Dissections may develop in the internal carotid artery (ICA) or in any of its branches, as well as in the vertebral and basilar arteries. Dissection may arise either extracranially or intracranially. Risk factors for a dissection include trauma, cervical manipulation, connective tissue disorders, and fibromuscular dysplasia.
Clinical presentation of arterial dissection
Arterial dissection’s clinical features are variable. Patients may incur stroke, which typically occurs within the first 30 days of the dissection. The most common presentation of ICA dissection is acute pain located on the ipsilateral forehead, around the orbit, or in the neck. Other manifestations include ipsilateral ophthalmic signs and contralateral neurologic deficits (see Chapter 10, Fig 10-4). A bruit may be present. Sometimes symptoms of arterial dissection are delayed for weeks or months after trauma. Transient or permanent neurologic symptoms and signs include amaurosis fugax, acute stroke, monocular vision loss, and ipsilateral Horner syndrome. If the dissection extends to the intracranial carotid segment, cranial neuropathies can occur, producing diplopia, dysgeusia, tongue paralysis, or facial numbness.
The vision loss associated with ICA dissection may be a result of embolic occlusion of the ophthalmic artery, central retinal artery, short posterior ciliary arteries, or retinal branch arteries. Alternatively, ophthalmic artery occlusion may be caused by the dissection itself. Reduced blood flow from ICA dissection is a rare cause of ocular ischemic syndrome.
The vertebral and basilar arteries are affected in 40% of dissections. General features of these dissections are headache, neck pain, and signs of brainstem and cerebellar dysfunction. Ocular motor CN palsies are common, and the consequences may progress to include quadriplegia, coma, and death.
Caplan LR, Biousse V. Cervicocranial arterial dissections. J Neuroophthalmol. 2004;24(4): 299–305.
Diagnosis of arterial dissection
MRI is the diagnostic test of choice for an extracranial ICA dissection. MRI shows a false lumen or an area of clotting in the cervical portion of the carotid artery (“crescent moon” sign; see Fig 10-4) and may identify areas of brain infarction. CTA or MRI/MRA has a sensitivity of 87%–100%. CTA has the added benefit of allowing visualization of the vertebrobasilar system. Digital subtraction angiography may also be used for diagnosis. Ultrasonography is not sufficient to detect a carotid dissection and can elicit a false-negative result in nearly one-third of cases.
Treatment of arterial dissection
The treatment of arterial dissection depends on the extent and location of the dissection and the patient’s overall condition. Treatment methods may include medical therapy using antiplatelet drugs or anticoagulants, endovascular therapy with stent placement, and, in rare cases, surgery with bypass procedures.
Excerpted from BCSC 2020-2021 series: Section 5 - Neuro-Ophthalmology. For more information and to purchase the entire series, please visit https://www.aao.org/bcsc.