Spontaneous bilateral internal carotid artery dissection

Abstract

Spontaneous internal carotid artery dissection is not an uncommon cause of ischaemic stroke in younger patients, but multiple cervical arterial dissections at presentation are uncommon. Recurrence of dissection in a previously normal artery is common. In this case report we review the history, clinical findings and management of a 42-year-old woman who presented with stroke and Horner syndrome and was found to have spontaneous bilateral internal carotid artery dissection. She was not anticoagulated due to concerns relating to the size of her infarct. She was treated with a combination of aspirin and clopidogrel. We use dual antiplatelets for the management of cervical dissections as a part of the CADISS trial. The patient made good progress with the multidisciplinary team and was discharged on day 22 with support from the community stroke team.

Background

Spontaneous internal carotid artery dissection is not an uncommon cause of stroke in the younger patient, but multiple cervical arterial dissections at presentation are uncommon. Incidence rates for internal carotid artery dissection have been reported to be 2–3 per 100 000¹ in the general population. Some recent North American studies showed even higher incidence rates. It may be spontaneous or traumatic and is caused by an intimal tear, which is usually extracranial. Spontaneous extra cranial dissection may be due to underlying arteriopathy, fibromuscular dysplasia, or connective tissue diseases including Ehlers–Danlos syndrome and Marfan syndrome. Several authors have suggested a genetic predisposition, but the majority of studies so far have been negative.² In spontaneous cervical artery dissection, multivessel dissection has been shown to be common at presentation.³

Carotid artery dissection should always be considered, particularly when the patient presents with a history of unilateral headache or neck pain. Magnetic resonance imaging (MRI) of the brain plus magnetic resonance angiography (MRA) of the neck vessels is the gold standard investigation to identify the dissection. Management of internal carotid artery dissection is not clear and further information is waited from the Cervical Artery Dissection in Stroke Study (CADISS) comparing anticoagulation versus antiplatelets.

Case presentation

A 42-year-old right handed woman was brought into the emergency department after being found collapsed at home four-and-half hours earlier. At the time of her collapse her speech was noted to be slurred and her left side week. For three days before her collapse she had complained of severe right sided headache and neck pain, which she described as sudden in onset. Past medical history included migraine and recent diagnosis of hypertension and hyperlipidaemia (untreated). She was noted to be taking the oral contraceptive pill. She was a non-smoker and there was no history of miscarriage or head/neck injury. There was no family history of stroke.

Examination revealed: right sided ptosis, miosis and anisocoria suggestive of Horner syndrome, left upper motor neurone facial weakness, and a dense left sided hemiplegia. She was initially aphasic and her speech gradually improved during her stay. She did not have any other cranial nerve palsies apart from seventh cranial nerve palsy. Her National Institutes of Health Stroke Score (NIHSS) was not recorded on admission. There was no joint hyperlaxity.

Investigations

Computed tomography (CT) head scan (fig 1) revealed low attenuation in the region of the right middle cerebral artery (MCA) territory with hyperdense right MCA. The patient was not thrombolysed due to her delayed presentation. An electrocardiogram (ECG) revealed her to be in sinus rhythm and her chest x-ray was clear. Carotid Doppler examination revealed low grade stenosis bilaterally (<30%) with cephalad flow present in the vertebral arteries.

Figure 1.

Computed tomography scan of the brain, showing hyperdense right middle cerebral artery.

The patient underwent MRI with diffusion weighted imaging (DWI) of the brain with MRA followed by gadolinium enhanced MRA of the carotids. MRI + DWI confirmed a large right cerebral infarct (fig 2). MRA of the neck vessels (figs 3 and 4) confirmed dissection of the distal half of the right internal carotid artery with a localised aneurysm and, in addition, extracranial left carotid artery dissection. Imaging of the vertebral arteries showed irregularity and ectasia. The combination of these changes raised the suspicion of fibromuscular dysplasia. However, subsequent MRA of the renal and visceral arteries did not show evidence of this.

Figure 2.

Magnetic resonance imaging of the brain showing right cerebral infarct.

Figure 3.

Magnetic resonance angiography (MRA) of the neck vessels (cross sectional image) showing bilateral carotid artery dissection.

Figure 4.

Contrast enhanced MRA showing narrowing of the internal carotid arteries and localised aneurysmal dilatation of the right internal carotid artery.

Vasculitis screen was negative and echocardiography and Holter monitor examination were unremarkable. Homocysteine values were normal.

Treatment

The patient was treated with a combination of aspirin and clopidogrel. She was not anticoagulated due to concerns relating to the size of her infarct. A statin was also commenced (total cholesterol 7.8 mmol/l). She underwent intense rehabilitation with stroke therapists.

When cerebral infarction has occurred, the risks of anticoagulation should be weighed individually. Anticoagulation should not be considered if there is a large infarct, mass effect, haemorrhagic transformation or intracranial extension.

The optimal approach to manage these patients, including medical treatment, is unclear and mainly aimed at preventing the development of neurological deficits secondary to emboli. The choice is between dual antiplatelet therapy and warfarin. Antiplatelet therapy may be as effective as or safer than warfarin, although no randomised prospective studies have addressed the issue of optimal medical treatment.⁴ One non-randomised study suggested that the frequency of new cerebral and retinal ischaemic events in patients with spontaneous dissection of the cervical carotid artery is low and probably independent of the type of antithrombotic treatment.⁵ Patients are usually anticoagulated for 3–6 months before changing to antiplatelet treatment.

Outcome and follow-up

The patient made excellent progress with the multidisciplinary team. She was discharged on day 22 with support from the community stroke team. At this time she was mobile with assistance from one person, and was taking a normal diet and fluids.

Discussion

Clinical presentation of extracranial internal carotid artery dissection includes ipsilateral headache, neck and/or facial pain, and partial Horner syndrome followed by retinal or cerebral ischaemia.¹ The average progression of symptoms is around 4 days. Cerebral ischaemia (transient ischaemic attack/stroke) is commonly due to thromboembolism from dissection. Most cerebral infarcts are embolic rather than haemodynamic in origin.⁶ Horner syndrome is secondary to stretching and ischaemia of the sympathetic fibres surrounding the internal carotid artery.

Cranial nerve palsies have been reported as rare in dissection of the internal carotid artery; however, one study did show that this was present in 12% of extracranial cases.⁷ They may be secondary to compression/stretching of the nerves or through disruption of blood supply.

Recurrence of dissection is common within the first couple of months and thereafter it is around 1% per year after the first year.

Once suspected, the imaging of choice is MRI of the brain with MRA (time of flight) through the neck. This helps in identifying mural thrombus. To evaluate the luminal narrowing and the vessels, contrast enhanced MRA has also been shown to be useful.¹

Learning points

• Internal carotid artery dissection should be considered in young patients with ischaemic stroke.

• Ipsilateral head, neck and facial pain are common with internal carotid artery dissection.

• If suspected, urgent MRI brain with MR angiography of neck vessels should be requested.

• Risks/benefits of anticoagulation should be weighed on an individual case basis.

• Recurrence of dissection in the normal carotid artery following unilateral dissection is common and underlying hereditary arteriopathy should be excluded.