Location of Carotid Dissection
Extracranial carotid dissections generally occur 2 cm or more beyond the carotid bifurcation, near or adjacent to the base of the skull. Intracranial carotid dissections are most frequent in the supraclinoid segment. Vertebral artery dissection most often occurs in the cervical transverse processes from C6 to C2 (V2 segment) or in the extracranial segment between the transverse process of C2 and the foramen magnum at the base of the skull (V3 segment).
Pathophysiology
The separation of the layers of the arterial wall leads to a dissection. A false lumen appears in the space where blood infiltrates the vessel wall. The hemorrhage may be due to an intimal tear or result from a rupture or other pathology in the vasa vasorum. Subintimal carotid dissections cause stenosis or occlusion of the lumen, while subadventitial dissections primarily lead to the formation of dissecting aneurysms.
Etiology of Carotid Dissection
Dissection may result from a combination of intrinsic deficiencies in the integrity of the arterial wall and extrinsic factors, including minor trauma. Many proposed risk factors and triggering activities have been associated with dissection.
Epidemiology
Carotid dissection of the cervical and cerebral arteries occurs in about 3 out of 100,000 individuals of all ages but is responsible for a quarter of all strokes in young people.
Clinical Manifestation of Carotid Dissection
Data from population studies and hospital reports suggest that dissection most often results in an ischemic event or a transient ischemic attack, usually preceded or accompanied by local symptoms such as neck pain, headache, Horner's syndrome, and/or cranial neuropathies.
However, these studies may underestimate the proportion of cases that are asymptomatic or associated with local symptoms only. Intracranial carotid dissection can exceptionally lead to subarachnoid hemorrhage.
Evaluation and Diagnosis of Carotid Dissection
We perform urgent non-invasive multimodal imaging by magnetic resonance imaging (MRI) and magnetic resonance angiography (MRA) of the head and neck, or by computed tomography (CT) and computed tomography angiography (CTA) of the head and neck to confirm an initial diagnosis of cervico-cephalic dissection and guide serial treatment decisions.
Although clinical features may raise suspicion of carotid dissection, the diagnosis is confirmed by brain imaging findings. In particular, the identification of a long, tapered arterial stenosis, tapered occlusion, dissecting aneurysm (pseudoaneurysm), intimal flapping, double lumen, or intramural hematoma.
Source: UpToDate