External Carotid Artery Territory Research Articles

Analysis of vascular perfusion territory using selective intraarterial injection CT angiography before and after revascularization surgery in patients with moyamoya disease.

In moyamoya disease (MMD), blood flow to the internal carotid artery (ICA) system is supplied via the basal fine vascular network, leptomeningeal anastomoses, and transdural collateral vessels from the external carotid artery (ECA). After revascularization, there is a dramatic change in cerebral perfusion to the ECA system. Understanding this shift in blood supply is important for evaluating treatment efficacy and elucidating the postoperative pathophysiology. However, anatomical and quantitative methods for doing so have not yet been established. In the present study, selective intraarterial injection CT angiography (iaCTA) was performed in patients with MMD, and blood supply changes in each arterial system before and after revascularization surgery were evaluated. This study included 10 hemispheres in 10 patients who underwent combined revascularization surgery for adult MMD. Digital subtraction angiography was performed before and 3 months after surgery, and selective iaCTA was performed from the ICA, ECA, and vertebral artery (VA) at the same times in a hybrid CT/digital subtraction angiography suite. The anatomical distribution of each vessel was determined and perfusion volume was measured quantitatively on contrast-enhanced axial CT images. Selective iaCTA clearly depicted the anatomical distribution of perfusion for each vessel. Conversion of blood supply from the ICA and VA to the ECA system was observed in the cerebral cortices and insulae but not in the basal ganglia. The mean volume of perfusion territories of the ECA (preoperative 0.9 cm3, postoperative 98.8 cm3); ICA (preoperative 225.7 cm3, postoperative 159.3 cm3); and VA (preoperative 244.0 cm3, postoperative 163.6 cm3) in the cerebral hemispheres changed significantly after revascularization. There was a correlation between increase in the ECA territory volume and decrease in the VA territory volume due to revascularization (R = -0.84, p < 0.005). Selective iaCTA enabled clear visualization of anatomical changes in each vascular perfusion territory and quantitative measurement of each perfusion volume. Perfusion conversion to the ECA system after bypass surgery was observed in the cortical regions and in the insulae on the bypass operation sides, but not in the basal ganglia. Combined revascularization promoted the development of ECA-perfused territory, which correlated with a decrease in hemodynamic burden of the posterior cerebral artery.

Functional Arterial Anatomy of the Cranial Base

Two main vascular routes supply the brain, internal carotid arteries (ICAs) and vertebral arteries. The external carotid artery (ECA) mainly supplies the skin, muscle, and skull; thus, neurointerventionalists should be aware of ECA‐ICA, ECA‐vertebral artery, and extracranial–intracranial anastomoses. These anastomoses are not newly formed but are arteries that are remnants of developmental processes. During development, the ICA has anastomoses with the original ECA at the first and second pharyngeal arches, and carotid‐basilar anastomoses exist between the ICA and vertebral artery/basilar artery. Advances in neurointerventional technology are increasingly expanding the indications for transarterial embolization in the ECA territory. To avoid embolic complications to the brain and cranial nerve palsy, knowledge and understanding of such extracranial–intracranial anastomosis are crucial for neurointerventionalists interested in neurovascular diseases. The arterial contributions to these anastomoses are mainly the branches of the maxillary artery, ascending pharyngeal artery (extracranial), ophthalmic artery, and branches of the ICA (intracranial). Knowledge of the embryological processes is essential for understanding the routes and patterns of these anastomoses. This review discusses ECA development, the ICA segmental concept and functional anatomy of the extracranial‐intracranial anastomoses in the orbit, cavernous sinus, petrosal bone, and posterior fossa from an embryological point of view.

Extracerebral Tissue Damage in the Intraluminal Filament Mouse Model of Middle Cerebral Artery Occlusion.

Middle cerebral artery occlusion is the most common model of focal cerebral ischemia in the mouse. In the surgical procedure, the external carotid artery (ECA) is ligated; however, its effect on the tissue supplied by the vessel has not been described so far. C57BL/6 mice underwent 1 h of transient MCAO (tMCAO) or sham surgery. Multi-spectral optoacoustic tomography was employed at 30 min after surgery to assess oxygenation in the temporal muscles. Microstructural changes were assessed with magnetic resonance imaging and histological examination at 24 h and 48 h after surgery. Ligation of the ECA resulted in decreased oxygenation of the left temporal muscle in most sham-operated and tMCAO animals. Susceptible mice of both groups exhibited increased T2 relaxation times in the affected muscle with histological evidence of myofibre degeneration, interstitial edema, and neutrophil influx. Ligatures had induced an extensive neutrophil-dominated inflammatory response. ECA ligation leads to distinct hypoxic degenerative changes in the tissue of the ECA territory and to ligature-induced inflammatory processes. An impact on outcome needs to be considered in this stroke model.

Dynamic cerebral autoregulation is unrelated to decrease in external carotid artery blood flow during acute hypotension in healthy young men.

What is the central question of this study? Dynamic cerebral autoregulation (CA) is impaired by sympathetic blockade, and the external carotid artery (ECA) vascular bed may prevent adequate internal carotid artery blood flow. We examined whether α1 -receptor blockade-induced attenuation of dynamic CA is related to reduced ECA vasoconstriction. What is the main finding and its importance? α1 -Receptor blockade attenuated dynamic CA, but in contrast to our hypothesis did not affect the ECA blood flow response to acute hypotension. These findings suggest that the recovery of cerebral blood flow during acute hypotension is unrelated to vasoconstriction within the ECA territory. External carotid artery (ECA) vasoconstriction may defend internal carotid artery (ICA) blood flow during acute hypotension. We hypothesized that the α1 -receptor blockade-induced delay in ICA recovery to the baseline level from acute hypoperfusion is related to attenuated ECA vasoconstriction. The ICA and ECA blood flow were determined by duplex ultrasound during thigh-cuff release-induced acute hypotension while the α1 -receptor blocker prazosin [1mg(20kg)(-1) ] was administered to nine seated young healthy men. Both ICA (mean±SD; by 17±8%, P=0.005) and ECA (by 37±15%, P<0.001) blood flow decreased immediately after occluded thigh-cuff release, with a more rapid ICA blood flow recovery to the baseline level (9±5s) than for the ECA blood flow (17±5s; P=0.019). The ICA blood flow recovery from hypoperfusion was delayed with prazosin (17±4s versus control 9±5s, P=0.006), whereas ECA recovery remained unchanged (P=0.313) despite a similar reduction in mean arterial pressure (-20±4mmHg versus control -23±7mmHg, P=0.148). These findings suggest that α1 -receptor blockade-induced attenuation of the ICA blood flow response to acute hypotension is unrelated to the reduction in ECA blood flow. The sympathetic nervous system via the ECA vascular bed does not contribute to dynamic CA during acute hypotension.

Non-invasive near-infrared fluorescence imaging of the neutrophil response in a mouse model of transient cerebral ischaemia

Near-infrared fluorescence (NIRF) imaging enables non-invasive monitoring of molecular and cellular processes in live animals. Here we demonstrate the suitability of NIRF imaging to investigate the neutrophil response in the brain after transient middle cerebral artery occlusion (tMCAO). We established procedures for ex vivo fluorescent labelling of neutrophils without affecting their activation status. Adoptive transfer of labelled neutrophils in C57BL/6 mice before surgery resulted in higher fluorescence intensities over the ischaemic hemisphere in tMCAO mice with NIRF imaging when compared with controls, corroborated by ex vivo detection of labelled neutrophils using fluorescence microscopy. NIRF imaging showed that neutrophils started to accumulate immediately after tMCAO, peaking at 18 h, and were still visible until 48 h after reperfusion. Our data revealed accumulation of neutrophils also in extracranial tissue, indicating damage in the external carotid artery territory in the tMCAO model. Antibody-mediated inhibition of α4-integrins did reduce fluorescence signals at 18 and 24, but not at 48 h after reperfusion, compared with control treatment animals. Antibody treatment reduced cerebral lesion volumes by 19%. In conclusion, the non-invasive nature of NIRF imaging allows studying the dynamics of neutrophil recruitment and its modulation by targeted interventions in the mouse brain after transient experimental cerebral ischaemia.

Different ophthalmic artery origins: Embryology and clinical significance

This retrospective study gives a summary of ophthalmic artery (OA) variations to serve as guidelines for surgical interventionists and trainees. Pubmed and Medline searches were conducted. The OA usually arises intradurally (superomedial, anteromedial, or rarely superolateral) from the internal carotid artery (ICA). Rare extradural origin (primitive dorsal OA) (PDOA) remnant and extremely rare interdural origin (primitive ventral OA) (PVOA) remnant are of significance when sectioning the dural ring. Rarely, a persistent PDOA with ICA origin, or a PDOA remnant with inferolateral trunk origin, enters the orbit via the superior orbital fissure (SOF) for sole or partial orbital supply. Extremely rare, the PDOA and PVOA persist and form double OAs that arise from the ICA and run via the SOF and optic foramen. Occasionally, the OA arises from the middle meningeal artery (MMA), when both the PDOA and VDOA regress and enter the orbit via the SOF. Sole orbital supply via the external carotid artery (ECA), i.e. meningo-ophthalmic artery and/or MMA branches, or dual OAs (ECA and ICA origins) may occur. Other rare OA origins include anterior or posterior communicating artery; anterior or middle cerebral artery; basilar artery; posterior inferior cerebellar artery; and the carotid bifurcation. Primitive arteries (persistent or remnant), and/or abnormal anastomoses play pivotal roles in manifestations of OA variations. Of clinical importance are orbital collateral routes and dangerous extracranial-intracranial anastomoses. Awareness of OA origins and collateral routes is imperative for transarterial embolizations or infusion chemotherapy in the ECA territory to prevent visual complications.

Quantitative Assessment of External Carotid Artery Territory Supply with Modified Vessel-Encoded Arterial Spin-Labeling

In patients with carotid stenosis or occlusion, cerebral blood could be supplied through collateral pathways to improve regional blood flow and protect against ischemic events. The contribution of collaterals from the ICA can be assessed by depiction of vascular perfusion territories with ASL. However, so far there is no method available to evaluate the collateral perfusion territory from the ECA in MR imaging. In this study, we present a new labeling scheme based on VE-ASL to quantitatively assess the perfusion territory of the ECA. A new labeling approach with a Hadamard encoding scheme was developed to label major arteries, especially the ECA. Twelve healthy subjects with normal cerebrovascular anatomy were examined to demonstrate their perfusion territories. Eight patients with carotid artery stenosis or occlusion were assessed before and after surgery to show changes of their collateral blood supply. The proposed method enables assessment of the perfusion territories of the ECA. Good agreement was found between the vascular territories and normal cerebrovascular anatomy in healthy subjects. For the patients with carotid stenosis or occlusion, our noninvasive results provided information on collateral flow comparable with that from DSA. Their collateral flows from the ECA, moreover, could be quantitatively estimated pre- and postoperatively. The modified approach has been validated by the consistency of collateral perfusion territories with cerebrovascular anatomy, and quantitative assessment of collaterals proved useful for assisting in evaluating therapeutic interventions.

P-026 Avoiding perils during endovascular embolization of skull base tumors: a pictorial review

IntroductionEndovascular embolization in the external carotid artery territory has become a widely accepted treatment for preoperative embolization of head and neck tumors. Tumors about the skull base present a difficult...

Preoperative cellulose porous beads for therapeutic embolization of meningioma: provocation test and technical considerations

Cellulose porous beads (CPBs) are exceptionally uniform in size and nonabsorbable and they provide highly effective tumor devascularization. The risk of cranial nerve palsy must not be overlooked when embolization with CPBs is considered in meningioma patients. We attempted to identify patients at risk of cranial nerve palsy after meningioma embolization. Prior to preoperative superselective embolization with 200 mum diameter CPBs, 141 patients with meningioma underwent provocation test with lidocaine and amytal. They were divided into two groups on the basis of whether they were or were not considered eligible for embolization. We evaluated the differences between the two groups with respect to tumor anatomy, angiographic findings, and clinical presentation and recorded complications associated with the embolization of the meningioma. Of the 141 patients, 128 underwent CPB embolization (group 2); 13 were not embolized because their provocation test results were positive (group 1, n = 11) or because they showed vasospasm (n = 2). Group 1 patients had meningioma in the cavernous sinus or petroclival region. Characteristically, the feeders were of middle meningeal artery origin and exhibited a posteromedial course toward the petrous apex or cavernous sinus. In group 2 patients the middle meningeal artery was the feeder, but it lacked branches coursing posteromedially. Three of these patients experienced complications which included intratumoral hemorrhage (n = 2) and post-embolization hearing disturbance (n = 1). Patients with meningioma whose tumor-feeding arteries run posteromedially toward the petrous apex or cavernous sinus are at increased risk of post-embolization cranial nerve palsy. Appropriate protocols, including lidocaine and amytal provocation tests, may reduce the risk of complications after CPB embolization of the external carotid territory in this group of patients.

Influence of sumatriptan on the autonomic system during migraine attacks

gy of migraine provided evidence that the autonomic nervous system may contribute to the development of the headache phase [1, 2]. Although the effectiveness of the 5HT 1B/1D receptor agonists (triptans) on pain relief is thought to be due to their specific action on the trigeminovascular system, a potential effect on the autonomic system, though unproven, may also be speculated [3]. Because of its effectiveness in investigating skin microcirculation by detecting thermic changes of a specific cutaneous area, infrared imaging may be a useful tool to test the functional effects of triptans on the autonomic system in physiological and pathophysiological conditions. The typical infrared pattern of migraine is the forehead cold patch, an asymmetrical focus of temperature decrease of 0.5°C within the external carotid territory, which represents the end result of the haemodynamic changes due to the activity of the autonomic and the trigeminovascular systems [4, 5]. In a pilot study, we tested a sample of 40 consecutive patients who met the diagnosis of migraine without aura and who reported a monthly frequency of one to six attacks. All the patients underwent clinical and infrared evaluation (PM395 Thermacam, Inframetrics, Inc., Billerica, MA) within 30 min of the onset of a spontaneous migraine attack and before treatment (t0), and 5 (t1), 30 (t2) and 120 min (t3) after treatment. Subjects were randomly assigned to receive 6 mg of injectable sumatriptan (n=30) or the same volume of placebo (n=10) within 30 min of the attack onset. Efficacy endpoint consisted of improvement in headache intensity to mild or painfree levels (optimal response) and a complete disappearance of the asymmetric infrared pattern at t3. Twentythree subjects (57.5%) had an optimal response to treatment and a complete disappearance of the asymmetric pattern at infrared imaging. All these were in the subgroup of individuals who received sumatriptan. In contrast, no substantial modification of the asymmetric pattern was observed in the remaining 7 subjects (23.3%) who did not have an optimal response after treatment. The same findings were also observed in the subgroup of subjects receiving placebo: none of them had an optimal response to treatment and none showed any significant modification of the asymmetric infrared pattern. These results demonstrate that the beneficial clinical effect of sumatriptan on pain relief is associated with the disappearance of the cold patch at the infrared investigation. As the mechanism underlying the disappearJ Headache Pain (2006) 7:116–117 DOI 10.1007/s10194-006-0289-z

The role of ECA transection in the development of masticatory lesions in the MCAO filament model

In the intraluminal suture model of middle cerebral artery occlusion (MCAO) in the rat, lesions of the masticator muscles associated with impaired functional outcome occur. We evaluated the role of external carotid artery (ECA) transection. We assessed whether isolated interruption of an arterial or a venous connection to the ECA territory was sufficient to induce masticatory hypoperfusion and lesions. We also evaluated a direct access to the common carotid artery (CCA) with subsequent vascular closure with regard to its feasibility, frequency of masticatory lesions, complications, and cerebral ischemia. Cerebral and masticatory lesions and perfusion deficits were assessed by in vivo magnetic resonance imaging (MRI). Vessel patency was evaluated using computerized tomography angiography and histology. An interruption of arterial blood flow led to masticatory hypoperfusion. Masticatory lesions occurred in 6% of the rats. Access to and closure of the CCA were feasible in all animals, leading to moderate or severe vessel stenosis in 20%, and intraarterial thrombosis in 25% of the rats. Reproducible cerebral infarctions were obtained in all animals. In 24% of the rats, hyperintense MRI signal changes were observed in the ipsilateral temporal muscle. Thus, the induction of masticatory hypoperfusion and lesions by arterial transection supports the role of the ECA in this context. Direct access to the CCA with subsequent vessel closure led to stenosis in most animals. Preservation of ECA continuity was not suitable to fully prevent masticatory lesions.

Response:

Response:

Response: Determinants of Body Weight Changes in the MCAO Filament Model

Response: Determinants of Body Weight Changes in the MCAO Filament Model

Functional Vascular Anatomy of the Head and Neck

The External carotid artery (ECA) supplies all the structures of the head and neck area, excluding the central nervous system and optic nerve in general. However, as seen in some species, the ECA can supply part (or entire) of the intracranial nervous system even in man. Traditionally, the external carotid arterial system and its branches have been described as arterial tree, which divides into multiple branches. However, this concept does not apply in all situations, and gives an erroneous idea of not only consistency in the anatomy of this system, but also the reliability on its branching modality. On the contrary, the ECA and its primary branches are extremely variable, and their embryonic origins are different. Therefore, we insist that ECA system should be analyzed as a collection of various primary branches, not as an arterial tree. Thus, the embryology of the cervical carotid arteries will be discussed first. There are dual systems within the external carotid territory, the neuromeningeal and the oral systems, which regroup pivotal arterial sources: superior laryngeal, pharyngo-occipital and maxillo-meningeal arteries for the former and superior thyroidal, facial and lingual for the latter one. The cutaneous and muscular branches will be grafted on this arterial frame as an embryo grows and develops. Three types of variations will then be encountered: neuromeningeal, oral, and cutaneo-muscular. In addition, junctions with central nervous arterial system (internal carotid and vertebral arteries) and lower cranial arterial system will create new variations. Knowledge of anatomy of the external carotid system and understanding of these variations will improve reliability and safety of endovascular therapeutic procedures. Dangerous anastomoses and territories represent the major dangers of therapeutic angiography therefore; we are emphasizing again this anatomy.

External carotid artery territory ischemia impairs outcome in the endovascular filament model of middle cerebral artery occlusion in rats.

Middle cerebral artery occlusion (MCAO) by an intraluminal filament is a widely accepted animal model of focal cerebral ischemia. In this procedure, cutting of the external carotid artery (ECA) is a prerequisite for thread insertion. However, the implications of ECA transsection have not yet been described. After 90 minutes of filament MCAO or sham surgery, rats were evaluated for up to 14 days in terms of body weight development, core temperature, and motor performance. Repeated in vivo MRI of the head and neck was performed for quantification of brain edema and infarct volume. The temporal muscles were histologically analyzed postmortem. In 47% of all rats, ischemic tissue damage to the ipsilateral ECA area, including temporal, lingual, and pharyngeal musculature, was detectable by MRI. Histology of temporal muscles confirmed acute ischemic myopathy. Animals with ECA territory ischemia (ECA-I) showed delayed body weight development and poorer recovery of motor function. There was no difference in the extent of brain edema or final cerebral lesion size between ECA-I-affected and unaffected rats. Filament MCAO was complicated by the consequences of ECA ischemia in approximately half of all rats. Impaired mastication and swallowing functions restricted ingestion and resulted in postsurgical body weight loss and worse motor performance. Impaired cerebral microperfusion resulting from dehydration and reduced spontaneous motor activity resulting from reduced food and water uptake might have contributed to poorer neurological recovery in ECA ischemic rats. Thus, adverse effects caused by extracerebral ischemia with potential impact on outcome have to be considered in this stroke model.

Glubran 2: A New Acrylic Glue for Neuroradiological Endovascular Use

A new acrylic glue, Glubran 2, is now available on the European market. It bears the CE mark with several surgical indications and the specific indication for neuroradiological endovascular use. Despite this approval, to our knowledge its use is still limited to surgery and no injections have been made in human patients. This study was designed to evaluate the behavior of Glubran 2 in endovascular injection in a simulation of brain AVM. Six sheep were operated on opening a fistula between the right common carotid artery and the jugular vein. This fistula modifies blood flow in the skull base rete mirabilis, which then functions as an AVM. In two sheep, the rete mirabilis was occluded by injection of 1.5 ml of Histoacryl diluted 1:1 and 1:3 with Lipiodol. In two sheep, the rete was embolized by injection of 1.5 ml of Glubran 2 diluted 1:1 with Lipiodol. The last two sheep were embolized by injection of Glubran 2 diluted 1:3 with Lipiodol. The procedures were documented by DSA angiographic acquisitions and by fluoroscopic VHS. The sheep were killed immediately after the procedures and the rete mirabilis isolated for histologic examination. Embolization was obtained with both kinds of glue. Glubran 2 diffuses in a very similar way to Histoacryl with an apparently more complete diffusion. Reflux in the ascending pharyngeal artery showed that Glubran 2 tended not to produce bubbles but diffused more homogeneously. The subjective conclusion of this work is that Glubran 2 can be used in endovascular embolizations. Before approaching brain AVMs, a further study will investigate embolization of the external carotid territory.

Endogenous nitric oxide synthesis differentially modulates pressure-flow and pressure-conductance relationships in the internal and external carotid artery circulations of the rat.

The role of endogenous nitric oxide (NO) synthesis was investigated in the regulation of the internal (ICA) and external carotid artery (ECA) beds of ventilated, anesthetized rats in a model in which the left common carotid artery was perfused from the aorta via an extracorporeal circuit under conditions of non-pulsatile controlled flow. The territories supplied by the extracranial ICA and ECA were studied separately following occlusion of the appropriate artery. An inhibitor of nitric oxide synthesis, N(G)-monomethyl-L-arginine (L-NMMA), and the NO synthase substrate L-arginine were administered via a jugular venous catheter. NO synthesis exerted an important influence on the pressure-flow relationships of the ICA and ECA circulations as L-NMMA increased input perfusion pressure at any given flow rate. However, in the presence of NO synthesis, hydraulic conductance increased rapidly with flow in the ICA, thereby stabilizing perfusion pressures over a wide range of flow rates, whereas this phenomenon was not evident in the ECA territory. Differences between the two circulations were further emphasized by observations that L-arginine antagonized the systemic hemodynamic response to L-NMMA and its effects on the conductance of the ECA bed, whereas the effects of L-NMMA were irreversible in the ICA territory.

Embolización selectiva terapéutica en epistaxis incoercibles

AbstractEpistaxis is a common otolaryngologic emergency that is controlled frequently with conservative measures. on the other hand, more aggresive treatments are requiered in refractory or severe epistaxis, which may have systemical impact. about intractable posterior epistaxis, selective embolization of external carotid territory is an effective option for managing. three patients with severe epistaxis successfully treated with selective embolization and a review of literature are exposed

Influence of acetazolamide and CO2 on extracranial flow volume and intracranial blood flow velocity.

The vasomotor response can be tested by means of transcranial Doppler sonography. If a constant vessel diameter is assumed, the flow velocity changes will reflect blood flow volume changes. This hypothesis is difficult to verify. Simultaneous assessment of intracranial flow velocity and extracranial flow volume changes may solve this problem. We tested vasomotor response in 32 volunteers (age, 42+/-18 years) with 5% CO2. Acetazolamide (1 g) was tested in 15 volunteers (age, 28+/-8 years). To evaluate drug-dependent flow changes in the external carotid artery territory, acetazolamide was administered in 7 patients with unilateral occlusion of the internal carotid artery without evidence of collateralization through the ophthalmic artery (age, 67+/-12 years). Simultaneous recording included measurements of flow volume in the common carotid arteries (M-mode color duplex system) and flow velocity in the middle cerebral arteries. With CO2 and acetazolamide, intracranial flow velocity increased by 31% and 39%, respectively, with a simultaneous increase of common carotid artery flow volume of 47% and 50%, respectively. No change in extracranial flow volume was observed in patients with an occluded internal carotid artery. These data show not only the expected increase of flow velocity in the middle cerebral artery but also suggest an increase in cross-sectional vessel diameter of 6% and 4% with CO2 and acetazolamide, respectively. It remains unresolved whether this observation is due to a direct effect of the drug on the vessel walls or is simply pressure dependent.

Abstracts of Literature

Abstracts of Literature