Carotid and vertebrobasilar rete mirabile: a case report

Composition of encephalic arteries and origin of the basilar artery are different between vertebrates

Intracranial arterial anatomy is lacking for most mammalian and non-mammalian model species, especially concerning the origin of the basilar artery (BA). Enhancing the knowledge of this anatomy can improve animal models and help understanding anatomical variations in humans. We have studied encephalic arteries in three different species of birds and eight different species of mammals using formalin-fixed brains injected with arterial red latex. Our results and literature analysis indicate that, for all vertebrates, the internal carotid artery (ICA) supplies the brain and divides into two branches: a cranial and a caudal branch. The difference between vertebrates lies in the caudal branch of the ICA. For non-mammalian, the caudal branch is the origin of the BA, and the vertebral artery (VA) is not involved in brain supply. For mammals, the VA supplies encephalic arteries in two different ways. In the first type of organization, mostly found in ungulates, the carotid rete mirabile supplies the encephalic arteries, the caudal branch is the origin of the BA, and the VA is indirectly involved in carotid rete mirabile blood supply. The second type of encephalic artery organization for mammals is the same as in humans. The caudal branch of the ICA serves as the posterior communicating artery, and the BA originates from both VAs. We believe that knowledge of comparative anatomy of encephalic arteries contributes to a better understanding of animal models applicable to surgical or radiological techniques. It improves the understanding of rare encephalic variations that may be present in humans.

Revised concept of rete-like collateral formation: Rete mirabile does not exist in humans

The carotid rete is a physiological network between the external and internal carotid arteries (ICA) in lower vertebrates. However, true carotid rete does not exist in humans. This review aimed to contrast the physiological function of human "rete-like collaterals" with that of lower vertebrate "rete mirabile". An explanation for the development of rete-like collaterals in human intracranial arteries was also discussed. The rete mirabile (carotid, vertebral, spinal, and thoracic) in lower vertebrates has a specific physiological role and does not form vasculature for the same purpose in humans. Therefore, the term "rete mirabile" should not be used for cases reported in humans. Instead, "rete-like collaterals" is preferred. In the literature, rete-like or arterial anastomosis was observed in the ICA cavernous portion and the intradural arteries. Based on the hypothesis of the segmental concept, it applies to the ICA and intracranial arteries. Whether in the ICA, middle cerebral artery, posterior cerebral artery, or posterior inferior cerebellar artery, the segmental concept is the same and should be considered to have formed secondary collaterals after segmental regress or dysgenesis of affected arteries. Summarily, the significance of this review lies in its reevaluation of vascular structures previously described as "carotid rete" in humans to a true and preferred term, "rete-like collaterals". It also provides insights into the historical context and potential genetic factors associated with the formation of arteries in humans, contributing to a better understanding of human vascular anatomy.

Bilateral Internal Carotid Artery Agenesis and Posterior Circulation Stroke: A Rare Association

Bilateral ICA agenesis is a rare developmental anomaly of the anterior circulation. It can be accompanied by various posterior circulation abnormalities including aneurysms, dolichoectatic vessels. We report the clinical presentation, imaging findings and management of a unique case of a 25 year old man having bilateral internal carotid agenesis with cerebellar ischemic lesions secondary to thrombus formation in dolichoectatic basilar artery.

Unilateral cervical and petrosal segment agenesis of the internal carotid artery with rete mirabile

The carotid rete mirabile (RM) is a physiological network between the internal and external carotid arterial systems. In this paper, an extremely rare case is presented, in which internal-external carotid artery anastomoses and a dilated ascending pharyngeal artery, due to unilateral agenesis of the cervical and petrous segments of the internal carotid artery (ICA), is presented.

Rete mirabile associated with pial arteriovenous fistula: imaging features with literature review

A rete mirabile is a vascular network of intercommunicating small arteries or arterioles that replace the definitive adult artery supplying the brain. It supplies the brain in lower mammals but is not seen in normal human embryological development. A 26-year-old man presented with worsening tinnitus that was interfering with his sleep. On CT and digital subtraction angiography he was found to have a temporal lobe pial arteriovenous fistula with bilateral carotid and vertebral rete mirabile. The patient was offered open surgical and endovascular treatment options for pial arteriovenous fistula but he refused both and opted for conservative medical management. At 6-month follow-up he continued to have pulsatile tinnitus but was otherwise neurologically normal. We present the first described association of rete mirabile with pial arteriovenous fistula and discuss its clinical presentation and imaging features, with a review of the literature for bilateral carotid and vertebral rete mirabile.

Stenting for symptomatic vertebral artery stenosis associated with bilateral carotid rete mirabile: the long-term clinical and angiographic outcome

Symptomatic vertebral artery (VA) stenosis associated with bilateral carotid rete mirabile (CRM) has not been reported. We report the long-term clinical and angiographic outcome after stenting for symptomatic VA stenosis in the patient with bilateral CRM. This report is the first case that symptomatic VA stenosis associated with bilateral CRM was treated with stenting.

Carotid rete mirabile associated with subarachnoid hemorrhage from intracranial aneurysm: A case report and systematic review

Carotid rete mirabile (CRM) is a rare physiological vascular network in humans that is most often found in Eastern populations. This paper describes a CRM associated with an aneurysmal subarachnoid hemorrhage (aSAH) and discusses the details of the patient's treatment. A 28-year-old woman was admitted to our service with clinical signs and symptoms of a spontaneous aSAH. Computed tomography revealed a diffuse and extensive SAH (Fisher group IV), while an angiogram showed an abnormal collateral network in the right carotid system and a hypoplastic aspect to the internal carotid artery (ICA) on the same side. In addition, a saccular aneurysm with a diameter of 9.5 mm was present in the ophthalmic segment of the left ICA. This case is extremely uncommon. To avoid rebleeding in the patient, we successfully treated the patient by clipping the aneurysmal lesion. No procedure was performed for the CRM.

Bilateral carotid and vertebral rete mirabile with vein of Galen aneurysmal malformation: an unreported association

Rete mirabile is a fine meshwork of anastomosing vessels that replace the parent artery. A 30-year-old woman complained of slurring of speech, right eye proptosis, recurrent vomiting, and loss of bladder and bowel control, followed by drowsiness lasting 30-40 min, for the past 6 months. On cross sectional imaging and angiography, the patient was found to have a vein of Galen aneurysmal malformation, with bilateral carotid and vertebral rete mirabile. The patient was offered both endovascular and open surgical options but she refused any form of surgical treatment and opted for conservative management. At the 6 month follow-up, she continued to have occasional episodes of headache and vomiting but was otherwise normal. We describe the clinical, cross sectional, and angiographic features of this patient. A comparison with other patients with bilateral carotid and vertebral rete mirabile is also reported.

Johann Vesling (1598-1649): seventeenth century anatomist of Padua and his Syntagma Anatomicum

Johann Vesling (1598-1649) was a German anatomist and surgeon who belonged to the golden period of the illustrious University of Padua. He made significant contributions to the advancement of anatomical knowledge during the 17th century and is remembered most for his remarkable anatomical work, the Syntagma Anatomicum, which was published in 1641. He was the first to describe the soleus muscle and to emphasize its resemblance to the sole fish. He produced the earliest illustrations of the human lymphatic system and was one of the first to document observations about the thoracic duct. He was also the first to report the bifurcation of the human hepatic portal vein on entering the fissure of the liver. His observations from embryological experiments were critical for understanding the development of the four-chambered heart. He was one of the first authors to state that four pulmonary veins empty into the left atrium of the heart. Syntagma Anatomicum (1641) was the most widely used anatomical text in Europe for almost a century and was republished a number of times with editions in Latin, German, Dutch, and English. Syntagma was the first illustrated western anatomical text to reach Japan and laid the foundation for the development of European medicine there. The illustrations used in it deviated from the artistic convention that had characterized anatomical figures from the time of Vesalius, and focused instead on representing anatomical details to make them helpful for medicine and surgery. Clin. Anat. 27:1122-1127, 2014. © 2014 Wiley Periodicals, Inc.

Bilateral segmental agenesis of carotid and vertebral arteries with rete mirabile and the prominent anterior and posterior spinal arteries as compensations

Agenesis of carotid or vertebrobasilar arteries with rete formation is rare. The anterior spinal artery or posterior spinal arteries supplying the posterior circulation with steno-occlusion or agenesis of bilateral vertebral arteries is also uncommon. Here, we describe a very rare case of concomitant segmental agenesis of bilateral carotid and vertebral arteries with collateral compensations from the prominent anterior spinal artery and posterior spinal arteries, as well as some transdural arterial networks which were considered a rete mirabile. We discuss its embryological and anatomic significance.

Unilateral rete mirabile as a result of segmental agenesis of the ascending petrous segment of the internal carotid artery: embryology, differential diagnosis and clinical implications

We describe an extremely rare case of unilateral rete mirabile in a young woman and discuss its significance in embryological development as well as its radiological aspects, differential diagnosis and potential clinical implications.

Bilateral carotid and vertebral rete mirabile presenting with a prominent anterior spinal artery mimicking a spinal dural AV fistula at MRI

Bilateral carotid and vertebral rete mirabile (CVRM) is a very rare condition. We report a new case of CVRM initially detected by magnetic resonance imaging (MRI) of the cervical spine. MRI demonstrated tortuous vascular signal voids limited to the anterior cerebrospinal fluid space mimicking spinal dural arteriovenous fistula. A diagnosis of CVRM was confirmed on the basis of angiographic findings of rete formation associated with bilateral aplasia of the cavernous internal carotid and vertebral arteries without abnormal arteriovenous connection.