Extracranial Vessels Research Articles

Atherosclerotic Plaque Progression in Carotid Arteries: Monitoring with High-Spatial-Resolution MR Imaging—Multicenter Trial

To estimate the annualized rate of progression of vessel-wall volume in the carotid arteries in 160 patients by using magnetic resonance (MR) imaging and to establish the fraction of studies that have acceptable image quality. The study procedures and consent forms were reviewed and approved by each site's institutional review board. All U.S. study sites conducted all phases of this study in compliance with HIPAA requirements. Written consent was obtained from each participant. One hundred sixty patients with greater than 50% narrowing of the diameter of the carotid artery were recruited at six centers for prospective imaging of the carotid arteries at baseline and 1 year later by using high-spatial-resolution, 1.5-T MR imaging. Studies with unacceptable image quality were excluded. Quantitative changes in atheroma volume were measured on unenhanced T1-weighted images. A multiple linear regression analysis was used to correlate progression with several clinical factors, including statin therapy. All 160 patients completed both baseline and follow-up studies. Of these studies, 67.5% were deemed to have image quality that was acceptable for quantitative analysis. The causes of rejection were motion (46%), deep location of the carotid artery (22%), low bifurcation of the carotid artery (13%), and "other" (19%). The mean annual change in vessel-wall volume was 2.31% +/- 10.88 (standard deviation) (P = .014). At 1-year follow-up, vessel-wall volumes in patients not receiving statin therapy had increased faster compared with those in patients receiving statin therapy: 7.87% +/- 13.58% vs 1.14% +/- 9.9%, respectively (P = .029). Evaluation of results of a multicenter study indicates that quantitative evaluation of the progression of volume of extracranial carotid vessel walls is feasible with 1.5-T MR imaging despite limitations due to patient motion or habitus. In patients who had preexisting carotid disease, the rate of increase in vessel-wall volume was slower in patients receiving statin therapy.

Use of Magnetic Resonance Angiography to Predict Long-Term Outcomes of Ischemic Stroke Patients with Concurrent Stenoses in Hong Kong

Purpose: To determine the long-term outcome of ischemic stroke patients with concurrent intracranial and extracranial atherosclerosis using magnetic resonance angiography. Methods: A prospective cohort of patients in Hong Kong with acute ischemic stroke was studied with magnetic resonance angiography of the brain and carotid duplex. All patients were followed up regularly for the development of recurrent stroke, cardiac events, or death. Results: Totally 343 patients with acute ischemic stroke were included, of whom 104 (30%) had concurrent intracranial and extracranial lesions. The follow-up period was up to 76 months (mean 44.5 months). Overall, 55 patients (15.5%) died of any cause and 91 patients (26.5%) suffered a further nonfatal vascular event. The overall 5-year cumulative rates of mortality, restroke and poor outcomes (combined death and further vascular events) were 18, 27 and 37%, respectively. In patients with concurrent lesions, these rates were 31, 41 and 51%, respectively. The corresponding rates were 13, 22 and 31% in patients without concurrent lesions. The risks were highest in the first year after stroke. More deaths (log rank, 16.3; p = 0.0001), restrokes (log rank, 9.71; p = 0.002) and poor outcomes (log rank, 13.87; p = 0.0001) were found among patients with concurrent lesions. The presence of concurrent vascular lesions, advanced age, smoking, hyperlipidemia and previous history of stroke were independent predictors of poor outcomes. Conclusions: The long-term prognosis of ischemic stroke patients with concurrent atherosclerosis of intracranial and extracranial vessels is poor. They are at high risk of further vascular events or death.

Feasibility of Superficial Temporal Artery as the Input Artery for Cerebral Perfusion CT

The purpose of this study was to determine whether the superficial temporal artery as a surrogate arterial input function, compared with the anterior cerebral artery as the arterial input function, generates accurate perfusion CT maps with significant correlates for cerebral blood flow, cerebral blood volume, and mean transit time. One hundred perfusion CT examinations performed on 90 patients (51 women and girls, 39 men and boys) were retrospectively reviewed and postprocessed by one investigator using CT perfusion software at a workstation. Color-coded cerebral blood flow, cerebral blood volume, and mean transit time maps were constructed with the superficial temporal artery as a surrogate arterial input function and the anterior cerebral artery as the arterial input function. The effect of input artery choice on mean cerebral blood flow, cerebral blood volume, and mean transit time values in six regions of interest (one region of interest in each anterior cerebral artery, middle cerebral artery, and posterior cerebral artery territory) was assessed. All graphs of correlation between the anterior cerebral artery as the arterial input function and the superficial temporal artery as a surrogate arterial input function produced significant results (p < 0.0001). Excellent correlation existed between the cerebral blood flow (r = 0.96 [Pearson correlation coefficient]; rho(c) = 0.96 [concordance correlation coefficient]), cerebral blood volume (r = 0.97; rho(c) = 0.97), and mean transit time (r = 0.97; rho(c) = 0.97) values obtained with the anterior cerebral artery and the values obtained with the superficial temporal artery. Linear regression lines produced strong agreement between use of the anterior cerebral artery and use of the superficial temporal artery (cerebral blood flow, y = 1.03x + 0.65; cerebral blood volume, y = 1.05x - 0.09; mean transit time, y = 0.92x + 0.21). The preliminary results show that using an extracranial vessel such as the superficial temporal artery as a surrogate input artery can generate perfusion maps comparable with those generated with an intracranial vessel such as the anterior cerebral artery. This knowledge can be useful if the proximal intracranial vessels typically used for arterial input are not visible owing to diffuse disease, such as diffuse vasospasm and atherosclerosis, or are not included in the field of view of perfusion CT.

Introduction: Endovascular approaches to cerebral ischemia

The treatment of stroke has rapidly evolved over the past decade, particularly as data concerning the natural history have emerged and endovascular treatment options have matured. Therapies for acute stroke have expanded as intraarterial thrombolysis and mechanical clot retrieval have been validated. Furthermore, angioplasty and stenting of intra- and extracranial vessels have evolved with the development of new devices coupled with increasing operator experience. Endovascular therapy is now a widely accepted treatment option for cerebral ischemia in many clinical situations.

Hypoplasia of the internal carotid artery: collateral circulation and ultrasonographic findings. A case report

Introduction Hypoplasia of the internal carotid artery (HICA) is a rare congenital anomaly caused by an incomplete development of the organ, and only a few cases are reported in the literature. The prevalence of HICA (including agenesia and aplasia) is estimated to about 0.01%. Case report We describe a case of a 66-year-old man with hearing loss on the left side and no other symptoms or signs related to vascular impairment. HICA was discovered incidentally by color duplex sonography of the extracranial cerebral vessel and confirmed by magnetic resonance imaging angiography (angio MRI) and computed tomography (CT) of the head. Discussion Compensatory flow allows HICA patients to remain asymptomatic, but complications may occur. The pathways of the collateral circulation in association with aplasia or HICA are described. A differential diagnosis was made on the basis of ultrasonographic (US) detection of diffuse luminal narrowing of the internal carotid artery (ICA). Recognition of this disease has important clinical implications.

Books

Acta Neurologica ScandinavicaVolume 72, Issue 1 p. 76-78 Books First published: July 1985 https://doi.org/10.1111/j.1600-0404.1985.tb01553.xAboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinked InRedditWechat Abstract Pediatric head injuries caused by traffic accident A prospective study with 5 year follow-up Non-functional stereotaxy Erik-Olof Backlund Alexander B. Todorov (ed.): Clinical neurology, the residents guide. Leontino Battistin, George A. Hashim & Abel Lajtha (eds.): Clinical and biological aspects of peripheral nerve diseases. David M. Barrett & Allan J. Wein: Controversies in neuro-urology. A. E. Harding: The hereditary ataxias and related disorders. Roberg R. Schmith (ed.): Stroke and the extracranial vessels. Robert B. Aird, Richard L. Masland & Dixon M. Woodbury: The epilepsies. A critical review. James F. Tole: Cerebrovascular disorders. 3rd ed. G. Racagni, R. Paoletti & P. Kielholz (eds): Clinical neuropharmacology. A. Bernsmeier, A. Schrader, A. Struppler (eds): Bodechtes's Differential-diagnose neurologischer Krankenheits-bilder. J. M. S. Pearce: Dementia. A clinical approach. D. Voth & P. Krauseneck (eds): Chemotherapy of gliomas. Basic research, experiences and results. R. Bannister (ed.): Brain's Clinical Neurology. Volume72, Issue1July 1985Pages 76-78 RelatedInformation

Fibromuscular Dysplasia of the Distal Internal Carotid and Middle Cerebral Artery

Fibromuscular dysplasiais an uncommon condition of idiopathic, non-inflammatory and non-atherosclerotic disease of the musculature of arterial walls. The disease is rare, but it commonly affects young and middle aged women. Isolated intracranial cerebral fibromuscular dysplasia is extremely rare because cerebral fibromuscular dysplasia usually affects extracranial vessels. A 20-year-old woman was admitted with light hemiplegia and global aphasia. Brain MRI and MRA demonstrated acute left middle cerebral artery territory infarction with a multifocal stenosis and dilatation of the left middle cerebra artery and left internal carotid. The characteristic conventional cerebral angiographic findings demonstrated a typical string-of-beads appearance in the left distal internal carotid artery and proxiaml portion of the left middle cerebral artery, which suggested a medial type fibromuscular dysplasia. We report a case of isolated intracranial fibromuscular dysplasia with left middle cerebral artery territory infarction. Fibromuscular dysplasia should he considered as a stroke risk factors in children and young adults, especially in patients with no known cardiovascular risk factors.

Transcranial route of brain targeted delivery of methadone in oil

The unique anatomical arrangement of blood vessels and sinuses in the human skull and the brain, the prevalence of a high density of skin appendages in the scalp, extracranial vessels of the scalp communicating with the brain via emissary veins and most importantly, the way that the scalp is used in Ayurvedic medical system in treating diseases associated with the brain show that a drug could be transcranially delivered and targeted to the brain through the scalp. The present study was to investigate by measuring the antinociceptive effect on rats whether the opioid analgesic methadone could be delivered and targeted to the brain by transcranial delivery route. A non aqueous solution of methadone base in sesame oil was used for the application on the scalp. Animal studies were carried out using six groups of male rats consisting of group 1, the oral control treated with distilled water 1 ml; group 2, the oral positive control treated with methadone hydrochloride solution 316.5 μg/ml; group 3, the negative control treated transcranially with the blank sesame oil 0.2 ml and three test groups 4, 5 and 6 treated with three different dose levels of the transcranial oil formulation of methadone base, 41.6 μg/0.2 ml, 104 μg/0.2 ml and 208 μg/0.2 ml, respectively. The antinociceptive effects were examined by subjecting the rats to the hot plate and tail flick tests. The two higher concentrations of the three transcranial methadone formulations yielded response vs time curves showing nearly equal maximum antinociceptive effects similar to that of the oral positive control. Maximum analgesic effect after transcranial administration was observed between 1st and 2nd h and declined up to 6th hour. The results indicate that the transcranial brain targeted delivery of methadone base in the form of an oil based non aqueous solution results in statistically significant antinociceptive effects under experimental conditions. Therefore, it is possible to deliver central nervous system drugs through the proposed transcranial route when suitably formulated.

Takayasu’s disease presenting with atherothrombotic ischaemic stroke

Takayasu's arteritis is a chronic inflammatory disease of the aorta and its main branches, and a well known cause of stroke. Pathogenesis of ischaemic stroke has been attributed to intracranial vasculitic involvement or emboli from either stenoocclusive extracranial vessels or cardiac disease such as aortic regurgitation. We present a patient with Takayasu's arteritis and recurrent cerebral infarctions associated with intracranial atherosclerosis. We postulate that the intracranial atherosclerotic process is an important mechanism in Takayasu's arteritis-related ischaemic stroke.

Sports-Related Internal Carotid Artery Dissection

Extracranial and intracranial internal carotid artery (ICA) dissections following sports-related activities have been reported as a result of blunt traumatic injuries. The incidence of carotid artery dissection in sports is not known. Failure of physicians to suspect a dissection in the context of a minor injury or to obtain a history from the patient can lead to permanent neurologic deficits. The presentation of this entity is variable. We present 2 cases of ICA dissection with differences in causative mechanism and management in order to emphasize the importance of a physician's awareness, and we review the literature on this subject. Pathogenesis of sports-related ICA dissections may be multifactorial. Structural aberrations in the arterial walls and defective connective tissue components are assumed in some patients. Several genes have been shown to be candidates for the connective tissue aberrations. Since sports-related ICA dissection can occur extracranially or intracranially, the combined use of proper diagnostic techniques that provides information on the extracranial and intracranial vessels is recommended. Although the mechanisms and treatment modalities for intracranial and extracranial dissections might be different, the initial steps of evaluation and stabilization should be standardized for both. There is no randomized controlled study for the best treatment or management of ICA dissection.

THE ACCESSORY MIDDLE CEREBRAL ARTERY

Abstract Objective: An accessory middle cerebral artery (MCA) usually originates between the A1 and proximal A2 segment of the anterior cerebral artery, reaches the sylvian fissure, and supplies the territory of the MCA. This anomaly has been associated with cerebral aneurysms and Moyamoya disease. We report an accessory MCA arising from the A2 segment. Methods: A cadaveric head, fixed in formalin solution and injected with red and blue silicone on its vascular tree to trace intracranial and extracranial vessels, was dissected. Results: An accessory MCA was found arising from the A2 segment of the anterior cerebral artery and feeding the basal and inferior surface of the inferior frontal gyrus. In our specimen, the vessel was associated with intracranial aneurysms at other locations. Conclusion: Although anomalies of the MCA are rare, neurosurgeons must be familiar with such anatomic variations. An accessory MCA can be associated with Moyamoya disease and aneurysms at its junction with the anterior cerebral artery. Patients with this anomaly may, therefore, have an increased risk for developing aneurysms and other neurovascular complications. By obstructing the surgical view, an accessory MCA may increase the difficulty of exposing lesions in the vicinity of the optic chiasm.

The accessory middle cerebral artery: anatomic report.

An accessory middle cerebral artery (MCA) usually originates between the A1 and proximal A2 segment of the anterior cerebral artery, reaches the sylvian fissure, and supplies the territory of the MCA. This anomaly has been associated with cerebral aneurysms and Moyamoya disease. We report an accessory MCA arising from the A2 segment. A cadaveric head, fixed in formalin solution and injected with red and blue silicone on its vascular tree to trace intracranial and extracranial vessels, was dissected. An accessory MCA was found arising from the A2 segment of the anterior cerebral artery and feeding the basal and inferior surface of the inferior frontal gyrus. In our specimen, the vessel was associated with intracranial aneurysms at other locations. Although anomalies of the MCA are rare, neurosurgeons must be familiar with such anatomic variations. An accessory MCA can be associated with Moyamoya disease and aneurysms at its junction with the anterior cerebral artery. Patients with this anomaly may, therefore, have an increased risk for developing aneurysms and other neurovascular complications. By obstructing the surgical view, an accessory MCA may increase the difficulty of exposing lesions in the vicinity of the optic chiasm.

WE-D-342-02: Parallel Acquisition Methods for Neuroimaging

Parallel Imaging is one of the recent revolutions in Magnetic Resonance Imaging. As conventional gradient encoding is reaching its limits by dB/dt limits, spatial encoding via localized receiver coil sensitivities has brought a dramatic performance boost into the arena of MRI. Essentially, the use of parallel imaging affords less phase encoding steps and hence speeds up data acquisition. Aside from faster imaging, parallel imaging also caused giant leaps in RF receiver array technology development and thus to massive improvements in image quality and improved SNR at similar B0 levels. For many MRI pulse sequences parallel imaging helps to cut down scan time by factors ranging from 2 to 4, whilst for 3D sequences further speed up factors can be achieved along the second phase encode dimension, pushing the overall scan time reduction ever higher. In this fashion, the scan duration for time-of-flight (TOF) or phase-contrast (PC) angiographic sequences can be considerably shortened and increases patient comfort. Alternatively, larger volumes or better resolved data can be acquired within the same scan time. For contrast-enhanced MRA the faster scanning allows one to minimize the venous overlap in regions with extremely short arterio-venous transit times, such as seen in normal intra and extra-cranial vessels. In addition to reduce scan time, parallel imaging is also used very often in fast spin echo (FSE) and echo planar imaging (EPI) sequences to reduce geometric distortions and blurring. FSE acquires multiple lines of k-space per repetition interval (TR). During the course of each FSE readout train, the MR signal decays with T2 and impresses a considerable weighting on the k-space, which in turn, leads to noticeable blurring, especially for long FSE trains (e.g. T2-weighted FSE or single-shot FSE/HASTE). By scanning fewer lines in k-space, FSE traverse k-space much faster with parallel imaging and therefore reduces the blurring. In a similar fashion EPI, particularly single-shot EPI, suffers from T2*-weighting of the k-space data. As the T2* decay occurs more rapidly, the blurring in EPI is even more pronounced as with FSE sequences. Faster k-space traversal can again reduce blurring. EPI suffers also from marked geometric distortions that are typically induced by off-resonant spins (e.g., susceptibility differences, B0 inhomogeneities, lipids, eddy currents) and are proportional to how fast one traverse through k-space along the phase encode dimension. Here, parallel imaging helps to reduce these distortions R-fold if it accelerates the EPI readout R-times. The consequences to image quality enhancement are even more important to neuroimaging than overall scan time reduction as single-shot EPI is the backbone sequence for many highly important sequences that are used in clinical practice. Specifically, diffusion-weighted imaging (DWI), perfusion-weighted imaging (PWI), and functional MRI (fMRI) have benefited the most, thus far. Clearly, distortion correction and resolution enhancement are the driving factors behind that. Whilst better image quality in DWI offers better lesion conspicuity and detection of smaller lesions (which might help to better understand the etiology of a disease, such as stroke), fMRI benefits from better spatial localization and the ability to image regions that would have been otherwise too distorted. The price that one needs to paid for faster imaging is a loss in SNR that is proportional to the square-root of the acceleration factor and that is also proportional to the so-called geometry factor. The latter takes into account the size, number, and orientation of the individual receiver coils, which ultimately determine the conditioning of the inverse reconstruction problem. In summary, parallel imaging has led to a considerable boom in neuroimaging. By making acquisitions faster and less distorted patient comfort and motion artifacts could be reduced. Moreover, one can achieve spatial resolutions that would have been unthinkable before with regular gradient encoding. The field of parallel imaging is still growing at a very fast pace and is now paralleled by similar developments on the RF transmit side, for example, to shorten complex RF pulses and for advanced B1+ shimming methods.

A Study of the Validity of Performing Carotid Duplex Ultrasound with the Patient in a Seated Position

Objective: The purpose of this study was to compare pulsed wave (PW) Doppler velocity measurements obtained from duplex ultrasound of the carotid arteries with subjects in the seated and supine positions in an attempt to determine if this would influence the velocity criteria used in the classification of the severity of internal carotid artery disease. Methods: Carotid duplex ultrasound examinations were performed on 42 volunteers with measurement of peak systolic velocities (PSV) and end diastolic velocities (EDV) using a Doppler angle of 60°. The measurements were obtained from both the right and left extracranial carotid vessels in both the seated and supine positions. t-tests were used to compare the mean velocities obtained in the seated versus supine positions. Results: PSV and EDV measurements obtained in the seated position were lower than those in the supine position. Statistical analysis comparing the means in the seated versus the supine position showed statistical significance at the p=0·05 level for all measurements except the PSV of the internal carotid artery (ICA). Conclusions: Duplex ultrasound PW Doppler derived velocity criteria are used to classify the severity of stenosis, which in turn impacts on patient treatment options. The carotid duplex scan can be adequately performed on patients in the seated position but velocities measured will be reduced and modification to the existing velocity criteria may be needed.

Methods for discriminating flow direction with continuous wave Doppler equipment

The application of ultrasound Doppler units for the localization of incompetent venous valves, the examination of extracranial vessels, and the evaluation of the hemodynamic effect of certain cardiac dysfunctions requires directional models with the possibility of recording Doppler wave forms. Various techniques are used to determine flow direction all of them presenting specific advantages and disadvantages in practical use. After briefly explaining the basic Doppler technique, the three most commonly used methods, the two-channel filter technique, the McLeod system, and the outphaser system, are described. The characteristics of the various signal processing techniques are discussed, particularly in the case of complex hemodynamic conditions.

Multiple aneurysms of the facial artery in hereditary hemorrhagic teleangiectasia—Case report and review of the literature

This report describes the infrequent case of the occurrence of eight aneurysms of the facial artery in association with hereditary hemorrhagic teleangiectasia (HHT, Rendu–Osler–Weber disease, ROW). The aneurysms and the teleangiectatic nodules of the tongue were successfully treated by endovascular embolization in a combined technique using particles (polyvinyl alcohol, PVA) and fibred platinum coils. Endothelial cell degeneration, fragmentation of the elastic lamina and loss of muscularis in the vessel wall may be causal and give rise to multiple aneurysms of the intracranial and extracranial circulation in hereditary hemorrhagic teleangiectasias. This case and a review of the literature are presented because in the literature neither combined occurrence of ROW with a single aneurysm nor with multiple aneurysms of extracranial vessels are described.

Modification of outcomes by lowering ischemic events after reconstruction of extracranial vessels (MOLIERE): An internet-based prospective study to evaluate and improve the effectiveness of carotid endarterectomy

Independent audits have been proposed to improve carotid endarterectomy (CEA) effectiveness. This study used the online registry Modification of Outcomes by Lowering Ischemic Events after Reconstruction of Extracranial Vessels (MOLIERE) to evaluate the effectiveness of CEA in the Province of Quebec. The concept of MOLIERE is that surgeon involvement in a prospective manner is a prerequisite for them to evaluate, compare, and improve their practice. All Quebec surgeons who performed CEA were invited to participate in this study sponsored by the Société des sciences vasculaires du Québec, the Canadian Society for Vascular Surgery and the Association des chirurgiens vasculaires du Québec. Surgeons prospectively entered data for 60 variables relevant to CEA in an online, secure, and confidential database between May 24, 2004, and May 31, 2005. Patient inclusion had to occur before surgery. After the study was completed, charts of all CEAs performed in each participating center were reviewed to validate the results of MOLIERE. For each participating institution, results of CEA that were not entered in the registry were also reviewed. A total of 279 patients (mean age, 69 years; range, 46-91 years) undergoing a CEA were enrolled in MOLIERE by 23 surgeons from 10 institutions in Quebec; 157 (56%) were symptomatic, and 122 (44%) were asymptomatic. Carotid endarterectomies were performed with patch angioplasty in 252 (89%), primary closure in 24 (9%), and by eversion in six (2%). Follow-up at 30 days was achieved for all patients. The 30-day stroke or death rates for symptomatic and asymptomatic patients were 3.2% (5 of 157, 95% confidence interval [CI], 1.2%-7.4%) and 0%. Validation was excellent for patients who were entered in the registry, with no additional deaths or strokes than those reported by the surgeons. The validation process revealed that participating surgeons entered 66% (279 of 424) of their patients in the registry. Indications and stroke or death rates (SDRs) for those patients who were not entered in the registry were not statistically different (symptomatic, 54% [79 of 145]; SDR of 1.3% [1 of 76] for symptomatic and 1.5% [1 of 66] for asymptomatic). In participating institutions, 11 surgeons did not participate. The SDRs for patients operated on by nonparticipating surgeons were higher but not statistically different than rates for patients operated on by participating surgeons (3.7% [5 of 136] vs 1.7% [7 of 424], P = .16). There was a trend toward higher stroke rate for patients operated on by nonparticipating surgeons (3.7% [5 of 136] vs 1.2% [5 of 424], P = .056). Mean postoperative length of stay was statistically higher for patients operated on by nonparticipating surgeons (4.7 vs 3.4 days, P = .046). The SDRs were adequate for all surgeons in participating centers, with 95% CI within accepted standards for symptomatic and asymptomatic patients. MOLIERE is the first Canadian online prospective registry allowing surgeons to audit CEA results. The SDRs for participating surgeons were valid and within standards. Scientific vascular societies played a key role in supporting this project. Such audits allow surgeons and medical stroke experts to examine the appropriateness and results of CEAs in their institutions to improve them. The future of MOLIERE is in validation of its concept, increased participation by surgeons, and integration of a multidisciplinary approach.

Superficial temporal artery to middle cerebral artery bypass: past, present, and future

The aim of this study was to review the historical developments and current status of superficial temporal artery (STA) to middle cerebral artery (MCA) bypass. A literature review was performed to review the origins and current uses of the STA bypass procedure in neurosurgery. The idea of providing additional blood supply to the brain to prevent stroke and maintain neurological function has been present in the mind of neurosurgeons for many decades. In 1967 the first STA-MCA bypass was done by M. G. Yaşargil, and an enormous step was made into the field of microneurosurgery and cerebral revascularization. During the decades that followed, this technique was used as an adjuvant or a definitive surgical treatment for occlusive disease of the extracranial and intracranial cerebral vessels, skull base tumors, aneurysms, carotid-cavernous fistulas, cerebral vasospasm, acute cerebral ischemia, and moyamoya disease. With the results of the first randomized extracranial-intracranial (EC-IC) bypass trial and the development of endovascular techniques such as angioplasty for intracranial atherosclerotic disease and cerebral vasospasm, the indications for STA-MCA bypass became limited. Neurosurgeons continued to perform EC-IC bypasses as an adjuvant to clipping of aneurysms and in the treatment of skull base tumors and moyamoya disease; the procedure is less commonly used for atherosclerotic carotid artery occlusion (CAO) with definite evidence of hemodynamic insufficiency. The evidence that patients with symptomatic CAO and "misery perfusion" have an increased stroke risk has prompted a second trial for evaluating EC-IC bypass for stroke prevention. The Carotid Occlusion Surgery Study is a new trial designed to determine whether STA-MCA bypass can reduce the incidence of stroke in these patients. New trials will also reveal the role of the STA-MCA bypass in the prevention of hemorrhages in moyamoya disease. The role of STA-MCA bypass in the management of cerebrovascular disease continues to be refined and evaluated using advanced imaging techniques and by performing randomized trials for specific purposes, including symptomatic CAO.

3-T MRI detects inflammatory stenosis of the vertebral artery in giant cell arteritis

Giant cell arteritis (GCA) is a granulomatous vasculitis. Early diagnosis is important for the initiation of corticosteroid treatment because the arteritis can result in blindness. In most of the cases, the superficial cranial arteries are affected. However, extracranial involvement of various arteries is known. Here, we report a case of histologically proven GCA with an inflammatory stenosis of the right vertebral artery. For complete evaluation of the extension of the disease, an optimized protocol of high-resolution magnetic resonance imaging at 3 T in combination with contrast-enhanced magnetic resonance angiography was performed. This non-invasive method facilitates the differentiation of inflamed and healthy segments of small cranial arteries, may help to find appropriate sites for biopsy, and allows the assessment of affected extracranial vessels. In this patient case, even the cause of vertebral stenosis--inflammatory versus arteriosclerotic--could be elucidated.

Contrast-enhanced magnetic resonance angiography (CE-MRA) of intra- and extra-cranial vessels in dogs

Until recently intra- and extra-cranial vessels in dogs have been imaged using conventional X-ray or digital subtraction angiography. As both of these methods are surgically demanding and involve the use of complex equipment with potential risks for the animal, they are now mainly used in experimental work. In this study, a method for delineating the intra- and extra-cranial vessels of dogs using contrast-enhanced magnetic resonance angiography (CE-MRA) has been examined. The MR images were acquired on a 1.5-T scanner after a bolus injection of gadolinium contrast medium. CE-MRA showed most of the major intra- and extra-cranial arteries and veins as well as most venous sinuses and plexuses of the brain. Difficulties may arise in differentiating between minor arterial and venous vessels as well as in the measurement of vessel diameter. More frequent use of this diagnostic method in clinical cases will indicate whether MRA of the head and brain is of as much use in veterinary medicine as it has become in human medicine. There is certainly potential value in detecting rare conditions in animals such as aneurysms and vascular malformations, as well as in examining vessels feeding intracranial masses and the investigation of cerebrovascular accidents.