Case Reports

A Spontaneous Internal Carotid Artery Dissection Presenting With Headache and Miosis

Emergency Medicine. 2016 July;48(7):300-304 | 10.12788/emed.2016.0035

References

1. CADISS trial investigators, Markus HS, Hayter E, et al. Antiplatelet treatment compared with anticoagulation treatment for cervical artery dissection (CADISS): a randomised trial. Lancet Neurol. 2015;14(4):361-367.

2. Thanvi B, Munshi SK, Dawson SL, Robinson TG. Carotid and vertebral artery dissection syndromes. Postgrad Med J. 2005;81(956):383-388.

3. Lucas C, Moulin T, Deplanque D, Tatu L, Chavot D. Stroke patterns of internal carotid artery dissection in 40 patients. Stroke. 1998;29(12):2646-2648.

4. Schievink WI, Mokri B, O’Fallon WM. Recurrent spontaneous cervical-artery dissection. N Engl J Med. 1994;330(6):393-397.

5. Biousse V, D’Anglejan-Chatillon J, Touboul PJ, Amarenco P, Bousser MG. Time course of symptoms in extracranial carotid artery dissections. A series of 80 patients. Stroke. 1995;26(2):235-239.

6. Kasravi N, Leung A, Silver I, Burneo JG. Dissection of the internal carotid artery causing Horner syndrome and palsy of cranial nerve XII. CMAJ. 2010;182(9):E373-E377.

1. Borgman CJ. Horner syndrome secondary to internal carotid artery dissection after a short-distance endurance run: a case study and review. J Optom. 2012;5:209-216.

2. Mohler ER III, Fairman RM. Management of symptomatic carotid atherosclerotic disease. UpToDate Web site. http://www.uptodate.com/contents/management-of-symptomatic-carotid-atherosclerotic-disease. Updated February 24, 2016. Accessed May 6, 2016.

3. Mann J. Anisocoria guidemap. Life in the Fastlane Web site. http://lifeinthefastlane.com/resources/jeff-manns-em-guidemaps/anisocoria-guidemap/. Accessed March 15, 2016.

10. Kedar S, Biousse V, Newman NJ. Horner syndrome. UpToDate Web site. http://www.uptodate.com/contents/horner-syndrome. Updated July 14, 2015. Accessed May 6, 2016.

11. Vertinsky AT, Schwartz NE, Fischbein NJ, Rosenberg J, Albers GW, Zaharchuk G. Comparison of multidetector CT angiography and MR imaging of cervical artery dissection. AJNR Am J Neuroradiol. 2008;29(9):1753-1760.

12. Pham MH, Rahme RJ, Arnaout O, et al. Endovascular stenting of extracranial carotid and vertebral artery dissections: a systematic review of the literature. Neurosurgery. 2011;68(4):856-866.

13. Caplan LR. Dissections of brain-supplying arteries. Nat Clin Pract Neurol. 2008;4(1):34-42.

14. Schievink WI. Spontaneous dissection of the carotid and vertebral arteries. N Engl J Med. 2001;344(12):898-906.

In ICAD, a tear in the artery wall causes blood to enter the tunica media of the vessel, forming an intramural hematoma.^2,6 This may result in either stenosis of the lumen of the vessel from the enlarging hematoma or an outward aneurysmal dilatation of the vessel that compresses surrounding structures.^2,6 Subsequent cerebral ischemia is the result of either arterial embolism or hemodynamic compromise from vessel stenosis.^2,3

Causes

Dissections often occur secondary to trauma, though the severity of the trauma may be quite minor.^2,6 Seemingly trivial mechanisms that have been associated with dissections include nose blowing, coughing, sudden neck turning, and prolonged telephone conversations. Other known causes are motor vehicle accidents and chiropractic maneuvers. Inherited connective tissue disorders, including Ehlers-Danlos syndrome, Marfan syndrome, fibromuscular dysplasia, and osteogenesis imperfecta, are associated with spontaneous ICAD.^2,6

Symptoms

The most common presenting symptom of carotid dissection in approximately two-thirds of patients is ipsilateral head, face, or neck pain,^2,6 typically described as sharp, constant, and nonthrobbing. Patients report a subjective bruit in 21% to 39% of cases.⁷ An acute partial painful Horner syndrome is strongly associated with ICAD, but is present in fewer than half of such patients.⁶ It is characterized by miosis and ptosis and is the result of compression of the ascending sympathetic fibers that travel alongside the ICA within the carotid sheath. Anhidrosis is not present because the fibers for sweat function in the face travel along the external carotid artery.²

Differential Diagnosis

While there is overlap between strokes caused by ICAD versus plaque, some features can help guide the clinician. Symptomatic carotid disease will frequently present with a history of one or more transient ischemic attacks characterized by focal neurological dysfunction or transient monocular blindness—typically within the previous 6 months.⁸ This history is not usually present in patients with ICAD. Secondly, pain is a much more prominent symptom in ICAD compared to patients with severe carotid atherosclerosis. The history of trauma, even minor, should make dissection higher on the differential diagnosis. Fortunately, the imaging studies to evaluate for these two diseases are the same.

Assessing Pupillary Asymmetry and Ptosis

Careful attention must be paid to assessing a patient for pupillary asymmetry. In a patient with anisocoria, determining the abnormal pupil may require examination of the patient in both bright and dark lighting conditions. The first step is to examine the patient’s pupils under normal lighting conditions. The next step is to assess each pupil’s response to shining a bright light in each eye. The abnormal pupil is the pupil that does not respond well or at all to bright light shone directly in the eye. If the anisocoria is greatest in bright light, the larger pupil is the abnormal pupil. When the anisocoria is greater in dark conditions, the smaller pupil is the abnormal pupil. In this case, the patient’s abnormal pupil was incorrectly diagnosed as the contralateral larger pupil (ie, left)—highlighting the importance of performing a complete pupillary examination in all patients presenting with neurological symptoms.⁹

Furthermore, as demonstrated in this case, ptosis in a patient with Horner syndrome caused by an ICAD can be subtle. The ptosis is the result of paralysis of Müeller’s muscle, which is innervated by the sympathetic pathway. The levator palpebrae superioris, which causes the more profound ptosis seen in third nerve palsies, is unaffected.¹⁰

Imaging Studies

Once the diagnosis of ICAD is suspected, appropriate vascular imaging must be obtained. Digital subtraction angiography has historically been the gold standard for vascular imaging of the neck vessels, but it has largely been replaced by less invasive and more readily available imaging modalities such as CTA and MRI/MRA.¹¹

Computed Tomography Angiography. This is a widely available, rapid imaging choice and has a sensitivity of 80% to 95% in the detection of ICAD.⁷ It has a greater ability than MRI to identify dissection features such as intimal flaps, pseudoaneurysms, and high-grade stenosis versus occlusion. One of its disadvantages is the need for iodinated contrast, which can limit the ability to obtain the test in those with renal disease or patients with true allergies to IV contrast material. In addition, a mural hematoma can be mistaken for a noncalcified atherosclerotic plaque in the vessel lumen.⁶

Magnetic Resonance Imaging and Magnetic Resonance Angiography. Both MRI and MRA are also frequently used to diagnose ICAD. The intramural hematoma displays a hyperdense signal on T1-weighted images and has a characteristic crescent shape adjacent to the lumen.¹¹ Magnetic resonance imaging studies are also sensitive in detecting cerebral ischemia resulting from the dissection. However, the sensitivity of MRI/MRA is highest 2 days after the dissection has occurred.²