Surgical and embryological perspective of a big loop of internal carotid artery extending laterally beyond internal jugular vein.

Knowledge of variations of the internal carotid artery is significant to surgeons and radiologists. The internal carotid artery normally runs a straight course in the neck. Its anomalies can lead to its iatrogenic injuries. We report a case of a large loop of the internal carotid artery in a male cadaver aged about 75 years. The common carotid artery terminated by dividing it into the external carotid artery and internal carotid arteries at the level of the upper border of the thyroid cartilage. From the level of origin, the internal carotid artery coursed upwards, backwards and laterally, and formed a large loop behind the internal jugular vein. The variation was found on the left side of the neck and was unilateral. The uncommon looping of the internal carotid artery might result in altered blood flow to the brain and may lead to misperceptions in surgical, imaging, and invasive procedures.

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.

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.

Cavernous sinus and abducens nerve in human fetuses near term.

A long tortuous course of the abducens nerve (ABN) crossing a highly curved siphon of the internal carotid artery is of interest to neurosurgeons for cavernous sinus surgery. Although a "straight" intracavernous carotid artery in fetuses can change into an adult-like siphon in infants, there is no information on when or how the unique course of ABN is established. Histological observations of 18 near-term fetuses (12 specimens of frontal sections and 6 specimens of sagittal sections) demonstrated the following: (I) the ABN consistently took a straight course crossing the lateral side of an almost straight intracavernous carotid artery; (II) the straight course was maintained when sympathetic nerves joined; (III) few parasellar veins of the developing cavernous sinus separated the ABN from the ophthalmic nerve; and (IV) immediately before the developing tendinous annulus for a common origin of extraocular recti, the ABN bent laterally to avoid a passage of the thick oculomotor nerve. Since the present observations strongly suggested morphologies at birth and in infants, major angulations of the ABN as well as the well-known course independent of the other nerves in the cavernous sinus seemed to be established during childhood. In the human body, the ABN might be a limited example showing a drastic postnatal change in course. Consequently, it might be important to know the unique course of ABN before performing endovascular interventions and skull base surgery for petroclival and cavernous sinus lesions without causing inadvertent neurovascular injuries to neonates or infants.

Prevalence and Clinical Implications of the Primitive Trigeminal Artery and its Variants: A Meta-Analysis.

BACKGROUND: The primitive trigeminal artery (PTA) is the most common and the largest persistent carotid-basilar anastomosis. Primitive trigeminal artery variants (PTAVs) are anastomoses between the internal carotid artery and cerebellar arteries. These vessels pose a risk of hemorrhagic or ischemic complications during neurosurgical procedures in the parasellar and intrasellar regions. The aim of this study was to determine the prevalence of both PTA and PTAVs and their clinically important anatomic features. METHODS: Major electronic databases were thoroughly searched for studies on PTA and PTAV. References in the included articles were also evaluated. Data regarding prevalence, laterality, origin, course patterns, and associated anomalies were extracted and pooled into a meta-analysis. RESULTS: A total of 39 studies (110,866 patients) were included in the meta-analysis. The total pooled prevalence estimate of PTA and PTAVs combined was 0.4% (95% confidence interval [CI], 0.3-0.5). Individually, PTA was present in 0.3% of patients and PTAV in 0.2%. Both arteries most often originated from the C4 internal carotid artery and took a course lateral to the dorsum sellae. The anterior inferior cerebellar artery type was the predominant PTAV (72.1%). Basilar artery hypoplasia was found in 42.5% of patients with a PTA. CONCLUSIONS: PTA and PTAVs are rare vessels, but they are clinically important because they can contribute to trigeminal neuralgia. Knowledge of the potential course of these arteries is essential in neuroradiology and neurosurgery, especially in minimally invasive procedures such as the endoscopic endonasal transsphenoidal approach to the pituitary gland and the percutaneous gasserian ganglion procedure.

The ophthalmic artery: a new variant involving two branches from the supracavernous internal carotid artery.

PURPOSE: We report an extremely rare, double ophthalmic artery configuration. METHODS: We present 2D- and 3D-angiographic features of an anomalous origin of the ophthalmic artery. RESULTS: The double ophthalmic artery was the result of the persistence of the primitive dorsal ophthalmic artery combined with the presence of a second orbital artery originating from the supracavernous internal carotid artery, passing through the superior orbital fissure and into the orbit to furnish the muscular, lacrimal and ethmoidal arteries and the medial long posterior ciliary artery. CONCLUSIONS: A heretofore undocumented instance of ophthalmic artery duplication is presented. Knowledge of such variations is important for the planning of endovascular treatments and the comprehension of unusual angiographic images. Such fine arterial variants may very well be frequent, but difficult to demonstrate on simple 2D angiographies. Multiplanar reconstructions of 3D angiography data make it possible to diagnose rare, but embryologically predictable arterial variants.

Dolichoectasia of the internal carotid artery terminus, posterior communicating artery, and posterior cerebral artery: The embryonic caudal ramus internal carotid segmental vulnerability legacy.

Dolichoectasia of the distal internal carotid artery, posterior communication artery (PCoA) and posterior cerebral artery is an extremely rare abnormality. Dolichoectasia of the internal carotid artery, PCoA and the P1 segment of posterior cerebral artery can be postulated its pathogenesis by the embryological perspective basis from caudal ramus of the internal carotid artery terminus. The pathogenesis and treatment strategy are not well established. We reviewed and proposed embryological perspective, pathogenesis, clinical setting, radiological findings and management of this rare malformation.

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.

Congenital absence of the bilateral internal carotid artery: a review of the associated (ab)normalities from a newborn status to the eighth decade of life.

PURPOSE: Due to the fact that the internal carotid artery (ICA) is responsible for nourishing two thirds of the brain volume, our aim was to inspect the morphofunctional consequences of the bilateral lack of this artery. METHODS: In order to examine this condition, we referred to both the library archive of our Faculty of Medicine and electronic databases of anatomical and clinical reports that included the following keywords: "absence," "aplasia," or "agenesis" in combination with "internal carotid artery," "common carotid artery," or only "carotid artery." RESULT: We found 60 recorded cases of the bilateral ICA absence in the subjects of newborn status to the eighth decade of life, which had been discovered in 20 countries. The following ten parameters were described: the embryological base, terminology, history, incidence, general data, differential diagnosis, collateral circulation, the associated vascular aplasia and/or other variants, pathophysiology, and the importance in praxis. CONCLUSION: This review noted all the cases of the bilateral ICA aplasia published for the past 104 years. Although there were 11.6% of cases of the associated cerebral aneurysms and 1-4 cases of 16 other diseases, approximately one quarter of the cases was without any pathology.

Bilateral Internal Carotid Artery Segmental Agenesis: Embryology, Common Collateral Pathways, Clinical Presentation, and Clinical Importance of a Rare Condition.

BACKGROUND: Bilateral segmental agenesis of the internal carotid artery is a rare congenital anomaly. We present a case of bilateral internal carotid artery segmental agenesis in an asymptomatic 18-year-old man. Embryology, common collateral pathways, clinical presentation, and clinical importance of this condition are discussed. According to our review of the literature, this report is the first to describe bilateral internal carotid artery segmental agenesis in a patient studied with magnetic resonance imaging, computed tomography, Doppler ultrasonography, and digital subtraction angiography. CASE DESCRIPTION: An 18-year-old man presented to our hospital complaining of occasional mild headaches. Neurologic examination was unremarkable. Imaging findings consisted of bilateral segmental agenesis of the internal carotid arteries. CONCLUSION: Bilateral segmental agenesis of internal carotid artery may be completely asymptomatic and harmless, but associated conditions, such as cerebral aneurysms or abnormal collateral circulation, should alert clinicians to the possibilities of subarachnoid hemorrhage or cerebral ischemia.

[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.

Doppler ultrasonographic assessment of maternal and fetal arteries during normal feline gestation.

The aim of this study was to describe Doppler parameters of uterine, umbilical, fetal abdominal aorta, fetal renal and fetal internal carotid arteries, as well as fetal heart rate (FHR), during normal feline gestation. Fifteen, 1-4 years of age, weighing 2.5-3.9kg, domestic short-hair pregnant queens, which were born in our institutional cat colony were included in this study. Color and pulsed-wave Doppler evaluations of uterine arteries were performed every 10 days (Day 0, 10, 20, 30, 40, 50, 60) from mating. Fetal Doppler and M-mode ultrasonography were performed to assess umbilical, fetal abdominal aorta, fetal renal, fetal internal carotid arteries and FHR. Both peak systolic velocity (PSV) and end diastolic velocity (EDV) of uterine artery increased up to parturition (P<0.01), while resistance index (RI) decreased from Day 10 onwards (P<0.01). From Day 40 onwards, RI of umbilical artery diminished, while PSV and EDV augmented (P<0.01). Fetal abdominal aorta (P<0.01), renal (P<0.01) and internal carotid (P<0.01) arteries diminished their RI from Days 40, 60 and 40 onwards, respectively. Both PSV and EDV of these three arteries increased progressively. Fetal heart rate was first registered on Day 20 when it began to increase up to Day 40 and then diminished to the end of gestation (P<0.01). It is concluded that blood flow of uterine, umbilical, fetal abdominal aorta, fetal renal and fetal internal carotid arteries progressively increased during normal feline pregnancy, while FHR rose to mid gestation and then decreased up to parturition.

Childhood cognitive development after fetal growth restriction.

OBJECTIVE: To examine the relationship between prenatal umbilical artery (UA) and internal carotid artery (ICA) Doppler findings and cognitive development at 3 and 6 years in low-birth-weight children. METHODS: This was a study of 209 low-birth-weight (< 10(th) centile) children born after 28 gestational weeks with UA resistance index (RI) measured within 2 weeks before delivery. Children with normal UA- and ICA-RI were defined as small-for-gestational age (SGA) and those with abnormal UA or ICA Doppler findings as having fetal growth restriction (FGR). Cognitive ability at 3 and 6 years' corrected age was assessed using the fourth edition of the Stanford-Binet Intelligence Scale (SBIS) and compared between SGA and FGR groups. An SBIS score < 85 was considered to indicate delayed development. RESULTS: The median gestational age at diagnosis of abnormal fetal growth was 36.6 (range, 28-41) weeks. There were 87 (41.6%) children classified as having FGR and 122 (58.4%) as SGA. The mean global SBIS score at 3 years was 109.4 (SD, 22.8) and at 6 years it was 110.5 (SD, 13.9). Overall, 22 (10.5%) children had delayed development at 3 years. Total SBIS scores and individual domain scores did not differ between FGR and SGA groups at 3 or 6 years and similar proportions in each group had delayed development. CONCLUSION: Abnormal prenatal UA and ICA Doppler findings are not associated with lower developmental scores in low-birth-weight children delivered in the third trimester of pregnancy.

Association of cervical internal carotid artery aneurysm with ipsilateral vertebrobasilar aneurysm in two children: a segmental entity?

INTRODUCTION: A combination of cervical and intradural aneurysm in children in the absence of systemic disorders has previously not been reported. CASE REPORT: We report two boys with an identical combination of fusiform cervical internal carotid aneurysm and ipsilaterally located vertebrobasilar aneurysm. They had no history of trauma, they did not display any personal or familial signs of systemic disease, and the testing for collagen disease was negative. The location and appearance of the aneurysms and the identical anatomical disposition in the patients indicated a non-randomly distributed segmental vulnerability. CONCLUSION: The cases demonstrate primary morphological signs of a developmental error being expressed in two seemingly separate segments but linked by the hypoglossal artery. It suggests a segmental error related to this embryonic vessel. They also show that few phenotypes are specific for a genotypic disorder and highlight the importance of analysing different etiologies for aneurysm formation and anatomical disposition when taking treatment strategy decisions.

Embryology of the internal carotid artery dural crossing: apropos of a continuous series of 48 specimens.

The aim of this study was to describe the embryologic and foetal development of the anterior paraclinoid region and more precisely the relationship of the internal carotid artery to the dura mater. This has been done by examining a collection of histological sections, representing a continuous series of 48 embryologic and foetal specimens, covering the period of the first 6 months of intra-uterine life. Neurological and vascular elements develop during the embryologic period; the internal carotid artery is recognizable in the various sections of its course and acquires a histological adult parietal constitution. The foetal period corresponds to the development of the meningeal structures. The superior, medial and lateral walls appear on the fifteenth week of amenorrhoea and do not change after that. The internal carotid artery enters subarachnoid space accompanied by a sleeve of mesenchymatous cells, which fixes it to the anterior clinoid process. The constitution of this sleeve, arising from the superior wall of the lateral sellar compartment, remained independent of the principle vascular part, which allows the formation of a plan of cleavage. The foetal relations of the dura mater and the internal carotid artery were seen to be different from those of adult subjects described in the literature, suggesting an existence of period of maturation postnatally.

Segmental agenesis of the internal carotid artery distal to the posterior communicating artery leading to the definition of a new embryologic segment.

We report a case of segmental agenesis of the right internal carotid artery (ICA) in a 53-year-old woman, associated with a saccular aneurysm of the left anterior cerebral artery (A1 segment) presenting with a right hemispheric transient ischemic attack. The agenetic segment was located distal to the origin of the posterior communicating artery (PComA), as documented both angiographically and by direct surgical inspection. This observation suggests the existence of a previously unrecognized embryologic segment of the ICA, located between the PComA origin and the terminal bifurcation of the ICA into the anterior and middle cerebral arteries.

Surgical approach to kinking and coiling of the internal carotid artery.

AIM: Whether kinking or coiling of the internal carotid artery (ICA) simply represents a morphological variation without clinical relevance still remains an object of debate. While most patients are incidentally diagnosed in an asymptomatic state due to the broad use of non-invasive investigations (like colour coded Doppler sonography), associated neurological deficits are often unspecific and might be related to coexisting proximal stenotic lesions. Its etiology is unclear. Beside artherosclerotic genesis, a persistent embryological condition or underlying fibromuscular dysplasia is discussed. Moreover, in contrast to precise recommendations concerning the indication for endarteriectomy in carotid artery stenosis, general guidelines for surgical intervention in case of kinking or coiling are not yet established. METHODS: The characteristics of 16 patients who underwent a total of 21 reconstructive operations for isolated kinking or coiling of the ICA during 5 years of observation were retrospectively analyzed. RESULTS: In 10 out of 14 kinkings and 5 out of 7 coilings central nervous symptoms were noted including unspecific vertigo, syncope, tinnitus synchronous to pulse, transient ischemic attacks and manifest cerebral infarction. All these individual complaints disappeared postoperatively. In 1 patient presenting with an ICA coiling histological examination revealed signs of fibromuscular dysplasia. The other specimens showed typical changes of artherosclerotic disease. CONCLUSION: By precluding significant proximal stenosis and effective elimination of symptoms after surgical correction, a causal connection between cerebral dysfunction and severe ICA kinking or coiling can be supposed. An actual abnormality of the arterial wall structure only exists in exceptional cases. Rather, a sequential development from kinking to coiling was noticed.