Carotid artery dissection | |
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Specialty | Vascular surgery |
Carotid artery dissection is a separation of the layers of the artery wall in the carotid arteries supplying oxygen-bearing blood to the head. It is the most common cause of stroke in younger adults. [1] The term 'cervical artery dissection' should also be considered in the context of this article. [2]
The carotid arteries are a pair of large bore arteries in the neck, they further divide into smaller vessels, the external and internal carotids on both the right and left side of the head/neck. [3] Carotid arterial dissections occur when a tear or rip in the layers of the carotid arterial wall allows blood to flow between the layers of the artery. Artery dissection is not unique to the carotid artery system and can happen in numerous arteries in the body.
Blood within the walls of a dissected artery can compromise the flow of blood, leading to a slowing of oxygenated blood flow to the brain, complete blockage, or clot creation inducing a full blown stroke. [4]
Dissection may occur after direct physical trauma, traffic collision, strangulation, or any phenomenon that causes hyperextension of the neck. They can also happen spontaneously. [5] [6]
The signs and symptoms of carotid artery dissection may be divided into ischemic and non-ischemic categories: [7] [8]
Non-ischemic signs and symptoms:
Ischemic signs and symptoms:
The causes of carotid artery dissection can be broadly categorized into two classes: spontaneous or traumatic. [10]
Once considered uncommon, spontaneous carotid artery dissection is an increasingly recognized cause of stroke that preferentially affects the middle-aged. [11] [12]
The incidence of spontaneous carotid artery dissection is low, and incidence rates for internal carotid artery dissection have been reported to be around 2.6 to 2.9 incidents per 100,000. [13] Though the incidence is low - it is the cause of the vast majority of strokes in young people. [14]
Observational studies and case reports published since the early 1980s show that patients with spontaneous internal carotid artery dissection may also have a history of stroke in their family and/or hereditary connective tissue disorders, such as Marfan syndrome, Ehlers-Danlos syndrome, autosomal dominant polycystic kidney disease, pseudoxanthoma elasticum, fibromuscular dysplasia, and osteogenesis imperfecta type I. [15] IgG4-related disease involving the carotid artery has also been observed as a cause. [16]
However, although an association with connective tissue disorders does exist, most people with spontaneous arterial dissections do not have associated connective tissue disorders. Also, the reports on the prevalence of hereditary connective tissue diseases in people with spontaneous dissections are highly variable, ranging from 0% to 0.6% in one study to 5% to 18% in another study. [15]
Internal carotid artery dissection can also be associated with an elongated styloid process (known as Eagle syndrome when the elongated styloid process causes symptoms). [17] [18]
Carotid artery dissection is thought to be more commonly caused by severe violent trauma to the head and/or neck. An estimated 0.67% of patients admitted to the hospital after major motor vehicle accidents were found to have blunt carotid injury, including intimal dissections, pseudoaneurysms, thromboses, or fistulas. [19] Of these, 76% had intimal dissections, pseudoaneurysms, or a combination of the two. Sports-related activities such as surfing [20] and Jiu-Jitsu [21] have been reported as causes of carotid artery dissection.
The probable mechanism of injury for most internal carotid injuries is rapid deceleration, with resultant hyperextension and rotation of the neck, which stretches the internal carotid artery over the upper cervical vertebrae, producing an intimal tear. [19] After such an injury, the patient may remain asymptomatic, have a hemispheric transient ischemic event, or have a stroke. [22]
Artery dissection has also been reported in association with some forms of neck manipulation. [5] There is significant controversy about the level of risk of stroke from neck manipulation. It may be that manipulation can cause dissection, [23] or it may be that the dissection is already present in some people who seek manipulative treatment. [24]
Arterial dissection of the carotid arteries is a condition that arises when a small tear forms in the innermost lining of the arterial wall, known as the tunica intima. This tear allows blood to enter the space between the inner and outer layers of the vessel, leading to either narrowing (stenosis) or complete occlusion. Notably, the stenosis in the early stages of arterial dissection is a dynamic process, and some occlusions can quickly transition back to stenosis. When complete occlusion occurs, it can result in ischemia, a condition characterized by insufficient blood supply to a particular area. [25]
It is interesting to note that even in cases of complete occlusion, symptoms may not always be evident due to the presence of collateral circulation, which helps to adequately perfuse the brain. However, complications can arise when blood clots develop at the site of the tear and subsequently break off, forming emboli. These emboli can then travel through the arteries and reach the brain, where they may block the blood supply. This blockage leads to an ischemic stroke, also known as a cerebral infarction. [26] In fact, it is believed that blood clots or emboli originating from the dissection are responsible for causing infarctions in the majority of cases involving strokes in the presence of carotid artery dissection. [27] [28]
Cerebral infarction, as a result of carotid artery dissection, can cause irreversible damage to the brain. Studies have demonstrated a significant number of patients with dissections do go on to experience full blown strokes, often some time after the original dissection event. [29] [30] This emphasizes the serious and potentially life-altering consequences associated with this condition.
The goal of treatment is to prevent the development of an actual stroke or limit the continuation of neurologic deficits should a stroke occur after dissection. Treatments include observation, anti-platelet agents, anticoagulation, stent implantation, carotid endarterectomy, and carotid artery ligation. [10] [31]
Carotid dissections events can occur at any age. They tend to occur more often in younger individuals - under 50. Such events are slightly more common in men than in women. [32] Spontaneous internal carotid artery dissection is a rare event with an incidence rate of approximately 2.6 to 2.9 per 100,000 individuals. However, such events account for ~5% to ~22% of strokes in patients under the age of 45 years. [33]
A transient ischemic attack (TIA), commonly known as a mini-stroke, is a minor stroke whose noticeable symptoms usually end in less than an hour. TIA causes the same symptoms associated with strokes, such as weakness or numbness on one side of the body, sudden dimming or loss of vision, difficulty speaking or understanding language, slurred speech, or confusion.
Cerebrovascular disease includes a variety of medical conditions that affect the blood vessels of the brain and the cerebral circulation. Arteries supplying oxygen and nutrients to the brain are often damaged or deformed in these disorders. The most common presentation of cerebrovascular disease is an ischemic stroke or mini-stroke and sometimes a hemorrhagic stroke. Hypertension is the most important contributing risk factor for stroke and cerebrovascular diseases as it can change the structure of blood vessels and result in atherosclerosis. Atherosclerosis narrows blood vessels in the brain, resulting in decreased cerebral perfusion. Other risk factors that contribute to stroke include smoking and diabetes. Narrowed cerebral arteries can lead to ischemic stroke, but continually elevated blood pressure can also cause tearing of vessels, leading to a hemorrhagic stroke.
Ischemia or ischaemia is a restriction in blood supply to any tissue, muscle group, or organ of the body, causing a shortage of oxygen that is needed for cellular metabolism. Ischemia is generally caused by problems with blood vessels, with resultant damage to or dysfunction of tissue i.e. hypoxia and microvascular dysfunction. It also implies local hypoxia in a part of a body resulting from constriction. Ischemia causes not only insufficiency of oxygen, but also reduced availability of nutrients and inadequate removal of metabolic wastes. Ischemia can be partial or total blockage. The inadequate delivery of oxygenated blood to the organs must be resolved either by treating the cause of the inadequate delivery or reducing the oxygen demand of the system that needs it. For example, patients with myocardial ischemia have a decreased blood flow to the heart and are prescribed with medications that reduce chronotrophy and ionotrophy to meet the new level of blood delivery supplied by the stenosed vasculature so that it is adequate.
Vascular surgery is a surgical subspecialty in which vascular diseases involving the arteries, veins, or lymphatic vessels, are managed by medical therapy, minimally-invasive catheter procedures and surgical reconstruction. The specialty evolved from general and cardiovascular surgery where it refined the management of just the vessels, no longer treating the heart or other organs. Modern vascular surgery includes open surgery techniques, endovascular techniques and medical management of vascular diseases - unlike the parent specialities. The vascular surgeon is trained in the diagnosis and management of diseases affecting all parts of the vascular system excluding the coronaries and intracranial vasculature. Vascular surgeons also are called to assist other physicians to carry out surgery near vessels, or to salvage vascular injuries that include hemorrhage control, dissection, occlusion or simply for safe exposure of vascular structures.
Cerebral angiography is a form of angiography which provides images of blood vessels in and around the brain, thereby allowing detection of abnormalities such as arteriovenous malformations and aneurysms. It was pioneered in 1927 by the Portuguese neurologist Egas Moniz at the University of Lisbon, who also helped develop thorotrast for use in the procedure.
A thunderclap headache is a headache that is severe and has a sudden onset. It is defined as a severe headache that takes seconds to minutes to reach maximum intensity. Although approximately 75% are attributed to "primary" headaches—headache disorder, non-specific headache, idiopathic thunderclap headache, or uncertain headache disorder—the remainder are secondary to other causes, which can include some extremely dangerous acute conditions, as well as infections and other conditions. Usually, further investigations are performed to identify the underlying cause.
Moyamoya disease is a disease in which certain arteries in the brain are constricted. Blood flow is blocked by constriction and blood clots (thrombosis). A collateral circulation develops around the blocked vessels to compensate for the blockage, but the collateral vessels are small, weak, and prone to bleeding, aneurysm and thrombosis. On conventional angiography, these collateral vessels have the appearance of a "puff of smoke".
Carotid endarterectomy is a surgical procedure used to reduce the risk of stroke from carotid artery stenosis. In endarterectomy, the surgeon opens the artery and removes the plaque. The plaque forms and thickens the inner layer of the artery, or intima, hence the name of the procedure which simply means removal of part of the internal layers of the artery.
Carotid artery stenosis is a narrowing or constriction of any part of the carotid arteries, usually caused by atherosclerosis.
Cerebral infarction is the pathologic process that results in an area of necrotic tissue in the brain. It is caused by disrupted blood supply (ischemia) and restricted oxygen supply (hypoxia), most commonly due to thromboembolism, and manifests clinically as ischemic stroke. In response to ischemia, the brain degenerates by the process of liquefactive necrosis.
Vertebrobasilar insufficiency (VBI) describes a temporary set of symptoms due to decreased blood flow (ischemia) in the posterior circulation of the brain. The posterior circulation supplies the medulla, pons, midbrain, cerebellum and supplies the posterior cerebellar artery to the thalamus and occipital cortex. As a result, symptoms vary widely depending which brain region is predominantly affected.
A watershed stroke is defined as a brain ischemia that is localized to the vulnerable border zones between the tissues supplied by the anterior, posterior and middle cerebral arteries. The actual blood stream blockage/restriction site can be located far away from the infarcts. Watershed locations are those border-zone regions in the brain supplied by the major cerebral arteries where blood supply is decreased. Watershed strokes are a concern because they comprise approximately 10% of all ischemic stroke cases. The watershed zones themselves are particularly susceptible to infarction from global ischemia as the distal nature of the vasculature predisposes these areas to be most sensitive to profound hypoperfusion.
Fibromuscular dysplasia (FMD) is a non-atherosclerotic, non-inflammatory disease of the blood vessels that causes abnormal growth within the wall of an artery. FMD has been found in nearly every arterial bed in the body, although the most commonly affected are the renal and carotid arteries.
Vertebral artery dissection (VAD) is a flap-like tear of the inner lining of the vertebral artery, which is located in the neck and supplies blood to the brain. After the tear, blood enters the arterial wall and forms a blood clot, thickening the artery wall and often impeding blood flow. The symptoms of vertebral artery dissection include head and neck pain and intermittent or permanent stroke symptoms such as difficulty speaking, impaired coordination, and visual loss. It is usually diagnosed with a contrast-enhanced CT or MRI scan.
Carotid artery stenting is an endovascular procedure where a stent is deployed within the lumen of the carotid artery to treat narrowing of the carotid artery and decrease the risk of stroke. It is used to treat narrowing of the carotid artery in high-risk patients, when carotid endarterectomy is considered too risky.
Eagle syndrome is an uncommon condition commonly characterized but not limited to sudden, sharp nerve-like pain in the jaw bone and joint, back of the throat, and base of the tongue, triggered by swallowing, moving the jaw, or turning the neck. First described by American otorhinolaryngologist Watt Weems Eagle in 1937, the condition is caused by an elongated or misshapen styloid process and/or calcification of the stylohyoid ligament, either of which interferes with the functioning of neighboring regions in the body, such as the glossopharyngeal nerve.
Ocular ischemic syndrome is the constellation of ocular signs and symptoms secondary to severe, chronic arterial hypoperfusion to the eye. Amaurosis fugax is a form of acute vision loss caused by reduced blood flow to the eye; it may be a warning sign of an impending stroke, as both stroke and retinal artery occlusion can be caused by thromboembolism due to atherosclerosis elsewhere in the body. Consequently, those with transient blurring of vision are advised to urgently seek medical attention for a thorough evaluation of the carotid artery. Anterior segment ischemic syndrome is a similar ischemic condition of anterior segment usually seen in post-surgical cases. Retinal artery occlusion leads to rapid death of retinal cells, thereby resulting in severe loss of vision.
Lacunar stroke or lacunar cerebral infarct (LACI) is the most common type of ischemic stroke, resulting from the occlusion of small penetrating arteries that provide blood to the brain's deep structures. Patients who present with symptoms of a lacunar stroke, but who have not yet had diagnostic imaging performed, may be described as having lacunar stroke syndrome (LACS).
Cervical artery dissection is dissection of one of the layers that compose the carotid and vertebral artery in the neck (cervix). They include:
Posterior spinal artery syndrome(PSAS), also known as posterior spinal cord syndrome, is a type of incomplete spinal cord injury. PSAS is the least commonly occurring of the six clinical spinal cord injury syndromes, with an incidence rate of less than 1%.
In persons younger than 45 years, there is an association between chiropractic care and vertebro-basilar artery (VBA) stroke; there is a similar association between family physician care and VBA stroke. This suggests that there is no increased risk of VBA stroke after chiropractic care, and that these associations are likely due to patients with headache and neck pain from vertebral artery dissection seeking care while in the prodromal stage of a VBA stroke. Unfortunately, there is no practical or proven method to screen patients with neck pain and headache for vertebral artery dissection. However, VBA strokes are extremely rare, especially in younger persons.