Anastomotic Connections Research Articles

Microsurgical Angioarchitectonics of Deep Brain Structures and Deep Arterial Anastomoses

Surgeries for deep and eloquent cerebral lesions require a detailed knowledge of normal brain anatomy and accurate planning. Important parts of brain anatomy are the cerebral blood supply and collateral circulation system. In addition to well-known cortical and basal (circle of Willis) anastomoses, there is also a deep interarterial anastomotic circle that is not described in the literature. Twenty brain specimens were studied for deep arterial anastomotic connections between branches of the anterior and posterior choroidal arteries. We have marked 3 symmetric zones of deep arterial anastomoses that form an epithalamic circle. Epithalamic anastomoses provide an additional mechanism of blood distribution that may play a role during surgical interventions or stroke.

Anatomic Limitations of the Transmetatarsal Amputation With Consideration of the Deep Plantar Perforating Branch of the Dorsalis Pedis Artery

The transmetatarsal amputation is considered a durable procedure with respect to limb salvage when managing the consequences of diabetic foot disease. The success of the procedure is, in part, determined by the preoperative appreciation of arterial and functional status. The objectives of the present investigation were to determine the length of the remaining first metatarsal required during transmetatarsal amputation to preserve the anastomotic connection of the deep plantar perforating artery and subsequent “vascular arch” of the foot and the insertion of the tibialis anterior tendon. The primary outcome measure of our investigation was a measurement of the distance between the first metatarsal–medial cuneiform articulation and the distal extent of the deep plantar perforating artery in 85 embalmed lower limbs. As a secondary outcome measure, the insertion of the tibialis anterior tendon was evaluated relative to the deep plantar perforating artery. The most distal extent of the deep plantar perforating artery was observed at a mean ± standard deviation of 15.62 ± 3.74 (range 6.0 to 28.28) mm from the first metatarsal–medial cuneiform articulation. Most (89.41%) of the arteries were found within 20 mm of the first metatarsal–medial cuneiform articulation. The insertion of the tibialis anterior tendon was found to be proximal to the deep plantar perforating artery in all specimens (100.0%). In conclusion, 2.0 cm of remnant first metatarsal might represent an anatomic definition of how “short” a transmetatarsal amputation can safely be performed in most patients when considering the vascular and biomechanical anatomy.

Heart Transplant in Patient With Isolated Left Superior Vena Cava by Atrial Appendage Rotation

Orthotopic heart transplantation in patients with an isolated persistent left superior vena cava is extremely rare, and the anastomotic connection between a right-sided donor superior vena cava and left-sided recipient superior vena cava can be challenging to perform. We present a novel technique used in an infant female, using the left atrial appendage to extend the superior vena cava anastomosis.

Recurrent Hematemesis in a Patient With Aorto-enteric Fistula

We report a case of an aorto-enteric fistula (AEF) in a patient with history of celiac artery aneurysm and graft repair. AEFs are a communication between the aorta and the adjacent gastrointestinal tract. AEFs are a rare, but life-threatening cause of upper gastrointestinal tract bleeding and should be on the differential in patients with history of abdominal vascular surgery. A 32-year-old woman underwent celiac artery aneurysm resection with aorto-common hepatic artery graft interposition. This was complicated by pancreatic head, common bile duct, and portal vein necrosis requiring Whipple pancreaticoduodenostomy, Roux-en-Y hepaticojejunostomy, and portal vein resection with graft interposition. She also developed a pancreatico-cutaneous fistula, eventually closed by EUS-guided pancreatic pseudocyst gastrostomy. The patient was later reassessed with EGD, which showed a gastro-jejunal (GJ) junction Forrest class III ulcer. The patient presented to our institution with hematemesis, melena, and hemoglobin of 4.2 g/dL. EGD showed the known GJ ulcer with new friability and was treated with epinephrine and argon plasma coagulation. However, the patient returned with hematemesis and repeat EGD showed the GJ ulcer had an adherent clot with a visible vessel which was clipped. Abdominal CT angiography (CTA) did not reveal evidence of acute hemorrhage. The patient returned with GI bleeding and repeat abdominal CTA showed a tubular structure concerning for AEF, with possible erosion of the celiac stump into the jejunal blind limb. Vascular surgery was consulted for endovascular graft of the AEF. AEFs can be spontaneous or secondary to a previous aortic surgery. Aortic pseudoaneurysms and/or grafts can cause fistula through aortic pulsation into the intestinal tract and present with GI bleeding. EGD, CT with contrast, and CTA are the most common imaging modalities that aid in diagnosis. EGD can be useful if a graft or pulsatile mass is visualized, but most AEFs occur in the distal duodenum and may not be seen on EGD. CT with contrast is relatively sensitive for signs of AEF such as loss of peri-aortic fat pad, gas around the graft, fluid or soft tissue collection around the aorta, and IV contrast extravasation into the bowel or around the aorta. As in our case, CTA can be helpful in patients with altered anatomy. In addition to CT findings typical for AEF, CTA has greater spatial resolution allowing better visualization of the aortic contour and side branches.Figure: Gas shadow and inflammation surrounding aorta at the level of celiac stump, likely indicative of anastomotic connection to walled off necrosis, which is adjacent to the jejunum.

The Relationship of Superficial Cutaneous Nerves and Interperforator Connections in the Leg: A Cadaveric Anatomical Study.

The lower limb is a source of many flaps both for closure of local defects and for free transfer. Fasciocutaneous flap techniques have been progressively refined, although the vascular basis for their success needs clarification. Archival studies of 48 lower limbs were reviewed and combined with 20 studies of lower limbs from fresh cadavers, making a total of 68 investigations. Lower limbs were injected with a dilute lead oxide solution; the integument was removed and radiographed; and the cutaneous nerves were dissected, tagged with wire, radiographed again, and their paths traced on the original images. The major cutaneous nerves in the leg are paralleled by a longitudinal vascular axis often comprising long branches with large-caliber true anastomotic connections between perforators. The most highly developed vascular axes followed the medial sural cutaneous and saphenous nerves, together with their accompanying veins, immediately superficial to the deep fascia. The intervening areas were characterized by shorter branches usually connected by small-caliber choke anastomotic connections. These findings provide the anatomical basis for the observed reliability of longitudinal flaps in the leg. The superficial cutaneous nerves of the leg, especially the saphenous and medial sural cutaneous nerves, are paralleled by a vascular axis on or beside the nerve comprising long perforator branches connected usually but not always by large-caliber true anastomotic connections. This emphasizes the importance of understanding the characteristics of interperforator anastomoses when designing and raising flaps.

Restoring dinosaur cephalic vascular anatomy and thermophysiology using osteological correlates and anastomotic connections

The restoration of dinosaur cephalic blood vessels is critical to understanding physiological thermoregulatory strategies in dinosaurs. Cephalic blood vessels of extant diapsids are known to support physiological thermoregulatory capabilities that modulate head and neurosensory tissue temperatures. Given their close phylogenetic relationship to extant diapsids, dinosaurs are hypothesized to have had similar vascular arrangements and physiological abilities. To test this hypothesis, the cephalic vascular anatomy of extant diapsids (turtles, squamates, crocodilians, and birds) was investigated using CT‐scanning, vascular injection, and gross dissection with special attention given to blood vessels within known sites of thermal exchange (oral, nasal, and orbital regions). Vascular osteological evidence in skull bones of both extant and extinct specimens was collected to test hypotheses of vascular anatomy within the heads of dinosaurs. CT data were segmented in Avizo and vascular restorations were made using Maya. The large blood vessels that supply and drain diapsid heads displayed a conserved branching pattern, as the common carotid artery reliably bifurcates into internal and external carotid arteries. Further evidence for the subsequent branching patterns of these blood vessels adds support for a highly conserved diapsid vascular pattern. An important detail for identifying not only the blood vessels forming osteological correlates, but also identifying the blood vessels that passed between soft‐tissues, is the anastomotic connections that each blood vessel shared. For example, within the orbit, evidence for anastomoses between the supraorbital, ophthalmotemporal and branches of the cerebral carotid arteries was found in all three extant clades sampled. This evidence indicates the location of each participating artery and subsequently highlights the course of all three blood vessels back to their parent vessel. Within the narial region, near the maxilla‐premaxilla suture, evidence for anastomotic connections between the maxillary and nasal vessels was found. This anastomosis often included the palatal vessels, indicated by a canal that opened onto the palate. The connection between these vessels would have allowed blood to pass from the palate to the nasal region, or vice‐versa, serving as a potential collateral blood flow pathway to both of these regions. Additionally, some of the blood vessels to the nasal region are branches of the cerebral carotid arteries, which in large dinosaurs do not appear to be emphasized and seem inadequately sized to supply a large nasal region. This indicates that collateral blood flow was important for supplying emphasized sites of thermal exchange in large dinosaurs. When several dinosaur taxa were compared, different foramina sizes highlighted not only the potential diameter of blood vessels supplying sites of thermal exchange, but also which blood vessels supplied a majority of the blood to physiologically relevant regions of the head. Enabled by an understanding of the vascular anatomy of dinosaurs, we can begin to investigate the physiology of sites of thermal exchange and what important role they served in dinosaur thermoregulatory strategies.Support or Funding InformationUnited States National Science Foundation (IOB‐0517257, IOS‐1050154), Ohio University Heritage College of Osteopathic Medicine, Ohio University Student Enhancement Award, Jurassic Foundation Grant‐in‐aid of Research, Ohio Center for Ecological and Evolutionary Studies Research Fellowship, Ohio University Graduate Student Senate Grant–in‐aid of Research, Sigma Xi Grant‐in‐aid of Research, and the University of California Welles Fund.

Vascular patterns in the heads of crocodilians: blood vessels and sites of thermal exchange.

Extant crocodilians are a highly apomorphic archosaur clade that is ectothermic, yet often achieve large body sizes that can be subject to higher heat loads. Therefore, the anatomical and physiological roles that blood vessels play in crocodilian thermoregulation need further investigation to better understand how crocodilians establish and maintain cephalic temperatures and regulate neurosensory tissue temperatures during basking and normal activities. The cephalic vascular anatomy of extant crocodilians, particularly American alligator (Alligator mississippiensis) was investigated using a differential-contrast, dual-vascular injection technique and high resolution X-ray micro-computed tomography (μCT). Blood vessels were digitally isolated to create representations of vascular pathways. The specimens were then dissected to confirm CT results. Sites of thermal exchange, consisting of the oral, nasal, and orbital regions, were given special attention due to their role in evaporative cooling and cephalic thermoregulation in other diapsids. Blood vessels to and from sites of thermal exchange were studied to detect conserved vascular patterns and to assess their ability to deliver cooled blood to neurosensory tissues. Within the orbital region, both the arteries and veins demonstrated consistent branching patterns, with the supraorbital, infraorbital, and ophthalmotemporal vessels supplying and draining the orbit. The venous drainage of the orbital region showed connections to the dural sinuses via the orbital veins and cavernous sinus. The palatal region demonstrated a vast plexus that comprised both arteries and veins. The most direct route of venous drainage of the palatal plexus was through the palatomaxillary veins, essentially bypassing neurosensory tissues. Anastomotic connections with the nasal region, however, may provide an alternative route for palatal venous blood to reach neurosensory tissues. The nasal region in crocodilians is probably the most prominent site of thermal exchange, as it offers a substantial surface area and is completely surrounded by blood vessels. The venous drainage routes from the nasal region offer routes directly to the dural venous sinuses and the orbit, offering evidence of the potential to directly affect neurosensory tissue temperatures. The evolutionary history of crocodilians is complex, with large-bodied, terrestrial, and possibly endothermic taxa that may have had to deal with thermal loads that likely provided the anatomical building-blocks for such an extensive vascularization of sites of thermal exchange. A clear understanding of the physiological abilities and the role of blood vessels in the thermoregulation of crocodilians neurosensory tissues is not available but vascular anatomical patterns of crocodilian sites of thermal exchange indicate possible physiological abilities that may be more sophisticated than in other extant diapsids.

Variability and reliability of the vastus lateralis muscle anatomy

Purpose: The aims of this study are to investigate the variability of the morphological and neurovascular anatomy of the vastus lateralis (VL) muscle and to describe the relationships among its intramuscular partitions and with the other muscles of the quadriceps femoris. Clinical implications in its reliability as a flap donor are also discussed.Methods: In 2012, the extra- and intramuscular neurovascular anatomy of the VL was investigated in 10 cadaveric lower limbs. In three specimens, the segmental arterial pedicles were injected with latex of different colors to point out their anastomotic connections. The morphological anatomy was investigated with regard to the mutual relationship of the three muscular partitions and the relation of the VL with the other muscles of the quadriceps femoris.Results: The VL has a segmental morphological anatomy. However, the fibers of its three partitions interconnect individually and with the other bellies of the quadriceps femoris, particularly, in several variable portions with the vastus intermedius and mainly in the posterior part of the VL. The lateral circumflex femoral artery and its branches have variable origin, but demonstrate constant segmental distribution. Intramuscular dissection and colored latex injections show a rich anastomotic vascular network among the three partitions.Conclusions: Moderate variability exists in both the myological and the neurovascular anatomy of the VL. Despite this variability, the anatomy of the VL always has a constant segmental pattern, which makes the VL a reliable flap donor. Detailed knowledge of the VL anatomy could have useful applications in a broad clinical field.

Upper and middle third auricular reconstruction with a peninsular conchal flap

Background: Traumatic or iatrogenic full thickness auricular defects can be reconstructed in many ways. The defects exceeding 2 cm require challenging reconstruction techniques. The reconstruction options for those should include an- terior and posterior skin envelope repair with cartilaginous content. Providing color and texture match, while maintaining anatomic landmarks, should be considered. The outcomes of patients in which we used a peninsular conchal axial pattern flap (PCF) to reconstruct the composite defects of the auricle were outlined in this case series. Materials and Methods: Five patients with different etiologies were evaluated and operated with PCF between March 2012 and January 2015. The ages of the patients ranged from 21 to 91 years with a median age of 80. The mean follow-up period was 16.8 months. In PCF, the conchal subpart of the auricle was elevated as an axial pattern composite flap relied on the anastomotic connections between the superficial temporal artery and the posterior auricular artery. Donor sites were left to secondary healing. The statistical assessment was carried out with the Mann-Whitney U test. Results: The median age of the patients was 80 (21-91) years. The median percentage of flap survival was 100,00. The median operation duration was 92,00 minutes. Donor site epithelialization was 21 and 20 days in the first two patients, with a median of 20,5 days. In the latter three patients, a silver-containing dressing material was used prophylactically to suppress contamination by skin bacteria, which led to a decrease of the length of healing time to a median of 11,00 days, with a range of 3,00. Conclusion: PCF offers a one-stage procedure and can be used in the reconstruction of defects of the auricle exceeding 2 cm. The use of axial pattern peninsular conchal flap is recommended to all of our colleagues.

Life saving collaterals: Right-to-left and left-to-right

Coronary collaterals are anastomotic connections between portions of the coronary arteries. The coronary collateral circulation as an alternative source of blood suply has shown benefits such as limited infarct size, left ventricular remodelling and preserved left ventricular systolic functions.

Vascular Patterns in Iguanas and Other Squamates: Blood Vessels and Sites of Thermal Exchange.

Squamates use the circulatory system to regulate body and head temperatures during both heating and cooling. The flexibility of this system, which possibly exceeds that of endotherms, offers a number of physiological mechanisms to gain or retain heat (e.g., increase peripheral blood flow and heart rate, cooling the head to prolong basking time for the body) as well as to shed heat (modulate peripheral blood flow, expose sites of thermal exchange). Squamates also have the ability to establish and maintain the same head-to-body temperature differential that birds, crocodilians, and mammals demonstrate, but without a discrete rete or other vascular physiological device. Squamates offer important anatomical and phylogenetic evidence for the inference of the blood vessels of dinosaurs and other extinct archosaurs in that they shed light on the basal diapsid condition. Given this basal positioning, squamates likewise inform and constrain the range of physiological thermoregulatory mechanisms that may have been found in Dinosauria. Unfortunately, the literature on squamate vascular anatomy is limited. Cephalic vascular anatomy of green iguanas (Iguana iguana) was investigated using a differential-contrast, dual-vascular injection (DCDVI) technique and high-resolution X-ray microcomputed tomography (μCT). Blood vessels were digitally segmented to create a surface representation of vascular pathways. Known sites of thermal exchange, consisting of the oral, nasal, and orbital regions, were given special attention due to their role in brain and cephalic thermoregulation. Blood vessels to and from sites of thermal exchange were investigated to detect conserved vascular patterns and to assess their ability to deliver cooled blood to the dural venous sinuses. Arteries within sites of thermal exchange were found to deliver blood directly and through collateral pathways. The venous drainage was found to have multiple pathways that could influence neurosensory tissue temperature, as well as pathways that would bypass neurosensory tissues. The orbital region houses a large venous sinus that receives cooled blood from the nasal region. Blood vessels from the nasal region and orbital sinus show anastomotic connections to the dural sinus system, allowing for the direct modulation of brain temperatures. The generality of the vascular patterns discovered in iguanas were assessed by firsthand comparison with other squamates taxa (e.g., via dissection and osteological study) as well as the literature. Similar to extant archosaurs, iguanas and other squamates have highly vascularized sites of thermal exchange that likely support physiological thermoregulation that “fine tunes” temperatures attained through behavioral thermoregulation.

Dual Origin of Extradural Posterior Inferior Cerebellar Artery From Vertebral and Occipital Arteries: Anatomic Case Report.

Small anastomotic channels exist between the occipital artery (OA) and muscular branches of the vertebral artery; however, no direct connection has been reported between an extradural origin of the posterior inferior cerebellar artery (PICA) and the OA. To describe a rare anatomic connection between the extradural PICA and the OA. A far lateral exposure was completed on a cadaveric head prepared for surgical simulation. The course and branches of the OA were followed, and the relations to their immediate anatomic structures were studied. The origin of the PICA was found at the second segment of the vertebral artery, between the C1 and C2 transverse foramina. There was a large anastomotic connection between the superficial descending branch of the occipital artery and the PICA 12 mm proximal to the dural entrance of the artery. Awareness of the angioarchitecture of the suboccipital region and the existence of patent vertebrocarotid anastomotic connections is important to avoid complications during surgical or endovascular interventions. When present, a pre-existing OA-PICA anastomosis can be exploited to facilitate treatment in certain vascular pathologies (eg, vertebral artery aneurysms). Awareness of the existence of both an extradural origin of the PICA and a direct connection of this vessel with the OA is of great relevance to the muscular stage of surgical approaches to the posterior craniovertebral junction.

Optical Coherence Tomography Angiography Signs of Vascular Abnormalization With Antiangiogenic Therapy for Choroidal Neovascularization

To investigate the vascular appearance of choroidal neovascularization (CNV) treated with recurrent intravitreous anti-vascular endothelial growth factor (VEGF) injections, which have been proposed to cause transient vascular normalization along with decreased vascularity and leakage. Retrospective case series with perspective on the topic. Patients with treated CNV secondary to age-related macular degeneration from a community-based retinal referral practice were evaluated with optical coherence tomography angiography employing split-spectrum amplitude decorrelation. The choroidal neovascular morphology of the 17 eyes of 14 consecutive patients was described. The mean age of the patients, 8 men and 6 women, was 78.4 (standard deviation ± 9.3) years. The mean greatest linear dimension of the lesion was 3600 μm. The mean number of anti-VEGF injections was 47 (±21). The vascular diameter of the vessels in the CNV appeared large even in small lesions, with feeder vessels approaching the size of the major arcade vessels of the retina. The vessels had few branch points and many vascular anastomotic connections among larger vessels. There was a paucity of capillaries visualized within the lesions. The findings of this study do not support the hypothesis of vascular normalization in eyes receiving recurrent periodic antiangiogenic treatment. The observed "abnormalization" of the vessels may be explained by periodic pruning of angiogenic vascular sprouts by VEGF withdrawal in the face of unimpeded arteriogenesis. As the eye is a readily accessible VEGF laboratory, features expressed therein may also apply to neovascularization elsewhere in the body, such as in tumors.

Microsurgical anatomy of the arterial basket of the conus medullaris.

OBJECT The arterial basket of the conus medullaris (ABCM) consists of 1 or 2 arteries arising from the anterior spinal artery (ASA) and circumferentially connecting the ASA and the posterior spinal arteries (PSAs). The arterial basket can be involved in arteriovenous fistulas and arteriovenous malformations of the conus. In this article, the authors describe the microsurgical anatomy of the ABCM with emphasis on its morphometric parameters and important role in the intrinsic blood supply of the conus medullaris. METHODS The authors performed microsurgical dissections on 16 formalin-fixed human spinal cords harvested within 24 hours of death. The course, diameter, and branching angles of the arteries comprising the ABCM were then identified and measured. In addition, histological sections were obtained to identify perforating vessels arising from the ABCM. RESULTS The ASA tapers as it nears the conus medullaris (mean preconus diameter 0.7 ± 0.12 mm vs mean conus diameter 0.38 ± 0.08 mm). The ASA forms an anastomotic basket with the posterior spinal artery (PSA) via anastomotic branches. In most of the specimens (n= 13, 81.3%), bilateral arteries formed connections between the ASA and PSA. However, in the remaining specimens (n= 3, 18.7%), a unilateral right-sided anastomotic artery was identified. The mean diameter of the right ABCM branch was 0.49 ± 0.13 mm, and the mean diameter of the left branch was 0.53 ± 0.14 mm. The mean branching angles of the arteries forming the anastomotic basket were 95.9° ± 36.6° and 90° ± 34.3° for the right- and left-sided arteries, respectively. In cases of bilateral arterial anastomoses between the ASA and PSA, the mean distance between the origins of the arteries was 4.5 ± 3.3 mm. Histological analysis revealed numerous perforating vessels supplying tissue of the conus medullaris. CONCLUSIONS The ABCM is a critical anastomotic connection between the ASA and PSA, which play an important role in the intrinsic blood supply of the conus medullaris. The ABCM provides an important compensatory function in the blood supply of the spinal cord. Its involvement in conus medullaris vascular malformations makes it a critical anatomical structure.

A new hemodynamic model for the study of cerebral venous outflow.

We developed a mathematical model of the cerebral venous outflow for the simulation of the average blood flows and pressures in the main drainage vessels of the brain. The main features of the model are that it includes a validated model for the simulation of the intracranial circulation and it accounts for the dependence of the hydraulic properties of the jugular veins with respect to the gravity field, which makes it an useful tool for the study of the correlations between extracranial blood redistributions and changes in the intracranial environment. The model is able to simulate the average pressures and flows in different points of the jugular ducts, taking into account the amount of blood coming from the anastomotic connections; simulate how the blood redistribution due to change of posture affects flows and pressures in specific points of the system; and simulate redistributions due to stenotic patterns. Sensitivity analysis to check the robustness of the model was performed. The model reproduces average physiologic behavior of the jugular, vertebral, and cerebral ducts in terms of pressures and flows. In fact, jugular flow drops from ∼11.7 to ∼1.4 ml/s in the passage from supine to standing. At the same time, vertebral flow increases from 0.8 to 3.4 ml/s, while cerebral blood flow, venous sinuses pressure, and intracranial pressure are constant around the average value of 12.5 ml/s, 6 mmHg, and 10 mmHg, respectively. All these values are in agreement with literature data.

The collateral circulation in pediatric moyamoya disease.

The descriptions of collateral circulation in moyamoya have so far been a mixture of topography-based and vessels' source-based analyses. We aimed to investigate the anatomy and systematize the vascular anastomotic networks in pediatric moyamoya disease. From a series of 25 consecutive complete angiographic studies of newly diagnosed children with moyamoya, 14 children had moyamoya disease and 11 were diagnosed with moyamoya syndrome, i.e., moyamoya angiopathy with some additional concomitant systemic disease. We retrospectively analyzed the arterial branches supplying the moyamoya anastomotic networks, their origin, course, location, and connections with the recipient vessels. We describe four types of anastomotic networks in children with moyamoya disease, two superficial-meningeal and two deep-parenchymal. As superficial-meningeal, we defined the leptomeningeal and the durocortical networks. Apart from the previously described leptomeningeal network observed in the convexial watershed zones, we report on the basal temporo-orbitofrontal leptomeningeal network. The second superficial-meningeal network is the durocortical network, which can be basal or calvarian in location. We define as deep-parenchymal networks the nonpreviously described subependymal network and the inner striatal and inner thalamic networks. The subependymal network is fed by the intraventricular branches of the choroidal system and diencephalic perforators, which at the level of the periventricular subependymal zone, anastomose with medullary-cortical arteries as well as with striatal arteries. The inner striatal and thalamic networks are constituted by intrastriatal connections among striatal arteries and intrathalamic connections among thalamic arteries when the disease compromises the origin of one or more sources of their supply. The previously inexplicitly described "moyamoya abnormal network" in pediatric moyamoya disease can be described as a composition of four anastomotic networks with distinct angioarchitecture. A better understanding of the collateralization in moyamoya may help in defining a new staging system of the disease with clinical relevance.

Vascularization of the Facial Bones by the Facial Artery

The maxillary artery is recognized as the main vascular supply of the facial bones; nonetheless, clinical evidence supports a codominant role for the facial artery. This study explores the extent of the facial skeleton within a facial allograft that can be harvested based on the facial artery. Twenty-three cadaver heads were used in this study. In 12 heads, the facial, superficial temporal, and maxillary arteries were injected. In one head, facial artery angiography was performed. Ten facial allografts were raised. The soft tissues were dissected to show the arterial anastomotic connections. Radiographs and computed tomographic scans were obtained. Constant anastomosis between the facial, inferior alveolar, and infraorbital arteries at the mental and infraorbital foramina were found. The facial artery vascularized the homolateral mandibular symphysis, body, and ramus. The condylar and coronoid processes were vascularized in 67 percent of the allografts. The homolateral maxilla was contrasted in all allografts. The alveolar and palatine processes contained the contrast in 83 percent of specimens. The maxillary process of the zygomatic bone was perfused in all allografts, followed by the body, frontal (83 percent), and temporal processes (67 percent). The nasal lateral wall and septum were vascularized in 83 percent of the allografts. The medial and lateral orbital walls and the orbital floor were stained in all specimens. The zygomatic process of the temporal bone was the least perfused bone. A composite allograft containing 90 to 95 percent of the facial bones can be based on bilateral facial arteries.

Bilateral Cervical Spinal Dural Arteriovenous Fistulas with Intracranial Venous Drainage Mimicking a Foramen Magnum Dural Arteriovenous Fistula

We describe a unique case of bilateral cervical spinal dural arteriovenous fistulas mimicking an intracranial dural arteriovenous fistula near the foramen magnum. We review its detection via MRI and digital subtraction angiography and subsequent management through surgical intervention. Pitfalls in diagnostic angiography are discussed with reference to accurate location of the fistula site. The venous anastomotic connections of the posterior midline spinal vein to the medial posterior medullary vein, posterior fossa bridging veins, and dural venous sinuses of the skull base are discussed with reference to problem-solving in this complex case. The mechanism of myelopathy through venous hypertension produced by spinal dural fistulas is also emphasized.

Intrahepatic venous anastomoses with a focus on the middle hepatic vein anastomoses in normal human livers: anatomical study on liver corrosion casts

The aim of this study is to present the anatomical data about intrahepatic venous anastomoses found in normal human livers. The focus is on the middle hepatic vein (MHV) anastomoses, because their existence or non-existence could be of crucial importance in tumour resections as well as in split or living donor liver transplantations. The frequency of livers with intrahepatic venous anastomoses was determined on 164 corrosion casts and the diameter of each anastomosis was measured. Additionally, the type of connection and the position within the liver (liver segment) was determined for each MHV anastomosis. Intrahepatic venous anastomoses were found in 46 % (75/164), whereas MHV anastomoses were found in 28 % (44/164) of liver casts. Most commonly (39/44), MHV had anastomotic connections with the right hepatic vein (RHV), and also with the inferior RHV, the left hepatic vein and the short subhepatic vein. In more than three quarters of liver casts, MHV-RHV anastomoses were found in liver segment 8; in 45 % of cases, there was more than one anastomosis in this liver segment. The diameter of MHV-RHV anastomoses found in segment 8 was ≥1 mm in 90.6 % of cases. As MHV anastomoses were present in more than a quarter of all examined liver casts, we believe that detailed anatomical data presented in this article, together with up to date radiologic technics which enable even 3D reconstruction of venous anastomoses in the liver, could contribute to the clinician's decisions when planning surgical procedures.

Microscopic Clusters of Sensory Neurons in C1 Spinal Nerve Roots and in the C1 Level of the Spinal Accessory Nerve in Adult Humans

This study examined C1 spinal nerve roots and their anastomotic connections with the spinal accessory nerve for histological evidence of sensory neurons in adult humans. C1 spinal nerves and roots with the adjacent segments of the spinal accessory nerve and the spinal cord were dissected en bloc from cadaveric specimens, and prepared for histological study. Results show that in 39.3% of specimens studied, no sensory component to the C1 spinal nerve could be identified. The C1 dorsal root was present 35.7% of the time, and when present it always contained neuronal cell bodies. In the remaining specimens, the sensory contribution to the C1 spinal nerve came through an anastomotic connection with the spinal accessory nerve. The investigators were able to identify clusters of neuronal cell bodies along the spinal accessory nerve at the level of C1 in 100% of the specimens examined.