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Concept: Posterior communicating artery

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Background The effect of endovascular thrombectomy that is performed more than 6 hours after the onset of ischemic stroke is uncertain. Patients with a clinical deficit that is disproportionately severe relative to the infarct volume may benefit from late thrombectomy. Methods We enrolled patients with occlusion of the intracranial internal carotid artery or proximal middle cerebral artery who had last been known to be well 6 to 24 hours earlier and who had a mismatch between the severity of the clinical deficit and the infarct volume, with mismatch criteria defined according to age (<80 years or ≥80 years). Patients were randomly assigned to thrombectomy plus standard care (the thrombectomy group) or to standard care alone (the control group). The coprimary end points were the mean score for disability on the utility-weighted modified Rankin scale (which ranges from 0 [death] to 10 [no symptoms or disability]) and the rate of functional independence (a score of 0, 1, or 2 on the modified Rankin scale, which ranges from 0 to 6, with higher scores indicating more severe disability) at 90 days. Results A total of 206 patients were enrolled; 107 were assigned to the thrombectomy group and 99 to the control group. At 31 months, enrollment in the trial was stopped because of the results of a prespecified interim analysis. The mean score on the utility-weighted modified Rankin scale at 90 days was 5.5 in the thrombectomy group as compared with 3.4 in the control group (adjusted difference [Bayesian analysis], 2.0 points; 95% credible interval, 1.1 to 3.0; posterior probability of superiority, >0.999), and the rate of functional independence at 90 days was 49% in the thrombectomy group as compared with 13% in the control group (adjusted difference, 33 percentage points; 95% credible interval, 24 to 44; posterior probability of superiority, >0.999). The rate of symptomatic intracranial hemorrhage did not differ significantly between the two groups (6% in the thrombectomy group and 3% in the control group, P=0.50), nor did 90-day mortality (19% and 18%, respectively; P=1.00). Conclusions Among patients with acute stroke who had last been known to be well 6 to 24 hours earlier and who had a mismatch between clinical deficit and infarct, outcomes for disability at 90 days were better with thrombectomy plus standard care than with standard care alone. (Funded by Stryker Neurovascular; DAWN ClinicalTrials.gov number, NCT02142283 .).

Concepts: Stroke, Modified Rankin Scale, Middle cerebral artery, Internal carotid artery, Common carotid artery, Anterior cerebral artery, Posterior communicating artery, Disability

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The assessment of both geometry and hemodynamics of the intracranial arteries has important diagnostic value in internal carotid occlusion, sickle cell disease, and aneurysm development. Provided that signal to noise ratio (SNR) and resolution are high, these factors can be measured with time-resolved three-dimensional phase contrast MRI. However, within a given scan time duration, an increase in resolution causes a decrease in SNR and vice versa, hampering flow quantification and visualization. To study the benefits of higher SNR at 7 T, three-dimensional phase contrast MRI in the Circle of Willis was performed at 3 T and 7 T in five volunteers. Results showed that the SNR at 7 T was roughly 2.6 times higher than at 3 T. Therefore, segmentation of small vessels such as the anterior and posterior communicating arteries succeeded more frequently at 7 T. Direction of flow and smoothness of streamlines in the anterior and posterior communicating arteries were more pronounced at 7 T. Mean velocity magnitude values in the vessels of the Circle of Willis were higher at 3 T due to noise compared to 7 T. Likewise, areas of the vessels were lower at 3 T. In conclusion, the gain in SNR at 7 T compared to 3 T allows for improved flow visualization and quantification in intracranial arteries. Magn Reson Med, 2013. © 2012 Wiley Periodicals, Inc.

Concepts: Internal carotid artery, Common carotid artery, Anterior cerebral artery, Posterior communicating artery, Sickle-cell disease, Arteries of the head and neck, Circle of Willis, Signal-to-noise ratio

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Aberrant regeneration of a third nerve palsy (oculomotor synkinesis) excludes an ischaemic cause and in the absence of relevant trauma strongly suggests a compressive aetiology. A scan is mandatory in such cases. We describe the case of a 52-year-old woman who presented with complete pupil-involving third nerve palsy from a posterior communicating artery aneurysm, who later developed widespread aberrant regeneration of pupil, eyelid and third nerve territory rectus muscles.

Concepts: Muscle, Posterior communicating artery, Cerebral aneurysm, Case, Oculomotor nerve, In the Absence of Truth, Oculomotor nerve palsy

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BACKGROUND: Endovascular treatment of intracranial aneurysms relies on coaxial catheter support systems to provide safe and stable access. Large-bore distal intracranial catheters have become necessary for aneurysm treatment with flow diverting devices including the Pipeline embolization device (PED). These catheters must accommodate 0.027 inch microcatheters, be supple enough to track distally and be able to provide sufficient support for manipulations required for PED deployment. METHODS: A single-center aneurysm database was reviewed to identify patients who underwent anterior circulation aneurysm embolization with the PED while using the Navien distal intracranial catheter. Data were collected regarding the equipment used, cervical internal carotid artery (ICA) tortuosity, intraprocedural Navien positions and periprocedural complications. RESULTS: The Navien catheter (5 Fr, 0.070 inch outer diameter, 0.058 inch inner diameter, 115 cm) was used in 78 cases of anterior circulation PED. It was tracked into position over a Marksman microcatheter in 76 of the 78 cases (97%). The final catheter tip position was in the cervical ICA (1/78, 1%), petrous ICA (23/78, 30%), proximal cavernous ICA (48/78, 62%), distal cavernous/clinoidal ICA (3/78, 4%), supraclinoid ICA (2/78, 2%) and the M1 segment (1/78, 2%). In each case the catheter was tracked to its desired position (100% clinical success) despite significant proximal vessel tortuosity in 34 cases (44%). No clinically significant catheter-related complications occurred. CONCLUSIONS: The Navien intracranial catheter is an important component of the triaxial system for embolization of cerebral aneurysms with the PED. This catheter is highly trackable to distal positions, atraumatic and provides sufficient support for the microcatheter manipulations used during typical PED deployments.

Concepts: Internal carotid artery, Common carotid artery, Posterior communicating artery, External carotid artery, Aneurysm, Cerebral aneurysm, Catheter, Cavernous sinus

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BACKGROUND The circle of Willis is a major collateral pathway important in ischemic conditions. The aim of our study was to assess the structural characteristics of the circle of Willis within the Turkish adult population, along with variations and arteries involved in the measurement of diameters and lengths on cranial computed tomography angiography (CTA). MATERIAL AND METHODS One hundred adult patients who underwent CTA images were evaluated retrospectively. RESULTS Results of the study revealed 82% adult, 17% fetal, and 1% transitional configurations. A complete polygonal structure was observed in 28% of cases. Variations of the circle of Willis were more common in the posterior portion. Hypoplasia was found to be the most common variation and was observed as a maximum in the posterior communicating artery (AComP). CONCLUSIONS The patency and size of arteries in the circle of Willis are important in occlusive cerebrovascular diseases and cerebrovascular surgery. Although CTA is an easily accessible non-invasive clinical method for demonstrating the vascular structure, CTA should be evaluated taking into account image resolution quality and difficulties in the identification of small vessels.

Concepts: Blood vessel, Medical imaging, Posterior communicating artery, Cardiovascular system, Circle, Circle of Willis, Posterior cerebral artery

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Acute tandem occlusions of the cervical and distal internal carotid artery (ICA) or middle cerebral artery (MCA) are associated with major stroke with intravenous (i.v.) thrombolysis alone in approximately 90 % of patients. The data on endovascular management of tandem occlusions is still limited. The purpose of this study was to review technical aspects and the current state of the literature on acute ICA stenting in combination with stent retriever-based intracranial thrombectomy.

Concepts: Stroke, Middle cerebral artery, Internal carotid artery, Common carotid artery, Anterior cerebral artery, Posterior communicating artery, External carotid artery, Arteries of the head and neck

4

Intravenous thrombolytic therapy is the only proven treatment for acute ischemic stroke, but its use is limited by a brief time window of up to 4.5 hours after the onset of symptoms(1) and a recanalization rate of less than 50%. Large clots in vessels such as the distal internal carotid artery or the first segment of the middle cerebral artery respond poorly to intravenous thrombolysis.(2) The need for a treatment for patients who do not have a good response to intravenous treatment alone remains pressing. On the basis of compelling anecdotal experience, stroke specialists had hoped that transvascular recanalization would . . .

Concepts: Stroke, Middle cerebral artery, Internal carotid artery, Common carotid artery, Anterior cerebral artery, Posterior communicating artery, External carotid artery, Arteries of the head and neck

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OBJECTIVE The aim of this investigation was to modify the mini-pterional and mini-orbitozygomatic (mini-OZ) approaches in order to reduce the amount of tissue traumatization caused and to compare the use of the 2 approaches in the removal of circle of Willis aneurysms based on the authors' clinical experience and quantitative analysis. METHODS Three formalin-fixed adult cadaveric heads injected with colored silicone were examined. Surgical freedom and angle of attack of the mini-pterional and mini-OZ approaches were measured at 9 anatomical points, and the measurements were compared. The authors also retrospectively reviewed the cases of 396 patients with ruptured and unruptured single aneurysms in the circle of Willis treated by microsurgical techniques at their institution between January 2006 and November 2014. RESULTS A significant difference in surgical freedom was found in favor of the mini-pterional approach for access to the ipsilateral internal carotid artery (ICA) and middle cerebral artery (MCA) bifurcations, the most distal point of the ipsilateral posterior cerebral artery (PCA), and the basilar artery (BA) tip. No statistically significant differences were found between the mini-pterional and mini-OZ approaches for access to the posterior clinoid process, the most distal point of the superior cerebellar artery (SCA), the anterior communicating artery (ACoA), the contralateral ICA bifurcation, and the most distal point of the contralateral MCA. A trend toward increasing surgical freedom was found for the mini-OZ approach to the ACoA and the contralateral ICA bifurcation. The lengths exposed through the mini-OZ approach were longer than those exposed by the mini-pterional approach for the ipsilateral PCA segment (11.5 ± 1.9 mm) between the BA and the most distal point of the P2 segment of the PCA, for the ipsilateral SCA (10.5 ± 1.1 mm) between the BA and the most distal point of the SCA, and for the contralateral anterior cerebral artery (ACA) (21 ± 6.1 mm) between the ICA bifurcation and the most distal point of the A2 segment of the ACA. The exposed length of the contralateral MCA (24.2 ± 8.6 mm) between the contralateral ICA bifurcation and the most distal point of the MCA segment was longer through the mini-pterional approach. The vertical angle of attack (anteroposterior direction) was significantly greater with the mini-pterional approach than with the mini-OZ approach, except in the ACoA and contralateral ICA bifurcation. The horizontal angle of attack (mediolateral direction) was similar with both approaches, except in the ACoA, contralateral ICA bifurcation, and contralateral MCA bifurcation, where the angle was significantly increased in the mini-OZ approach. CONCLUSIONS The mini-pterional and mini-OZ approaches, as currently performed in select patients, provide less tissue traumatization (i.e., less temporal muscle manipulation, less brain parenchyma retraction) from the skin to the aneurysm than standard approaches. Anatomical quantitative analysis showed that the mini-OZ approach provides better exposure to the contralateral side for controlling the contralateral parent arteries and multiple aneurysms. The mini-pterional approach has greater surgical freedom (maneuverability) for ipsilateral circle of Willis aneurysms.

Concepts: Middle cerebral artery, Internal carotid artery, Anterior cerebral artery, Posterior communicating artery, Arteries of the head and neck, Circle of Willis, Posterior cerebral artery, Anterior communicating artery

2

Vascular dementia, being the most severe form of vascular cognitive impairment (VCI), is caused by cerebrovascular disease. Whether organophosphorus causes VCI remains unknown. Isocarbophos (0.5 mg/kg per 2 days) was intragastrically administrated to rats for 16 weeks. The structure and function of cerebral arteries were assayed. The learning and memory were evaluated by serial tests of step-down, step-through and morris water maze. Long-term administration of isocarbophos reduced the hippocampal acetylcholinesterase (AChE) activity and acetylcholine (ACh) content but did not alter the plasma AChE activity, and significantly damaged the functions of learning and memory. Moreover, isocarbophos remarkably induced endothelial dysfunction in the middle cerebral artery and the expressions of ICAM-1 and VCAM-1 in the posterior cerebral artery. Morphological analysis by light microscopy and electron microscopy indicated disruptions of the hippocampus and vascular wall in the cerebral arteries from isocarbophos-treated rats. Treatment of isocarbophos injured primary neuronal and astroglial cells isolated from rats. Correlation analysis demonstrated that there was a high correlation between vascular function of cerebral artery and hippocampal AChE activity or ACh content in rats. In conclusion, chronic administration of isocarbophos induces impairments of memory and learning, which is possibly related to cerebral vascular dysfunction.

Concepts: Temporal lobe, Cerebrum, Middle cerebral artery, Anterior cerebral artery, Posterior communicating artery, Cardiovascular system, Acetylcholine, Posterior cerebral artery

1

Microsurgical treatment of suprasellar tumors, in particular tuberculum sellae meningiomas, poses significant challenge. These tumors are surrounded by vital neurovascular structures, such as optic apparatus, pituitary stalk, internal carotid artery and its branches, and anterior cerebral arteries. In large and complex cases, early identification and decompression of these structures may facilitate safer dissection and resection. Therefore, extradural anterior clinoidectomy with optic unroofing facilitates the internal carotid artery exposure and optic nerve decompression. In this video, we describe a 37-year-old female patient who presented with new onset of severe headaches. On visual examination, she was found to have bitemporal visual defects. MRI scan of the head showed a large, approximately 3 cm suprasellar tumor consistent with tuberculum sellae meningioma. She underwent surgical resection via pterional craniotomy with extradural anterior clinoidectomy and optic unroofing. Microsurgical gross total resection was achieved and histopathology was WHO grade II meningioma. She had an uneventful postoperative course and visual field examination improved significantly. In this video, surgical technique in performing extradural anterior clinoidectomy and optic unroofing and steps of microsurgical resection are demonstrated. The link to the video can be found at: https://youtu.be/oPZ8NTyvxJc .

Concepts: Brain tumor, Middle cerebral artery, Internal carotid artery, Common carotid artery, Anterior cerebral artery, Posterior communicating artery, Circle of Willis, Optic nerve