Identification of intima-to-media signals for flow-induced vascular remodeling using correlative gene expression analysis.

Changes in blood flow can induce arterial remodeling. Intimal cells sense flow and send signals to the media to initiate remodeling. However, the nature of such intima-media signaling is not fully understood. To identify potential signals, New Zealand white rabbits underwent bilateral carotid ligation to increase flow in the basilar artery or sham surgery (n = 2 ligated, n = 2 sham). Flow was measured by transcranial Doppler ultrasonography, vessel geometry was determined by 3D angiography, and hemodynamics were quantified by computational fluid dynamics. 24 h post-surgery, the basilar artery and terminus were embedded for sectioning. Intima and media were separately microdissected from the sections, and whole transcriptomes were obtained by RNA-seq. Correlation analysis of expression across all possible intima-media gene pairs revealed potential remodeling signals. Carotid ligation increased flow in the basilar artery and terminus and caused differential expression of 194 intimal genes and 529 medial genes. 29,777 intima-media gene pairs exhibited correlated expression. 18 intimal genes had > 200 medial correlates and coded for extracellular products. Gene ontology of the medial correlates showed enrichment of organonitrogen metabolism, leukocyte activation/immune response, and secretion/exocytosis processes. This demonstrates correlative expression analysis of intimal and medial genes can reveal novel signals that may regulate flow-induced arterial remodeling.

Microvascular decompression for trigeminal neuralgia attributable to the vertebrobasilar artery: decompression technique and significance of separation from the nerve root.

BACKGROUND: Separation of the vertebrobasilar artery (VBA) from the trigeminal nerve root in microvascular decompression (MVD) is technically challenging. This study aimed to review the clinical features of VBA involvement in trigeminal neuralgia and evaluate surgical decompression techniques in the long term. METHODS: We retrospectively reviewed the surgical outcomes of 26 patients (4.4%) with VBA involvement in 585 consecutive MVDs for TGN using a Teflon roll for repositioning the VBA. The final operative status of the nerve decompression was categorized into two groups: the separation group and the contact group. Separation of the VBA from the nerve root was completed in 13 patients in the separation group, and slight vascular contact remained in the remaining 13 patients of the contact group. The clinical features of VBA-related TGN were investigated and the operative results were analyzed. RESULTS: Multiple arteries are involved in neurovascular compression (NVC) in most cases. The anterior inferior cerebellar artery was the most common concomitant artery (69%). The site of the NVC varies from the root entry zone to the distal portion of the root. All patients were pain-free immediately after surgery and maintained medication-free status during the follow-up period, except for one patient (3.8%) who had recurrent facial pain 8 years after surgery. Postoperative facial numbness was observed in six patients (23%). Of these, one patient showed improvement within 3 months and the other five patients had persistent facial numbness (19.2%). Other neurological deficits include one dry eye, one diplopia due to trochlear nerve palsy, two decreased hearing (< 50 db), two facial weaknesses, and two cerebellar ataxia. Although most of them were transient, one dry eye, two hearing impairments, and one cerebellar ataxia became persistent deficits. Statistical analyses revealed no difference in surgical efficacy or complications in the long term between the two groups. CONCLUSIONS: Slightly remaining vascular contact does not affect pain relief in the long term. Our study indicated that once the tense trigeminal nerve is loosened, further attempts to mobilize the VBA are not necessary.

Systematization, distribution, and territories of the caudal cerebral artery on the surface of the brain in nutria (Myocastor coypus) / Sistematização, distribuição e territórios da artéria cerebral caudal na superfície do cérebro em Nutria (Myocastor coypus)

The nutria (Myocastor coypus) is a medium-sized, semi-aquatic rodent valued by the skin and meat industry. This study aimed to describe and systematize the caudal cerebral artery on the brain surface in nutria, establishing a standard model and its main variations in this species. The thirty animals used were euthanized according to animal welfare rules. The vessels were filled with latex stained with red pigment and the samples were fixed in formaldehyde. In nutria, the brain was vascularized by the vertebral basilar system. The terminal branches of the basilar artery originated the rostral cerebellar, caudal cerebral, rostral choroidal and middle cerebral arteries, and its terminal branch, the rostral cerebral artery. The terminal branch of the basilar artery projected the caudal cerebral artery, which is usually a single medium-caliber vessel, into the transverse fissure of the brain. The caudal cerebral artery was presented as a single (66.7% of the cases to the right and 76.7% to the left) and double vessel (33.3% of the cases to the right and 23.3% to the left). It originated the rostral mesencephalic artery, the proximal component, and the caudal inter-hemispheric artery. The terminal branches of the rostral and caudal tectal mesencephalic arteries formed a typical anastomotic network. The caudal inter-hemispheric artery emitted central branches, the caudal choroidal artery, hemispherical occipital arteries, rostral tectal mesencephalic branches and distal components, and anastomosed "in osculum" with the terminal branches of the rostral inter-hemispheric artery. The caudal choroidal artery anastomosed with the rostral choroidal artery, where it branched out on the thalamic mass, vascularizing all diencephalic structures and the hippocampus. The caudal cerebral artery and its terminal branches anastomosed with the terminal branches of the rostral and middle cerebral arteries in a restricted region of the caudal pole of the cerebral hemisphere. The vascularization area of the caudal cerebral artery and its central branches in the paleopallial of the piriform lobe is extremely restricted, caudomedially.(AU)

A nutria (Myocastor coypus) é um roedor semi-aquático de tamanho mediano, apreciado na indústria de peles e carne. Este trabalho tem por objetivo descrever e sistematizar a artéria cerebral caudal na superfície do cérebro em nutria, estabelecendo um modelo padrão e suas principais variações e territórios nesta espécie. Os trinta animais utilizados foram eutanasiados segundo as regras de bem-estar animal, os vasos foram preenchidos com látex, corado em vermelho e as peças foram fixadas em formoldeído. O cérebro foi vascularizado exclusivamente pelo sistema vértebro-basilar. Os ramos terminais da artéria basilar originaram as artérias cerebelar rostral, cerebral caudal, corióidea rostral, cerebral média e seu ramo terminal, a artéria cerebral rostral. O ramo terminal da artéria basilar lançou a artéria cerebral caudal, um vaso normalmente único, de médio calibre, para o interior da fissura transversa do cérebro. A artéria cerebral caudal foi um vaso único em 66,7% à direita e em 76,7% à esquerda e mostrou-se dupla em 33,3% à direita e em 23,3% à esquerda. Ela lançou a artéria tectal mesencefálica rostral, componente proximal e a artéria inter-hemisférica caudal. Os ramos terminais das artérias tectais mesencefálicas, rostral e caudal, formavam uma rede anastomótica típica. A artéria inter-hemisférica caudal lançou ramos centrais, a artéria corióidea caudal, as artérias hemisféricas occipitais, os ramos tectais mesencefálicos rostrais, componentes distais e anastomosou-se "em ósculo" com o ramo terminal da artéria inter-hemisférica rostral. A artéria corióidea caudal anastomosava-se com a artéria corióidea rostral, onde ramificavam-se sobre a massa talâmica, vascularizando todas as estruturas do diencéfalo e hipocampo. A artéria cerebral caudal com seus ramos terminais apresenta anastomoses com os ramos terminais das artérias cerebrais rostral e média em uma região restrita do pólo caudal do hemisfério cerebral. A área de vascularização da artéria cerebral caudal com seus ramos centrais no páleo-palio do lobo piriforme é extremamente restrita, caudo-medialmente ao mesmo.(AU)

A study on age- and gender-dependent differences in distance and angle between the internal carotid artery and basilar artery.

BACKGROUND: Variations or malformation of the internal carotid artery (ICA) and basilar artery (BA) can be risk factors during simple surgery. So medically the focus has been on information about the positional relationship between the blood vessels based on the distance and angle between the ICA and BA. OBJECTIVE: This study measured the distance and angle between the ICA and BA in 188 healthy Korean male and female subjects in their 20s and 40s and analyzed the differences in terms of age and gender. METHODS: Magnetic resonance images were obtained; the distance between the right ICA and BA was defined as R1 [cm], the distance between the left ICA and BA was defined as L2 [cm], and the distance between the right ICA and left ICA was defined as M3 [cm]. The angles between the right and left ICA and BA were defined as AR1 [degree] and AR2 [degree], respectively. RESULTS: With increasing age, R1 and M3 became shorter in both men and women, and L2 became shorter only in women. CONCLUSION: The results of this study provide data on the average distance and angle between the ICA and BA of healthy Korean men and women in their 20s and 40s, which may later be used to support the diagnosis of relevant brain diseases and simple routine surgical procedures.

Anatomical location of the vertebrobasilar junction: computed tomography morphometrics for planning endoscopic transsphenoidal transclival approaches.

BACKGROUND: The aim of this study was to determine the anatomical localisation and morphometry of vertebrobasilar junction (VBJ) by computed tomography (CT) images which may be helpful in planning the correct procedure before surgery such as endoscopic transsphenoidal transclival approach to the retroclival space. MATERIALS AND METHODS: Vertebrobasilar junction level was determined on axial, coronal reformat and sagittal reformat images. Clivus length, the distances of the VBJ to the upper and lower end of the clivus and to the bottom of the sphenoid sinus were measured. In addition, the position and distance of the VBJ relative to the midline were measured. The vertebral artery dominance was determined and the position of VBJ relative to the midline was evaluated. RESULTS: When compared by gender, 1, a, b and c values were significantly longer in males than in females (p < 0.05). The location of the bottom of the sphenoid sinus was higher than the VBJ level in 263 (98.1%) cases, equal to the VBJ level in 1 (0.4%) case, and lower than the VBJ level in 4 (1.5%) cases. There was no statistically significant difference between the distances to the midline when the VBJs with right and left localisation were compared (p > 0.05). A statistically significant relationship was found between vertebral artery predominance and localisation of VBJ relative to the midline (p < 0.001). CONCLUSIONS: Careful perusal of CT images and the described VBJ morphometrics can help in accurate procedure planning to avoid basilar artery injury.

The Anatomic Study of Intracranial Structures Related to Clival Screw Placement.

BACKGROUND: A clival plate and screw fitted to the craniovertebral junction (CVJ) were developed in our previous studies. However, the anatomy of intracranial structures related to clival screw placement has not been studied. OBJECTIVE: To measure the intracranial anatomic parameters delineating the basilar plexus and vertebrobasilar artery (VBA) course and to determine the relationship between brainstem and clivus for safer screw placement. METHODS: Morphometric analysis of the VBA was conducted on 95 patients (48 men, 47 women) by CT angiography (CTA) and of the basilar plexus and brainstem on 80 patients (44 men, 36 women) by magnetic resonance imaging (MRI) The narrowest distance between the VBA and the intracranial clivus and the distance between the VBA and the median line of the skull were measured on the axial plane at different parts. The relative positions of point I (intersection of vertebral artery and basilar artery) and the pharyngeal tubercle were analyzed. The distance between the clivus and the brainstem was measured at different levels. RESULTS: As the VBA ascended the distances to the intracranial clivus and the midline decreased. In 83.3% cases, point I was above the pharyngeal tubercle, and in only 9.5% cases was it located on the vertical line drawn from pharyngeal tubercle. The smallest safe space between the intracranial clivus and the brainstem was 7.46 mm at the lower part. CONCLUSION: Appropriate screw size at the lower clivus and the pharyngeal tubercle may help avoiding inadvertent injury to the brainstem and the VBA. Preoperative CTA and MRI of the CVJ are suggested to guide the surgeon in this regard.

Clinical and imaging features of vertebrobasilar dolichoectasia combined with posterior circulation infarction: A retrospective case series study.

This study aims to analyze the clinical and imaging features of vertebrobasilar dolichoectasia (VBD) combined with posterior circulation infarction, and to explore risk factors for the occurrence of posterior circulation infarction in VBD patients.VBD patients were divided into 2 groups, according to the results of the imaging examination: posterior circulation infarction group and nonposterior circulation infarction group. The demographics, vascular risk factors, imaging, and other clinical data of the VBD patients were collected and retrospectively compared, and the risk factors for the occurrence of posterior circulation infarction in VBD patients were analyzed. The relationship between imaging features of the VBD blood supply artery and the infarct site was also analyzed.A total of 56 VBD patients were included into the analysis. Among these patients, 26 patients had posterior circulation infarction. Infarction occurred in the blood supply area of the posterior cerebral artery in 14 patients. The difference in the height of the basilar artery bifurcation between patients with vertebrobasilar artery blood supply area infarction and patients with posterior cerebral artery supply area infarction was statistically significant. Hypertension and posterior circulation intracranial atherosclerosis were the risk factors for posterior circulation infarction in VBD patients.Elevated basilar artery bifurcation is a risk factor for infarction in the posterior cerebral artery supply area in VBD patients. Posterior circulation infarction in VBD may be the comprehensive result of multiple factors, such as congenital defects of the basilar artery wall, hypertension, and atherosclerotic lesions.

Variation in the Position and Diameter of Basilar Artery in Different Ages of Bangladeshi People.

Basilar artery is formed by the fusion of right and left vertebral artery and terminates as right and left posterior cerebral arteries. The aim of the study is to observe the diameter of basilar artery at three different levels (at its formation, at its midlevel and at its termination). This cross sectional descriptive study was performed on total 60 postmortem human hindbrain to find out the variation of position and diameter of the basilar artery of Bangladeshi people in relation to age. The specimens were collected from morgue in the department of Forensic Medicine, Mymensingh medical College, Mymensingh, Bangladesh by purposive sampling technique. All the specimens were grouped into four categories: Group A (20 to 29 years), Group B (30 to 39 years), Group C (40 to 49 years) and Group D (50 to 59 years). Diameter of basilar artery was measured with the help of digital slide calipers at three different levels. At the level of its formation, mean±SD diameter was 3.76±0.37 mm, 3.75±0.32 mm, 3.68±0.24 mm & 3.54±0.46 mm in Group A, B, C & D respectively. At mid-level, it was 3.49±0.36 mm, 3.48±0.30 mm, 3.45±0.21 mm & 3.36±0.44 mm in Group A, B, C & D respectively. At the termination, it was 3.55±0.35 mm, 3.51±0.30 mm, 3.48±0.22 mm & 3.38±0.38 mm in Group A, B, C & D respectively. This knowledge of variations of the diameter of basilar artery is of diagnostic importance for the neurosurgeons and radiologists for clinical investigation and surgery.

Geometric features of vertebrobasilar arterial system in adult black Kenyans / Características geométricas del sistema arterial vertebrobasilar en kenianos negros adultos

Geometric features of vertebrobasilar system influence occurrence of posterior circulation atherosclerosis, aneurysms, stroke and neuroradiological procedures. These features show ethnic variation, but data from black Africans in Sub Saharan Africa are scarce. This study aimed to describe geometric features of vertebrobasilar system in a black Kenyan population. It was a descriptive cadaveric study at Department of Human Anatomy, University of Nairobi. One hundred and seventy three formalin-fixed adult brains of individuals (99 male; 74 female; Age range 20 - 79) who had died of non cerebrovascular causes were studied. Level and angle of confluence of vertebral artery; diameter, length and bifurcation angles of basilar artery were measured. Data were analysed by SPSS version 21 for windows. The student t - test was used to determine the sex differences at 95 % confidence interval. Data are presented in macrographs, tables and bar charts. Confluence of vertebral arteries occurred at the sulcus bulbopontinus in 79.8 %; rostral to it in 11.5 % and caudal to it in 8.7 % of cases. Mean angle of vertebral artery confluence was 46.7º and 68.9º in males and females respectively (p£0.042). Mean length of the basilar artery was 26.8 mm; 26.3 mm in males and 27.1 mm in females (p=0.465). Mean diameter was 3.52 mm; 3.32 mm in males and 3.72 mm in females (p=0.002). The mean angle of basilar artery bifurcation was 120.3º ± 15.2; 99.3º ± 32.9 in males and 140.3º ± 16.1 in females (p=0.024). It was wider than 90º in 82.9 % of males and 95.9 % females (p=0.032). In 85 (49.1 %) it was wider than 120º. The vertebrobasilar system in the Kenyan population has geometric features that constitute risk factors for atherosclerosis. These features display sex dimorphism which may explain differences in prevalence of atherosclerosis and aneurysms. Neurosurgeons and neurologists should be aware of these differences. Individuals with risk prone geometric features should be followed up for atherosclerosis.

Las características geométricas del sistema vertebrobasilar influyen en la aparición de aterosclerosis en la circulación posterior, aneurismas, apoplejía, detectados durante procedimientos neurorradiológicos. Estas características muestran variación étnica, pero los datos de los africanos negros en el África Subsahariana son escasos. Este estudio tuvo como objetivo describir las características geométricas del sistema vertebrobasilar en una población negra de Kenia. Fue un estudio descriptivo cadavérico en el Departamento de Anatomía Humana de la Universidad de Nairobi. Se estudiaron 173 cerebros adultos (99 varones, 74 mujeres, rango de edad 20-79), fijados en formalina, de individuos que habían fallecido por causas no cerebrovasculares. Se midieron el nivel y ángulo de confluencia de la arteria vertebral, diámetro, longitud y bifurcación de la arteria basilar. Los datos fueron analizados por SPSS versión 21 para Windows. La prueba t de Student se utilizó para determinar las diferencias de sexo con un intervalo de confianza del 95 %. Los datos se presentan en macrografías, tablas y gráficos de barras. La confluencia de las arterias vertebrales se produjo en el surco bulbopontino en el 79,8 %; rostral al surco en 11,5 % y caudal al surco en 8,7 % de los casos. El ángulo medio de la confluencia de la arteria vertebral fue 46,70 y 68,90 en hombres y mujeres, respectivamente (p£0,042). La longitud media de la arteria basilar fue de 26,8 mm; 26,3 mm en hombres y 27,1 mm en mujeres (p=0,465). El diámetro promedio fue de 3,52 mm; 3,32 mm en hombres y 3,72 mm en mujeres (p=0,002). El ángulo medio de la bifurcación de la arteria basilar fue de 120,30 ± 15,2; 99.30 ± 32,9 en hombres y 140,30 ± 16,1en mujeres (p=0,024). Era más amplio que 90º. En un 82,9 % de los hombres y 95,9 % de las mujeres (p=0,032) se observó un ángulo más amplio que 90°. En 85 (49,1 %) fue más amplio que 120°. El sistema vertebrobasilar en la población de Kenia tiene características geométricas que constituyen factores de riesgo para la aterosclerosis. Estas características muestran dimorfismo sexual que puede explicar las diferencias en la prevalencia de aterosclerosis y aneurismas. Los neurocirujanos y los neurólogos deben tener en cuenta estas diferencias. Las personas con características geométricas propensas al riesgo deben ser seguidas por aterosclerosis.

Microsurgical Anatomy of the Labyrinthine Artery and Clinical Relevance.

AIM: To describe the origin, the course, and relationships of the labyrinthine artery (LA). MATERIAL AND METHODS: Thanks to a colored silicone mix preparation, ten cranial bases were examined using x3 to x40 magnification under surgical microscope. RESULTS: The LA often arose from the meatal loop of the anterior inferior cerebellar artery (AICA) (90%), or basilar artery (10%). The loop was extra-meatal of the internal auditory meatus (IAM) in 30%, at the opening of the internal auditory meatus in 20%, or intra-meatal in 35%. The AICA coursed in closed relationship to the VII and VIII cranial nerves. It coursed between VII and VIII cranial nerve roots in 85%, or passed over the ventral side of both VII and VIII cranial nerve. The average diameter of the LA was 0.2 +/- 0.05 mm. LA was single trunk in 60%, and bi-arterial in 40%. CONCLUSION: The implication of these anatomic findings for cerebello-pontine angle tumors surgery and neurovascular pathology such as infarction, aneurysm of the LA or the AICA are reviewed and discussed.

Arterial supply of the lower cranial nerves: a comprehensive review.

The lower cranial nerves receive their arterial supply from an intricate network of tributaries derived from the external carotid, internal carotid, and vertebrobasilar territories. A contemporary, comprehensive literature review of the vascular supply of the lower cranial nerves was performed. The vascular supply to the trigeminal, facial, vestibulocochlear, glossopharyngeal, vagus, spinal accessory, and hypoglossal nerves are illustrated with a special emphasis on clinical issues. Frequently the external carotid, internal carotid, and vertebrobasilar territories all contribute to the vascular supply of an individual cranial nerve along its course. Understanding of the vasculature of the lower cranial nerves is of great relevance for skull base surgery.

Three-dimensional analysis of foramen magnum and its adjacent structures.

The goal of this effort is to evaluate the anatomy of the foramen magnum (FM) using 3-dimensional computed tomography (3D CT), and determine whether or not the anatomical features of vascular structures and condylar foramen (CF) affect the types of FM.The CT angiography records of 101 patients (44 men and 57 women) were retrospectively examined in this study. Details of the FM, CF, and the vertebral and basilar arteries were examined using maximum intensity projection and 3D rendering images. The average age of the 101 patients was 45.28 ± 16.3 years. The 8 types of FM, in order of their frequency of occurrence, are as follows: round (19 cases; 18.8%), 2 semicircles (18; 17.8%), egg-shaped (15; 14.9%), hexagonal (14; 13.9%), tetragonal (11; 10.9%), oval (11; 10.9%), pentagonal (9; 8.9%), and irregular (4; 4%). There was no statistically significant relationship between the anatomical features of the vertebral and basilar arteries and the CF with the different types of FM (P ≥ 0.05). In our study, the diameter of the anteroposterior (AP) FM was 34.7 ± 3.6 mm, and the transverse (T) diameter was 29.5 ± 2.5 mm. The AP and T diameters were significantly higher in men than in women (P = 0.006 and P ≤ 0.001, respectively).Our study revealed that 3D CT is a safe and easy method for visualizing the anatomical structure of the FM and neighboring structures. Furthermore, this study was the first to demonstrate that there is no correlation between the 8 types of FM and the vertebral artery, basilar artery, and CF.

Expresión morfológica de la arteria basilar: un estudio con material de autopsia de individuos colombianos / Morphological expression of the basilar artery: a study with colombian population's autopsy material

La arteria basilar (AB) presenta una expresión variable, la cual es determinante en la etiología de eventos clínicos que comprometen el tallo cerebral. El propósito de este trabajo fue determinar la expresión morfológica de la AB en una muestra de población colombiana. Fueron estudiados 100 tallos cerebrales de individuos a quienes se les practicó autopsia en el Institutode Medicina Legal de Bucaramanga. El sistema vertebro-basilar fue perfundido con resina sintética y evaluado los calibres, trayectorias, niveles de origen y finalización de la AB. La AB presentó trayectoria rectilínea en 68 por ciento, desviación a la derecha en 12 por ciento, sinuosa en 10 por ciento y desviación a la izquierda en 10 por ciento. La longitud total de la AB fue 30,2 mm DE 4,07 y la longitud con relación al origen de la arteria Cerebelar superior fue 28,1 mm DE 3,84. Los calibres proximal y distal de la AB fueron 3,96 mm DE 0,48 mm y 3,7 mm DE 0,58 respectivamente. Con relación a las arterias de origen de la AB, se observó hipoplasia ( 2 mm) de la arteria vertebral derecha en el 8 por ciento y de la arteria vertebral izquierda en el 11 por ciento (P = 0,30). Se observó el origen de la AB a tres niveles del surco pontomedular: a nivel en el 43 por ciento, por arriba de este en el 30 por ciento y por debajo de este surco en 27 por ciento de los casos. Las trayectorias sinuosas y desviadas de la AB observadas y la presencia de hipoplasias de la arteria vertebral son ligeramente superiores a los señalados en estudios previos, mientras que su longitud se ubica en un rango medio y su calibre es ligeramente inferior a lo señalado en la literatura.

The basilar artery (BA) has a variable expression which is determinant in the etiology of clinical events that compromise the brain stem. The purpose of this study was to determine the morphological expression of BA in a Colombian population sample. We studied 100 brainstems of individuals which underwent an autopsy at the Instituto de Medicina Legal of Bucaramanga. The vertebra basilar system was perfused with synthetic resin and its calibers, paths, levels of origin and end of the BA were evaluated. The BA presented a rectilinear trajectory in 68 percent, deviation to the right in 12 percent, sinuous in 10 percent and deviation to the left in 10 percent. The total length of the BA was 30.2 mm SD 4.07, its length in relation to the origin of the superior cerebellar artery was 28.1 mm SD 3.84. The proximal and distal caliber of the BA were 3.96 mm SD 0.48 mm and 3.7 mm SD 0.58 respectively. In relation to the origin arteries of the AB, hypoplasia was observed ( 2 mm) of the right vertebral artery in 8 percent and the left vertebral artery in 11 percent (P = 0.30). The origin of BA was observed at different spontomedullary groove levels: at level in 43 percent, above it in 30 percent and below it in 27 percent of the cases. The sinuous and diverted paths from the BA observed and the presence of vertebral artery hypoplasia are slightly higher than those reported in previous studies, while its length is at medium range and its caliber is slightly lower than reported in the literature.

A cadaveric study of the endoscopic endonasal transclival approach to the basilar artery.

The anterior transclival route to basilar artery aneurysms is not widely performed. The objective of this study was to carry out a feasibility assessment of the transclival approach to basilar aneurysms with advanced endonasal techniques on 11 cadaver heads. Clival dura was exposed from the sella to the foramen magnum between the paraclival segments of the internal carotid arteries (ICA) laterally. An inverted dural "U" flap was reflected inferiorly to expose the basilar artery. The maximal dimensions from operative measurements were recorded. Surgical manoeuvrability of multiple instruments and the proficiency to place proximal and distal vascular clips were evaluated. The mean operative depth (± standard deviation), measured from the anterior choanae to the basilar artery, was 110±6mm. The lateral corridors were limited distally by the medial pterygoids (mean width 21±2mm) and paraclival ICA (mean width 20±2mm). The mean transclival craniectomy dimensions were 19±2mm (width) and 23±4mm (height). Exposure of the basilar-anterior inferior cerebellar artery junction, superior cerebellar artery, and the basilar caput were possible in 100%, 91%, and 64% of instances, respectively. Placements of proximal and distal aneurysm clips were achieved in all instances. Based on our findings, the transclival endoscopic endonasal surgery approach provides excellent visualisation of the basilar artery. Clip application and manoeuvrability of instruments was considered adequate for basilar aneurysm surgery. Surgical skills and instrumentation to control significant haemorrhage can potentially limit the clinical applicability of this technique.

Dimensions of the posterior cerebral circulation: an analysis based on advanced non-invasive imaging.

BACKGROUND: Our goal was to provide measurements of the posterior cerebral circulation using non-invasive imaging and advanced software analysis tools. METHODS: 100 consecutive patients aged ≥ 40 years (50 men and 50 women) who had undergone CT angiography (CTA) but had no vascular abnormality were analyzed. Specific software was used to make vessel measurements along the center line. The length of the intracranial vertebral artery (VA), the basilar artery (BA) and the distance from the mid-basilar artery to the posterior cerebral artery (mBA-PCA) was recorded. Vessel diameter was measured at the proximal and distal ends of these vessel lengths. Vessel taper was calculated as the change in diameter in millimeters per centimeter of length. RESULTS: The mean lengths of the intracranial VA, the BA and the mBA-PCA were 40 ± 10.6 mm, 27.3 ± 5.7 mm and 25.6 ± 4.3 mm, respectively. The proximal and distal diameters were 3.9 ± 0.8 mm and 2.8 ± 0.6 mm for the VA and 3.6 ± 0.6 mm and 3.1 ± 0.5 mm for the BA, respectively. The mean mid-BA diameter and the proximal PCA diameter were 3.2 ± 0.5 mm and 2.2 ± 0.4 mm, respectively. There was a significant increase in arterial caliber in patients aged ≥ 60 years compared with those aged 40-59 years. Men also tended to have longer vessels with a larger diameter than women. CONCLUSIONS: Advanced software and non-invasive imaging can be used to perform accurate vessel analysis. The posterior circulation measurements showed an increase in arterial caliber with age. This baseline information may be useful in planning neurovascular procedures and endovascular device development.

Anatomical arrangement and distributionof the cerebral arterial circle in rats

The cerebral arterial circle is a polygonal shape-like arterial anastomosis placed in the brain base, whereit rounds the optic quiasm and the tuber cinereum, and also related to the interpeduncular fossa and theanterior perfurated substance. It is formed by the proximal parts of the anterior, middle and posterior cerebralarteries, and the right and left posterior communicating arteries. In order to describe the cerebral arterial circledisposition we investigated the brains of twenty rats. For each animal, the heart left ventricle was probed andacetone, distilled water at 37 °C and a solution of Neoprene Latex “450” stained with a specific red pigmentwere injected in sequence into it. To fix the brain in a better way, we isolated the head and made an apertureat the dorsal wall of the cranium and the whole specimen was fixed in a 15% formaldehyde solution. We tookoff the brain from the skull with the aid of a cold light source monocular magnifier. To take the photographicdata we used a semi-professional camera. The results showed that the cerebral arterial circle in rats is formedby branches of both internal carotid arteries and of the basilar artery, and is closed rostrally by the rostralcommunicating artery, and caudally by the right and left terminal branches of the basilar artery. We concludedfrom our data that the cerebral arterial circle in rats is compound by branches of both internal carotid arteriesand basilar artery, and that it is rostrally and caudally closed.

Morfologia dos vasos da base do encéfalo do quati (Nasua nasua) / Morphology of the main vessels of the coati brain (Nasua nasua)

Estudou-se a morfologia do encéfalo de Nasua nasua - quati, buscando comparar estes achados com outras espécies já descritos. Foram utilizados cinco encéfalos de quatis, provenientes do Criatório Científico (Cecrimpas), Unifeob. Os animais foram eutanásiados de acordo com a legislação (Cobea). Canulou-se a artéria carótida comum e a veia jugular externa sentido cranial, injetou-se solução de látex/bário corado de vermelho na artéria carótida, e solução de látex corado de azul na veia jugular. Em seguida os animais fixados em solução de formaldeído a 10%. O encéfalo tem sua nutrição dependente de quatro artérias, as artérias carótidas internas e as artérias vertebrais direitas e esquerdas. Esses vasos compuseram o circuito basilar e carotídeo que se anastomosam através das artérias cerebrais caudais. Correm na base do encéfalo sob a meninge pia mater.

The morphology of the brain of coati, Nasua nasua, was studied, to compare the findings with other species described. The brains of five coatis were used, proceeding from the Scientific Breeding School (Cecrimpas), Unifeob. The animals were sacrificed in accordance with the legislation (Cobea). With a needle, the common carotid artery and the external jugular vein was cannulated to cranial direction, injected latex solution stained with colored red barium respectively. Afterwards the animals were fixed in 10% formaldehyde solution. Brain has its dependent nutrition of four arteries, the internal carotid arteries and the right and left vertebral arteries. These vessels had composed the basal and carotid circuits that anastomose through the cerebral arteries volumes. They run in the base of the brain under piamater meninges.

Vasculature and neurovascular relationships of the trigeminal nerve root.

BACKGROUND: Specific microanatomical characteristics of the trigeminal nerve root (TNR) blood supply and close neurovascular relationships with surrounding vessels as well as their possible clinical significance were the main reasons for this study. METHOD: The vasculature of 25 adult and four fetal TNRs were microdissected and examined under the stereoscopic microscope, after injecting their arteries with India ink. RESULTS: The trigeminal vessels, which varied between two and five in number, arose from two or three of the following arteries: the superolateral pontine (92%), anterior inferior cerebellar (AICA) (88%), inferolateral pontine (72%), and superior cerebellar (SCA) (12%). The trigeminal vascular twigs had a mean diameter of 0.215 mm. A single vessel may supply either the motor portion of the nerve root or the sensory portion or both. The trigeminal vasculature formed the proximal and distal rings. The proximal ring was located at the trigeminal root entry zone. Its central branches extended along the TNR to the principal sensory and motor trigeminal nuclei while its peripheral longitudinal twigs followed the TNR fascicles. The incomplete distal arterial ring embraced the middle portion of the TNR before the level of its entrance into the arachnoid sleeve. The most frequent contact of the TNR was noticed with the SCA (20%), the petrosal or Dandy's vein (24%), and the AICA (12%). CONCLUSIONS: The observed characteristics of the TNR vasculature could be the anatomical basis for decompressive neurovascular surgery.

Use of the arachnoid membrane of the cerebellopontine angle to transpose the superior cerebellar artery in microvascular decompression for trigeminal neuralgia: technical note.

BACKGROUND: Microvascular decompression is an accepted, safe, and useful surgical technique for the treatment of trigeminal neuralgia. Autologous muscle or implant materials such as shredded Teflon are used to separate the vessel from the nerve but may occasionally be inadequate, become displaced or create adhesions and recurrent pain. OBJECTIVE: The authors evaluated the use of arachnoid membrane of the cerebellopontine angle to maintain the transposition of vessels from the trigeminal nerve. METHODS: The authors conducted a retrospective review of microvascular decompression operations in which the offending vessel was transposed and then retained by the arachnoid membrane of the cerebellopontine cistern, specifically by the lateral pontomesenchepalic membrane. RESULTS: This technique was used in 30 patients of the most recently operated series. Postoperatively, complete pain relief was achieved in 90% of the patients without any observed surgical complications. CONCLUSION: To the authors' knowledge this is the first report in which the arachnoid membrane is used in the microvascular decompression of the trigeminal nerve. While this technique can be used only for selected cases, the majority of the vascular compressions on the trigeminal nerve are due to the SCA, so this sling transposition technique can be useful and effective.

Extended endoscopic endonasal approach to the clival region.

OBJECTIVE: The objective of this study was to recognize the endoscopic anatomy of the clival region of the skull base and its neurovascular relations, which will make us able to perform safer and minimal invasive endoscopic approaches to this region with lower rate of complications. MATERIALS AND METHODS: Six fresh cadavers were studied (n = 5). We approached the clivus by performing binostril extended endoscopic endonasal approach. After locating the sphenoid sinus as a key point, the vomer was totally removed to expose the clival region located inferiorly to the sphenoid sinus. Mucosal incision is done vertically from the sphenoidal portion the clivus caudally to the inferior portion of nasal cavity just medially to vidian nerve. The mucosal flap is then dissected and retracted. The clivus was resected until the foramen magnum inferiorly. The lateral limit of the resection is the paraclival portion of the internal carotid artery (ICA).The dura and the meningohypophyseal artery is exposed. A vertical dural incision was done and retracted laterally to expose the intradural structures. The prepontine cistern and basilar artery were visualized. RESULTS: The clivus was best localized by orienting the endoscope +15 degrees rostrally. After resecting the inferior wall of the sphenoid sinus and vomer and the overlying mucosa is retracted laterally until the vidian nerve, we obtained sufficient exposure of the clivus. The safe lateral limit of the surgical corridor was the vidian nerve. The clivus is resected until the foramen magnum inferiorly. The safe lateral limit of the resection in this step was the proximal cavernous and the distal petrosal portions of the ICA. This resection provided us with a wide exposure of the clival dura. The basilar plexus, the abducens nerve (sixth cranial nerve) passing through the basilar plexus, and the paraclival portion of the ICA can be injured when careful dissection is not performed. After dural incision, the prepontine cistern and the basilar artery were able to be exposed widely. CONCLUSION: Binostril extended endoscopic endonasal approach is an appropriate approach to the clival region of the skull base. With good knowledge of the endoscopic anatomic features of this region and its neurovascular relations, surgical procedures can be performed safely with more minimal invasiveness.