Color-coded duplex ultrasonography of the origin of the vertebral artery: normal values of flow velocities.

The introduction of color-coded duplex ultrasonography has improved the ease of performing ultrasound investigations of the vertebral arteries. So far, normal values of flow velocities have been reported only for the intertransverse region of the vertebral artery (V2 segments). Atherosclerotic disease at the origin of the vertebral arteries (V0 segment) is frequent and is one of the risk factors for vertebrobasilar ischemic disease. Normal values of flow velocities of the vertebral artery origin are needed to assess pathologic findings, such as vertebral artery origin stenosis or dissection. The aim of this study was to describe the normal flow velocities of vertebral artery origin (V0 segment) and the pre- (V1 segment) and intertransverse (V2 segment) part in 50 age-matched neurologic patients (mean age 54) without ischemic cerebral disease. The V0 segment could be visualized in 46 persons (92%) on the right side and in 43 (86%) on the left. The peak systolic blood velocity ranged from 30 to 100 cm/s (mean 63.6 +/- 17.5 cm/s), and end-diastolic blood velocity ranged from 10 to 35 cm/s (mean 16.1 +/- 5.1 cm/s). Analysis of side-to-side differences showed no significant differences of flow velocities in all subjects. It is concluded that color duplex ultrasonography is a feasible method to insonate the origin of the vertebral artery, and that nomogram data could be established. It is suggested that color-coded duplex ultrasonography of the vertebral artery origin should be performed in all patients with clinical symptoms or signs of vertebrobasilar ischemic disease. Nevertheless, further studies are needed to determine the normal and pathologic values of flow velocities of the vertebral artery origin and their reproducibility.     

Percutaneous transluminal angioplasty of extracranial vertebral artery stenosis--a case report

Due to improvement in intravascular therapeutic procedures significant stenoses of vertebral and basilar arteries can presently be treated by means of percutaneous transluminal angioplasty (PTA). The reported case was a 34-year-old man with symptomatic stenosis of the distal left vertebral artery and hypoplastic right vertebral artery. The patient underwent PTA and the lesion was sufficiently dilated. No complications occurred during or after the procedure. After a year duplex Doppler follow-up examination showed normal blood flow and patency of both vertebral arteries. PTA may prove to be a useful therapeutic option in patients with symptoms of vertebro-basilar insufficiency.     

Power-based versus conventional transcranial color-coded duplex sonography in the assessment of the vertebrobasilar-posterior system

Background: Power Doppler (PD) is a new ultrasonic technique that allows improved visualization of vascular structures. The aim of our study was to compare the ability of power-based transcranial color-coded duplex sonography (p-TCCS) to conventional transcranial color-coded duplex sonography (TCCS) and contrast-enhanced transcranial color-coded duplex sonography (CE-TCCS) in the visualization of the vertebrobasilar system. Methods: In 41 patients without cerebrovascular diseases, we evaluated and compared identification rates of major vessels of the vertebrobasilar system and branches using both ultrasound (US) techniques. In 9 patients we performed additional CE-TCCS studies. Furthermore, the possibility of visualization of the basilar artery (BA) and the vertebral arteries (VA) over the long course was investigated. Results: TCCS and p-TCCS were equally effective at showing the VAs (74 of 82 v 80 of 82), proximal segments of the BA (37 of 41 v 41 of 41) and P1 segments of the posterior cerebral artery (PCA) (72 of 82 v 82 of 82). However, the diagnostic sensitivity of p-TCCS was significantly better for peripheral segments of the PCA (34 of 82 v 68 of 82 for P2 and 2 of 82 v 24 of 82 for P3 segments, P<.001), distal parts of the BA (25 of 41 v 38 of 41, P<.01), the anterior inferior cerebellar artery (AICA) (0 of 82 v 8 of 82, P<.0001) and the posterior inferior cerebellar artery (PICA) (13 of 82 v 34 of 82, P<.001). Furthermore, using transtemporal coronal sections, p-TCCS allowed visualization of the BA over the complete course in connection with one or both VAs in half of the patients. Except P2 and P3 segments, CE-TCCS did not increase resolution compared with p-TCCS. Conclusions: PD offers significant advantages over color-coded sonography in imaging the BA and small-calibre vessels like the PICA, AICA, and peripheral segments of the PCA. P-TCCS in combination with TCCS increases the diagnostic sensitivity to identify vascular structures of the vertebrobasilar system.     

Power Doppler Imaging and Color Doppler Flow Imaging for the Evaluation of Normal and Pathological Vertebral Arteries

Recently, an ultrasound method for vascular applications using the amplitude of the reflected echosignal for the generation of intravascular color signals has been introduced. We compared the utility of this power Doppler imaging (PDI) with conventional color Doppler flow imaging (CDFI) for examination of vertebral arteries (VA) Forty-nine patients with signs and symptoms suggesting ischemia within the posterior circulation were evaluated. Quality of blood flow visualization by PDI and CDFI at the different VA segments was classified according to a four point scale. Furthermore, combined sonographic findings were correlated with the results of digital substraction and/or magnetic resonance angiography (DSA, MRA). Power Doppler imaging provided a significantly superior visualization of the intertransversal VA, whereas display of the intracranial V4 segment was superior 1ignificantly on CDFI. Both methods were complementary for the evaluation of the VA at the origin. With respect to the angiographic findings, combined CDFI and PDI achieved a sensitivIty of 90.63% and a specificity of 97.22% for the differentiation of healthy and pathologic VAs. Power Doppler imaging is complementary to CDFI for the sonographic assessment of VA disease. Combined use of PDI and CDFI achieves a high sensitivIty and specificity, thus increasing diagnostic confidence.     

Magnetic resonance angiography of spontaneous vertebral artery dissection suspected on Doppler ultrasonography

Spontaneous vertebral artery dissection (VAD) is a rare but well-known cause of cerebrovascular disease and is often difficult to diagnose even using conventional arteriography. While noninvasive tests such as Doppler ultrasonography and magnetic resonance imaging (MRI) have failed to provide reliable criteria for the diagnosis of VAD, the diagnostic value of magnetic resonance angiography (MRA) has not yet been undetermined. To establish the reliability of a combined noninvasive approach, 11 patients were prospectively examined for VAD by means of colour-coded duplex studies, MRI and three-dimensional time-of-flight MRA prior to conventional angiography. Among 11 patients with VAD suspected clinically as well as on Doppler ultrasonography, angiography confirmed the diagnosis in seven patients but found a vertebral artery occlusion in three and a vertebral artery stenosis in one. The combination of MRI and MRA findings led to the correct diagnosis of dissection in three patients, of vertebral artery occlusion in three patients, and of vertebral artery stenosis in one. VAD was misinterpreted as vertebral artery occlusion in four patients. Doppler ultrasonography is a valuable screening method for the detection of vertebral artery pathologies. The diagnosis of VAD can only be established if a typical intramural vessel wall haematoma is seen on T1-weighted MRI in combination with MRA findings of irregular artery stenosis or occlusion.     

Imaging of the intracranial vertebrobasilar system using color-coded ultrasound.

BACKGROUND: Anatomic variety and difficult accessibility of the vertebrobasilar arteries pose considerable problems to conventional ultrasound. We evaluated the diagnostic potential of transcranial color-coded sonography in the distal part of this system. METHODS: We insonated the intracranial section of the vertebrobasilar arteries through the foramen magnum window in 24 healthy individuals using a Doppler color flow imaging system in connection with a 2.5-MHz sector transducer. Magnetic resonance images in special inclination planes were performed and compared with the color-coded duplex images in five cases. RESULTS: The B-mode image of the craniocervical junction and the intracranial parenchymal structures in addition to the color-coded blood flow allowed an unambiguous identification of the vertebrobasilar arteries (vertebral artery, 96%; basilar artery, 79%; and posterior inferior cerebellar artery, 50%). Blood flow velocities were measured considering the insonation angles: vertebral arteries, 50/24 cm/sec (30 degrees); basilar artery, 59/28 cm/sec (4 degrees); and posterior inferior cerebellar artery, 56/30 cm/sec (20 degrees) [peak systolic/end diastolic blood flow velocity (mean angle correction)]. CONCLUSIONS: Transcranial color-coded sonography enables accurate identification and differentiation of the intracranial vertebrobasilar arteries and improves accuracy of Doppler measurements. It may prove useful for evaluation of tortuosity and for hemodynamic studies in this vascular territory.     

Duplex scanning of normal vertebral arteries

Vertebral arteries were studied by Duplex scanning in 50 normal subjects. Pretransverse and C6-C5, C5-C4 intertransverse segments were visualized in all cases on both sides; segment C4-C3 was visualized in 100% of the cases on the right side and in 90% on the left; ostium was obtained in 94% of the cases on the right and in 60% on the left. The left vertebral artery was dominant in 48% of the cases while the right vertebral artery was dominant in 14%. Three vertebral arteries were hypoplasic. Duplex scanning was thus found to be an easily performed noninvasive method to study morphological and hemodynamic characteristics of vertebral arteries from their origin to the C4-C3 level.     

An association between vertebral artery dominance and steno-occlusion of the vertebral artery segments: A retrospective angiographic study

ObjectivesThis study investigated whether there was a relationship between steno-occlusion of the vertebral artery (VA) segments and the dominant VA side.Materials and methodsAngiography results of 215 patients (146 men; 69 women) were retrospectively analyzed in this study. The patients were divided into three groups: dominant, non-dominant and co-dominant. These groups were compared according to the presence of steno-occlusion in the vertebral artery segments. The results were evaluatedusing X², Mann-Whitney U and Kruskal-Wallis tests. For correlation analysis, Spearman's Rho test was used.ResultsThe findings showed that 55 of 215 patients (25.6%) had a right dominant VA, and 103 (47.9%) had left dominant VA. There was no significant relationship between dominance and age or gender (p > 0.05). More vertebral artery stenosis (VAS) was found on the dominant side. However, a significant relationship only in the right dominant V1 segment (p = 0.044) was noticed. Hypoplastic VA was detected in 13 patients (6%). Most of the VAs (98.4%, n = 423) arose from the subclavian artery.ConclusionsIn conclusion, we found more vertebral artery stenosis on the dominant side than the co-dominant side, especially on the origin of the vertebral arteries. However, it was only significant on the right dominant V1 segment, regardless of age and gender of the patients (p > 0.05).     

Carotid Steal Syndrome: A Case Study

The progression of subclavian arterial stenosis and the subsequent formation of collateral pathways serve to alter the pressure gradients in subclavian steal syndrome, altering ipsilateral vertebral artery flow from its normal state to “latent,” “transient,” and “continuous” steals. A similar altered flow in the carotid arteries can be observed with stenosis of the proximal common or innominate artery. A 59-year-old man was seen in the vascular laboratory for evaluation of symptomatic peripheral arterial disease. An incidental asymptomatic stenosis of the right innominate and left proximal subclavian artery was found . Further cerebral vascular evaluation displayed a continuous right subclavian steal and a latent steal in the right internal carotid artery. Transcranial Doppler examination displayed “transient” steal in the terminal right internal carotid artery. Combining duplex and transcranial Doppler evaluation s allows sequential evaluation of the progression of arterial disease and its effect on the flow patterns in the cerebral vasculature.     

Accuracy of color-Doppler in the quantification of proximal vertebral artery stenoses

BACKGROUND: Vertebrobasilar (VB) strokes appear to have the same causes as carotid strokes. Obstructive lesions of proximal vertebral arteries probably occur in about 30% of stroke patients. PURPOSE: Our aim was to assess the validity of color Doppler sonography compared to selective intra-arterial angiography in the quantification of proximal vertebral artery stenoses. MATERIALS AND METHODS: A prospective blind study of 316 vertebral arteries was undertaken between 1996 and 1998. One hundred and fifty-eight patients with cerebrovascular disorders without cerebral hemorrhage were studied consecutively by frequency or amplitude color Doppler flow imaging and intra-arterial angiography. The lesions were quantified by morphological and hemodynamic criteria and classified into 6 groups: 0% 207 arteries; 1-29% 32 arteries; 30-49% 29 arteries; 50-69% 13 arteries; 70-99% 23 arteries; 100% 12 arteries. RESULTS: Ten of the 12 occlusions were identified, the 2 false-negatives were due to 2 revascularized vessels. Moderate stenoses (<50%) were differentiated from tight stenoses (>50%) using hemodynamic criteria. The majority of false-negative stenoses (38) in the different groups were related to intrathoracic or very deep origin of the artery, anechogenic stenosis or a tortuous vessel. Stenoses greater than 70% were diagnosed in 71% of cases with a specificity of 99%. The kappa value was 0.80. CONCLUSION: Duplex sonography should be proposed first in VB attacks or stroke to detect and quantify vertebral artery stenoses for surgery and angioplasty.     

Pitfall of Electron Beam Computed Tomography Angiography in Diagnosis of Subclavian Steal Syndrome

A patient presented with vertebrobasilar insufficiency during exertion. Vertebral duplex and transcranial Doppler ultrasonography showed reversal of flow in both intracranial and extracranial vertebral and basilar arteries, suggesting bilateral subclavian and vertebrobasilar steal. Electron beam computed tomography angiography (CTA) showed no evidence of subclavian artery stenosis including normal vertebral artery origin on both sides. However, digital subtraction angiography revealed complete occlusion of both subclavian arteries with retrograde flow from both vertebral and basilar arteries to reconstitute both subclavian arteries. This false-negative finding on CTA in detection of subclavian steal syndrome (SSS) is due to inappropriate contrast administration technique and postprocessing method, inability to differentiate flow direction, and lack of hemodynamic time sequences. This study demonstrates a pitfall of CTA in diagnosis of SSS compared to more reliable hemodynamic information obtained by duplex and transcranial Doppler ultrasonography, and digital subtraction angiography.     

Evaluation of the vertebrobasilar-posterior system by transcranial color duplex sonography in adults.

BACKGROUND AND PURPOSE: The transcranial color duplex sonography technique was applied to the vertebrobasilar-posterior system to provide normal data for clinical application. METHODS: The intracranial posterior circulation was studied in 49 healthy volunteers (mean +/- SD age, 35 +/- 12 years) by a transcranial and suboccipital approach with a 2.0-MHz sector transducer of a computed sonography system. RESULTS: The posterior cerebral artery and the vertebrobasilar system were depicted clearly in the color Doppler mode. Pulsed Doppler signals could be recorded in the posterior cerebral (100%), basilar (92%), and vertebral arteries (89%). The following normal values were provided for all vessels: systolic peak, end-diastolic maximum, time-averaged, and time-averaged maximum velocities; resistance and pulsatility indexes; and a spectral broadening index. Mean +/- SD values were 45.9 +/- 9.6, 45.5 +/- 10.8, and 39.2 +/- 10.6 cm/sec for time-averaged maximum velocity, and 28.3 +/- 6.5, 30.6 +/- 7.2, and 24.7 +/- 8.4 cm/sec for time-averaged velocity in the posterior cerebral, basilar, and vertebral arteries, respectively. In a reproducibility study, duplex measurements of the posterior cerebral arteries were repeated in 27 subjects. The correlation between the two examiners was high (r = 0.56, p less than or equal to 0.0001 for time-averaged maximum velocity). CONCLUSIONS: Color duplex sonography of the vertebrobasilar-posterior system is a new, noninvasive, bedside investigative technique. It permits visualization of artery flow in real time, relating these to adjacent brain and cranial structures, as well as angle-corrected duplex measurement of "true" flow velocities at defined sites of the vessels. Thus, it will open new diagnostic possibilities in disorders of the posterior circulation.     

Color-coded Doppler imaging of normal vertebral arteries

Using color-coded Doppler sonography, we studied the vertebral arteries of 42 persons without history or physical signs of vertebrobasilar disease. The intertransverse portion of the vertebral artery was visualized in all persons on both sides. Its origin was visualized in 37 persons (88.1%) on the right side and in 28 (66.7%) on the left; the atlas loop was visualized in 32 persons (76.2%) on the right side and in 36 (85.7%) on the left. Four vertebral arteries were hypoplastic. Peak systolic blood velocity ranged from 19 to 98 (mean 56) cm/sec and peak diastolic blood velocity ranged from 6 to 30 (mean 17) cm/sec. Resistive indices ranged from 0.62 to 0.75 (mean 0.69). Thus, color-coded Doppler sonography seems to be a promising noninvasive method for the evaluation of hemodynamics in the extracranial portion of the vertebral arteries.     

Usefulness of carotid duplex ultrasonography in a patient with moyamoya disease]

The patient is a 35-year-old man who had a medical history of epilepsy in childhood. He came to our hospital because of transient disturbance of consciousness and left hemiplegia just after evacuation. At first, we thought that he had epilepsy with Todd's palsy. But we had to do a differential diagnosis for a transient ischemic attack such as paradoxical embolism, because his symptoms occurred just after evacuation. An electroencephalogram and brain computerized tomography were immediately performed, but no abnormality was detected. Hematologic studies were normal, and no deep vein thrombosis was detected in the veins of the lower extremities by duplex ultrasonography Doppler. But carotid duplex ultrasonography showed an increase in end-diastolic flow velocity and a decrease in vascular resistance in both external carotid arteries. These findings indicated that there was arteriovenous malformation such as moyamoya disease. Brain magnetic resonance imaging showed spotty high signal lesions in the subcortical areas on a fluid-attenuated inversion-recovery(FLAIR) image, and the middle cerebral artery was not visualized on magnetic resonance angiography (MRA). Cerebral angiography demonstrated moyamoya vessels in the brain and collateral circulation from the external carotid artery. Therefore, we diagnosed him as having moyamoya disease. Duplex ultrasonography of the common and, internal carotid, and vertebral arteries is a widely-used technique. Recently, cerebral angiography, MRA and transcranial Doppler have been applied to detect intracranial vascular malformation. But these results suggested that moyamoya disease could be detected by means of carotid duplex ultrasonography. Finally, we considered that carotid duplex ultrasonography was not only a noninvasive screening method but also a useful for the diagnosis of moyamoya disease.     

Color velocity imaging: introduction to a new ultrasound technology.

Noninvasive ultrasound is the preferred methodology for the initial evaluation of carotid atherosclerosis. Since the early use of continuous-wave Doppler to assess carotid artery flow velocity blindly, neurosonology has progressed through crude B-mode imaging, spectral analysis of the Doppler signal, and gray-scale duplex Doppler/B-mode imaging, to color-flow Doppler duplex imaging. The latter allows color coding of Doppler data based on the velocity of blood flow. The combination of color-flow Doppler with gray-scale B-mode imaging allows simultaneous visual display of anatomical and hemodynamic information. Physical limitations of color-flow duplex Doppler imaging may affect the clinical utility of these techniques. Problems with pulse repetition frequency, aliasing, resolution capability of the color data, and interpolation of data make some applications difficult. Color velocity imaging uses the data contained in the gray-scale B-mode image scan lines to determine velocity of blood flow, and it offers potential advantages over conventional color-flow duplex Doppler for the assessment of carotid atherosclerosis and hemodynamics. Initial comparison of spectral Doppler and color velocity imaging data suggests that the latter is an accurate method to assess blood flow velocity. Understanding of the validity, utility, and prognostic advantages offered by color velocity imaging awaits careful prospective clinical trials.     

The significance of color duplex ultrasonography for the diagnosis of temporal arteritis]

We examined the usefulness of color duplex ultrasonography in patients suspected of having temporal arteritis. Five patients, who were all aged 70 or older, developed a new onset of localized headache with temporal artery abnormalities, and had an elevated erythrocyte sedimentation rate of > 100 mm/hour. The final diagnoses were temporal arteritis in three patients, polymyalgia rheumatica in one, and probable healed temporal arteritis in one. Color duplex ultrasonography showed stenoses, which were confirmed histologically as well, in the superficial temporal artery of all patients. The characteristic findings of active temporal arteritis were, however, demonstrated in only three biopsy specimens, and in the remaining two the stenoses were thought to be related to previous arteritis. The hypoechoic halo, which has been reported to be a characteristic finding of color duplex ultrasonography in active temporal arteritis, was detected in only one patient with active temporal arteritis and another one with probable healed temporal arteritis. No stenoses were demonstrated in the superficial temporal arteries of 30 control subjects (20 with at least one risk factor of atherosclerosis and 10 without it). Color duplex ultrasonography can therefore be considered a powerful method for detecting stenoses in the superficial temporal artery. Its ability to identify their etiology is, however, unsatisfactory, so that temporal artery biopsy remains undoubtedly the most reliable test for etiological evaluation. We thus recommend color duplex ultrasonography as a supplementary method for the diagnosis of temporal arteritis, because it can provide useful information concerning the appropriate site of temporal artery biopsy.     

Reference values for vertebral artery flow volume by duplex sonography in young and elderly adults

BACKGROUND AND PURPOSE: Vertebrobasilar ischemia has been attributed to a reduction of net vertebral artery flow volume, the product of mean flow velocity and the cross-sectional area of the vessel. It can be determined by duplex sonography. There are no reference values for vertebral artery flow volume in an age group representative of patients with cerebrovascular disease. METHODS: We examined 50 nonvascular neurological patients (age 55.8+/-14.0 years). Flow velocities and vessel diameters were recorded in the intertransverse (V2) segments bilaterally, and the flow volume was calculated according to the following equations: (1) Q1=time-averaged mean velocity times area and (2) Q2=(time-averaged maximum velocity/2)times area. RESULTS: Flow velocities and vessel diameters tended to be lower on the right side, resulting in a lower flow volume. Flow volumes (according to Equation 1) were 77.2+/-29.8 mL/min on the right side, 105.3+/-46.4 mL/min on the left side, and 182.0+/-56.0 mL/min net. Side-to-side differences were not significant. Flow volumes calculated with the 2 equations did not differ significantly. An age dependence could not be shown, but vessel diameters and net vertebral artery flow volumes were significantly lower in women than in men. The normal range for net vertebral artery flow volume defined by the 5th to 95th percentiles is between 102.4 and 301.0 mL/min. This wide range is due to the high interindividual variability of the parameters. CONCLUSIONS: On the basis of the reference values presented here, the association of decreased vertebral artery flow volume and vertebrobasilar ischemia should be reevaluated. Additional areas for investigation include the quantification of collateral flow in the vertebral arteries in carotid artery occlusive disease and their contribution to overall cerebral blood flow volume.     

A Case of Posterior Circulation Embolism Due to a Subtype of Bow Hunter's Syndrome Diagnosed by Non-Invasive Examination

Bow hunter's syndrome is the mechanical compression of the vertebral artery due to cervical rotation, resulting in ischemic symptoms in the vertebrobasilar artery territory. However, some cases present without typical symptoms and exhibit compression of the non-dominant side of the vertebral artery. We encountered a case of posterior circulation embolism due to a subtype of bow hunter's syndrome in a 74-year-old man. Although the right vertebral artery was not visualized on time-of-flight magnetic resonance angiography in the neutral position, duplex ultrasonography and time-of-flight magnetic resonance angiography in the left cervical rotation position showed blood flow in the right vertebral artery. In this case, blood flow in the contralateral vertebral artery was normal, and typical bow hunter's syndrome symptoms did not occur. In a case of posterior circulation embolism with undetermined etiology, wherein the routine duplex ultrasonography and time-of-flight magnetic resonance angiography results were inconclusive, additional testing with head positioning led to the diagnosis of a subtype of bow hunter's syndrome.     

椎动脉起始位置与穿出颈椎横突孔高度关系的三维CT血管成像研究

目的通过三维CT血管成像(CTA)探讨椎动脉起始位置与穿出颈椎横突孔高度的关系。方法回顾性分析2017年3月至2019年3月河北医科大学第二医院神经外科行头颈上胸部CTA检查的480例患者的临床资料。将图像传输至图像后处理工作站进行骨质和血管重建,观察双侧椎动脉的起源、走行及穿出颈椎横突孔的高度。对于右侧椎动脉起源正常者,根据穿出颈椎横突孔的高度分为C₄、C₅、C₆组,每组随机选取10例分别测量右侧椎动脉起始位置至右侧颈总动脉起始的距离(L1)和右侧甲状颈干的距离(L₂),以L₁/(L₁+L₂)×100%计算椎动脉起始的相对位置。结果480例患者中,457例(95.2%)双侧椎动脉起源位置正常,均起源于锁骨下动脉,另23例(4.8%)起源异常,其中左侧椎动脉起源于主动脉弓19例、左侧颈外动脉1例;右侧椎动脉起源于右侧颈总动脉3例,且均合并迷走右锁骨下动脉。480例患者中,405例(84.4%)双侧椎动脉经C₆横突孔穿出;另75例(15.6%)穿出高度异常,其中左侧34例,经C₃、C₄、C₅、C₇横突孔穿出的分别有1、4、24、4例,直接入枕骨大孔1例;右侧41例,经C₃、C₄、C₅横突孔穿出的有1、14、26例。椎动脉起源异常的患者,左侧椎动脉起自主动脉弓的占比最高(19/20),且多数穿出颈椎横突孔的高度异常(18/19);右侧椎动脉均起自右侧颈总动脉合并迷走右锁骨下动脉(3/3),且穿出颈椎横突孔的高度均异常(3/3)。椎动脉起源正常的患者,96.7%(445/460)的左侧椎动脉穿出颈椎横突孔的高度正常,92.0%(439/477)的右侧椎动脉穿颈椎横突孔高度正常。3组右侧椎动脉起源正常的患者椎动脉起始的相对位置的差异有统计学意义[C₄组:(24.3±2.1)%、C₅组:(47.9±6.6)%、C₆组:(77.7±1.7)%,H=20.178,P<0.001]。结论椎动脉起始位置异常时,其穿出颈椎横突孔的高度多异常。右侧椎动脉的起始相对位置越靠近右侧颈总动脉时,穿出颈椎横突孔的高度越高;而越靠近右侧甲状颈干,穿出颈椎横突孔的高度越低。     

Common Carotid Artery Agenesis: Duplex Ultrasonographic Findings

Background

Agenesis of the common carotid artery (CCA) resulting in separation of the origin of the external carotid artery (ECA) and internal carotid artery (ICA) from the aortic arch is rare. Fewer than 25 cases have been reported, and correlative ultrasound data were available for only 1 of them.

Case Report

A 52-year-old woman visited the hospital with a 3-day history of vertigo and headache. Color-coded duplex ultrasonography performed to evaluate the carotid and vertebral arteries revealed a normal configuration on the left side. However, the right CCA could not be found; instead, there were two vessels of approximately equal size in close proximity to each other. The cerebral angiographic findings were consistent with the ultrasonographic findings. The ECA and ICA originated directly from the brachiocephalic trunk, and the ECA arose proximal to the ICA.

Conclusions

The ultrasonographic findings revealed absence of the CCA, the ECA and ICA originating separately from the aortic arch. Color-coded duplex ultrasonography appears to be an effective and sensitive method for detecting absence of the CCA. These findings should help to further our understanding of the embryologic development of the carotid arteries.