INTRODUCTION

Section 2 of 10  

• Authors and Editors
• Introduction
• Clinical
• Differentials
• Workup
• Treatment
• Medication
• Follow-up
• Miscellaneous
• References

Background

Carotid artery dissection is a significant cause of ischemic stroke in all age groups. Spontaneous carotid dissection can occur, most frequently in the fifth decade of life. Dissection of the internal carotid artery can occur intracranially or extracranially, with the latter being more frequent. Internal carotid artery dissection can be caused by major or minor trauma, or it can be spontaneous in which case genetic, familial, and/or heritable disorders are likely etiologies. Patients can present in a variety of settings, such as a trauma bay with multiple traumatic injuries; their physician's office with nonspecific head, neck, or face pain; or to the emergency department with a partial Horner syndrome. A high index of suspicion is required to make this difficult diagnosis. Sophisticated imaging techniques, which have improved over the last 2 decades, are required to confirm the presence of dissection. Early institution of antithrombotic treatment provides the best outcome.

Pathophysiology

Although the cause of internal carotid artery dissection remains elusive, mechanical forces (trauma, blunt injury, stretching) and underlying arteriopathies (Ehlers-Danlos syndrome IV, other connective tissue disorders/aberrations) alone, or in combination, account for most of the pathophysiology. Carotid artery dissection begins as a tear in the tunica intima or between the tunica media and tunica adventitia (possibly originating from the vasa vasorum). The blood under arterial pressure dissects along the artery to create an intramural hematoma, which can either narrow the carotid artery lumen or cause an aneurysmal dilatation. Both processes may cause stenosis or thromboemboli. The aneurysm resulting from an internal carotid artery dissection is a true, as opposed to a false, aneurysm because the wall is composed of blood vessel elements. Sometimes, the pathognomonic "intimal flap" may be noted with vascular imaging.

Frequency

United States

The annual incidence of symptomatic spontaneous internal carotid artery dissection ranges from 2.5-3 per 100,000. The incidence of carotid artery dissection as a result of blunt injury (mainly high-speed motor vehicle accidents) ranges from less than 1% to 3%. The actual incidence may be higher because some dissections are asymptomatic or cause only minor transient symptoms and remain undiagnosed.

Mortality/Morbidity

Spontaneous internal carotid artery dissection has a reported mortality rate of less than 5%, although the morbidity and mortality of internal carotid artery dissection due to blunt trauma may be much higher.

• Morbidity from carotid artery dissection varies in severity from transient focal deficits to permanent cerebral or retinal ischemic injury, and even death in the setting of trauma.

Sex

No gender-based difference exists for spontaneous internal carotid artery dissection.

Age

• Spontaneous internal carotid artery dissection is a common cause of ischemic stroke in patients younger than 50 years and accounts for up to 25% of ischemic strokes in young and middle-aged patients.
• The mean age for ischemic stroke secondary to internal carotid artery dissection from blunt traumatic injury is even younger at 35-38 years old.
• Dissection of the intracranial part of the internal carotid artery is rare at any age because the skull absorbs most of the force.

CLINICAL

Section 3 of 10  

• Authors and Editors
• Introduction
• Clinical
• Differentials
• Workup
• Treatment
• Medication
• Follow-up
• Miscellaneous
• References

History

Patients with internal carotid artery dissection can present with nonspecific complaints and in all settings. Maintaining a high index of suspicion for carotid dissection is critical anytime a patient presents with unusual focal neurologic complaints, particularly involving the cranial nerves and particularly after either major mechanism trauma or minor mechanism stress or impact involving the neck directly. In cases of high-impact trauma, a history of cervical hyperextension, flexion, and/or rotation should alert the physician to the possibility of dissection. In patients with multiple traumatic injuries, these nonspecific symptoms may be delayed from 1-5 days postinjury.

• Even patients with seemingly minor trauma can develop dissection of the internal carotid artery. Symptoms may range from headache to hemiparesis. Precipitating events should be sought and may include chiropractic manipulation, yoga, gymnastics, sports injuries (including direct impact of high-velocity ball or other direct impact to the neck), overhead painting, coughing, or sneezing.
• Pain is the initial symptom of a spontaneous internal carotid artery dissection presenting to a physician. Head, neck, or facial pain ipsilateral to the dissection is common. The headache is usually described as constant and severe. Unilateral facial or orbital pain is also common, and 25% of patients have isolated ipsilateral neck pain. Hypoageusia, or decreased taste sensation, may also be a presenting symptom.
• In less than half of patients presenting with a carotid artery dissection, a unilateral oculosympathetic palsy, or a partial Horner syndrome, may develop, and these patients will experience miosis, visual disturbance, and mild ptosis that may not be detected clinically. Isolated transient vision loss may also be a presenting complaint. Irreversible blindness from an ischemic optic nerve injury is rare. Also up to 20% of patients may present with an ischemic stroke without any warning signs.
• Typical presenting symptoms are as follows:
• • Headache, including neck and facial pain, can be constant, instantaneous, gradual, throbbing, or sharp.
    • Headache is commonly ipsilateral to the dissected artery.
    • Headache usually precedes a cerebral ischemic event, unlike a headache associated with stroke, which usually follows or accompanies the ischemic event.
    • Recurrence of neck pain suggests extension or recurrence of the dissection.
  • Transient episodic blindness, or amaurosis fugax, is caused by decreased blood flow to the retina.
  • Ptosis with miosis, which is a partial Horner syndrome, is usually painful in internal carotid artery dissections.
  • Neck swelling
  • Pulsatile tinnitus can occur in up to 25% of patients with dissection of the internal carotid artery.
  • Decreased taste sensation, or hypoageusia
  • Focal weakness
  • Migrainelike symptoms such as a scintillating scotoma, which is loosely defined as a transient visual field disturbance in the form of shimmering or arcs of light.

Physical

In the setting of high-impact trauma, a history may be unobtainable, so physical signs indicating a possible internal carotid artery dissection need to be identified. Furthermore, signs may be masked in patients with concomitant head trauma, coma, or multiple traumatic injuries.

• The signs that should be appreciated when entertaining the diagnosis of internal carotid artery dissection include the following:
• • Focal neurologic deficit and frank stroke occur hours to days postinjury and may be present in up to 93% of patients at the time of diagnosis of internal carotid artery dissection secondary to high-impact blunt trauma.
  • Hemiparesis
  • Oculosympathetic palsy, or a partial Horner syndrome (ptosis with miosis), may be present in less than 50% of patients, and when accompanied by ipsilateral pain and retinal ischemia suggests an internal carotid artery dissection. The term partial Horner syndrome is used because anhydrosis is absent. The sympathetic fibers innervating the facial sweat glands are anatomically located on the external rather than internal carotid artery; thus, anhydrosis is not a finding in the setting of internal carotid dissection.
  • Cranial nerve palsy can be present in up to 12% of patients, with the lower cranial nerves affected more often than the facial, trigeminal, and oculomotor nerves.
  • Cervical bruit
  • Cervicothoracic seat belt sign, which is ecchymosis to the neck and chest, raises the incidence of cerebrovascular injuries (internal carotid or vertebral) to 3%.
  • Neck hematoma and/or ecchymosis
  • Cervical spine injuries, maxillofacial trauma, basilar skull fractures
  • Massive epistaxis
  • Near hanging injury

Causes

• Heritable connective-tissue disorders
• Ehlers-Danlos syndrome type IV
• Fibromuscular dysplasia
• Cystic medial necrosis
• Marfan syndrome
• Autosomal dominant polycystic kidney disease
• Osteogenesis imperfecta type I
• Oral contraceptives
• Hypertension
• Neck manipulation or strain - This can result from intentional manipulation or from other strain that may occur during sports activities, yoga, or even from minimal activity (eg, overhead painting).
• Blunt trauma from high impact and seemingly minor mechanisms of injury
• Penetrating trauma
• Wearing a 3-point restraint seat belt during a motor vehicle crash (MVC)
• Smoking
• Respiratory tract infections

DIFFERENTIALS

Section 4 of 10  

• Authors and Editors
• Introduction
• Clinical
• Differentials
• Workup
• Treatment
• Medication
• Follow-up
• Miscellaneous
• References

WORKUP

Section 5 of 10  

• Authors and Editors
• Introduction
• Clinical
• Differentials
• Workup
• Treatment
• Medication
• Follow-up
• Miscellaneous
• References

Lab Studies

• If a physician is considering spontaneous internal carotid artery dissection, laboratory studies are irrelevant for diagnosis.
• If surgery is planned, the patient's blood type, complete blood count, and coagulation profile (prothrombin and activated partial thromboplastin time) should be obtained.
• Baseline coagulation studies may be appropriate in certain settings prior to initiation of anticoagulation therapy or in cases where a patient is already taking anticoagulation therapy at the time that dissection is identified.

Imaging Studies

• Conventional angiography
• • Conventional angiography is the criterion standard for the diagnosis of internal carotid artery dissection. Conventional angiography has a 1% overall risk of complications; it is invasive, resource-intensive, and costly; and should be reserved for patients in whom internal carotid artery dissection is suspected. Conventional angiography currently has the highest sensitivity and specificity compared with other imaging modalities.
  • The pathognomonic finding is an intimal flap, or double lumen, secondary to an intramural hematoma. This finding is rarely detected.
• Magnetic resonance angiography
• • As technology improves, magnetic resonance angiography (MRA) may soon replace conventional angiography for the diagnosis of internal carotid artery dissection. Improved resolution, speed, noninvasiveness, and good negative predictive value make MRA an excellent screening tool and in some cases superior to angiography. Furthermore, MRA does not require the use of an iodinated contrast dye, which can increase morbidity and mortality, although minimally. One current drawback to MRA studies are long image acquisition times.
  • MRA signs of dissection include irregular vessel margins, filling defects, extravasation of contrast, vascular occlusion, and caliber changes of the vessel. The latter sign is important and appreciated on axial views, but 3-dimensional reconstructed views allow study from any angle.
• Helical computed tomographic angiography
• • Helical CT angiography (CTA) also has an evolving role in the diagnosis of internal carotid artery dissection and has emerged as a promising screening technique. CTA may be the first and possibly the only modality used for screening purposes for trauma patients who fit general screening criteria (based on signs, symptoms, and mechanism) for carotid artery dissection and who will already be undergoing CT scan for another indication. Helical CTA is fast and noninvasive, but currently remains limited in comparison to conventional angiography. When obtaining a CTA of the neck, the physician must specifically request for the study to rule out internal carotid artery dissection.
  • When performing a noncontrast CT, dissection of the internal carotid artery may be inferred from indirect findings, which include soft-tissue swelling, hematoma adjacent to the internal carotid artery, and infiltration of perivascular fat planes. Also, fracture or fracture/dislocation of the cervical bones should raise suspicion for internal carotid artery injury. Noncontrast CT scan is not an adequate screening test for internal carotid artery dissection.
  • The hallmark of injury to the internal carotid artery using CT angiography is a change in the caliber of the vessel. Other findings indicating a dissection may include oval, irregular, or slitlike cross section of the vessel lumen. In comparison to conventional angiography, CTA has the added benefit of imaging extravascular structures. Also, axial images can be reconstructed for 3-dimensional viewing.
• Doppler ultrasonography, or Duplex scanning
• • This modality is soon becoming an extension of the physical examination and has an increasing role in the diagnosis of a myriad of medical and surgical cases. With its increasing resolution, applicability, speed, and ease-of-use, Doppler ultrasonography can currently be used for the initial assessment of patients with suspected carotid artery dissection and is usually already at the bedside in trauma cases for focused assessment with sonography for trauma (FAST). An abnormal blood flow pattern can be appreciated in up to 90% of patients with carotid artery dissection, but the actual site of injury is usually not seen because of limited ability to evaluate past the carotid bulb.
  • Abnormalities found by duplex scanning should always be followed up with conventional angiography or magnetic resonance angiography.

Other Tests

• These supplementary tests may be needed for evaluation of patients with a possible internal carotid artery dissection.
• • Electrocardiography
  • Echocardiography
  • Neuroimaging such as noncontrast CT, or MRI of the brain
  • Electroencephalography

TREATMENT

Section 6 of 10  

• Authors and Editors
• Introduction
• Clinical
• Differentials
• Workup
• Treatment
• Medication
• Follow-up
• Miscellaneous
• References

Prehospital Care

Cervical spine immobilization, as is usually appropriate, should be performed in the setting of any significant traumatic injury that could involve the neck.

Emergency Department Care

Patients with internal carotid artery dissection can present in various ways and with nonspecific complaints but, in all cases, the emergency physician should maintain a high index of suspicion.

• Although it depends on the patient's presentation, an initial CT of the head is usually warranted. A negative scan, or findings that do not correlate with the patient's symptoms and signs, should be followed up by a more definitive imaging modality such as MRA, CTA, or conventional angiography depending on the institution.
• A general consensus does not exist for the management of internal carotid artery dissection, but surgical, endovascular, and medical options may depend on the type of injury, anatomic location, mechanism of injury, coexisting injuries, and comorbidities. Therefore, after the diagnosis is made, the risk versus benefit of antithrombotic therapy should be weighed, especially in cases of high-impact trauma, and neurosurgical or interventional radiology consultations should be obtained.
• Anticoagulation with intravenous heparin followed by warfarin has generally been accepted as medical management to prevent thromboembolic complications. Antiplatelet therapy has also been used when systemic anticoagulation is contraindicated.

Consultations

The risk and benefit of initiating antithrombotic therapy must be weighed for each patient with carotid artery dissection. Consultation with one or more of the following services may be useful, particularly in difficult situations such as multiple trauma, traumatic brain injury, preexisting brain lesion, or upper GI bleed.

• Neurology
• Neurosurgery
• Interventional radiology

MEDICATION

Section 7 of 10  

• Authors and Editors
• Introduction
• Clinical
• Differentials
• Workup
• Treatment
• Medication
• Follow-up
• Miscellaneous
• References

The goal of medical management, using antithrombotics, is to prevent progressive neurologic deficits. Antiplatelet and anticoagulation therapy have been used in combination or separately.

Drug Category: Anticoagulants

These agents prevent thrombus formation and decrease the number of emboli following arterial dissection. Anticoagulation therapy also aids intimal healing, decreases smooth muscle cell proliferation, and decreases intimal thickening.

Drug Name	Warfarin sodium (Coumadin)
Description	Interferes with hepatic vitamin K–dependent carboxylation. Used for prophylaxis and treatment of thromboembolic disorders. Usually prolongs PT in 48 h.
Adult Dose	Loading dose: 10 mg PO qd for 2-4 d; adjust daily dosage to desired PT or INR (usually in range of 2-3)
Pediatric Dose	0.05-0.34 mg/kg/d PO; adjust dose according to desired INR; infants may require doses at or near high end of this range
Contraindications	Documented hypersensitivity; severe liver or kidney disease; open wounds or GI ulcers
Interactions	Drugs that may decrease anticoagulant effects include griseofulvin, carbamazepine, glutethimide, estrogens, nafcillin, phenytoin, rifampin, barbiturates, cholestyramine, colestipol, vitamin K, spironolactone, oral contraceptives, and sucralfate Medications that may increase anticoagulant effects include oral antibiotics, phenylbutazone, salicylates, sulfonamides, chloral hydrate, clofibrate, diazoxide, anabolic steroids, ketoconazole, ethacrynic acid, miconazole, nalidixic acid, sulfonylureas, allopurinol, chloramphenicol, cimetidine, disulfiram, metronidazole, phenylbutazone, phenytoin, propoxyphene, sulfonamides, gemfibrozil, acetaminophen, and sulindac
Pregnancy	D - Unsafe in pregnancy
Precautions	Do not switch brands after achieving therapeutic response; caution in active TB or diabetes mellitus; patients with protein C or S deficiency are at risk of developing skin necrosis

Drug Name	Enoxaparin (Lovenox)
Description	Produced by partial chemical or enzymatic depolymerization of unfractionated heparin (UFH). Binds to antithrombin III, enhancing its therapeutic effect. Heparin-antithrombin III complex binds to and inactivates activated factor X (Xa) and factor II (thrombin). Does not actively lyse but is able to inhibit further thrombogenesis. Prevents reaccumulation of clot after spontaneous fibrinolysis. Advantages include intermittent dosing and decreased requirement for monitoring. Heparin anti–factor Xa levels may be obtained if needed to establish adequate dosing. LMWH differs from UFH by having a higher ratio of antifactor Xa to antifactor IIa compared with UFH. Prevents DVT, which may lead to pulmonary embolism in patients undergoing surgery who are at risk for thromboembolic complications. Used for prevention in hip replacement surgery (during and following hospitalization), knee replacement surgery, or abdominal surgery in those at risk of thromboembolic complications, or in nonsurgical patients at risk of thromboembolic complications secondary to severely restricted mobility during acute illness. Used to treat DVT or PE in conjunction with warfarin for inpatient treatment of acute DVT with or without PE or for outpatient treatment of acute DVT without PE. No utility in checking aPTT (drug has wide therapeutic window and aPTT does not correlate with anticoagulant effect). Average duration of treatment is 7-14 d.
Adult Dose	1 mg/kg administered SC q12h in conjunction with oral aspirin (100-325 mg daily); maximum antifactor Xa and antithrombin activities occur 3-5 h postadministration CrCl <30 mL/min: 1 mg/kg SC qd
Pediatric Dose	Not established
Contraindications	Documented hypersensitivity; major bleeding; thrombocytopenia
Interactions	Platelet inhibitors or oral anticoagulants such as dipyridamole, salicylates, aspirin, NSAIDs, sulfinpyrazone, and ticlopidine may increase risk of bleeding
Pregnancy	B - Usually safe but benefits must outweigh the risks.
Precautions	Decrease dose if CrCl <30 mL/min; if thromboembolic event occurs despite LMWH prophylaxis, discontinue drug and initiate alternate therapy; elevation of hepatic transaminases may occur but is reversible; heparin-associated thrombocytopenia may occur with fractionated low-molecular-weight heparins; 1 mg of protamine sulfate will reverse effect of approximately 1 mg of enoxaparin if significant bleeding complications develop; cases of epidural/spinal hematomas have been reported in adults receiving spinal or epidural anesthesia (holding 2 doses prior to LP or surgery is recommended)

Drug Category: Antiplatelets

These agents may be used in trauma patients in whom anticoagulation is contraindicated.

Drug Category: Thrombolytics

The research involving thrombolytics for the treatment of extracranial internal carotid artery dissection is limited, and, thus, its usefulness and appropriateness are yet unknown.

FOLLOW-UP

Section 8 of 10  

• Authors and Editors
• Introduction
• Clinical
• Differentials
• Workup
• Treatment
• Medication
• Follow-up
• Miscellaneous
• References

Further Inpatient Care

• Patients should be closely monitored for delayed ischemic or embolic neurologic symptoms and for the hemorrhagic side effects of antithrombotic medication.

Further Outpatient Care

• If anticoagulation therapy is initiated, continue for 3-6 months with the appropriate follow-up for international normalized ratio (INR) and PT monitoring. Target INR should between 2.0 and 3.0.
• A follow-up angiogram, Duplex ultrasonography, or other angiography should be obtained several months after the event to reevaluate the dissection.

Complications

• Ischemic stroke, mainly from thromboembolic complications of the initial dissection, may occur.
• Hemorrhagic stroke may be a complication secondary to anticoagulant use in some patients.
• Recurrence of dissection may occur in the unaffected artery and may be greater than 1% per year in patients with a known heritable arteriopathy.
• The usual complications associated with surgical or endovascular procedures may occur if they are used in the early management of the dissection.
• There has been no documented complication in mistakenly giving thrombolytic therapy in an internal artery dissection.

Prognosis

• Prognosis of internal carotid artery dissection depends on the severity of the initial ischemic injury and the extent of collateral circulation.
• Overall, the prognosis for spontaneous internal carotid artery dissection is favorable, with about 75% of patients making a good recovery. The mortality rate is about 5%. Patients who have a dissection secondary to trauma have a much higher rate of mortality and neurologic deficit on discharge.
• Recurrence risk is highest in the first month and then about 1% per year for about a decade.
• Headache has been described to persist, in some cases for years after the dissection.

Patient Education

• For excellent patient education resources, visit eMedicine's Stroke Center. Also, see eMedicine's patient education articles Worst Headache of Your Life, Transient Ischemic Attack (Mini-stroke), and Stroke.

MISCELLANEOUS

Section 9 of 10  

• Authors and Editors
• Introduction
• Clinical
• Differentials
• Workup
• Treatment
• Medication
• Follow-up
• Miscellaneous
• References

Medical/Legal Pitfalls

• Failure to consider the diagnosis in young patients presenting with neurologic symptoms
• Failure to rule out intracranial hemorrhage prior to initiation of anticoagulation therapy
• Failure to initiate anticoagulation therapy when a thrombus is detected
• Administration of anticoagulant, especially warfarin, or antiplatelet therapy to a pregnant patient

Special Concerns

• Trauma: Do not initiate anticoagulation therapy in trauma patients without first ruling out intracranial bleeds and extracranial sources of hemorrhage.
• Pregnancy: Do not initiate anticoagulation or antiplatelet therapy in pregnant patients without consultation with an obstetrician.
• Multiple medications: Multiple drugs displace warfarin from albumin, thus increasing its anticoagulant effect.

REFERENCES

Section 10 of 10

• Authors and Editors
• Introduction
• Clinical
• Differentials
• Workup
• Treatment
• Medication
• Follow-up
• Miscellaneous
• References

• Baker WE, Wassermann J. Unsuspected vascular trauma: blunt arterial injuries. Emerg Med Clin North Am. Nov 2004;22(4):1081-98. [Medline].
• Berne JD, Norwood SH, McAuley CE, Villareal DH. Helical computed tomographic angiography: an excellent screening test for blunt cerebrovascular injury. J Trauma. Jul 2004;57(1):11-7; discussion 17-9. [Medline].
• Cothren CC, Moore EE, Biffl WL, et al. Anticoagulation is the gold standard therapy for blunt carotid injuries to reduce stroke rate. Arch Surg. May 2004;139(5):540-5; discussion 545-6. [Medline].
• Dziewas R, Konrad C, Drager B, et al. Cervical artery dissection--clinical features, risk factors, therapy and outcome in 126 patients. J Neurol. Oct 2003;250(10):1179-84. [Medline].
• Kremer C, Mosso M, Georgiadis D, et al. Carotid dissection with permanent and transient occlusion or severe stenosis: Long-term outcome. Neurology. Jan 28 2003;60(2):271-5. [Medline].
• Mazighi M, Saint Maurice JP, Rogopoulos A, Houdart E. Extracranial vertebral and carotid dissection occurring in the course of subarachnoid hemorrhage. Neurology. Nov 8 2005;65(9):1471-3. [Medline].
• Schievink WI. Spontaneous dissection of the carotid and vertebral arteries. N Engl J Med. Mar 22 2001;344(12):898-906. [Medline].
• Schoenen J, Sandor PS. Headache with focal neurological signs or symptoms: a complicated differential diagnosis. Lancet Neurol. Apr 2004;3(4):237-45. [Medline].
• Slovut DP, Olin JW. Fibromuscular dysplasia. N Engl J Med. Apr 29 2004;350(18):1862-71. [Medline].
• Stallmeyer MJ, Morales RE, Flanders AE. Imaging of traumatic neurovascular injury. Radiol Clin North Am. Jan 2006;44(1):13-39, vii. [Medline].
• Volker W, Besselmann M, Dittrich R, et al. Generalized arteriopathy in patients with cervical artery dissection. Neurology. May 10 2005;64(9):1508-13. [Medline].

Article Last Updated: Nov 29, 2006