eMedicine Specialties > Neurology > Neuro-vascular Diseases

Dissection Syndromes

Author: Chelsea S Kidwell, MD, Associate Professor, Department of Neurology, Georgetown University; Medical Director, Washington Hospital Center Stroke Center
Coauthor(s): Richard E Burgess, MD, PhD, Consulting Staff, Department of Neurology, Georgetown University Hospital, Consulting Staff, Suburban Hospital and Washington Hospital Center
Contributor Information and Disclosures

Updated: Dec 15, 2008

Introduction

Background

Dissection occurs when blood extrudes into the connective tissue framework of a vessel wall, causing separation of the natural vessel layers. Dissection of the cervical and intracranial vessels is an uncommon but increasingly recognized condition.

The cervical (extracranial) internal carotid artery is affected in 75% of patients (usually approximately 2 cm distal to the bifurcation) and the extracranial vertebral artery in 15% of patients. The remaining cases usually involve the intracranial internal carotid artery, intracranial vertebral artery, middle cerebral artery, or basilar artery. Cervicocephalic dissections may occur spontaneously or secondary to major or minor trauma. In some patients, they are associated with an underlying arteriopathy. Fifteen percent of cases are bilateral, and one half of these occur in patients with underlying fibromuscular dysplasia.

Pathophysiology

The hallmark of dissection is hemorrhage within the vessel wall. In some patients, an intimal tear allows intravascular blood to communicate directly with the vessel wall cavity. In others, an intramural hematoma develops without a direct connection with the vessel lumen.

In extracranial carotid and vertebral dissections, hemorrhage into the medial-adventitial layers occurs most commonly. This occasionally causes the external vessel wall to bulge outward, forming a dissecting aneurysm that can compress local structures. In intracranial carotid and vertebral dissections, subintimal tears occur more commonly, leading to formation of intramural hematomas that protrude inward and narrow the vessel lumen. Most ischemic symptoms (85-95%) are caused by emboli from the site of the dissection, while the remainder are due to vessel narrowing with hemodynamic insufficiency (5-15%).

Frequency

United States

Hospital-based series suggest that cervicocephalic dissections are responsible for 1-2.5% of ischemic strokes in the general population and for 5-20% of strokes in individuals younger than 45 years. In one community-based study, the average annual incidence of spontaneous cervical internal carotid artery dissections was 2.6 cases per 100,000. While improved imaging techniques and growing awareness of the disorder have led to increased recognition of these syndromes, mild cases likely will remain undiagnosed.

International

International frequency of dissection syndromes is similar to that in the United States.

Mortality/Morbidity

Morbidity and mortality of cervicocephalic dissections vary according to the vessel and location of the dissection. Death rates for extracranial carotid and vertebral dissections are approximately 5-10%. In contrast, mortality rates for intracranial carotid and basilar dissections approach 70% or higher.

Race

No racial preponderance is demonstrated.

Sex

While males and females are affected equally in extracranial carotid dissections, intracranial dissections are more common in younger males than in females. Extracranial vertebral artery dissections and multiple vessel dissections are more common in women than in men.

Age

Persons of all ages may be affected; however, dissections occur more frequently in younger individuals. In extracranial carotid dissection, 70% of cases occur in persons aged 35-50 years. Intracranial carotid dissection tends to occur particularly in adolescents and adults younger than 30 years.

Clinical

History

• The most frequent presenting complaints with cervicocephalic dissections are ischemic symptoms that include transient ischemic attack (TIA) or stroke (cerebrovascular accident).
• Up to two thirds of patients complain of ipsilateral neck, scalp, or head pain, occurring in both carotid and vertebral artery dissections.
• Up to one fourth of patients report pulsatile tinnitus or a subjective bruit, particularly with carotid artery dissections.

Physical

• Extracranial carotid artery
  • Cerebral ischemia occurs in at least 75% of reported cases (TIAs in 30%, infarcts in 45-50%).
  • Neurologic deficits reflect the ultimate site of ischemia in the ipsilateral anterior circulation.
  • In extracranial carotid dissections, local symptoms may occur as the intramural hematoma expands outward, compressing local structures.
  • Examination findings may include the following:
    • Ipsilateral partial Horner syndrome (32-82% of patients in various series)
    • Ipsilateral cranial nerve palsies, particularly cranial nerves IX, X, XI, and XII (5-12% of patients in various series)
    • Audible bruit (up to 20% of patients)
• Intracranial carotid artery
  • Patients with intracranial carotid dissections usually present with headache followed by a major ischemic stroke.
  • Some patients initially may present with a seizure, syncope, or altered level of consciousness.
  • One fifth of patients develop subarachnoid hemorrhage.
• Extracranial vertebral artery
  • This dissection is characterized by headache (often occipital) or neck pain and signs of ischemia in the posterior circulation.
  • Infarcts in the territory of the posterior inferior cerebral artery (commonly with a lateral medullary syndrome) are frequent.
• Intracranial vertebrobasilar dissection: This dissection may present with symptoms of posterior circulation ischemia (particularly brainstem), subarachnoid hemorrhage (occurs in one half of patients), or both.

Causes

• Major blunt trauma to the head and neck can produce cervicocephalic dissection. In spontaneous dissections (dissection in absence of major trauma), a history of minor trauma is a precipitating factor in at least 25% of dissections. The remaining cases appear to be truly spontaneous.
• Types of trauma associated with cervicocephalic dissections include chiropractic neck manipulations, sporting activities, coughing, sneezing, sexual activity, and more intense forms of blunt trauma (eg, motor vehicle accidents, falls, strangulation, hanging).
• Arteriopathies have been associated with cervicocephalic dissections.
  • Fibromuscular dysplasia (the most common underlying arteriopathy, found in as many as 15% of patients)
  • Extreme vessel tortuosity
  • Marfan syndrome
  • Ehlers-Danlos syndrome
  • Alpha-1-antitrypsin deficiency
  • Cystic medial necrosis
  • Type 1 collagen point mutation
  • Other connective tissue disorders
  • Moyamoya disease
  • Meningovascular syphilis
• Associations also have been reported with systemic infections, hypertension, migraine, elevated homocysteine levels, alcohol use, and oral contraceptive use.

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