What is the likely origin of stenosis/lesions causing strokes in multiple locations including the left occipital lobe, right occipital lobe, left parietal lobe, left frontal lobe, and right cerebellar hemisphere?

Origin of Stenosis/Lesions for Multiple Territory Strokes

When strokes occur in multiple vascular territories (bilateral occipital, left parietal, left frontal, and right cerebellar), the most likely origin is a proximal embolic source—either cardiac embolism or aortic arch atherosclerosis—rather than individual arterial stenoses. 1

Diagnostic Reasoning for Multiple Territory Involvement

Pattern Recognition

• Scattered emboli in multiple territories strongly indicate a proximal embolic source (cardiac chambers, heart valves, or aortic arch) rather than individual arterial stenoses 1
• The specific distribution you describe involves:
  • Bilateral posterior cerebral artery territories (both occipital lobes) 2
  • Left middle cerebral artery territory (left parietal and frontal lobes) 1
  • Posterior inferior cerebellar artery territory (right cerebellar hemisphere) 1

Most Likely Etiologies

Primary consideration: Cardioembolic source 1

• Atrial fibrillation (most common)
• Valvular disease
• Recent myocardial infarction
• Left ventricular thrombus
• Patent foramen ovale with paradoxical embolism

Secondary consideration: Aortic arch atherosclerosis 1

• Can shower emboli to multiple territories
• Particularly relevant if cardiac workup is negative

Less likely: Vertebrobasilar insufficiency alone 1, 3

• Would explain bilateral occipital and cerebellar involvement
• Does NOT explain left frontal/parietal involvement
• Would require additional anterior circulation pathology

Required Vascular Imaging Strategy

Immediate Evaluation

Perform CTA or MRA of head and neck vessels to assess for: 1

• Vertebrobasilar system patency (for bilateral occipital and cerebellar strokes) 1
• Carotid artery stenosis or occlusion (for frontal/parietal involvement) 1
• Intracranial arterial stenosis or occlusion 1

Cardiac Evaluation (MANDATORY)

An appropriate cardiac evaluation must be performed given the multiple territory involvement: 1

• Transthoracic echocardiography at minimum 1
• Transesophageal echocardiography if transthoracic is non-diagnostic 1
• Continuous cardiac monitoring for atrial fibrillation 1

Specific Anatomic Considerations

Bilateral Occipital Involvement

• Suggests vertebrobasilar system compromise with bilateral posterior cerebral artery territory infarction 2
• Can result from complete vertebral artery occlusion with embolic showering 2
• Alternatively, "top of the basilar" embolism affecting both PCAs 1

Left Frontal and Parietal Involvement

• Indicates left middle cerebral artery territory involvement 1
• These are strategic locations where infarcts are highly likely to impair cognition 1
• Left frontotemporal region involvement specifically associated with increased likelihood of cognitive impairment 1

Right Cerebellar Involvement

• Suggests posterior inferior cerebellar artery (PICA) or superior cerebellar artery territory 1
• Part of vertebrobasilar system 1

Critical Pitfall to Avoid

Do not assume these are isolated arterial stenoses at each location. The involvement of both anterior (left MCA) and posterior (bilateral PCA, cerebellar) circulations in a single event makes individual arterial stenoses extremely unlikely and points definitively toward an embolic mechanism from a proximal source 1. Treating only one vascular territory while missing the cardiac or aortic source will result in recurrent strokes.

Management Implications

• If cardiac source identified: Anticoagulation is typically indicated (unless contraindicated by hemorrhagic transformation risk) 1
• If no cardiac source found: Aggressive antiplatelet therapy and search for aortic arch disease 1, 3
• Regardless of source: Intensive atherosclerotic risk factor modification including blood pressure control (target SBP <120 mmHg in appropriate patients), high-dose statin therapy, and diabetes management 1, 3