Unilateral cervical and petrosal segment agenesis of the internal carotid artery with rete mirabile

The carotid rete mirabile (RM) is a physiological network between the internal and external carotid arterial systems. In this paper, an extremely rare case is presented, in which internal–external carotid artery anastomoses and a dilated ascending pharyngeal artery, due to unilateral agenesis of the cervical and petrous segments of the internal carotid artery (ICA), is presented.     

Stenting for Symptomatic Vertebral Artery Stenosis Associated with Bilateral Carotid Rete Mirabile: The Long-Term Clinical and Angiographic Outcome

Symptomatic vertebral artery (VA) stenosis associated with bilateral carotid rete mirabile (CRM) has not been reported. We report the long-term clinical and angiographic outcome after stenting for symptomatic VA stenosis in the patient with bilateral CRM. This report is the first case that symptomatic VA stenosis associated with bilateral CRM was treated with stenting.     

Absence of the carotid canals at skull base CT.

Congenital absence of one or both internal carotid arteries (ICAs) has a high association with circle of Willis aneurysm formation. Since the carotid canals in the skull base form secondary to the presence of the embryonic ICA, absence or hypoplasia of a carotid canal on a computed tomographic (CT) scan through the skull base should suggest a congenital ICA abnormality and prompt a search for associated intracranial vascular abnormalities. Of four patients with carotid canal underdevelopment evident at CT, two had associated circle of Willis aneurysms and a third had an extensive skull base rete mirabile supplying an abnormal tangle of vessels in the basal cisterns. Only two patients (one with an aneurysm, one with the skull base rete mirabile) presented with subarachnoid hemorrhage. One patient presented with monocular decreasing vision due to an enlarging aneurysm, and one patient was essentially asymptomatic. If asymmetry or absence of the carotid canals is evident on CT scans of the head, further evaluation to rule out a potentially life-threatening intracranial vascular abnormality such as those found in these patients should be seriously considered, even in a young or asymptomatic patient.     

VCT对头颈部血管狭窄与闭塞的诊断价值

目的 探讨64排螺旋CT(VCT)头颈部血管成像对头颈部血管慢性狭窄性病变的临床诊断价值.资料与方法 对62例可疑头颈部血管慢性狭窄性病变的患者应用CT血管成像(CTA)技术行头颈动脉成像检查,观察两侧椎动脉(VA)、颈内动脉(ICA)以及大脑前动脉(ACA)、大脑中动脉(MCA)和大脑后动脉(PCA).对所有图像行曲面重组(CPR)、容积再现(VR)、最大密度投影(MIP)及多平面重组(MPR)处理.结果 62例中头颈部CTA未见异常19例,发现血管异常43例.其中VA狭窄18支,闭塞7支;ICA狭窄30支,闭塞7支;ACA和MCA狭窄11支,闭塞2支,PCA发育不良2支.烟雾病2例,脑内动静脉畸形2例.血管起源变异4例.结论 VCT头颈部血管成像能准确显示头颈部血管正常解剖与异常改变,二维与三维图像相结合对头颈部血管狭窄或闭塞诊断和治疗方案的制定具有指导意义.     

Congenital absence of the internal carotid artery diagnosed during investigation of trigeminal neuralgia

Congenital absence of the unilateral internal carotid artery (ICA) was found in a patient during MR imaging examination for right trigeminal neuralgia. Magnetic resonance angiography showed complete absence of the right ICA and a large tortuous basilar artery (BA). The source images revealed a deformed right trigeminal nerve resulting from compression by the BA. Computed tomography of the skull base showed absence of the right carotid canal, suggesting agenesis of the right ICA. Longstanding hemodynamic stress may have caused the BA to become extremely tortuous, resulting in the trigeminal neuralgia.     

The two-in-one model: a new variation of the arteriovenous malformation model in swine

We report a new variation of the well-established experimental arteriovenous malformation (AVM) model in swine. To provide high flow through the rete mirabile (nidus, RM) and thereby to reduce the rate of spontaneous thrombosis of the AVM, we performed an end-to-end anastomosis of the left common carotid artery (CCA) and the external jugular vein (EJV) microsurgically in three micropigs. After 1 and 4 months the animals underwent angiograms of the CCA and vertebral artery (VA). In all cases the diversion of the blood through the RM was patent, up to the 4 months follow-up. We observed an arteriovenous fistula (arteriovenous pseudomalformation, pAVF) between the VA and the EJV in each case at both 1 and 4 months. This modification of the well-known AVM model in the micropig could be used to monitor long-term changes after embolisation, avoiding the naturally high rate of spontaneous thrombosis. This two-in-one model is thus well suited for preclinical testing of embolic materials. Received: 2 December 1999 Accepted: 31 August 2000     

Multiple segmental agenesis of the cerebral arteries: case report

A case of multiple segmental agenesis of the cerebral arteries is presented. Cerebral angiography demonstrated bilateral socalled carotid rete mirabile, a similar rete of the right vertebral artery and intradural duplication of the left vertebral artery. These abnormalities are thought to be caused by multiple segmental agenesis of the cerebral arteries as they penetrate the dura mater, the embryological and anatomical significance of these findings is discussed.     

Anomalous External Carotid Artery-Internal Carotid Artery Anastomosis in Two Patients with Proximal Internal Carotid Arterial Remnants

Two angiographic instances of anomalous external carotid artery (ECA) and internal carotid artery (ICA) anastomosis are described, each occurring at the C2-3 level and bearing remnants of proximal ICA. The ICA remnant of one patient (identifiable immediately upon bifurcation of the common carotid artery) was hypoplastic, and that of the other patient was an occluded arterial stump. These features are not typical of non-bifurcating ICA. The occipital artery originated from an anomalous connection in one instance and from the main trunk of the ECA (just past the ECA-ICA connection) in the other.     

Missed Total Occlusion Due to the Occipital Artery Arising from the Internal Carotid Artery

A 56-year-old man was referred for digital subtraction angiography (DSA) with an ultrasound diagnosis of right proximal internal carotid artery (ICA) stenosis for possible carotid artery stenting. DSA revealed total occlusion of the ICA and an occipital artery arising from the stump and simulating continuation of the ICA. An ascending pharyngeal artery also arose from the same occipital artery. This case is of interest because this is a rare variation besides being a cause of misdiagnosis at carotid ultrasound.     

三维对比增强颈部动脉MRA动脉期及延迟期影像分析

目的：评价颈部动脉增强MRA动脉期及延迟期的临床应用价值。方法：对85例颈部3D CE-MRA图像显示的动脉形态进行分析,观察每例颈部动脉的6支血管即双侧颈总动脉、双侧颈内动脉和双侧椎动脉。扫描采用3.0TMR系统（Siemens,Trio）,使用高压注射器经肘静脉注射对比剂马根维显后动态扫描。结果：统计85例的双侧颈总动脉、颈内动脉及椎动脉共510支动脉,比较分析动脉期与延迟期就颈部动脉的形态,结果显示完全一致375支,占73.5%,不一致135支,占26.5%。增强MRA动脉期上,有95支颈动脉或椎动脉表现为轻度狭窄,占不一致135支的70.4%,而在延迟期表现为正常。表现在左侧颈总动脉起始部18支,右侧颈总动脉起始部5例,左侧椎动脉起始部38支,右侧椎动脉起始部7例,左侧颈内动脉虹吸段15支,右侧颈内动脉虹吸段12支。另有40支动脉在增强MRA动脉期图像表现为中—重度狭窄,在延迟期则表现为轻度狭窄,夸大了狭窄的程度,占不一致135支的29.6%。其中左侧颈总动脉起始部19支,右侧颈总动脉起始部2支,左侧椎动脉起始部16支,右侧椎动脉起始部3支。结论：3D CE-MRA动脉期易导致动脉的起始部及迂曲部位狭窄的假阳性或夸大狭窄程度,因此在进行3D CE-MRA时不应只进行动脉期扫描,还要进行延迟期的扫描。同时还应结合原始图像,这样才能准确评价动脉的狭窄程度。     

A simplified arteriovenous malformation model in sheep: feasibility study.

BACKGROUND AND PURPOSE: Recently, a swine model of a cerebral arteriovenous malformation (AVM) has been developed that closely resembles a human AVM of the brain. The creation of such a model requires sophisticated neurointerventional techniques. The purpose of this study was to develop a simple and cost-effective AVM animal model that does not require additional endovascular techniques. METHODS: A surgical anastomosis was created in seven sheep between the common carotid artery and the ipsilateral jugular vein, followed by ligation of the jugular vein above the anastomosis and of the proximal common carotid artery below the anastomosis. The anastomosis was created on the left side in four animals and on the right side in three. Cerebral angiography from the contralateral carotid artery was performed before and immediately after surgery to delineate the relevant cerebral vascular anatomy and to determine the direction of blood flow. RESULTS: An angiographic appearance simulating an AVM was found in all the animals. The ramus anastomoticus and arteria anastomotica functioned as the feeding vessels to the rete mirabile, which represented the nidus in our model, and to the jugular vein, which represented the draining vein from the malformation. Extensive collateral flow through the rete mirabile into the distal segment of the external carotid artery above the ligature was observed angiographically, with retrograde flow through the surgical anastomosis into the jugular vein. CONCLUSION: A simple surgically created experimental model for cerebral AVMs was developed in sheep without the need for additional complex endovascular catheter manipulations of intracranial branches. Such an animal model can substantially reduce the cost of research and training in the neurointerventional or radiosurgical management of AVMs.     

Use of a new mixture for embolization of intracranial vascular malformations

Summary The internal carotid artery system in swine has a special anatomic configuration similar to a brain arterial-arterial malformation. The internal carotid artery breaks up into a multitude of fine channels (rete mirabile) situated at the base of the skull on the side of the hypophysis. This anatomic arterial model was used to analyze acute and chronic angiographic and histological changes after occlusion of the rete mirabile with I) avitene, II) avitene, and 50% ethanol, III) avitene, 30% ethanol and Polyvinyl alcohol, IV) avitene 50% ethanol and Polyvinyl alcohol, V) IBCA and VI) silk. Histopathological changes observed in the rete mirabile six weeks following occlusion demonstrated that a mixture of avitene, 30% ethanol and Polyvinyl alcohol and IBCA produced the best anatomic results. Embolization with avitene, PVA and ethanol induced a more bland histological reaction than the one observed with IBCA. Preliminary clinical experience with this mixture is reassuring in those cases in which the AVM was surgically resected. The partially thrombosed AVM was easily depressed and compressed by the neurosurgeon allowing for satisfactory hemostasis in and around the nidus of the AVM.This paper was presented in part at the International Symposium on Cerebral Stroke, Sendai, Japan, 1987     

Carotid and vertebral artery dissection: Magnetic Resonance findings in 15 cases

PURPOSE: Spontaneous dissection of the carotid and vertebral arteries represents a rare pathology. Its pathogenesis, probably multi-factorial, can be related to neck trauma and to a genetic basis, extensively demonstrated in the cases of association with type IV fibromuscular dysplasia, Ehlers-Danlos syndrome, Marfan's syndrome, pseudoxanthoma elasticum and osteogenesis imperfecta. Onset symptoms include neck, facial pain and diffuse headache. Cranial nerve palsy has been also described. The aim of this study was to evaluate MR angiography and MR findings in a population of patients with carotid and vertebral artery dissections. MATERIALS AND METHODS: We reviewed the MR angiography and MR exams of 15 patients (10 males, 5 females, average age 42.0, age range 30-55) with carotid and/or vertebral artery dissection; the serial MR follow-up studies were also examined. RESULTS: Twelve internal carotid arteries (ICA) showed the presence of an irregular stenosis; three of these showed complete occlusion. In two patients both ICA were involved. Six vertebral arteries (VA) showed irregular stenosis (only one patient suffered from both CI and VA dissection); in one case there was also a pseudoaneurysm of the VA. Follow-up studies showed vessel lumen re-opening in 5/11 ICA (one patient underwent vascular stent positioning) and in 3/6 VA. CONCLUSIONS: The present study confirms the usefulness of MR angiography and MR in the diagnosis and follow-up of patients with carotid and vertebral artery dissection.     

Impact of COPD exacerbation on cerebral blood flow

We aimed to investigate the impact of chronic obstructive pulmonary disease (COPD) exacerbation on cerebral blood flow (CBF). In 21 COPD patients - in both exacerbation and stable phases -Doppler ultrasonographies of internal carotid artery (ICA) and vertebral artery (VA) were performed. There were significant differences in total, anterior and posterior CBF, ICA and VA flow volumes in exacerbated COPD compared to stable COPD. Total CBF was correlated with cross-sectional areas of left and right ICA, whereas independent predictor of total CBF was cross-sectional area of right ICA. Increased CBF might indicate cerebral autoregulation-mediated vasodilatation to overcome COPD exacerbation induced hypoxia.     

Endovascular treatment in proximal and intracranial carotid occlusion 9 hours after symptom onset

INTRODUCTION: A debate is emerging over whether the treatment time window in acute stroke can be extended beyond 6 h if penumbral tissue can be identified. Treatment decisions are very difficult in cases of tandem proximal carotid occlusion with arterioarterial intracranial embolism. We enter this debate with the present report on a case of atherosclerotic proximal carotid occlusion and resulting periocclusional carotid T embolism that was successfully treated 9 h after symptom onset. METHODS: The case of a 68-year-old man with fluctuating symptoms of right-hemispheric stroke is presented (NIHSS score 12-20 on admission). CT angiography demonstrated proximal carotid occlusion and periocclusional embolism of the entire internal carotid artery (ICA) including the carotid T segment. Penumbral tissue was diagnosed by nonenhanced and perfusion CT imaging 7.5 h after symptom onset. Treatment was initiated 9 h after symptom onset by passing the proximal occlusion with a microcatheter and local administration of recombinant tissue plasminogen activator (rt-PA) into the carotid T segment at the level of posterior communicating artery (PCoA) origin. RESULTS: Recanalization of the ICA and middle cerebral artery was accomplished within 1 h by flow establishment via the PCoA. The atherosclerotic proximal ICA occlusion was not stented due to the risk of embolism from remnant thrombi in the petrous and cavernous ICA segments. Follow-up MRI showed only mild haemorrhagic infarct transformation of the initial infarct core. The patient was discharged from hospital 18 days after treatment with NIHSS score 5. CONCLUSION: If penumbral tissue can be conclusively identified, endovascular treatment in proximal and intracranial tandem occlusion can be successful, even in treatments initiated 6-9 h after stroke onset. If the intracranial flow after recanalization can be established via the circle of Willis, the underlying proximal ICA occlusion may not require treatment.     

Non-visualization of the internal carotid artery with a normal ipsilateral common carotid artery Doppler waveform: a finding suggesting congenital absence of the ICA on colour Doppler ultrasound

We report a case of congenital absence of the left internal carotid artery (ICA) that presented with left-sided facial numbness. On MRI of the brain, occlusion of the left cavernous ICA was suggested. On colour Doppler ultrasound (CDS), the left ICA was not visualized and the ipsilateral common carotid artery (CCA) showed normal flow in systole and diastole. Combined with the correct identification of the left external carotid artery (ECA), these findings were suggestive of congenital absence of the ICA rather than occlusion. The final diagnosis of congenital absence of the ICA was confirmed with CT of the skull base.     

Congenital absence and aberrant course of the internal carotid artery

We retrospectively reviewed the imaging features of an aberrant course of the internal carotid artery (ICA) in one patient and its unilateral absence in four. Absence of the ICA was initially detected by MRI and MR angiography in both patients who underwent these examinations. CT revealed an abnormal or absent carotid canal in all cases. Radiological diagnosis by MRI and MR angiography could play an important role in the diagnosis. Correspondence to: S. Takahashi     

Assessment of steal syndromes with colour and pulsed Doppler imaging

The purpose of this study was to assess the incidence of and determine the types of steal phenomena occurring in the extracranial arteries of the head (common carotid artery [CCA], internal carotid artery [ICA], external carotid artery [ECA], vertebral artery [VA] and ophthalmic artery [OA]). A total of 3759 extracranial carotid artery sonographic examinations (7518 carotid arteries) of consecutive patients were reviewed. In every case an attempt was made to also evaluate the vertebral arteries. Reverse flow was found in 37 arteries in the examined regions in 36 patients. One of the most common findings was reversed flow in one of the VA as a sign of subclavian steal syndrome. This occurred in 17 cases (0.22%). The OA was examined in 15 cases when occlusion of the ICA was found in the neck region. In 14 (93.3%) of these cases the flow in the OA proved to be reversed. In 4 cases of occlusion of the CCA (0.05%) the ICA was fed through the main branch of the ECA, in which the flow was reversed. More rarely, in 2 cases (0.027%) both the CCA and ICA were occluded, and the main branch of the ECA was supplied through its dilated side branch, in which the flow direction was reversed. Colour and pulsed Doppler imaging are appropriate noninvasive methods for imaging these steal syndromes. Their diagnosis cannot only explain clinical signs, but can also lead to therapeutic consequences. Correspondence to: Z. Morway     

利用猪颅底奇网制作动静脉畸形模型的实验研究

目的 利用猪颅底奇网制作一种简单、经济的动静脉畸形模型.方法 通过显微外科手术,将猪一侧颈总动脉与颈内静脉或颈外静脉吻合,建成动静脉畸形模型.吻合术后行血管造影及组织学检查.结果 8头家猪手术后全部成活.血流自右侧咽升动脉流经奇网和对侧咽升动脉,进入颈内/外静脉.术后3周1头家猪死亡.另1头家猪1个月时吻合口闭塞.结论...