Embryology and anatomical variations of the ophthalmic artery.

PURPOSE: The ophthalmic artery (OA) has one of the most complex anatomy and the most fascinating embryological development. METHODS: The complexity of the embryologic development of the OA resides in the implication of three different embryological systems: the carotid system, the stapedial system, and the ventral pharyngeal system. RESULTS: This explains very well the numerous variations in origin of the OA and the importance of vascular anastomoses developed with branches of the external carotid artery and with the middle meningeal artery. CONCLUSION: In this review, authors propose a comprehensive description of different hypotheses on the embryologic development of the OA and, in a second part, explain all anatomical variations and clinical implications of this artery.

Bilateral persistent stapedial arteries associated with unilateral moyamoya disease: a particular anatomic variant.

PURPOSE: The persistence of the stapedial artery is a rare vascular variant that could explain the origin of the middle meningeal artery from the petrous segment of the internal carotid artery. The anatomic variations are illustrated and a summary of the possible hypothesis of the origin of the middle meningeal artery from the internal carotid artery is discussed, analysing the embryological works of the Carnegie Institute and the vascular development of the middle meningeal. METHODS AND RESULTS: The authors present a young patient showing a particular vascular variant on diagnostic imaging. These showed a bilateral internal carotid artery that gives origin of the middle meningeal artery in a patient affected by moyamoya disease. A literature review was performed to analyze the particular variant of the radiologic anatomy. CONCLUSION: The internal carotid artery origin of the middle meningeal artery is a wonderful anatomic variant that permits to understand the complex embryological development and then involution of the stapedial artery.

Fetal anatomy of the facial nerve trunk and its relationship with posterior auricular artery.

PURPOSE: The aims of the study are to define anatomy of the facial nerve (FN) and its main trunks as well as their relationship with the posterior auricular artery in fetal period to evaluate the data for regional surgery in newborns and young infants. METHODS: Formalin-fixed 34 fetuses from anatomy laboratory collection with a mean gestational age of 26.4 ± 4.6 (20-36) weeks were dissected. Parameters regarding the presence of major or minor trunks, width, length, branching pattern of FN were evaluated according to side, gender and trimester. The positional relationship of posterior auricular artery with the FN trunk was inspected. RESULTS: On all sides only the major trunk of the FN was detected. For length and width parameters, there was no statistically significant difference for side and gender except for trimester. Linear functions were found as 0.329 + 0.025 × weeks for width and 5.264 + 0.185 × weeks for length. There are statistically significant linear relationships between width and length of the FN trunk and week parameters as r = 0.507, p < 0.001 and r = 0.484, p < 0.001, respectively. Posterior auricular artery crossed FN trunk laterally in 42 of 53 sides, medially in 9 sides while it was puncturing it proximally in 2 sides. In all cases, it was in close contact to the FN trunk. FN trunk showed bifurcation in 82% and trifurcation in 18%. CONCLUSION: Dimensions of FN trunk, growth ratio and linear functions can be beneficial in understanding the fetal growth of FN trunk and its usage for grafts. Data about the relationship of the posterior auricular artery with FN trunk may be crucial in avoiding iatrogenic injuries during surgery in early ages.

Arterial supply to the thyroid gland and the relationship between the recurrent laryngeal nerve and the inferior thyroid artery in human fetal cadavers.

The aim of this study was to identify the arterial supply to the thyroid gland and the relationship between the inferior thyroid artery (ITA) and the recurrent laryngeal nerve (RLN) in fetal cadavers using anatomical dissection. The anterior necks of 200 fetuses were dissected. The origins of the superior thyroid artery (STA) and the ITA and location of the ITA in relation to the entrance of the thyroid lobe were examined. The relationship between the ITA and the RLN was determined. The origins of the STA were classified as: external carotid artery, common carotid artery (CCA), and the thyrolingual trunk. The origins of the ITA were the thyrocervical trunk and the CCA. The ITA was absent on the left side in two cases. The relationship of the RLN to the ITA fell into seven different types. Type 1: the RLN lay posterior to the artery; right (42.5%), left (65%). Type 2: the RLN lay anterior to the artery; right (40.5%), left (22.5%). Type 3: the RLN lay parallel to the artery; right (11.5%), left (7%). Type 4: the RLN lay between the two branches of the artery; right (1%), left (3.5%). Type 5: The extralaryngeal branch of the RLN was detected before it crossed the ITA; right (4.5%), left (0%). Type 6: the ITA lay between the two branches of the RLN; right (0%), left (0.5%). Type 7: the branches of the RLN lay among the branches of the ITA; right (0%), left (0.5%). The results from this study would be useful in future thyroid surgeries.

A symptomatic atherosclerotic persistent pharyngo-hyo-stapedial artery: Treatment management and embryological considerations.

The stapedial artery (SA) is an embryonic vessel connecting the internal carotid artery (ICA) to the branches of the future external carotid artery (ECA). It passes through the primordium of the stapes that progressively develops around the SA. Normally, SA disappears during the tenth week in utero. Approximately 0.4% of the population can have a persistent SA. It can persist as four types of embryological variations, of which the pharyngo-hyo-stapedial variant has been rarely described before. We reported a case of a 61-year-old woman presented with transient ischemic attacks (TIAs). Computed tomography angiography showed an unusual "duplicated" aspect of the left ICA. Digital subtraction angiography depicted a persistent pharyngo-hyo-stapedial artery with an atherosclerotic wall and was considered the cause of the TIAs. After failure of the antiplatelet therapy in preventing recurrent TIAs, stenting of the artery was planned and successfully performed. Patient was asymptomatic during 12-month follow-up. The pharyngo-hyo-stapedial artery is a very rare variation in which the SA is supplied by the inferior tympanic (rising from the ascending pharyngeal artery) and the hyoid artery (rising from the ICA). To our knowledge, this is a unique case of a pharyngo-hyo-stapedial artery in a patient presenting associated ischemic symptoms. Radiological and embryological findings are discussed.

Congenital Aplasia of the Common Carotid Artery: A Comprehensive Review.

In an attempt to describe the morphofunctional consequences of uni- and bilateral aplasia of the common carotid artery (CCA), which is usually a vascular source of the external carotid (ECA) and internal carotid (ICA) arteries, we investigated online databases of anatomical and clinical papers published from the 18th century to the present day. We found 87 recorded cases of uni- and bilateral CCA aplasia in subjects from the first hours to the eighth decade of life, which had been discovered in 14 (known) countries. Four crucial parameters were described: the embryology of the carotid arteries, morphophysiology of the carotid arteries, CCA aplasia, and unilateral versus bilateral CCA aplasia, including history, general data, diagnosing, vascular sources, caliber, course of the separated ECA and ICA, associated vascular variants, and pathological disorders. To complete the knowledge of the morphofunctional consequences of the absence of some artery of the carotid system, and risking the possibility of repeating some words, as "carotid artery", or "carotid aplasia" and the headings from our previous article about bilateral ICA absence, this review is the first in the literature that recorded all cases of the CCA aplasia published and/or cited for the past 233 years. Main characteristic of the CCA absence is its association with 21 different diseases, among which the aneurysms were in 13.69% of cases, and 17.80% of cases were without pathology.

Nonbifurcating Carotid Artery: A Case Report with a Review of Embryogenesis.

BACKGROUND Vascular anomalies of the carotid vessels can be attributed to false embryogenesis. A rare variant called a nonbifurcating carotid artery (NBCA) exists, where typical carotid bifurcation is not recognizable with its typical branches of the external carotid artery (ECA) and internal carotid artery (ICA). This paper describes a case of this anomaly and reviews the embryogenesis of the carotid arteries for explanation. CASE REPORT A 66-year-old man received a routine health examination at our hospital. Initial carotid ultrasound indicated an absence of bifurcation in the right cervical carotid artery, and magnetic resonance imaging of the brain indicated an absence of the proximal cervical segment of the right ICA, with a remnant arterial stump at the expected bifurcation level. No evidence of the carotid bulb was identified. The common carotid artery seemed to continue cranially in the trunk of the ECA, where it exhibited extracranial branches. After distributing these branches, the carotid artery coursed medially at the C2 level, where it ascended into the carotid canal to become the petrosal segment of the ICA. This carotid anomaly was labelled an NBCA. No aberrant intracranial arteries were derived from the NBCA in this case. CONCLUSIONS In this case, the arterial stump was considered a remnant from agenesis of the right ICA. We assumed that the NBCA most likely developed because of false regression of the third embryogenic aortic arch with persistence of the second aortic arch.

Proatlantal intersegmental arteries of external carotid artery origin associated with Galen's vein malformation.

Carotid basilar anastomoses can occasionally persist beyond the embryonic period. These anomalies are most often incidentally detected in adulthood, during workups for unrelated pathologies. Persistence of the proatlantal intersegmental arteries is a rare form of primitive carotid-basilar anastomoses. Bilateral proatlantal inter- segmental arteries are an extremely rare occurrence, of which only 3 cases have been reported in the literature. An analysis of vascular anomalies associated with Galen's vein malformations revealed 3 children in whom persistence of type II proatlantal arteries was seen. These included one child in whom proatlantal arteries were persistent bilaterally. We report the clinical and angiographic findings and discuss the embryologic and therapeutic implications of this unique association.

Investigation of the bifurcation level of the common carotid artery and variations of the branches of the external carotid artery in human fetuses.

Variations in the position of the bifurcation of the common carotid artery (CCA) and the origin or branching pattern of the external carotid artery (ECA) are well known and documented. In this study, the bifurcation levels of the CCA and origin variations of the branches of the ECA have been extensively investigated in human fetuses. Bilaterally, 40 carotid bifurcations and 40 ECA and their branches have been examined. A latex solution, which had been diluted with water at a ratio of 25% and colored with red India ink, was injected into the aortic arch. Fetuses were kept at room temperature for 24 h before the ECA and its branches were dissected under the microsurgery microscope. Cases of variation were determined and photographed. The bifurcation level of the CCA was determined to be 55% at the C3 level, 35% at the C4 level, 10% at the C5 level on the right side and 60% at the C3 level, 40% at the C4 level on left side. The distribution of the ECA trunks was determined as follows: A linguofacial trunk was present in 20% of the cases, a thyrolingual trunk in 2.5%, a thyrolinguofacial trunk in 2.5% and an occipitoauricular trunk in 12.5%. Beyond this the ascending pharyngeal artery (APA) was observed in one fetus to originate from the internal carotid artery (ICA). Knowledge of variations in the origin and course of the ECA and its branches is of great importance in surgery and radiological examinations.

Relationships between the parotid gland and the facial nerve during human development.

A correlation was sought between the organization of the parotid gland and the formation of the large vessels and nerves that passed through the glands of 12 human embryos and 12 human fetuses. There was no evidence that the gland became a bilobate structure as a result of the course of the facial nerve, whose interglandular branches were surrounded during development by the multidirectional ramifications of the expanding parotid anlage.

Persistent stapedial artery: does it prevent successful surgery?

Because of the important function of the embryologic stapedial artery, it is taken for granted by many surgeons that the finding of such a persistent artery in postnatal humans during middle ear surgery should urge maximal caution in order not to damage the artery. Often, discontinuation of the surgery is recommended. Yet this attitude is based on theoretic considerations rather than on any clinical evidence of complications following injury to this vessel. The present paper describes the embryology in relation to this specific aspect and reviews the literature on the persistent stapedial artery, emphasizing the papers dealing with injury to this vessel. In addition, we report 4 cases of persistent stapedial artery from the files of almost 20,000 patients in whom tympanotomy was performed. From all these data we conclude that injury to this artery or even complete section probably does not cause major, if any, postoperative sequelae, and that consequently, middle ear surgery is not necessarily hindered by the presence of this vessel.

The cervical sympathetic trunk--a new hypothesis.

There is a sympathetic ganglion, in relation to most if not all thoracic and lumbar segments whereas there are only 3 or 4 sympathetic ganglia in the cervical region. Thus it may be inferred that sympathetic ganglia are not directly related to spinal nerves. Therefore, the hypothesis is put forward that sympathetic ganglia are associated chiefly with intersegmental vessels such as the intercostal and lumbar arteries and that the differences seen in the neck region are due to the disappearance of most of the cervical intersegmental arteries and the subsequent modifications that follow during development. This results in the fusion of the upper 4 cervical ganglia to form the superior cervical sympathetic ganglion in relation to the developing external carotid artery which seems to provide the necessary inductive stimulus. Furthermore, the antero-inferior migration of the heart, its corresponding arch arteries and the dorsal aorta bring about the formation of the ansa subclavia around the subclavian artery and the positioning of the stellate ganglion behind the vertebral artery.

[A case report of hypoplasia of the root portion and the intermediate portion of the left internal carotid artery associated with an unusual primitive collateral circulation between the left internal carotid artery and the left external carotid artery].

The internal carotid artery is one of the most stable arteries and its absence is very rare. We reported a case of hypoplasia of the root portion and the intermediate portion of the left internal carotid artery associated with an usual primitive collateral circulation between the left internal carotid artery and the left external carotid artery. A 57-year-old male developed right hemiparesis of sudden onset 3 days prior to admission. On admission, right hemiparesis and right minimal facial palsy was observed. The left direct carotid angiogram revealed that the root portion and the intermediate portion of the left internal carotid artery were hypoplastic. There was an unusual primitive collateral circulation between the left internal carotid artery and the left external carotid artery. From an embryological point of view, normally, the internal carotid artery is derived from the third aortic arch and the dorsal aorta when the embryo is attained the 3-mm stage. The root portion of the internal carotid artery is formed from the third aortic arch. The dorsal aorta between the third and the first aortic arch form the intermediate portion. The distal part of the internal carotid artery originates from the dorsal end of the first aortic arch. The common carotid artery begins to form in the 12-mm to 14-mm embryo, following involution of portion of the ventral aortic root between the third and the fourth aortic arch. The external carotid artery arises from the aortic sac and migrate up to the third aortic arch.(ABSTRACT TRUNCATED AT 250 WORDS)

[Hypoplasia of internal carotid artery associated with carotid paraganglioma. A case report and review of the literature]. / Hipoplasia de arteria carótida interna asociado con paraganglioma carotideo. Reporte de un caso y revisión de la bibliografía.

BACKGROUND: Hypoplasia of the internal carotid artery is a rare congenital malformation. It has been mainly associated with aneurysms and other pathologies but not in association with paraganglioma. The incidence is 0.01% of all the anomalies of carotid vessels. Although the exact cause is unknown, it is thought to represent a sequel to an insult due to mechanical causes or hemodynamic stress but perhaps also involves aspects of molecular biology of embryonic development. CLINICAL CASE: We describe the case of a 37 year-old female patient with paraganglioma associated with hypoplasia of the internal carotid artery, which was found incidentally during surgery. Previous angiographic studies as well as other analyses were carried out, but we failed to detect hypoplasia of the internal carotid artery. Tumor was removed along with ligation of the external carotid artery due to injury. The hypoplastic internal carotid artery was left intact. CONCLUSION: Angiographic studies of the base of the skull are important as well as hemodynamic analysis in order to not overlook these anomalies. The patient had a satisfactory evolution without sequelae.

Antecedentes: la hipoplasia de la arteria carótida interna es una rara malformación congénita. Se le ha relacionado principalmente con aneurismas y otros padecimientos, pero no con paraganglioma. Su incidencia es menor de 0.01% de todas las anomalías de los vasos carotídeos. Aunque su origen exacto no se conoce, se cree que es una secuela de una lesión provocada por causas mecánicas o por estrés hemodinámico; sin embargo, también pudieran estar implicados aspectos de biología molecular del desarrollo embrionario. Caso clínico: se describe un caso raro de una mujer de 37 años de edad con paraganglioma concomitante con hipoplasia de la arteria carótida interna. En estudios angiográficos y análisis rutinarios previos no se había detectado alteración de la arteria carótida interna. En la intervención se extirpó el tumor y se ligó la arteria carótida externa dado que estaba involucrada en la lesión; se dejó intacta la arteria carótida interna hipoplásica. Conclusión: es importante realizar estudios angiográficos de la base del cráneo, así como análisis hemodinámicos para no pasar por alto estas anomalías. La evolución fue satisfactoria y sin secuelas.

A rare embryologic variation: carotid-anterior cerebral artery anastomosis or infraoptic course of the anterior cerebral artery.

Carotid-anterior cerebral artery anastomosis constitutes an anomaly of the anterior part of the arterial circle of the brain. The anterior cerebral a. arises a few millimeters above the emergence of the internal carotid from the cavernous sinus, at the usual level of origin of the ophthalmic a. It travels medially, beneath the optic n., and then describes a curve with a superolateral concavity to arrive at the anterior part of the optic chiasma, where it anastomoses with the anterior communicating a. This asymptomatic variant of course is often associated with other cerebral vascular anomalies, especially arterial aneurysms. On the basis of 2 new cases discovered by chance, together with a review of the literature, various hypotheses capable of explaining the embryologic origin of these anomalies are discussed.

The occipital artery. Anatomy--normal arteriographic aspects--embryological significance.

An anatomical and radioanatomical study of the intracranial branches of the occipital artery is presented and attempt to systematize the muscular branches of the occipital trunk and its vertebral anastomosis. An embryological hypothesis is presented to explain and memorize all the artrial variations of this area.