|Year : 2022 | Volume
| Issue : 2 | Page : 191-195
Spectrum of Vertebral Artery Pathologies on Imaging: Case Series
Prashant Madhukarrao Onkar, Avinash Parshuram Dhok, Varun Vasant Nimje, Priyanka Jayant Mane
Department of Radiodiagnosis and Imaging, N.K.P. Salve Institute of Medical Sciences and Lata Mangeshkar Hospital, Nagpur, Maharashtra, India
|Date of Submission||04-Oct-2021|
|Date of Decision||01-Nov-2021|
|Date of Acceptance||02-Nov-2021|
|Date of Web Publication||13-Jun-2022|
Varun Vasant Nimje
Department of Radiodiagnosis and Imaging, N.K.P. Salve Institute of Medical Sciences and Lata Mangeshkar Hospital, Nagpur, Maharashtra
Source of Support: None, Conflict of Interest: None
Background: Vertebral artery pathologies are not as common on ultrasound examination. Careful ultrasound examination of the vertebral artery can provide useful information about the proximal brachiocephalic vessels as well as the intracranial portion of the vertebral artery. Objectives: To illustrate a variety of vertebral artery pathologies on ultrasound and their abnormal color Doppler findings with confirmation of some cases on magnetic resonance imaging. Materials and Methods: A 3-12 MHz linear ultrasound probe was used to examine the vertebral artery segments. The examination began with a B-mode examination of the first and second portions of the vertebral arteries, followed by color Doppler examination to determine the direction of blood flow. Spectral Doppler is used to identify flow anomalies. Conclusion: Evaluation of proximal great vessels by ultrasound can sometimes be difficult, so careful examination of vertebral artery by ultrasound can be an important tool to detect occlusions or stenosis of proximal great vessels. In addition, vertebral artery waveforms in the cervical segment provide useful information regarding the intracranial portion of the vertebral artery.
Keywords: Partial subclavian steal, subclavian steal, vertebral artery, vertebral artery thrombosis
|How to cite this article:|
Onkar PM, Dhok AP, Nimje VV, Mane PJ. Spectrum of Vertebral Artery Pathologies on Imaging: Case Series. Indian J Vasc Endovasc Surg 2022;9:191-5
| Introduction|| |
Unless vertebrobasilar symptoms are suspected, many departments routinely do not examine the vertebral arteries while performing a carotid Doppler ultrasound scan. In addition to the carotid duplex ultrasound scan, a basic examination of the vertebral arteries, including the subclavian arteries, should be performed. Examination of vertebral artery in the neck provides significant information about the proximal brachiocephalic vessels as well as the distal intracranial vertebral artery. A preliminary examination of the vertebral arteries is to identify the presence of cephalic flow with a normal pulsed Doppler waveform at or near the carotid bifurcation. Digital subtraction angiography is the gold standard imaging test for diagnosing vertebrobasilar stenosis. However, it is a costly investigation and patients undergoing angiography have a 1%–2% risk of neurological complications.,
We present a series of cases of abnormal findings of vertebral artery on ultrasound and color Doppler with further confirmation of few of these cases on magnetic resonance imaging (MRI).
| Subjects and Methods|| |
All the patients referred to the department of radio-diagnosis and imaging having abnormal ultrasound findings in vertebral artery were included. 3–12 MHz linear ultrasound probe was used to examine the vertebral artery segments. The examination started with B-mode examination of the first and second part of vertebral arteries followed by color Doppler examination to establish the direction of blood flow. Next, spectral Doppler is used to display the waveform so as to identify abnormalities of the flow. Normal vertebral artery should display cephalic flow throughout the cardiac cycle and a low resistance waveform (i.e., a low peak systolic: end diastolic velocity ratio) [Figure 1].
|Figure 1: (a) Gray-scale image showing vertebral artery (VA) in the neck between the transverse processes of cervical vertebrae (blue arrows). (b) Origin of the right VA (blue arrow) from the right subclavian artery. (c) Normal spectral waveform of the VA showing continuous forward diastolic flow|
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Vertebral artery thrombosis
Following three cases of vertebral artery thrombosis were evaluated.
A 45-year-old male, known hypertensive on medications, presented with complaint of deviation of angle of mouth. Examination of the left vertebral artery in the neck with spectral Doppler showed high resistance waveform with reversal of blood flow in diastole. The contralateral vertebral artery showed normal waveform on spectral Doppler. This change in the waveform of left vertebral artery from normal low resistance flow to high resistance flow, with diastolic reversal indicates possibility of distal occlusion in that vertebral artery. The patient underwent MR angiography which showed nonopacification of the third and fourth part of left vertebral artery, with acute infarct involving pons [Figure 2].
|Figure 2: (a) Spectral waveform in left vertebral artery (VA) showing diastolic reversal. (b) Magnetic resonance angiography image in the same patient showing nonopacification of third and fourth part of left VA (yellow arrow). (c) Diffusion-weighted imaging sequence showing acute infarct in the pons on the left side|
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A 49-year-old female patient presented with cerebellar signs and suspicious for posterior circulation stroke. The patient was known hypertensive and diabetic on medications. Left vertebral artery on spectral examination showed attenuated flow as compared to the opposite vertebral artery. This finding was suspicious for distal thrombosis in the left vertebral artery [Figure 3].
|Figure 3: (a) Left vertebral artery (VA) in the cervical part showing attenuated flow with reduced peak systolic velocity. (b) Contralateral VA showing normal high diastolic flow pattern with normal peak systolic velocity. (c) Magnetic resonance angiography image in the same patient showing nonopacification of 3rd and 4th parts of the left VA|
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A 55-year-old male patient presented with suspected cerebellar signs. The right vertebral artery showed hypoechoic intraluminal contents and did not show flow on color Doppler suggestive of thrombosis of that segment [Figure 4].
|Figure 4: Hypoechoic content is seen within the second part of vertebral artery which does not show flow on color Doppler suggestive of thrombosis. The vertebral vein showing normal color flow|
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Subclavian steal syndrome
Five cases of complete subclavian steal were examined. Following are the representative images from few of the cases.
A 57-year-old male patient came with complaints of tingling numbness in the right upper limb for a week. On clinical examination, radio-radial delay was noted and the patient was referred for arterial Doppler of the right upper limb. Echogenic thrombus was seen at the origin of right subclavian artery with turbulent flow and increased peak systolic velocities. Right vertebral artery showed retrograde flow, while right common carotid artery (CCA) showed normal antegrade flow. Arteries of the right upper limb distal to the right subclavian artery showed damped tardus parvus waveform [Figure 5].
|Figure 5: (a) Retrograde flow in the vertebral artery and normal forward flow in the common carotid artery. (b) Echogenic thrombus at the origin of right subclavian artery from the brachiocephalic trunk. (c) Aliasing at the site of narrowing which shows high velocity turbulent flow on spectral Doppler examination. (d) Monophasic parvus tardus waveform in the right axillary artery|
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A 68-year-old male patient had complaints of intermittent episodes of dizziness. On carotid Doppler examination, there was reversal of flow in the left vertebral artery. A high-grade stenosis was present in the left subclavian artery causing monophasic tardus parvus flow in the left radial artery [Figure 6].
|Figure 6: (a) Left vertebral artery (VA) and vertebral vein are seen with reversal of flow in the VA as compared with left common carotid artery which shows forward flow. (b) High-grade stenosis of the left subclavian artery causing increased peak systolic velocity (about 400 cm/s) and diastolic flow. (c) Resultant parvus tardus flow in the left radial artery|
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A 59-year-old male patient referred for carotid Doppler examination in view of intermittent episodes of dizziness for the last 6 months. On color Doppler examination, complete reversal was present in the left vertebral artery [Figure 7].
|Figure 7: Left vertebral artery (VA) showing reversed flow which is same as the vertebral vein above. Spectral Doppler also showing reversed flow in the left VA|
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Partial subclavian steal
A 61-year-old female patient had weak peripheral pulse in the right upper limb as compared to the left side. Blood pressure difference was also present between both upper extremities. There was a calcified plaque at the origin of right subclavian artery with partial steal in the right vertebral artery. Distal subclavian artery shows flow reversal on spectral Doppler and dampened flow. The CCA shows normal color flow and waveform pattern [Figure 8].
|Figure 8: (a) Calcified plaque in the right subclavian artery showing aliasing at stenotic site. (b) Partial steal in vertebral artery showing flow reversal after the early systolic peak. The flow in diastole is forward. (c) Dampened flow in distal subclavian artery. (d) Normal color flow with spectral waveform in the right common carotid artery|
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Vertebral artery hypoplasia
This 53-year-old male patient presented with a history of transient ischemic attack and vertigo. The blood pressure was normal with no comorbidities. He was referred to the department of radio-diagnosis and imaging for carotid Doppler examination. The carotid arteries were unremarkable. The left vertebral artery diameter was 0.2 cm. Contralateral vertebral artery was normal in diameter. The patient underwent MRI brain which was within normal limits [Figure 9].
|Figure 9: (a) Gray-scale image showing vertebral artery (VA) below and vertebral vein above. The VA measures 0.2 cm. (b) Color Doppler image showing normal flow directions in the VA (arrow) and vertebral vein (arrowhead). (c) Magnetic resonance angiography image of the same patient showing hypoplastic left VA. (d) Right VA showing normal caliber and normal color flow with spectral waveform|
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| Discussion|| |
It is possible to insonate the first and second parts of the vertebral artery, with relative ease in most number of patients. On Duplex ultrasound, it is estimated that the origin of vertebral artery is visible in up to 65%–85% of cases, with the right one being more easily visualized than the left. The second vertebral artery segment is visible in approximately 95% of patients. Failure to identify vertebral artery flow does not necessarily indicate its occlusion though, as hypoplasia can mimic occlusion. True congenital hypoplasia is considered when the vertebral artery diameter is <2–3 mm. Normal peak systolic velocity for the second vertebral artery segment is approximately 20–60 cm/s.
Approximately one-fourth of ischemic strokes involve the posterior cerebral circulation. Vertebral artery occlusion can occur in either extra- or intra-cranial segments and account for approximately 20% of posterior circulation strokes. Intracranial vertebral artery occlusion is more frequently associated with brainstem infarction as compared with extracranial vertebral artery occlusion. The extracranial vertebral artery stenosis is due to several processes – the most common being atherosclerotic disease. Other causes include vertebral artery dissection, vasculitis, and extrinsic compression due to trauma or osteophyte impingement.
Imaging of the occlusion of the subclavian artery by ultrasound is often difficult; thus, the ultrasound diagnosis depends on detection of the hemodynamic disturbance, i.e., demonstration of retrograde flow in the vertebral artery during systole or throughout the cardiac cycle. Subclavian steal phenomenon occurs when a subclavian artery stenosis proximal to the vertebral artery origin, mainly due to atheromatous plaques, causes retrograde flow in the ipsilateral vertebral artery. This retrograde flow can be accentuated by ipsilateral brachial artery compression, performed with a sphygmomanometer cuff inflated above the systolic blood pressure level or by exercise of the affected arm. During the cuff inflation, retrograde flow in the vertebral artery is reduced and antegrade flow increased. When the cuff is deflated, there is reduced pressure within the brachial artery because of reactive hyperemia, due to which the duration and amount of flow reversal in the ipsilateral vertebral artery increases. The flow pattern in the ipsilateral vertebral artery will be the same as in other peripheral arteries, as the retrograde flow in vertebral artery is supplying the high-resistance vessels of the ipsilateral upper limb.
In partial steals, there is fluctuation of the pressure gradients from cephalocaudad to caudocephalad during systole and diastole. With reactive hyperemia of the arm, the pressure gradient in the vertebral artery is cephalocaudad during both systole and diastole, which causes complete steal.
With the help of physiological maneuvers such as arm exercise or postocclusive hyperemia, color Doppler with spectral tracings demonstrates conversion of partial steals to complete steals.
This text provides an overview of the pathologies and variations of vertebral artery that can be detected by ultrasound and thus highlight the importance of careful examination of the vertebral artery flow and waveform pattern.
| Conclusion|| |
The evaluation of proximal great vessels by ultrasound can be difficult at times; thus, careful examination of the velocity, direction of flow, and waveforms of vertebral artery by ultrasound can be an important tool to detect occlusions or stenoses of proximal great vessels. Further, waveforms of the vertebral artery in the cervical segment provide useful information regarding the intracranial part of vertebral artery.
Declaration of patient consent
The authors declare that they have obtained consent from patients. Patients have given their consent for their images and other clinical information to be reported in the journal. Patients understand that their names will not be published and due efforts will be made to conceal their identity but anonymity cannot be guaranteed.
Financial support and sponsorship
Conflicts of interest
There are no conflicts of interest.
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