Background

Carotid artery dissection involves a tear in one of the carotid arteries, which are the major blood vessels that supply oxygenated blood to the brain, neck, and face. There are two carotid arteries on each side of the neck, commonly referred to as the internal and external carotid arteries.

The most common cause of carotid artery dissection is trauma, such as a sudden and forceful movement of the neck, like a car accident or a sports injury. However, spontaneous dissections can also occur without any apparent trauma. Underlying conditions like connective tissue disorders or genetic factors may contribute to spontaneous dissections. 

Epidemiology

Carotid artery dissection is generally considered to be a rare condition. The incidence can vary, but estimates suggest it occurs in a range of 2 to 3 per 100,000 people per year. However, this figure may be underestimated as mild cases may go undiagnosed or be misattributed to other causes. Carotid artery dissection can affect individuals of any age, but it often occurs in younger adults.

There is a slight male predominance, with men being more commonly affected than women. The condition can also occur in children, although it is less common in this age group. Trauma is a common precipitating factor for carotid artery dissection, and it often occurs after activities that involve sudden and forceful movements of the neck, such as car accidents or sports injuries. However, a significant proportion of cases are considered spontaneous, meaning they occur without an identifiable trauma. 

Anatomy

Pathophysiology

A sudden rupture in the intimal layer of the carotid artery can occur due to various factors, including trauma or spontaneous events. This tear allows blood to infiltrate the intimal layer, leading to the formation of a hematoma within the blood vessel wall, commonly referred to as a false lumen.

As blood enters this false lumen, it induces stenosis, potentially resulting in the complete blockage of the carotid artery. This process is dynamic and may result in either stenosis of the vessel or dilation of the artery, depending on the direction of hematoma development—toward the adventitia or intima. 

This dynamic process may pose a risk of stroke due to complete vascular occlusion at the dissection site. Additionally, the hematoma can serve as a nidus for thrombus formation, which may subsequently migrate distally, leading to a transient ischemic attack or stroke. In cases where the vessel ruptures intracranially, a subarachnoid hemorrhage may occur. Furthermore, a carotid dissection can give rise to a pseudoaneurysm.  

It is crucial to recognize that this pathological sequence presents a complex and potentially serious medical condition, with the potential for various complications such as stroke, subarachnoid hemorrhage, transient ischemic attack, and pseudoaneurysm formation. 

Etiology

Traumatic Causes: 

• Physical Trauma: Carotid artery dissection often occurs as a result of direct physical trauma to the neck, such as during accidents, sports injuries, or falls. Sudden, forceful movements can lead to tears in the carotid artery’s intimal layer. 
• Whiplash Injury: Rapid acceleration or deceleration, as seen in whiplash injuries, can also contribute to carotid artery dissection. The abrupt neck movements may lead to mechanical stress on the blood vessel walls. 

Non-Traumatic Causes: 

• Spontaneous Dissection: In some cases, carotid artery dissection can occur without any apparent trauma. Spontaneous dissections may be associated with underlying connective tissue disorders, such as Ehlers-Danlos syndrome Marfan syndrome, or other conditions affecting blood vessel integrity. 
• Genetic Factors: There may be a genetic predisposition to arterial dissections, and individuals with a family history of arterial dissections may be at an increased risk. 
• Inflammatory Conditions: Certain inflammatory conditions, such as arteritis, may weaken the arterial walls, making them more susceptible to dissection. 
• Infection: In rare cases, infections affecting the blood vessels may contribute to arterial dissections. 
• Fibromuscular Dysplasia: This is a non-inflammatory, non-atherosclerotic vascular disease that can affect the carotid arteries and increase the risk of dissection. 

Mechanical Stress Factors: 

• Hyperextension or Hyperflexion of the Neck: Activities or positions that involve extreme neck movements, either hyperextension or hyperflexion, may contribute to mechanical stress on the carotid arteries. 
• Vascular Anomalies: Abnormalities in the structure of the carotid arteries, such as redundancy or tortuosity, may make them more susceptible to dissection. 

Genetics

Prognostic Factors

The prognosis for individuals with carotid artery dissection varies depending on factors such as the extent of the dissection, the rapidity of diagnosis and treatment, and the presence of any underlying medical conditions. 

Clinical History

Inquire about any recent trauma to the neck, such as a car accident, sports injury, or a fall. Alternatively, some cases may be spontaneous, without an apparent cause. The patient may have a medical history of any underlying conditions that might predispose them to arterial dissections, such as connective tissue disorders (Ehlers-Danlos syndrome, Marfan syndrome), fibromuscular dysplasia, or a family history of arterial dissections.

Assess for vascular risk factors like hypertension, smoking, and a history of migraines, as they may contribute to the susceptibility of arterial dissection. Symptoms often have a sudden onset, primarily if the dissection is related to trauma. Spontaneous dissections may have a more gradual onset of symptoms. The duration of symptoms can vary.

Some individuals may experience a rapid progression of symptoms, while others may have a more gradual evolution. The duration is influenced by factors such as the extent of the dissection and the development of complications.

Neck Pain: Sudden and severe neck pain is a common symptom, often described as sharp or stabbing. The pain may be localized to the side of the dissection. 

Headache: Individuals with carotid artery dissection may experience a sudden and severe headache, which can be similar to a migraine or cluster headache. 

Neurological Symptoms: Depending on the location and extent of the dissection, patients may exhibit neurological symptoms, such as: 

• Unilateral weakness or numbness 
• Visual disturbances 
• Difficulty speaking or understanding speech 
• Coordination problems

Horner Syndrome: This occurs when there is disruption to sympathetic nerve fibers and may manifest as ptosis (drooping of the upper eyelid), miosis (constricted pupil), and anhidrosis (lack of sweating) on the affected side of the face. 

Transient Ischemic Attack (TIA) or Stroke: Carotid artery dissection can lead to the development of blood clots, which may embolize the brain, causing a TIA or stroke. Symptoms can include sudden weakness, numbness, or difficulty speaking. 

Physical Examination

Comparing pulses on both sides of the neck may reveal a difference in strength or quality. A weaker or delayed pulse on one side could indicate compromised blood flow due to dissection. Measuring blood pressure in both arms is important. A significant difference in blood pressure between the arms may be a sign of impaired blood flow on the side of the dissection.

Bruits (abnormal sounds) may be audible over the affected carotid artery. These sounds may result from turbulent blood flow caused by the dissection. Ophthalmic examination may reveal signs of retinal ischemia, such as a cherry-red spot or other abnormalities.

Focused neurological examination may reveal signs of stroke, transient ischemic attack (TIA), or other neurological deficits. These may include weakness, numbness, coordination problems, or speech abnormalities. Localized tenderness or swelling over the carotid artery region may be present, especially if there is an inflammatory component to the dissection. 

Age group

Associated comorbidity

Associated activity

Acuity of presentation

Differential Diagnoses

• Cluster headache 
• Herpes simplex 
• Hemorrhagic stroke 
• Migraine headache 
• Retinal vein occlusion 
• Tension headache 
•  

Laboratory Studies

Imaging Studies

Procedures

Histologic Findings

Staging

Treatment Paradigm

The approach to treating cervical artery dissection is contingent upon several variables, including the etiology (traumatic or spontaneous), the presence of a previous stroke, and the location of the dissection (intracranial or extracranial). Treatment decisions are also influenced by factors such as active bleeding with hematoma expansion.

In cases without contraindications, antiplatelet agents or, more commonly, systemic anticoagulation may be prescribed to mitigate the risk of stroke. Additionally, endovascular stenting may be considered, particularly when anticoagulation is contraindicated or if initial medical management proves ineffective. It is noteworthy that the one-year recurrence rate stands at 0-10% 

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References