Imaging in the diagnosis and follow-up evaluation of vertebral artery dissection

Predictors of ischemic events in patients with unilateral extracranial vertebral artery dissection: A single-center exploratory study

Objective

Extracranial vertebral artery dissection (EVAD) is one of the main causes of stroke in young and middle-aged patients. However, the diagnosis is challenging. This study aimed to identify the characteristics of EVAD on color duplex ultrasonography (CDU) and high-resolution magnetic resonance imaging (hrMRI), hoping to improve the accuracy and determine the relative contribution of vessel findings and clinical factors to acute ischemic events.

Methods

Patients with unilateral EVAD were recruited and divided into ischemia and non-ischemia groups. Clinical features of patients and the lesion location; a variety of signs which indicate dissection, including the presence of an intimal flap, double lumen, intramural hematoma, dissecting aneurysm, intraluminal thrombus, and irregular lumen; and other quantitative parameters of each dissected segment on CDU and hrMRI were reviewed, respectively. Multiple logistic regression was performed to explore the association between clinical, imaging characteristics, and ischemic events in patients with unilateral EVAD.

Results

Ninety-six patients with unilateral EVAD who met the inclusion criteria were enrolled during a six-year period. Overall, 41 cases (42.7%) were confirmed as ischemic stroke (n = 40) or transient ischemic attack (n = 1) during the 48 h after the onset of symptoms. Men, infections during the last week, and smoking were more common in the ischemia group. Intraluminal thrombus and occlusion on CDU were more prevalent in patients with cerebral ischemia than in those without (36.6 vs. 5.5%; p < 0.001, and 39.0 vs. 9.1%; p = 0.001, respectively). On hrMRI, intraluminal thrombus and occlusion were also more frequent in the ischemia group than in the non-ischemia group (34.1 vs. 5.5%; p < 0.001, and 34.1 vs. 9.1%; p = 0.003, respectively). In addition, lesion length on hrMRI was significantly longer for patients with ischemia (81.5 ± 41.7 vs. 64.7 ± 30.8 mm; p = 0.025). In multivariable logistic regression analysis, male gender, infections during the last week, and the presence of intraluminal thrombus on CDU and hrMRI were independently associated with acute ischemic events.

Conclusion

Male sex, infections during the last week, and the presence of intraluminal thrombus due to dissection are associated with an increased risk of ischemic events in patients with unilateral EVAD.

Diagnostic vascular ultrasonography with the help of color Doppler and contrast-enhanced ultrasonography

The use of ultrasonography and especially of contrast-enhanced ultrasonography (CEUS) in the diagnosis of vascular pathologies before and after interventions has significantly increased over the past years due to the broader availability of modern ultrasound systems with CEUS capabilities and more trained user experience in this imaging modality. For the preinterventional and postinterventional work-up of carotid diseases, duplex ultrasound as well as CEUS have been established as the standard-of-care examination procedures for diagnosis, evaluation, and follow-up. In addition to its use for carotid arterial diseases, ultrasonography has also become the primary modality for the screening of vascular pathologies. This review describes the most common pathologies found in ultrasonography of the carotid arteries, the abdominal aorta, and the femoral arteries.

The role of contrast-enhanced ultrasound in imaging carotid arterial diseases

The standard of care for the initial diagnosis of carotid artery bifurcation diseases is carotid duplex ultrasound. Carotid abnormalities or difficult examinations may represent a diagnostic challenge in patients with clinical symptoms as well as in the follow-up after carotid endarterectomy, carotid artery stenting or other interventions. A promising new method in the diagnosis and follow-up of pathologic carotid diseases is contrast-enhanced ultrasound (CEUS). In comparison with magnetic resonance imaging or computed tomography, the contrast agents used for CEUS remain within the vascular space and hence can be used to study vascular disease and could provide additional information on carotid arterial diseases. This review describes the current carotid duplex ultrasound examination and compares the pathologic findings with CEUS.

Imaging characteristics of symptomatic vertebral artery dissection: a systematic review

BACKGROUND

Vertebral artery dissection (VAD) is an important cause of stroke in the young. VAD can present with a range of imaging findings. We sought to summarize the diagnostic value of various imaging findings in patients with symptomatic VAD.

METHODS

We conducted a systematic review of observational studies, searching electronic databases (MEDLINE, EMBASE) for English-language manuscripts with >5 subjects with clinical or radiologic features of VAD. Two independent reviewers selected studies for inclusion; a third adjudicated differences. Studies were assessed for methodological quality and imaging data were abstracted. Pooled proportions were calculated.

RESULTS

Of 3996 citations, we screened 511 manuscripts and selected 75 studies describing 1972 VAD patients. Most studies utilized conventional angiography or magnetic resonance angiography (MRA) to diagnose VAD; computed tomographic angiography (CTA) and Doppler ultrasonography were described less frequently. Imaging findings reported were vertebral artery stenosis (51%), string and pearls (48%), arterial dilation (37%), arterial occlusion (36%), and pseudoaneurysm, double lumen, and intimal flap (22% each). In cases where conventional angiography was the reference standard, CTA was more sensitive (100%) than either MRA (77%) or Doppler ultrasonography (71%) (P=0.001).

CONCLUSIONS

Imaging findings vary widely in patients with VAD, with no single radiographic sign present in the majority of VAD patients. Nonspecific radiographic signs predominate. CTA probably has greater sensitivity for dissection than MRA or ultrasound relative to conventional angiography. Higher quality studies on imaging techniques and radiographic criteria in subjects with VAD are needed. Future studies should compare imaging techniques in well-defined, undifferentiated populations of clinical VAD suspects.

Clinical characteristics of symptomatic vertebral artery dissection: a systematic review

BACKGROUND

Vertebral artery dissection (VAD) is an important cause of stroke in the young. It can present nonspecifically and may be misdiagnosed with adverse consequences. We assessed the frequency of head/neck pain, other neurological symptoms, and cerebrovascular events in symptomatic VAD.

METHODS

We conducted a systematic review of observational studies, searching electronic databases (MEDLINE, EMBASE) for English-language manuscripts with >5 subjects with clinical or radiologic features of VAD. Two independent reviewers selected studies for inclusion; a third adjudicated differences. Studies were assessed for methodological quality, and clinical data were abstracted. Pooled proportions were calculated.

RESULTS

Of 3996 citations, we screened 511 manuscripts and selected 75 studies describing 1972 VAD patients. The most common symptoms were dizziness/vertigo (58%), headache (51%), and neck pain (46%). Stroke was common (63%), especially with extracranial dissections (66% vs. 32%, P<0.0001), whereas transient ischemic attack (14%) and subarachnoid hemorrhage (10%) were uncommon. Subarachnoid hemorrhage was seen only with intracranial dissections (57% vs. 0%, P=0.003). Fewer than half of the patients had obvious trauma, and only 7.9% had a known connective tissue disease. Outcome was good (modified Rankin scale 0 to 1) in 67% and poor (modified Rankin scale 5 to 6) in 10% of patients.

CONCLUSIONS

VAD is associated with nonspecific symptoms such as dizziness, vertigo, headache, or neck pain. Ischemic stroke is the most common reported cerebrovascular complication. VAD should be considered in the diagnostic assessment of patients presenting with dizziness or craniocervical pain, even in the absence of other risk factors. Future studies should compare clinical findings as predictors in well-defined, undifferentiated populations of clinical VAD suspects.

[Horner syndrome as a manifestation of carotid artery dissection]

CLINICAL CASE

A 42-year-old man presented with ptosis and miosis in his left eye and a history of headache over the last 20 days. An angioresonance showed dissection of internal carotid artery.

DISCUSSION

"Painful Horner's Syndrome" is considered to be a medical emergency due possible onset of an internal carotid artery dissection. We consider that awareness of neuro-ophthalmologic emergencies is very important in the clinical praxis of an ophthalmologist. Multidisciplinary treatment and follow-up of these patients is required.

Imaging of carotid arterial diseases with contrast-enhanced ultrasound (CEUS)

Carotid duplex ultrasound is the standard of care for the initial diagnosis of carotid artery bifurcation diseases. But in difficult examinations, carotid abnormalities are commonly encountered and may represent a diagnostic challenge in patients with clinical symptoms as well as in the follow up after carotid endarterectomy or carotid artery stenting. Contrast enhanced ultrasound (CEUS) with low mechanical index (low MI) is a promising new method in the diagnosis and follow up of pathological carotid diseases. Unlike most contrast agents used for magnetic resonance imaging or computed tomography, the microbubbles used in CEUS with SonoVue(®) remain within the vascular space and hence can be used to study vascular disease. In addition to improving current carotid structural scans, CEUS has potential to improve or add extra information on carotid arterial diseases. This review describes the current carotid duplex ultrasound examination and compares the pathological findings with CEUS.

Practical noninvasive neurovascular imaging of the neck arteries in patients with stroke, transient ischemic attack, and suspected arterial disease that may lead to ischemia, infarction, or flow abnormalities

Stroke is the third leading cause of death in the United States, killing nearly 157,000 people a year with an estimated society cost of dollar 58 billion in 2006. A large percentage of ischemic strokes is secondary to extracranial carotid and vertebral arterial disease. While digital subtraction angiography has traditionally been used for the initial evaluation of the degree of stenosis, noninvasive imaging has moved to the forefront in the extracranial arterial evaluation. The importance of understanding the imaging techniques, findings, interpretation, artifacts, and pitfalls is essential to appropriate patient management.

Imaging the vertebral artery

Although conventional intraarterial digital subtraction angiography remains the gold standard method for imaging the vertebral artery, noninvasive modalities such as ultrasound, multislice computed tomographic angiography and magnetic resonance angiography are constantly improving and are playing an increasingly important role in diagnosing vertebral artery pathology in clinical practice. This paper reviews the current state of vertebral artery imaging from an evidence-based perspective. Normal anatomy, normal variants and a number of pathological entities such as vertebral atherosclerosis, arterial dissection, arteriovenous fistula, subclavian steal syndrome and vertebrobasilar dolichoectasia are discussed.

Improved diagnosis of vascular dissection by ultrasound B-flow: a comparison with color-coded Doppler and power Doppler sonography

The purpose was to evaluate the diagnostic results of different ultrasound techniques: color-coded Doppler (CCD), power Doppler (PD) and B-flow in the diagnosis of vascular dissection. Findings from 68 patients with arterial dissection proven either by vascular ultrasound (US) or by magnetic resonance angiography (MRA), computed tomographic angiography (CTA) or intra-arterial digital subtraction angiography (DSA) were reviewed in retrospect. The study compared results from three different modes of ultrasound, i.e., CCD, PD and B-flow, in dissections of the carotid artery (n=11), of the vertebral artery (n=9), of the abdominal aorta (n=13), of the iliac artery (n=12) and of the femoral artery (n=23). MRA, CTA and DSA were considered as reference standard. The sensitivity of CCD for detecting all dissections was 78%, 84% for the PD and 98% for B-flow. For carotid artery dissection, the sensitivity of CCD, PD and B-flow was 82, 91 and 98%, for the vertebral artery 67, 78 and 98%, for the abdominal aorta 85, 85 and 98%, for the iliac artery 67, 75 and 98%, for the femoral artery 83, 87 and 98%, respectively. Intima flaps, fissures of membranes and residual flow within the true and false lumen were better detected by B-flow than by CCD and PD. The lack of angle dependence of the US probe in B-flow made the examination procedure easier. In the cine mode of B-flow, the pulse synchronic movement of the membrane was more apparent than in any other imaging method. With B-flow, accuracy for the diagnosis of arterial dissection is improved compared to CCD and PD. Flow within the true and false lumen, low-echo thrombi, intramural hematoma and even movements of the dissection membrane are clearly distinguished.

Vertebral artery injuries

Vertebral artery injuries are identified more frequently now than in the past for both penetrating and blunt trauma. This is as a result of increased suspicion and awareness, liberal use of color flow Doppler, CT angiography, and traditional four-vessel angiography. The vast majority of patients who are not exsanguinating at the time of presentation can be managed nonoperatively or by angiographic embolization. Operative management should be reserved only for patients with severe active bleeding or when interventional radiology fails. The surgical exposure is complex and demands excellent knowledge of the local anatomy.