Common left carotid bifurcation at C7-Th1 level: a rare anatomical variant

The vertical topography of the carotid bifurcation - original study and review

PURPOSE

The vertical level of carotid bifurcation (CB) is commonly indicated at the superior margin of the thyroid cartilage. Few studies observed the CB vertical topography. It was aimed at studying the vertical location of the CB as referred to vertebral and anterior cervical landmarks.

METHODS

An archived lot of 147 computed tomography angiograms was documented for the vertical level of CB referred to vertebral and anterior cervical landmarks. The topography of the CB in relation to anterior landmarks was classified into seven types: (1) at the superior margin of the thyroid cartilage; (2) between the hyoid and the thyroid cartilage; (3) at the hyoid level; (4) between the hyoid and mandible; (5) subgonial or supragonial CB; (6) lower cervical level; (7) intrathoracic.

RESULTS

The most common locations of CB were at C3 (27.21%), C3/C4 (26.19%) and C4 (25.51%). Bilateral symmetry of CB was found in 51.7%, except for C2 and C5/C6. Type 7 was not found, type 3 occurred in 39.12%, type 2 in 24.49%, type 1 in 13.95%, type 4 in 13.61%, type 5 in 6.12%, and type 6 in 2.72% (294 CBs). Bilateral symmetry of anterior types was found in 59.86%. Statistically significant correlations were found between sex and both left and right types and vertebral levels of CB.

CONCLUSIONS

The vertical topography of the CB is highly variable and has sex-related specificity. This detail should be included in the teaching of anatomy. Surgeons and interventionists should better document the carotid anatomy on a case-by-case basis.

Common carotid artery medialization and fracture dislocation of the cervical spine

PURPOSE

To describe the management of the discovery of a retropharyngeal carotid artery in the context of a cervical dislocation.

DESCRIPTION OF THE CASE

A 68-year-old female presented acute neck pain and incomplete tetraplegia following a fall on the stairs. Radiographs, contrast-enhanced computed tomography scan and magnetic resonance of the cervical spine revealed a C5-C6 bi-articular dislocation. A detailed preoperative assessment of the images discovered a medialization of the left common carotid artery. An external reduction and a left anterior cervical approach allowed a careful management of the vascular variation and an anterior C5-C6 arthrodesis. At six months, a full neurological recovery was assessed and radiographs demonstrated successful fusion of the cervical arthrodesis.

DISCUSSION/CONCLUSION

Anatomical features such as medialization of the common carotid artery may affect patients with traumatic cervical spine injuries. The severity of the traumatic bone lesions should not overshadow the preoperative analysis of the adjacent anatomical structures encountered during the surgical approach, even in an emergency situation.

Persistent Primitive Hypoglossal Artery with Ipsilateral Symptomatic Carotid Artery Stenosis and Cerebral Aneurysm

OBJECTIVE

Persistent primitive hypoglossal artery (PPHA) is a rare type of persistent carotid-basilar anastomosis sometimes associated with other vascular lesions. We treated an extremely rare case of PPHA with concomitant ipsilateral symptomatic cervical internal carotid artery (ICA) stenosis and unruptured aneurysm.

CASE PRESENTATION

A 67-year-old woman visited our institution with acute onset of diplopia. Magnetic resonance imaging revealed multiple acute infarctions in the right anterior and posterior circulations. Digital subtraction angiography demonstrated the right PPHA concomitant with ipsilateral cervical ICA stenosis and an unruptured ICA aneurysm with maximum diameter of 8 mm. The multiple infarctions were considered to result from artery-to-artery embolism due to microthrombi from the ICA plaque passed along the PPHA, so carotid endarterectomy was performed as the first step with preoperative modified Rankin Scale (mRS) grade 1. During the operation, the patient had impaired ICA perfusion due to internal shunt catheter migration into the PPHA followed by acute infarction in the right hemisphere causing mild left hemiparesis. The patient was transferred to the rehabilitation hospital with mRS grade 3. After 3 months of rehabilitation, the patient recovered to mRS grade 1 and clipping surgery for the unruptured right ICA aneurysm was performed as the second step with uneventful postoperative course.

CONCLUSION

The treatment strategy should be carefully considered depending on the specific blood circulation for such cases of PPHA with unique vasculature.

The carotid axis revisited

The aim was to determine the variations in the level of origin of carotid bifurcation and diameters of the common, internal, and external carotid arteries which is clinically important for several interventional procedures. Therefore, 165 human embalmed corpses were dissected. The data collected were analyzed using the Chi square-test and the Pearson correlation test. The results of previous studies have been reviewed. In relation to the level of the carotid bifurcation, taking as a reference point the hyoid bone, the values ranged from 4 cm below the hyoid body to 2.5 cm above the body of the hyoid, being the average height—0.33 cm, with a standard deviation of 1.19 cm. The right carotid bifurcation was established at a higher level (x = − 0.19 cm.) than the left one (x = − 0.48 cm.) (p = 0.046). On the contrary, no significant gender differences could be observed. The arterial calibres of the common and internal carotid arteries were higher in male than female. In the internal carotid artery (X = 0.76 cm.), the left was greater than the right (X = 0.72 cm.) (P = 0.047). However, no differences in the distribution of the calibre of the external carotid artery were found neither by side nor gender. Variations in the level of bifurcation and calibres of carotid arteries are relevant for interventional radiology procedures and head and neck surgeries. Knowledge of these anatomical references might help clinicians in the interpretation of the carotid system.

Microsurgical Anatomy of the Anterior Circulation of the Brain Adjusted to the Neurosurgeon's Daily Practice

The study of cerebrovascular anatomy can be difficult and may take time due to its intrinsic complexity. However, it can also be difficult for the following reasons: the excessive description of neuroanatomy making articles hard to read, the unclear clinical application of what is written, the use of simplified or intricate schematic drawings that are not always appropriate for effective teaching, the poor quality of neuroanatomy dissections and the use of unusual views of figures that are not strictly related to the most frequent neuroimages to be interpreted in daily practice. Because of this, we designed an article that incorporates original and accurate anatomical dissections in an attempt to improve its comprehensibility. Five formalin-fixed adult cadaveric heads, whose vessels were injected with a colored silicone mixture (red for arteries and blue for veins), were dissected and examined under a microscope with magnifications from 3× to 40×. Special emphasis has been placed on correlating topographic anatomy with routine neuroimaging studies from computed tomographic angiography (CTA) and digital subtraction angiography (DSA). The essential surgical anatomy in a neurosurgeon’s daily practice is also described. The cadaveric dissections included in this study contribute to the understanding of the cerebrovascular anatomy necessary for the neurosurgeon’s daily practice.

Intrathoracic bifurcation of the left common carotid artery associated with rib fusion and Klippel-Feil syndrome

Common carotid artery usually bifurcates at the superior border of thyroid cartilage, corresponding to the C3-4 junction, however bifurcation level may vary. Common carotid bifurcation may have rare variations like separate origins of left internal and external carotid arteries from aortic arch, or bifurcation of common carotid artery within thoracic cavity. Intrathoracic carotid bifurcation is a rare variation with limited number of cases reported. The occurrence of a low carotid bifurcation seems to be embryologically related to the persistence of the ductus caroticus. Additionally, intrathoracic carotid bifurcation can be accompanied by findings of Klippel-Feil syndrome. Herein, we present imaging findings of an incidentally detected intrathoracic left common carotid artery bifurcation in a pediatric patient accompanied by fusion of the cervical vertebrae and ribs.