Welcome to Stroke Education.CO.UK

Learning objectives

  • Understand the aetiology and risk factors for Cervical dissection
  • Discuss diagnostics and treatment strategies

Introduction to Dissection

Dissection occurs when there is a tear in the intimal layer of a blood vessel with bleeding and haematoma within the vessel wall. The haematoma may be due to an intimal tear and entry of luminal blood or from vasa vasorum or both. This can lead to overlying thrombus or vessel stenosis or occlusion. The clot can cause complete or subtotal occlusion of the carotid artery or vertebral. Damage to the endothelium means that the vessel loses its natural "non-stick-surface" and so clot can form on the luminal intimal surface and cause artery to artery embolisation which is the rationale for anticoagulantion/antithrombotic therapy. There is a small risk that dissections can extend proximally and as intracranial vessels are more fragile when the dissection extends intracranially there is a risk of subarachnoid haemorrhage with typical SAH presentation. This may temper any desire to anticoagulate and as all of this is an evidence light area different clinicians may have different ways to manage these perceived risks. Trials such as CADISS aim to try and answer some of these questions.

Carotid artery dissection

Always consider this diagnosis in a young adult (under 50) with an anterior circulation stroke unless alternative cause is evident. Carotid dissection is about 3 times commoner than vertebral. Commonest in those in their mid 40s but seen at any age. This most commonly occurs in the internal carotid artery approximately 2-3 cm after the bifurcation. A very small minority (2%) can be associated with connective tissue diseases such as Marfan's syndrome, Ehlers Danlos Type IV or Fibromuscular dysplasia. Males and females are equally affected.

Dissection may be precipitated by accidental neck trauma or cervical manipulation. The trauma may preceded the dissection by several hours or days. Clinically the patient usually complains of pain anywhere along the internal carotid artery up into the face and behind the eye. Disruption to the sympathetic supply to the eye which is closely associated with the artery can cause an Ipsilateral Horner's syndrome - mild ptosis, small pupil, enophthalmos, Ipsilateral Stroke findings if embolises or ICA occludes,

Rarely dissection extends into intracranial vessels and leads to thunderclap headache and other SAH symptoms. The investigations of choice is an MRI with fat suppression of the neck which shows crescent shaped intramural clot and MRI-DWI may show infarction. The vessels and any obstruction can be imaged with MRA. Carotid Doppler may show an intimal flap, haematoma or an occluded vessel.

Clinical

Presentations of Carotid Dissection
  • Asymptomatic presenting only as stroke
  • Neck pain, Facial pain and retro-orbital pain
  • Ipsilateral Horner's syndrome due to damage to sympathetic supply that runs with carotid
  • Migrainous type headache
  • PACI or TACI type stroke due to Carotid occlusion or emboli to MCA
  • Subarachnoid haemorrhage


Something as simple as a sneeze can cause a dissection.

Imaging

Above: Left Carotid Dissection The crescentic flap within the left internal carotid artery can be seen on MRI with fat suppression/saturation. This crescent-shaped rim of hyperintense signal adjacent can be matched with a narrowed segment of artery on angiography. Infarction if it occurs is either embolic or due to complete occlusion of the vessel. There is a more tapered appearance than seen with an embolic or in situ blockage.

Management

In terms of management the main therapy is anticoagulation to reduce risk of thrombus formation and embolism and to maintain vessel patency. The choice is between Aspirin, clopidogrel and warfarin. There is no evidence base in favour of either. Some give Warfarin for 6 months. Others favour an aspirin and/or clopidogrel combination for several months and then long term anti-platelet therapy for at minimum one year. Choice of therapy depends on whether dissection has been accompanied by a stroke, the size of stroke and risks of haemorrhagic transformation. If the patient presents with an acute stroke then thrombolysis should certainly be considered and carotid dissection is not a contraindication. Risk of recurrence appears to be low [Debette S. 2009].

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