in the first few weeks 1.