Consequences of Left Basilar Artery Stenosis
Stenosis of the left basilar artery can cause posterior circulation ischemia leading to brainstem and cerebellar infarction, with symptoms including vertigo, ataxia, cranial nerve deficits, and motor deficits that can significantly impact mortality and quality of life. 1
Pathophysiology and Clinical Manifestations
Basilar artery stenosis affects the posterior circulation of the brain and can lead to several serious consequences:
Primary Clinical Manifestations:
- Brainstem ischemia/infarction: Primarily affecting the pons 2
- Cerebellar ischemia/infarction: Causing coordination problems and ataxia 2
- Thalamic infarction: Leading to sensory deficits 2
Common Symptoms:
- Vertigo and dizziness
- Ataxia (incoordination)
- Cranial nerve deficits
- Visual field defects
- Imbalance
- Motor weakness or paralysis 1
Mechanism of Injury:
Two primary mechanisms contribute to ischemic events:
- Compromised vertebrobasilar perfusion: Reduced blood flow through the stenotic basilar artery
- Atheroembolism: Plaque fragments breaking off and causing distal occlusion 1
Risk Assessment and Prognosis
The prognosis for patients with symptomatic basilar artery stenosis is concerning:
- Annual stroke recurrence rate: 8.2% in the same territory 2
- Overall stroke rate: 15.0 per 100 patient-years for basilar artery stenosis 3
- Mortality risk: Significant, with 4.5% experiencing fatal myocardial infarction or sudden death in one study 3
Diagnostic Approach
For suspected basilar artery stenosis:
- Preferred imaging: Contrast-enhanced MRA or CTA (sensitivity 94%, specificity 95%) 1
- Gold standard: Catheter-based angiography is typically required before revascularization 1
- Limitations: Neither MRA nor CTA reliably delineates the origins of the vertebral arteries 1
Management Options
Medical Management:
- First-line therapy: Medical management following guidelines for carotid artery disease 1
- Anticoagulation: Recommended for 3 months in patients with acute ischemic syndromes with angiographic evidence of thrombus 1
- Antiplatelet therapy: Aspirin and warfarin appear equally efficacious after initial noncardioembolic ischemic stroke 1
- Statin therapy: May prevent progression of symptomatic basilar artery stenosis and decrease risk of subsequent ischemic stroke 4
Interventional Approaches:
- Endovascular treatment: Angioplasty and stenting are technically feasible but lack strong evidence from randomized trials 1
- Complications: Periprocedural neurological complications occur in 5.5% for proximal vertebral artery interventions and up to 24% for distal vertebrobasilar disease 1
- Restenosis rates: 26% for proximal and 10% for distal interventions 1
Surgical Options:
- Rarely performed: Surgical approaches are less common than for carotid disease 1
- Techniques: Include trans-subclavian vertebral endarterectomy, transposition of the vertebral artery, and reimplantation with vein graft extension 1
Important Clinical Considerations
- Transient ischemic attacks (TIAs) often precede posterior circulation stroke and should be taken seriously 2
- Concomitant vertebral artery disease is common (found in 67% of patients with basilar stenosis in one study) 2
- Warfarin therapy (INR 2.0-3.0) appeared effective in preventing recurrent strokes in one observational study 2
- Collateral circulation plays an important role in determining symptom severity - if the contralateral vertebral artery is patent and dominant, it may provide sufficient blood flow to the basilar artery 1
Differential Diagnosis
- Subclavian steal syndrome: Can mimic posterior circulation symptoms but is typically aggravated by upper-limb exercise 5
- Cervical spinal stenosis: May present with similar motor symptoms but through a different mechanism 5
Left basilar artery stenosis represents a serious condition with significant risk for recurrent stroke and mortality, requiring prompt diagnosis and aggressive medical management, with consideration of interventional approaches in selected cases.