Clinical manifestations

Presentation and course

The neurologic sequelae of aortic diseases mainly depend on the location of the aortic lesion and the affected resultant area of the nervous system, rather than the specific aortic disease process. Hence, diseases involving the aortic arch may produce cortical symptoms, involvement of the thoracic aorta may cause spinal cord injury, and involvement of the abdominal aorta may result in peripheral nerve injury and sexual dysfunction. Although this anatomical distinction mostly holds, involvement of the distal aorta (such as in type B dissections) does not preclude the occurrence of cortical symptoms and ischemic strokes. These may still occur secondary to cerebral hypoperfusion, which may result iatrogenically (01).

Cerebral and brainstem ischemia. Diseases involving the aortic arch can result in transient ischemic attacks or strokes due to occlusion of one or more proximal branches of the aorta or embolization of atheroma/thrombus. The specific neurologic syndromes produced depend on the location and duration of the impaired blood flow within the cerebral vasculature.

Aortic diseases that impair blood flow in the brachiocephalic artery or left subclavian artery can produce a steal phenomenon, whereby the usual cephalad direction of blood flow in the ipsilateral vertebral artery is reversed, thus, “stealing” blood from the basilar artery. Patients may present with symptoms due to hypoperfusion of the posterior circulation, such as vertigo, visual deficits, or syncope. This is particularly evident when blood flow is increased in the affected arm during exercise. Proximal blockage of the brachiocephalic artery could also potentially cause right hemispheric anterior circulation ischemia via reversal of blood flow in the right common carotid artery. However, the majority of patients with documented reversal of flow are asymptomatic other than a difference in blood pressure (greater than 15 mm Hg) between both arms. This is mainly secondary to robust collateral flow from the circle of Willis. A markedly elevated pressure difference (greater than 40 to 50 mm Hg) is more likely to be associated with symptoms as this reflects a significant diversion of blood to the arm from the posterior circulation, resulting in vertebrobasilar insufficiency (39).

Spinal cord ischemia. Spinal cord ischemia may be caused by embolization, reduced blood flow in critical feeding vessels, or aortic hypotension. Within the spinal cord, certain vascular territories are selectively affected.

The anterior spinal artery, which supplies blood to the spinal gray matter and the white matter tracts in the anterior and lateral regions of the cord, is particularly prone to ischemic injury. Ischemia in this arterial territory results in diminished pain and temperature sensation while preserving vibratory and joint position sense governed by the posterior columns. Bilateral weakness occurs below the level of the lesion, often in association with other upper motor neuron signs, such as spasticity, hyperreflexia, or an extensor plantar response. Dysfunction of the bowel and bladder may occur. Involvement of segmental gray matter may also result in lower motor neuron signs at the level of the lesion, such as depressed tendon reflexes and amyotrophy. The level affected dictates the clinical symptoms. The anterior spinal artery syndrome generally presents abruptly but can have a more insidious and progressive course.

In rare instances, diseases of the aorta can result in a more restricted syndrome of cord ischemia limited to the gray matter supplied by the sulcal branches of the anterior spinal artery. Clinical impairment in these cases is often confined to the motor system and is associated with amyotrophy at the affected segmental levels. If the clinical onset is gradual, the presentation can resemble diseases such as amyotrophic lateral sclerosis or tumors of the spinal cord.

Selective ischemia of the posterior spinal circulation is characterized by loss of posterior column function with sparing of other sensory and motor functions. This syndrome is rare, likely reflecting the more significant number of feeding vessels and better anastomotic connections in this arterial system, which affords protection against ischemic damage.

Intermittent claudication. Difficulty walking that is elicited by the use of the lower extremities can occur due to ischemia of the spinal cord or cauda equina. Unlike classical claudication from peripheral arterial disease, the arterial pulses in the legs are preserved in this type of claudication, and associated pain may be dysesthetic, paresthetic, or absent. Lower-extremity neurologic symptoms are frequently present, especially after exercise. When the cauda equina is selectively involved, the sensory complaints are often radicular, and signs of cord involvement are not present. Clinical distinction between different types of neurogenic claudication can be difficult. However, spinal cord ischemia causing intermittent neurologic symptoms (such as transient paraplegia) is more frequently associated with intrinsic diseases of the aorta (15).

Peripheral nerve dysfunction and sexual dysfunction associated with diseases of the aorta. Aortic disease can cause neurologic symptoms through compression of nerve roots (within the cauda equina or root exist zones), the brachial plexus, or peripheral nerves. For example, the nerve roots of L4-S2 lie under the terminal aorta and iliac arteries; compression can result in unilateral radiating pain and a pattern of sensory and motor findings typical of radicular disease. The left recurrent laryngeal nerve wraps around the aortic arch; thus, diseases or aortic surgery may compress this nerve, producing a hoarse, low-pitched voice.

Aortic disease can also produce peripheral nerve dysfunction via an ischemic mechanism. Wilbourn and colleagues described "ischemic monomelic neuropathy" in one limb following sudden occlusion of a major vessel; for example, one patient had a saddle embolus to the distal aorta occluding the right common iliac artery (54). This syndrome consists of a predominantly axonal sensory neuropathy with a distal gradient affecting all sensory modalities and associated with deep, causalgia-like pain. Aortoiliac procedures can also produce ischemic neuropathy of the lumbosacral plexus and, thus, lower limb paralysis.

Sexual function in men may be impaired by aortic disease or surgery, mainly when the disease or operation involves the aortic bifurcation, which is closely associated with the sympathetic nerves of the superior hypogastric plexus. Ejaculation is commonly affected. Erection can be impaired by sympathetic dysfunction, reduced blood flow through the internal pudendal artery and penis, or from cavernovenous leakage.

Classic presentations of specific diseases of the aorta are listed below. A full description of non-neurologic symptoms is beyond the scope of this review.

Aortic dissection. Aortic thoracic dissection frequently presents with acute pain (classically radiating to the back), diminished peripheral pulses, or a greater than 20 mm Hg blood pressure difference between the arms, hypotension, aortic regurgitation murmur, and syncope (17). In ascending (type A) aortic dissection, the most frequent neurologic manifestation is ischemic stroke. Recurrent TIAs have also been reported as an initial presenting symptom. By contrast, descending (type B) dissection causes spinal cord infarction and ischemic neuropathy. There are case reports of aortic dissection presenting as pure transient global amnesia, although the pathogenic link remains unclear (33). Other neurologic deficits include Horner syndrome from compression of the superior cervical ganglion, hoarseness from recurrent laryngeal nerve compression, or acute paraplegia from spinal cord compression. It is imperative to recognize that aortic dissection presents with predominantly neurologic deficits and an absence of chest pain in 5% to 15% of patients (36).

Aortic aneurysm. Aneurysmal disease is generally clinically silent, except in cases of rapid expansion or dissection/rupture. Aneurysms may be associated with pain. Aneurysms of the aortic arch can present with heart failure from aortic regurgitation. Aortic aneurysm may cause stroke via a thromboembolic mechanism or may cause neurologic symptoms via compressive effect, such as radiculopathy by compression of a vertebral body. Neurologic symptoms are often due to aneurysmal rupture or direct compression of neural structures rather than CNS ischemia as abdominal aneurysms are generally situated below the important feeding vessels of the cord. Nevertheless, paraplegia can result from bony erosion through the vertebral bodies and direct compression of the spinal cord or cauda equina.

Aortitis. Systemic symptoms such as fever, night sweats, fatigue, and weight loss may characterize infectious and noninfectious aortitis. Giant-cell arteritis classically presents with headache, temporal scalp tenderness, jaw claudication, and vision loss. In contrast, Takayasu aortitis may present with concomitant arthralgias, limb claudication, unequal pulses, hypertension secondary to renal artery stenosis, and chest or abdominal pain due to cardiac/mesenteric ischemia. Aortitis can present with cerebral or spinal ischemia, depending on the segment involved.

Aortic coarctation. Coarctation of the aorta can cause ischemic stroke, either in the setting of isolated congenital heart disease or PHACE syndrome (posterior fossa brain malformations, hemangiomas, arterial anomalies, coarctation of the aorta and cardiac defects, and eye abnormalities). Coarctation can cause a variety of neurologic symptoms, including headache, ruptured intracranial aneurysms, hemorrhage, episodic loss of consciousness, and neurogenic claudication. Coarctation can also produce a spinal cerebral steal syndrome distal to the aortic stenosis.

Aortic occlusion. Acute aortic occlusion can present with back pain and monoplegia. Painless paraplegia due to spinal cord ischemia can be a presenting sign of acute occlusion. Acute ascending aortic thrombosis can give rise to anterior spinal syndrome. Femoral pulses are classically absent in such cases. It should be differentiated from peripheral nerve ischemia, which can present similarly but with intact pulses. Concomitant occurrence of aortic thrombosis and anterior spinal artery syndrome may mask the pain usually associated with aortic occlusion. Patients with subacute or chronic descending aortic thrombosis or advanced atherosclerosis classically present with Leriche syndrome (intermittent calf, thigh, or hip claudication associated with impotence). Aortic occlusive disease can also produce peripheral nerve injury.

Prognosis and complications

Mortality associated with aortic disease is high. For example, the mortality rate of ruptured abdominal aortic aneurysm (AAA) is approximately 90%. If left untreated, the mortality rate of acute aortic dissection exceeds 50% within 48 hours (21).

Patients who present with a stroke due to aortic dissection have higher in-hospital morbidity than those without neurologic impairment; however, long-term survival is similar, with acceptable neurologic outcomes (16; 06). In fact, in one study, more than half of the patients recovered completely from their initial neurologic deficit (34).

The severity of spinal cord infarction can be graded by the American Spinal Injury Association (ASIA) impairment scale, which assigns a letter grade to the degree of motor and sensory function below the level of injury (03). A lower letter signifies a poorer prognosis for recovery. Patients with flaccid paralysis have higher mortality and are unlikely to recover the ability to ambulate (09), whereas those with some degree of motor function have no increase in mortality, and most eventually recover the ability to walk. High cervical lesions, a more significant degree of impairment at baseline, older age, and lack of early improvement are associated with worsened outcomes. Of note, there is a long potential period for recovery (41).

Clinical vignette

Abdominal aortic aneurysm presenting as a radiculopathy. Six months prior to admission, a 79-year-old man developed persistent lower back pain that radiated into both lower extremities. Three months before admission, routine x-ray evaluation of the lumbar spine was within normal limits. One month prior to admission, the patient underwent a lumbar laminectomy, which provided no substantial relief of symptoms. Subsequently, the patient complained of increasing pain and weakness in both lower extremities. On admission to the hospital, examination demonstrated a pulsatile mass in the hypogastric region. In addition, there was generalized weakness and amyotrophy in both lower extremities. Deep tendon reflexes in the lower extremities were absent. Sensory examination was normal. Repeat x-rays at this time demonstrated destruction of the anterior aspects of the L3, L4, and L5 vertebral bodies. Aortography of the distal aorta revealed a fusiform aneurysm and a sizeable saccular aneurysm compressing the vertebral bodies at these three segmental levels. Because of concurrent medical comorbidities, the patient was not considered an operative candidate. He rapidly progressed to complete paraplegia and died shortly after that from bronchopneumonia.

Biological basis

Etiology and pathogenesis

Atherosclerosis. Atherosclerosis of the aortic arch or thoracic aorta is associated with stroke. Arch atheroma that is greater than or equal to 4 mm in thickness, ulcerated, or lipid-rich is mainly associated with cerebrovascular disease, especially in cryptogenic stroke patients (11). Embolization may occur spontaneously or as the result of arterial manipulation during surgical or endovascular procedures. Atheroma within the proximal portion of the descending aorta (ie, less than 30 mm beyond the outlet of the left subclavian artery) can result in cerebral embolization due to flow reversal (53).

Aortitis. Aortitis refers to inflammation of the intimal or medial layers of the aortic wall. Aortitis is broadly classified into infectious (eg, syphilis or seeding of septic emboli) and noninfectious (eg, giant cell aortitis or Takayasu aortitis) etiologies, with the latter being more common. Neurologic sequelae frequently occur secondarily through the development of aneurysmal dilatation or stenosis/occlusion, as well as related complications (eg, dissection, hematoma, ulceration, rupture, or thrombosis).

Aortic aneurysms. An aortic aneurysm of the ascending aorta is defined as the dilation of all aortic wall layers, with a resultant diameter greater than 50% of normal. Any pathological process that causes a weakening of the arterial wall, such as infection, inflammation, or atherosclerosis, can cause nondissecting aortic aneurysms. Thoracic aortic aneurysms can cause infarction by embolization of associated thrombus or atherosclerotic material. They can also cause neurologic symptoms by direct compression of neural structures, such as the recurrent laryngeal nerve. The distribution of aortic aneurysms mirrors the distribution of atherosclerosis; thus, abdominal aortic aneurysms are more common than thoracic.

Aortic dissection. Aortic dissection involves disruption of the medial layer of the aorta, resulting in separation of the wall layers. The pathophysiology of acute aortic dissection is diverse. However, it is generally caused by conditions that place stress on the aortic wall, such as chronic hypertension, Valsalva maneuver, or trauma. Other causes include conditions associated with abnormalities in the medial layer, either inflammatory, infectious, or genetic (ie, Marfan disease, Ehlers-Danlos disease, Loeys-Dietz syndrome, or mutations in smooth-muscle actin) (21). Neurologic involvement occur due to occlusion of the carotid, vertebral, or spinal arteries by the dissection flap, hypoperfusion secondary to shock or tamponade, or from thromboembolization of material from the false lumen. Neurologic symptoms can also occur due to occlusion of the vasa vasorum of peripheral nerves (17).

Coarctation of the aorta. Coarctation of the aorta, in which there is constriction distal to the origin of the left subclavian artery, is a relatively common congenital condition and may also be caused by radiation exposure or Takayasu arteritis. Cerebral infarcts are most likely the result of embolization of thrombotic material from the dilated aorta proximal to the obstruction. Spinal cord ischemia may be caused by the reversal of blood flow in spinal arteries distal to the constriction or by direct compression of the cord by the enlarged proximal radiculomedullary vessels that develop to supply collateral blood flow to the aorta.

Surgery of the aorta. Surgery involving the aorta can be complicated by stroke, spinal cord infarction, or peripheral neuropathy. Potential mechanisms for infarction include intraoperative hypotension, thromboembolization of protruding/mobile aortic arch atheroma, or prolonged aortic cross-clamping. Lower-extremity peripheral nerve ischemia can result from prolonged occlusion of the infrarenal aorta during surgery.

Aortic occlusion. The abdominal aorta below the renal arteries and the iliac axis are the most frequent anatomic sites for developing atherosclerotic occlusive disease, generally affecting nerve roots, lumbar plexus, or peripheral nerves. Occlusion can occur due to embolization (generally from a cardiac source), thrombosis secondary to hypercoagulability, sluggish aortic flow, or atherosclerosis.

Anatomy.

Vascular anatomy of the aortic arch. All major vessels supplying blood to the brain, brainstem, and cervical spinal cord branch off the aortic arch.

The first major branch, the brachiocephalic artery, divides into the right common carotid and right subclavian arteries. The right vertebral artery branches off the right subclavian artery and unites with the left vertebral artery to form the basilar artery and supply blood to the posterior circulation of the brain. The left common carotid artery is the second major branch off the aortic arch, and the third is the left subclavian artery, which gives rise to the left vertebral artery.

Vascular anatomy of the spinal cord. The spinal cord is supplied by three main arteries branching from the vertebral artery: two posterior spinal arteries and one anterior spinal artery. Along the length of the spinal cord, the three main arteries pick up collateral flow from the anterior and posterior radicular arteries. The artery of Adamkiewicz, also known as the “greater anterior medullary artery,” is a unilateral, large, radicular artery that enters between T8 and L4. Because the radicular arteries are spaced further apart in the lower thoracic/high lumbar region, the risk of spinal cord infarction is increased when the artery of Adamkiewicz is occluded.

Rostrally, the single anterior spinal artery is formed by the union of paired branches of the intracranial vertebral arteries.

At different levels, this artery is joined by anterior radiculomedullary arteries.

The anterior spinal artery in the lumbosacral region (T9 to the conus medullaris) derives its blood supply predominantly from the artery of Adamkiewicz.

The anterior spinal artery has both peripheral and sulcal branches.

The sulcal branches supply the gray matter of the anterior horn and deep white matter on each side. The peripheral branches form an anastomotic network of vessels on the anterior surface of the spinal cord–the anterior pial arterial plexus–that supplies the anterior and lateral white matter tracts via penetrating branches.

Branches of the intracranial vertebral arteries also give rise to the paired posterior spinal arteries. They are distinct vessels only at their origin; more caudally, they become intermixed as the posterior pial arterial plexus on the posterior surface of the spinal cord. This plexus is supplied at different levels by 10 to 23 posterior radiculomedullary vessels that accompany the posterior nerve roots. The posterior pial arterial plexus supplies blood to the posterior horns and posterior funiculi. The anastomotic network of the pial arterial plexus confers protection against infarction. The anterior and posterior plexuses are often poorly anastomotic with each other.

Sexual function. Sexual function in men has two components: erection and ejaculation. Erection is mediated mainly by the parasympathetic nervous system via the pelvic splanchnic nerves, which are supplied by spinal segments S2 to S4. Ejaculation has two phases. The first, the expulsion of seminal fluid into the prostatic urethra, is mediated by the sympathetic nervous system. Meanwhile, emission, the second phase, results from the clonic contraction of penile musculature, which is innervated by the somatic pudendal nerves. Efferent sympathetic nerve fibers arise from the intermediate region in the spinal cord and exit with each ventral root between T1 and L2.

Epidemiology

Aortic dissection. Neurologic complications were reported in 17% of patients with type A or B dissection (21). The most common presentations included stroke (8% of patients), coma/encephalopathy (12%), peripheral neuropathy (3%), and spinal cord ischemia (2%) (35). Acute aortic dissection is more likely to occur in men, whereas women tend to be older at the time of diagnosis (05). Risk factors include uncontrolled hypertension and family history. In younger patients, a genetic condition such as Marfan syndrome or Loeys-Dietz may contribute (21).

Aortic aneurysm. Risk factors include Caucasian race, age, male gender, family history, tobacco use, hypertension, and chronic obstructive pulmonary disease (COPD). Interestingly, diabetes appears to play a protective role (44; 38). The risk of rupture increases with size. Other predictors of rupture include tobacco use, hypertension, COPD, and female gender. Abdominal aortic aneurysms are more common than thoracic and affect 4% to 8% of the population; however, less than 1% are larger than 5.5 cm (49).

Aortitis. Giant cell arteritis is the most common noninfectious aortitis, with a lifetime risk of 1% in women and 0.5% in men (10). Over 80% of patients older than 70 years of age, women, and Caucasians are more frequently affected. Takayasu arteritis is an idiopathic condition occurring in young patients, typically with an age of onset of less than 30 years. Asian and Hispanic patients are particularly affected. More than 85% of patients are women. Syphilis historically accounted for nearly half of the infectious mycotic aneurysms; however, the majority currently are Staphylococcus aureus infections.

Aortic atherosclerosis. Arch atheroma increases the risk of stroke 4-fold (11). Embolic strokes are more likely in patients with complex arch atheroma, elevated inflammatory markers, plaque hemorrhage, lipid-rich plaque, and lack of calcification (28).

Cardiac/aortic surgery. Stroke occurs as a complication of cardiopulmonary bypass in 2% to 5% of patients. In a prospective study, stroke following aortic valve replacement occurred in 7% of cases (32), with radiographic evidence of silent infarction in a much larger number (54%). Cardiac catheterization is associated with stroke or peripheral emboli in 0.5% of cases. Embolic strokes can occur during TEVAR as the proximal seal is close to the takeoff of the carotid and subclavian arteries. The risk is 4% to 8%. Risk factors include proximal graft deployment, complex arch atheroma, and prior stroke (20). The risk of stroke may be related to the indication for TEVAR; for example, TEVAR performed for aortic aneurysm is associated with increased stroke risk compared to TEVAR performed for dissection (52).

The incidence of spinal cord ischemia following aortic surgery or TEVAR is approximately 2% to 6% (21). Perioperative complications are more likely with advanced age, emergent surgery, extensive disease burden, duration of aortic cross-clamping, chronic kidney disease, and involvement of the hypogastric artery. Neurologic complications were also seen more frequently in emergency cases rather than elective ones (42). A model was developed that includes patient age, coverage length, hypertension, chronic renal insufficiency, and COPD as predictive factors for spinal cord ischemia following TEVAR (43).

Prevention

Management of individual risk factors associated with aortic disease may help prevent neurologic complications by reducing the incidence of the disease. For example, cessation of smoking, weight loss, and control of hypertension may reduce the risk of aortic aneurysm formation.

Preventative strategies are recommended in patients undergoing aortic surgery to minimize neurologic complications (21). Intraoperative hypothermia is recommended for open surgical repair of the ascending aorta or aortic arch, along with either antegrade (via direct cannulation of the brachiocephalic arteries) or retrograde (via jugular vein) perfusion. Noninvasive CNS monitoring, such as electroencephalography or evoked potentials, can be utilized during aortic procedures with extracorporeal circulation to ensure sufficient CNS perfusion.

For spinal cord protection during thoracic surgical procedures, cerebrospinal fluid drainage via lumbar drain is recommended in both open and endovascular cases (21). Lumbar drainage is postulated to increase spinal cord perfusion pressure by reducing CSF pressure. Proximal hypertension can improve spinal cord perfusion by increasing circulation via the vertebral arteries. Minimizing aortic cross-clamp time is also helpful, with a negligible risk of ischemic complications seen following clamping that is shorter than 15 minutes (50). Intraoperative hypothermia (between 32°C to 35°C) can also be considered as a neuroprotective measure (30). However, hypothermia is challenging to utilize. Systemic hypothermia increases the risks of systemic side effects, whereas localized epidural hypothermia remains quite invasive. Somatosensory evoked potentials can be utilized to monitor for spinal cord ischemia. Glucocorticoids and mannitol may afford spinal cord protection via an anti-inflammatory mechanism and can be considered in patients at high risk for ischemic complications (21).

Differential diagnosis

The differential diagnosis is broad if one considers aortic disease as a single entity. It can cause (and thereby mimic) mononeuropathies, polyneuropathies, radiculopathies, stroke/TIA, motor neuron disease, claudication, or sexual dysfunction. Therefore, aortic disease should be kept in the differential diagnosis for these conditions.

Diagnostic workup

The aorta can be visualized by computerized tomography angiography (CTA), magnetic resonance angiography, digital subtraction angiography, or ultrasound. Transesophageal echocardiography can also be used to visualize the proximal thoracic aorta. Subclavian steal is best visualized by dynamic imaging such as carotid ultrasonography or transcranial Doppler.

A chest x-ray may reveal features of an aortic dissection such as the widened mediastinum, enlarged aortic knob, displaced trachea, or aortic calcification; however, a negative exam should not preclude CTA in high-risk patients (21).

Inflammatory markers such as erythrocyte sedimentation rate or C-reactive protein are generally elevated in noninfectious aortitis. Temporal artery biopsy is the definitive diagnostic modality for giant-cell arteritis. Blood cultures are frequently positive in infectious aortitis.

Management

Stroke/TIA. Stroke or TIA secondary to aortic disease should be treated according to established American Heart Association/American Stroke Association guidelines for acute management and secondary prevention, which are beyond the scope of this review. Of note, intravenous tPA is not recommended in patients with known or suspected aortic dissection (37).

Spinal cord ischemia. Patients should be monitored for hypotension and bradycardia indicative of neurogenic shock due to disruption of autonomic pathways. Respiratory support should be provided for high spinal injuries with resultant diaphragmatic weakness. Thrombolysis is experimental but may be considered if the condition is diagnosed within the standard tPA treatment window and the patient does not have contraindications (40). The mainstay of treatment is the elevation of blood pressure, with pressors if necessary, to ensure adequate spinal perfusion. Blood pressure should be titrated to symptom resolution, as tolerated from a cardiac perspective. Concurrently, lumbar drain placement with CSF diversion can also be considered to reduce CSF pressure and improve spinal cord perfusion pressure. Lumbar drains are often placed prophylactically in the preoperative period for open and endoscopic aortic repairs. This practice has led to a significant reduction in the rates of paraplegia or significant ischemia since its use in the 1980s (46). As is the case in ischemic strokes, there is no role of IV steroids once the diagnosis of spinal cord ischemia is established.

Subclavian steal syndrome. Symptomatic subclavian artery stenosis may be treated with carotid-subclavian bypass, carotid transposition, or endovascular angioplasty/stenting (07). There is no indication for treatment of asymptomatic patients.

Aortic dissection. The patient should be immediately stabilized with pain control and treated with a beta-blocker to reduce blood pressure and heart rate. The definitive treatment for type A dissection is immediate open surgical repair, and this remains a surgical emergency. Unlike endovascular procedures for the distal aorta, open repair remains the mainstay of treatment for type A dissection. This is partly due to the lack of specific devices for this region, rendering it experimental for the time being (27). Despite the presence of neurologic symptoms, these patients have acceptable early morbidity and mortality (18). Hence, neurologic symptoms should not be considered a “contraindication” for definitive repair. Surgical repair led to improvement in more than half of the treated population based on a systemic review (51). This benefit is more pronounced when surgery is performed as expeditiously as possible (18).

Type B aortic dissection may be managed medically or by thoracic endovascular aortic surgery (TEVAR). The introduction of this procedure has revolutionized surgical management, leading to a reduction in morbidity and mortality compared to open repair (22). TEVAR may also be superior to medical therapy for addressing type B aortic dissections (22). Similar to patients with type A aortic dissection, patients with preoperative neurologic symptoms have a reasonable chance of recovery and should not be excluded from emergency surgery (34).

Aortic aneurysm. Treatment for ruptured or symptomatic aneurysms is immediate surgery (21). For asymptomatic aneurysms, the decision to pursue surgery is based on the size of the aneurysm and patient-specific characteristics. A detailed discussion of the timing of intervention is beyond the scope of this article. Generally, in low-risk patients, aneurysms greater than 5 cm in the ascending thoracic aorta and greater than 5.5 cm in the descending thoracic aortic aneurysm may warrant surgical intervention (48; 23). In the case of abdominal aortic aneurysms, there are aneurysm shape and gender-specific cut-offs. Men presenting with fusiform aneurysms greater than 5.5 cm may warrant an intervention. This cut-off is reduced to greater than 5.0 cm in women (08). An elective repair may be considered in any patient with a saccular aneurysm (although this recommendation has weak evidence) (08). Patients with aneurysms secondary to genetic conditions have smaller size or growth thresholds for surgery (23). Medical management includes tobacco cessation and management of hypertension. Surveillance imaging guidelines depend on the region of the aorta being screened, the initial size of any aneurysm, the patient’s gender, and the presence of an intervention or endo-leak and remain beyond the scope of this article (08; 48).

Aortitis. The mainstay of treatment for noninfectious aortitis is immune suppression. For patients with giant cell arteritis, high-dose corticosteroids (1 mg/kg/day of prednisone up to a maximum of 80 mg per day) are recommended (31). An initial intravenous methylprednisolone pulse can be considered, especially if symptoms are severe, such as vision loss in giant cell arteritis. Prompt initiation of immunosuppression is essential and should occur before confirmative biopsy for patients with giant cell arteritis to avoid further complications. Tocilizumab is now FDA-approved for treating giant cell arteritis and is recommended in all patients with a new diagnosis of giant cell arteritis per the American College of Rheumatology. However, this differs from the European Alliance of Associations for Rheumatology (EULAR) European Union guidelines. Another steroid-sparing agent, such as methotrexate, can also be considered in place of tocilizumab to minimize the complications of long-term steroids in selected patients (31). Patients should be monitored longitudinally for recurrence by clinical and serum inflammatory markers.

In patients with Takayasu disease and giant cell arteritis, daily low-dose aspirin for stroke prevention can be considered in cases with significant or critical stenosis of the carotid or vertebrobasilar systems; however, this measure has low evidence (31). Similar to the management of giant cell arteritis, the mainstay of treatment includes a combination of high-dose glucocorticoids and glucocorticoid-sparing agents (methotrexate, azathioprine, or other TNF-alpha inhibitors). Unlike the management of giant cell arteritis, tocilizumab is not yet recommended, primarily due to low evidence of its efficacy in Takayasu disease (31).

Surgical intervention may be required in patients with Takayasu disease for symptomatic stenosis or large aneurysm. The specific timing of these interventions is challenging to determine. Ideally, surgery is best performed when the disease is quiescent (31). However, this may not always be possible. Unfortunately, the specifics of surgical intervention and its appropriate timing for issues such as limb claudication or renovascular hypertension remain beyond the scope of this article. However, emergent interventions may sometimes be needed in cases of sudden, symptomatic, high-grade stenosis of cerebral circulation. There are isolated cases of good outcomes in patients treated with mechanical thrombectomy (12). Noninvasive longitudinal reimaging should be considered for those with ongoing symptoms or indications of inflammation to monitor for cerebrovascular stenosis or aortic aneurysm formation. Ideally, CTA or MRA are recommended over catheter-based angiography (31). However, the ideal imaging frequency is unclear and must be determined for each patient. Ultimately, these patients will need a multidisciplinary approach with frequent collaboration with their rheumatologists and vascular surgeons.

For infectious aortitis, antibiotics, surgical debridement, and revascularization are the mainstay of treatment (45).

Aortic atheroma. The optimal antithrombotic regimen for secondary stroke prevention in patients with complex aortic atheroma remains uncertain. Subgroup analysis of the Warfarin-Aspirin Recurrent Stroke Study (WARSS) trial did not demonstrate a benefit of warfarin over aspirin in patients with complex atheroma (14). The Aortic Arch Related Cerebral Hazard (ARCH) trial compared warfarin and dual antiplatelet therapy (aspirin and clopidogrel) in patients with recent stroke and complex arch atheroma and found no statistically significant difference between treatment groups. However, the study lacked power overall (02). Current American Heart Association/American Stroke Association guidelines recommend aspirin for secondary stroke prevention in patients with arch atheroma (25). Prophylactic surgical management, such as aortic endarterectomy or stenting, is not routinely recommended, even in patients undergoing cardiac surgery with a risk for disruption of complex atheroma (21). Retrospective data in patients with severe aortic plaque support the use of statins to confer protective effect and prevent stroke (47).

Outcomes

Stroke. Outcomes specific to stroke caused by diseases of the aorta have not been systematically evaluated. In general, the degree and rate of recovery from a stroke is determined by the patient’s age, comorbidities, size of infarct, severity of initial neurologic deficits, and receipt of acute revascularization treatment.

Spinal cord infarction. Overall mortality rates are 10% to 20%. Patients experiencing delayed spinal cord infarction are more likely to have functional recovery. The timing of lumbar drain placement did not appear to have an impact on post-discharge functional improvement or long-term mortality (13).

Neurologic symptoms on presentation, including coma, worsen immediate prognosis but are not associated with increased mortality (16; 06). Temporary neurologic dysfunction (confusion, delirium, and agitation) after surgery of the thoracic aorta is a predictor of poor outcome, increased risk of stroke, permanent neurologic deficit, more extended hospital stays, and impaired quality of life (26).

Special considerations

Pregnancy

The risk of aortic dissection and rupture is elevated in pregnancy and the immediate postpartum period (24). In rare cases, pregnancy may cause direct compression of the aorta (especially in the third trimester) and produce spinal cord ischemia in the mother (04).

Anesthesia

Anesthesia plays a critical role during the surgical repair of aortic disease and in preventing spinal cord ischemia.

Intraoperative neuroprotection can be achieved by ensuring adequate cerebral and spinal perfusion pressure, either by elevation of systemic pressure, local antegrade/retrograde perfusion, or elevations in hematocrit. Moderate hypothermia can be considered. Mannitol and steroids are frequently used in clinical practice, although there is no formal evidence to support their use. The patient can be monitored for early detection of inadequate perfusion via electroencephalography or evoked potentials (21; 29).