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.     

In vitro validation of color velocity imaging and spectral Doppler for velocity determination.

Color velocity imaging (CVI) is a new non-Doppler ultrasound technique for vascular color flow imaging. Using information contained in the two-dimensional B-mode, gray-scale image to determine velocity, CVI offers potential advantages over Doppler color flow imaging methods. In order to be used clinically, velocity determination with CVI must be validated by other current methods. A Doppler string phantom was studied with a Philips CVI ultrasound system. Velocity measurements were obtained by both CVI and duplex Doppler spectral analysis for constant string speeds from 10 to 200 cm/sec, at intervals of 10 cm/sec. Twenty separate estimates were obtained with each method, at each string speed. Linear regression assessed the relationship between estimated and actual string velocities, with CVI and spectral Doppler analysis yielding highly valid results (CVI = -0.713 + 1.000997 x phantom; r 2 = 0.9979). At all string speeds tested, the averaged estimated and the actual velocities for both methods were within the 95% confidence estimates. The range for the CVI 95% confidence limits from the regression line varied from +/-1.07 cm/sec at the lowest speed of 10 cm/sec (11.6%) to +/-7.72 cm/sec at 200 cm/sec (3.87%). Based on in vitro testing, CVI is as accurate as Doppler spectral analysis for the estimation of flow velocity.     

Doppler color flow imaging of carotid body tumors

Doppler color flow imaging is a new ultrasound method for the simultaneous spatial display of tissue and vessel morphology (B-mode echotomograms) and of color-coded blood flow velocity information (Doppler-mode analysis). This new method is particularly useful in the neck, not only for the assessment of brain arteries but also for the safe and valid identification of carotid paragangliomas compared with other neck tumors. Early clinical detection of carotid paragangliomas is difficult since these lesions often occur sporadically and the patients remain symptom-free until the tumor becomes noticeable. Doppler color flow imaging allows the diagnosis of even small paragangliomas, which may improve management because of existing complications of surgical therapy.     

Transcranial Doppler ultrasonographic evaluation of vertebral artery hypoplasia and aplasia

BACKGROUND AND PURPOSE: Evaluation of vertebral artery (VA) with transcranial Doppler ultrasonography (TCD) is difficult due to anatomical variations of hypoplasia (HP) or aplasia (AP). TCD findings of HP or AP of VA are rarely known. Comparing with magnetic resonance angiography (MRA), we tried to evaluate characteristic findings of HP or AP of VA using TCD. METHODS: Consecutive healthy patients who underwent TCD and MRA were included. VA was classified as normal (NL), hypoplasia (HP), and aplasia (AP) according to MRA. TCD parameters of mean flow velocity (MFV), pulsatility index (PI), vertebral/basilar artery flow velocity ratio (VA/BA FVR), and asymmetry index (AI) of VA were compared between three groups. RESULTS: Four hundred and ten patients were included, and 298 patients (72.7%) were classified as NL, 98 (23.9%) as HP and 14 (3.4%) as AP. MFV, PI and VA/BA FVR of ipsilateral VA were not different between groups. However, MFV of contralateral VA and AI were significantly increased in HP and AP groups (p<0.001). AI was significantly different between the three groups (17.7% and 30.5%, p<0.001). Sensitivity and specificity for HP or AP were 20.5% and 90.9%, if AI over 40% were adopted as diagnostic criteria. CONCLUSION: MFV of VA should be interpreted with caution for its frequent anatomical variations. Increased MFV of unilateral VA may indicate not only as ipsilateral stenosis, but also as contralateral HP or AP. AI over 40% is specific to predict unilateral HP or AP with clinical correlation.     

彩色多普勒和经颅多普勒对椎动脉型颈椎病牵引治疗效果的评价

背景：适宜方向、角度的牵引对于椎动脉型颈椎病疗效显著。选择性血管造影被公认为是确定血管疾病的“金标准”,核磁共振血管造影虽为无创性检查,却存在检查时间较长、易受人为因素影响、具有一定侵袭性等不足。 目的：通过彩色多普勒和经颅多普勒加转颈试验,对不同牵引方向和牵引角度治疗前后椎动脉型颈椎病患者血流参数变化进行比较分析。 方法：选择椎动脉型颈椎病患者240例,根据解剖学角度按病变部位(上颈段病变、下颈段病变、混合型)和牵引方式、角度(坐位前倾分1°~10°、11°~20°、21°~30°组,坐位后伸1°~10°、11°~20°、21°~30°组,坐位中立位组)分组,以局部按摩为对照组。通过彩色多普勒加转颈试验检测治疗前后椎动脉最窄部位血管内径、收缩期峰值速度、平均血流速度。通过经颅多普勒加转颈试验测量治疗前后左、右椎动脉和基底动脉的收缩期峰值血流速度、平均血流速度等血流参数,并进行比较分析。 结果与结论：①根据解剖部位确立了椎动脉型颈椎病的类型。椎动脉型颈椎病根据病变部位划分为上颈段(C1~C3)、下颈段(C4~C6)和混合型,这从椎骨形态和力学角度等方面为临床牵引治疗提供了指导。②确定了最佳牵引角度。即上颈段椎动脉型颈椎病患者坐位后伸11°~20°牵引疗效较好,下颈段椎动脉型颈椎病患者坐位前屈11°~20°牵引疗效较好,混合型椎动脉型颈椎病患者坐位前屈1°~10°疗效较好。③确立了彩色多普勒及经颅多普勒超声检测是指导椎动脉型颈椎病牵引治疗的简便、无创、安全可靠、重复性好的验证手段。     

Spontaneous dissections of the vertebral arteries

Clinical and angiographic features and outcome in 25 patients with spontaneous dissections of the vertebral arteries are described. Most patients were in their fourth or fifth decade of life, and women predominated. Forty-eight percent of the patients were hypertensive. Angiographic evidence of fibromuscular dysplasia was noted in one only. Brainstem ischemic symptoms (usually a lateral medullary syndrome) and ipsilateral occipital headache and neck pain (often preceding but sometimes associated with or following the brainstem ischemic event) were the most common clinical findings. The angiographic features in decreasing order of frequency were luminal stenosis (often irregular and tapered), aneurysm, occlusion, and intimal flap. On follow-up, most of the patients (88%) made complete or very good recoveries. Angiographic abnormalities either subsided or improved in 76%. Multivessel dissection (involvement of both vertebral arteries or one or both vertebral arteries and one or both internal carotid arteries) was noted in about two-thirds of the patients. This tendency of vertebral artery dissections to involve multiple cervicocephalic vessels concurrently, if not simultaneously, implies that four-vessel angiography should be attempted if a vertebral artery dissection is visualized. It also raises the possibility of an underlying arteriopathy that predisposes the vessel to dissection.     

Transluminal angioplasty for arteriosclerotic disease of the distal vertebral and basilar arteries.

OBJECTIVE: Percutaneous transluminal angioplasty (PTA) for the distal vertebral and basilar artery is now being performed in selected patients with haemodynamically significant lesions of the posterior cerebral circulation. Its effect and overall results were examined. PATIENTS AND METHODS: A balloon dilatation catheter specifically developed for these procedures, with a 2.0-3.5 mm balloon diameter, at 6 atmospheres of pressure, was used. Angioplasty was performed in 12 patients (including six whose initial results have been reported) with angiographically documented stenotic lesions involving either the intracranial vertebral artery (C1-C2 portion) or the basilar artery, and satisfying the following criteria: (1) clinical symptoms suggestive or consistent with a transient ischaemic attack refractory to medical treatment, or small infarction of the posterior circulation; and (2) angiographically documented stenosis greater than 70%. Two of 12 patients had complete thrombosis of the distal vertebral and basilar artery and PTA was performed after successful intra-arterial thrombolysis. RESULTS: Successful results, without complications, were obtained in eight patients, with complete resolution of vertebrobasilar ischaemic symptoms. Immediate complications occurred in four patients including two with vessel dissection, and two with thromboembolism. The two patients with acute arterial dissection were reoperated but developed small infarctions with permanent neurological deficits. The two patients with thromboembolic complication showed transient neurological deficit. The overall stenosis ratio decreased from a mean of 84% pretreatment to 44% after the angioplasty procedure. Restenosis occurred in two patients. Long term clinical follow up in 11 patients who survived more than six months showed resolution of ischaemic symptoms after PTA in all except for one with a restenosis who had recurrent transient ischaemic attacks. CONCLUSION: Transluminal angioplasty may be an effective procedure to treat vertebrobasilar ischaemia secondary to high grade arteriosclerotic disease affecting either the distal vertebral or basilar artery regions that do not respond to medical treatment.     

Spontaneous dissection of the extracranial vertebral arteries

Though the syndrome of carotid artery dissection is well known, "spontaneous" vertebral artery dissection is rarely recognized. We now report clinical and radiologic findings in five patients with presumed vertebral dissection, one pathologically confirmed. Mean age was 35.2 years (range 27-41). Two were men; three women. None had hypertension, vascular disease, or trauma. Headache and neck or occipital pain was prominent in all, often preceding other symptoms. Four of five patients had unilateral partial alteral medullary syndromes, in one accompanied by medial medullary signs. One patient had a cerebellar infarct. Angiography in four patients showed severe irregular stenosis of the distal extracranial vertebral artery (three bilaterally). A fifth patient with irregular stenosis above the vertebral origin had verified extensive dissection in the resected segment. No patient developed late ischemia. Repeat angiography in three showed healing. We conclude that spontaneous vertebral artery dissection, though rare, has recognizable clinical and radiologic features.     

Doppler examination of the carotid arteries

The ability of Doppler ultrasound to detect extracranial carotid arterial disease was evaluated in 148 carotid arteries, examined also angio-graphically. A continuous wave, directional Doppler with zero-crossing meter was used. Doppler diagnosis was based on direct examination of the carotid bifurcation. Of four quantitative variables evaluated, only the end-diastolic ICA/CCA frequency ratio was found to be useful. In stenoses exceeding 75% a deranged Doppler recording was obtained. For stenoses ≥ 50% or occlusion sensitivity was 98.3%, specificity 96.6% and over-all accuracy 97.3% with the direct examination technique. Corresponding figures for an indirect Doppler test (frontal artery flow) were 45.8, 100% and 78.4%. Stenoses < 50% could not be separated from normal vessels. Direct Doppler examination with a zero-crossing detector is reliable, provided that the limitations of the frequency analysis are considered.     

Spontaneous dissection of carotid and vertebral arteries. II. Vertebral arteries and their branches]

Dissection of the extra- and ntracranial portions of vertebral arteries, as well as basilar artery and their branches are discussed based on the up-to-date literature. Formerly, arterial dissections were found exclusively at necropsy, yet they have currently arisen to the field of interest of not only neurologists but also radiologists, neurosurgeons, and vascular surgeons. Ischemic strokes frequently result from arterial dissection, in particular subintimal dissection (most often in the extracranial portion of vertebral artery), by formation of emboli or reduced perfusion. Conversely, subadventitial and transmedial dissections produce aneurysms (most often in the intracranial portion of vertebral arteries and basilar artery) which may result in subarachnoid or intracerebral hemorrhages. The other possible mechanism of focal lesions is the compression of adjacent structures by dissected artery, most frequently by dolichoectasia of basilar artery which originates from its multiple intramural lesions. The dissections may present with cranial nerve palsies, symptoms of ischemia of cervical spine, cerebellum, and cerebral trunk, as well as occipital lobe syndromes. Arterial dissection may occur in adolescents and young adults. The clinical symptom that should be stressed is headache which precedes the occurrence of stroke for several days. The right diagnosis gives a chance for proper treatment, including operative procedures, and improved prognosis.     

Connective tissue disorders in dissections of the carotid or vertebral arteries.

Dissections of the carotid or vertebral arteries are a significant cause of ischemic stroke. Their etiology includes not only mechanical forces but also underlying arteriopathies such as Ehlers-Danlos syndrome type IV and other connective tissue disorders. Furthermore, dissections often occur spontaneously or after minor trauma in otherwise healthy individuals without clinically evident underlying aberrations. However, in some of these patients ultrastructural connective tissue changes can be detected. An overview of connective tissue disorders associated with dissections of the carotid or vertebral arteries is presented.     

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.