Vertebral Artery Dissection: A Case Report and Review of the Literature

Abstract

Arterial dissection is the result of blood entering along the intima-media plane through a breach produced either spontaneously or traumatically. Cervical arterial dissections are an important cause of acute ischemic stroke in children, young adults, and patients with cranio-cervical traumatic injuries. Arterial dissections occur either spontaneously, in genetic diseases, the most important association being with fibromuscular dysplasia. In most of the cases dissection involve the extracranial portions of the internal carotid and vertebral arteries. Magnetic resonance with T1 fat-saturation (T1 FS) sequence of the cervical region or computed tomography (CT) with computed tomography angiography (CTA) shows a very high sensitivity and specificity in the diagnosis of cervical artery dissections. Therapeutic options are still debatable in patients with acute ischemic stroke and vertebral or carotid artery dissection.

Introduction

Cervical artery dissection is a rare cause of cerebral ischemia, but is a common cause of nonatherosclerotic vasculopathy causing ischemic stroke in young patients.

Arterial dissections occurs either spontaneously, as part of genetic diseases (fibromuscular dysplasia, Moya-Moya disease, Marfan syndrome, Ehler-Danlos syndrome type IV, Turner syndrome, Wiliam syndrome, osteogenesis imperfecta type I) or after cranio-cervical trauma, after Valsalva manoeuvres, strong coughing or sneezing.

The most frequent association is with fibromuscular dysplasia [1].

There have been described cases of cervical dissection in the literature after head extension or chiropractic manoeuvres even long time ago from the acute event.

The cumulative incidence of cervical artery dissections is 2.6 cases per 100,000.

While the incidence of carotid artery dissection is 1.72 cases per 100,000, the incidence of vertebral artery dissection is 0.97 cases per 100,000 [2].

Vertebral artery dissection occurs in younger patients than carotid artery dissection.

Women are 2.5 times more frequently affected by extracranial vertebral dissections while intracranial vertebral dissections are more frequent in males [3].

Intracranial dissections are frequently associated with subarachnoid haemorrhage in half of the cases [4] due to the rupture of the dissecting aneurysm [5].

This type of dissection is subintimal and follow trauma, fractures at the base of the skull or penetrating injuries.

Most frequently, the mechanism of cerebral ischemia in the case of an extracranial arterial dissection is through artery-to-artery embolism from an intraluminal thrombus, hence the rationale for the use of antithrombotics in secondary stroke prevention [6].

Case Presentation

We present the case of a 40-year-old male patient with cardiovascular risk factors (smoker, dyslipidaemia), but without a known pathological personal history, who presents obvious neurological signs after a traumatic effort of the cervical region.

This case presentation was carried out with the consent of the patient, after he was made aware about all the information regarding participation in the study.

Clinical and imaging data were used after obtaining consent from the patient and the imaging department.

The patient presented at the emergency department with gait and balance disturbance, vertigo, paraesthesia in all four limbs, diplopia and dysarthria, which started suddenly approximately one hour before admission, after prolonged flexion of the head in an effort of leaning forward.

From the patient's medical history, we only noted that he is a smoker, with elevated serum cholesterol values in the past, with no known personal pathological history or history of consumption illicit drugs or other medicines.

On clinical neurological examination we found dysarthria, diplopia due to right abducens nerve palsy with convergent strabismus in the right eye, left central facial palsy, left segmental ataxia (dysmetria in the index-nose and heel-knee test) and Babinski sign on the left.

The clinical picture was suggestive of a vertebro-basilary stroke.

By correlating clinical picture with the context of occurrence, it was raised the suspicion of cervical artery dissection.

Given that the patient presented in the therapeutic window for intravenous thrombolysis (IVT) with an NIHSS score of 5 and due to the availability of the imaging department to perform emergency brain MRI with FLAIR (fluid attenuated inversion recovery), DWI (diffusion weighted imaging), SWI (susceptibility weighted imaging), cervical T1 FS and 3D TOF (time-of-flight) sequences, although the protocol for thrombolysis requires only CT scan.

Acute ischemic lesions were seen as high DWI signal and low ADC (apparent diffusion coefficient) signal bilaterally in the cerebellar hemispheres (Figure 1), right lateral pons, without high signal on T2 and FLAIR (mismatch DWI-FLAIR [7]) and absence of signal void of the right vertebral artery on axial T2 (Figure 2) suggestive of occlusion oft the right vertebral artery.

Figure 1.

Brain MRI, axial DWI sections showing multifocal infra-centimetric areas of diffusion restriction bilaterally in the cerebellar hemispheres.

Figure 2.

MRI, axial T2 showing absence of signal void of the right vertebral artery

Also, 3D TOF shown lack of visualisation of the right vertebral artery in V2-V4 segment (Figure 3).

Figure 3.

3D TOF showing lack of visualization of the right vertebral artery in the V2-V4 segment, at the level of the C1-C6 vertebra.

On cervical T1 FS it was highlighted a crescent sign in the lumen of the left vertebral artery.

The patient did not present any absolute or relative contraindications for IVT, so it was decided that the patient is eligible for this therapy, and thrombolysis was initiated with a total alteplase dose of 68mg (door-to-needle 55 minutes).

After thirty minutes from the beginning of alteplase infusion, the patient developed hemiparesis in the left limbs and psychomotor agitation.

Because there was no worsening of more than 4 points on the NIHSS scale to justify interruption, the infusion was continued as indicated in the protocol.

At the end of the infusion, the patient remains with hemiparesis superimposed on initial symptoms, having a NIHSS score of 8 points.

Brain CT was repeated 24 hours after thrombolysis, according to the protocol, and revealed acute ischemic lesions in the cerebellar hemispheres bilaterally.

He received antiplatelet treatment according to the guidelines.

The patient performed a brain MRI 10 days after admission which revealed an increasing number of acute ischemic lesions (Figures 4, 5), so it was decided to switch to oral anticoagulant therapy from antiplatelet therapy (off label indication).

Figure 4.

Brain MRI, axial T1 FS showing the crescent sign at the level of the left vertebral artery lumen; the hyperintensity is due to the thrombus from the false lumen of the vessel

Figure 5.

Brain MRI, axial DWI sections: lesions in hypersignal in the cerebellar vermis, pontine tectum, right paramedian pons, left mesencephalic cerebral peduncle (responsible for clinical deterioration during thrombolysis).

It is doubtful that in this reported case, the occlusion of the right vertebral artery occurred simultaneously with the dissection of the left vertebral artery, most likely the occlusion pre-existed and the main source of blood supply to posterior territory was left vertebral artery.

At the time when the left vertebral artery dissection occurred, the patient presented multiple symptomatic, bilateral ischemia in the vertebro-basilar territory.

The clinical and imaging outcome of the patient led us to replace the antiplatelet therapy with oral anticoagulant therapy due to the increased number of new ischemic lesions on the MRI performed 10 days after admission.

The clinical outcome was favourable, with remission of deficits, practically at discharge, after 3 weeks, the NIHSS score was 1, which means almost complete improvement.

At follow up at three months, Rankin score was 0.

Discussions

The vertebral arteries have their greatest mobility and vulnerability to mechanical injury at the level of C1-C2 vertebra [8] at the exit site from the transverse foramen of the axis, as its entry into the skull.

The most common mechanism by which ischemia occurs in case of extracranial artery dissections is artery-to-artery embolism from an intraluminal thrombus, hence the rationale for using antithrombotic medication (antiplatelet or anticoagulant) in secondary prevention to decrease the risk of ischemic stroke.

Although most dissections heal spontaneously, a small proportion of patients will have disease progression with complications and formation of pseudo-aneurysms.

CT scan reveals early signs of ischemia (parenchymal hypoattenuation, loss of differentiation between gray/white matter), but several hours after the acute event must pass from the onset of symptoms to be able to visualize the infarcted area.

Cerebral MRI through DWI/ADC detects the ischemic lesions with great specificity and sensitivity from the first minutes ((hypersignal on DWI slices, hyposignal on ADC slices).

Patients with an acute ischemic stroke detected by DWI but not by FLAIR imaging are likely to be within the therapeutic window time of thrombolysis (the so-called mismatch DWI/FLAIR).

Through T1 FS, the "crescent sign" is detected with great accuracy, and MRA sequences can reveal the absence of "signal void" in the affected vessel.

Digital subtraction angiography, considered the "gold standard" in the past is no longer routinely used for diagnosis of dissection.

Therapeutic options are still debatable in patients with acute ischemic stroke and vertebral or carotid artery dissection.

The European guideline for the management of intra-and extracranial arterial dissections [9] recommends in case of extracranial artery dissection complicated with a stroke or TIA (transient ischemic attack), antiplatelet agents which have a better risk-benefit ratio than oral anticoagulants.

If oral anticoagulant treatment is still preferred, it is recommended to use a direct anticoagulant (DOAC) instead of an antivitamin K anticoagulant.

In case of minor stroke or TIA caused by an extracranial artery dissection the guideline indicates the use of dual antiplatelet treatment with aspirin and clopidogrel limited to a few weeks.

By comparison, according to the AHA guideline for secondary prevention of acute stroke [10], in patients with acute stroke or TIA less than 3 months after the acute event, it is reasonable to use either antiplatelet treatment (aspirin) or oral anticoagulant treatment (warfarin).

The CADISS clinical trial [11] included 250 patients, from which 118 patients with carotid artery dissection and 132 patients with vertebral artery dissection. 128 patients received antiplatelet treatment while 124 patients received oral anticoagulant treatment.

No statistical difference was found between the two groups regarding the recurrence of ischemic events or the recanalization rate at one year.

In exceptional cases, in which recurrent ischemic events occur despite optimal antithrombotic therapy or in the case of an expanding dissecting aneurysm, endovascular or surgical treatment may be considered after evaluation by a multidisciplinary team consisting of neuroradiologist, neurologist and neurosurgeon.

Conclusions

Cerebral imaging is essential in establishing the diagnosis of extracranial artery dissection and quantify lesion size and disease progression.

Our case reflects the importance of imaging techniques in the diagnosis and identification of the aetiology of cerebral ischemic lesions, each imaging investigation bringing additional information that helps us to choose the appropriate therapeutic management.

There is no "gold standard" in the diagnosis of cervical dissections.

We can use MRI with T1, T2, FLAIR and DWI/ADC sequences with cranial and cervical T1 FS which is useful for identifying small intramural haemorrhages, MRI should be complemented by MRA with contrast-enhanced and time-of-flight MRA.

As an alternative to MRI, we can use native CT with cerebral and cervical CTA.

The choice between these two methods is primarily based on the availability and experience of each center.

Therapeutic options are still debatable in patients with acute ischemic stroke and vertebral or carotid artery dissection.

Conflict of interests

None to declare