Lecture Notes on Vertebral Artery Dissection

Presented by: Kwan-Woong Park, M.D., et al.

Source: J Korean Neurosurg Soc 44 : 109-115, 2008

Introduction

• Dissection: Tear in the arterial wall leading to intramural hematoma.
• Causes stenosis or aneurysmal dilation.
• Rare cause of stroke but significant in young/middle-aged patients.
• Focus: Pathogenesis, clinical features, and treatment of Vertebral Artery Dissection (VAD).

Epidemiologic Features

• Incidence: ~1-1.5 per 100,000.
• Accounts for 2% of ischemic strokes but 10-25% in younger patients.
• Affects all ages, peak in the fifth decade.
• No sex-based predilection.

Pathologic Features

• Arterial wall: Intima, media, adventitia.
• Dissection: Blood collection leads to intramural hematoma.
• Initial tear site varies; possibly in media's connective tissue.

Genetic Factors

• Structural defect in arterial wall suspected.
• Heritable disorders include Ehlers-Danlos syndrome type IV.
• 1-5% of cases linked to known disorders, 20% to unnamed disorders.

Environmental Factors

• Minor precipitating events (e.g., neck movements, infections).
• Seasonal variation in incidence.
• Risk factors: Tobacco, hypertension, oral contraceptives, possibly migraines.

Natural History - Healing Process

• Two types of VAD: Ischemic and hemorrhagic.
• Follow-up angiography shows most extracranial VAD heal.
• Risk of rebleeding high initially, decreases with time.

Classification

• Patho-anatomical classification of aneurysms.
• Types based on IEL disruption and clinical course.
• Entry-only vs. entry-exit mechanisms.

Clinical Features

Extracranial VADs

• Preceded by neck trauma.
• Symptoms: Severe neck pain, ischemic symptoms.
• Common strokes: Lateral medullary syndrome, cerebellar infarctions.

Intracranial VADs

• Often leads to SAH (subarachnoid hemorrhage).
• High rebleeding rate, poor prognosis.
• Associated with posterior circulation, brain stem infarctions.

Diagnosis

• Catheter angiography is the gold standard; MRI and CT are alternatives.
• MRI can show intramural hematoma.

Prognosis

• Extracranial VAD: Generally good prognosis.
• Intracranial VAD: Poor prognosis, high rebleeding risk.
• Recurrent dissection risk in young patients with arteriopathy.

Therapeutic Considerations

Medical Treatment

• Anticoagulation therapy: Heparin, warfarin.
• No randomized trials, but indirect evidence of efficacy.
• Monitoring through MRI and MRA.

Surgical Interventions

• Necessary for patients with SAH or aneurysmal dilation.
• Includes endovascular treatment and arterial repair.

Endovascular Therapy

• Preferred over surgery; includes occlusion and trapping techniques.
• Use of stents has risks and complications.

Surgery

• Considered when endovascular treatment is not viable.
• Trapping and bypass can be curative but technically challenging.

Summary

• VAD: Tear in artery wall causing blood intrusion.
• Two main types: Ischemic and hemorrhagic.
• Extracranial VADs heal spontaneously; intracranial require urgent intervention.
• Prognosis varies between extracranial and intracranial VADs.