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.

The Axial Spin of the Carotid Bifurcation.

(1) Background: Twisted carotid bifurcations (CBs) lead to lateralized external carotid arteries (ECAs). Such variants are usually reported on a case-by-case basis. We aimed to study the anatomical possibilities of the axial spin of CB. (2) Methods: Determinations were made bilaterally on a retrospectively assessed sample of 150 cases, 88 males and 62 females. The following types of the axial spin of the CB were determined: type CK1-CB in the coronal plane, with ICA lateral of ECA; type CK3-CB in the coronal plane, with ECA lateral of ICA; the oblique type OK1, with the ECA antero-medial of ICA; the oblique type OK3a, with the ICA antero-medially; the oblique type OK3b, with the ICA postero-laterally; the sagittal type SK2a, with ECA anterior of ICA. (3) Results: In the overall group of 300 CBs, type OK1 was found in 40%, type OK3a in 1%, type OK3b in 2%, type CK1 in 9%, type CK3 in 5.67%, and type SK2a in 42.33% of the bilateral BC group. The types SK2a (46.67%) and OK1 (33.33%) prevailed on the right side. The types OK1 (46.67%) and SK2a (38%) prevailed on the left side. There was no statistically significant association between gender and left or right subtypes. A very strong symmetry existed between the left and right sides (Pearson Chi2 = 53.93 p < 0.001) for types OK1 and SK2a. Asymmetrical types were found in different bilateral combinations. (4) Conclusions: The spin of the CB is relatively symmetrical bilaterally, especially for the variants with the ECA antero-medial or anterior to ICA.

The Carotid-Hyoid Topography Is Variable.

Background and Objectives: The carotid bifurcation (CB) is presented in most anatomy textbooks as having a unique location at the upper margin of the thyroid cartilage. Although a number of case reports have provided evidence of the possibility of carotid artery location either lateral or medial to the greater hyoid horn, these reports have not established specific anatomic possibilities and prevalences. Materials and Methods: We retrospectively analysed a batch of 147 CT angiograms for 12 types of carotid-hyoid relationships and classified the bilateral combination possibilities of these types. Results: In 168/294 sides there were no carotid-hyoid relationships. Type I, external carotid artery (ECA) medial to the greater horn of the hyoid bone (GHHB), was observed in 0.34%; type II, internal carotid artery (ICA) medial to GHHB, in 0.34%; type III, ICA and ECA medial to GHHB, in 1.02%; type IV, common carotid artery (CCA) medial to GHHB, in 1.02%; type V, CB medial to GHHB, in 0.34%; type VI, ECA lateral to GHHB, in 20.41%; type VII, ICA lateral to GHHB, was not recorded; type VIII, ECA and ICA lateral to GHHB, in 3.74%; type IX, CCA lateral to GHHB, in 8.5%; type X, CB lateral to GHHB, in 6.46%; type XI, ECA lateral and ICA medial to GHHB, in 0.34%; and type XII, ICA lateral and ECA medial to GHHB, in 0.34%. Bilateral symmetry was found in 70.74% of cases, including the null types without carotid-hyoid relationships as well as types IV, VI, VIII, IX, and X. There was a highly significant association between the left and right variants of the carotid-hyoid relationship. Conclusions: Mechanical compression of the hyoid bone on the carotid arteries has various undesirable effects on the ICA and cerebral circulation. Underlying these are several variational anatomical patterns of carotid-hyoid relationships, which can be accurately documented on CT angiograms. A case-by-case anatomical study is better than assuming the carotid anatomy learned from textbooks.

Aortic Origins of the Celiac Trunk and Superior Mesenteric Artery.

(1) Background. The vertebral level of origin (VLO) of the celiac trunk (CT) and superior mesenteric artery (SMA) has been scarcely investigated. (2) Method. This study used 107 computed tomography angiograms and an eleven type grading system to classify the VLO of the CT and SMA. Each of the T12-L2 vertebra were divided in three horizontal levels. The intervertebral discs were considered distinct levels. (3) Results. The VLO of the CT ranged from the upper third of the T12 vertebra to the lower third of the L1 vertebra. The VLO of the SMA ranged from the lower third of the T12 vertebra to the upper third of the L2 vertebra. There was a highly significant association between the VLO of the CT and SMA (Chi2 = 201, p < 0.001), usually respecting a "plus two" rule. The mean CT-SMA distance was 1.82 +/- 0.66 cm in males and 1.55 +/- 0.411 cm in females, the difference being statistically significant. The mean CT-SMA distance tended to decrease with increasing CT-SMA types, the differences being statistically significant. (4) Conclusions. These characteristics of CT and SMA origins and their relations should be known by surgeons, as they could impact operative management and should be evaluated on a case-by-case basis.

Rare Anatomic Variation: The Hepatosplenomesentericophrenic Trunk.

The rare anatomic variants of the celiac trunk and superior mesenteric artery include the hepatosplenic, hepatosplenomesenteric (HSMT), celiacomesenteric, hepatomesenteric and gastrosplenic trunks. We report a 72-year-old female patient whose computed tomography angiograms indicated a rare anatomic feature whereby the right inferior phrenic artery was inserted in the origin of an HSMT, thus modifying it into a hepatosplenomesentericophrenic trunk (HSMPT). Above the HSMPT, the insertion of the left inferior phrenic artery in the origin of the left gastric artery determined a left gastrophrenic trunk (GPT). Proper identification of this type of rare anatomic variant is of utmost importance prior to different surgical procedures. For example, an HSMT origin of the right inferior phrenic artery is surgically relevant if this artery is an extrinsic pedicle of a hepatocellular carcinoma and is used for embolization of the tumor.

Pentafurcated Celiac Trunk.

BACKGROUND: Commonly, but not exclusively, the celiac trunk (CT) trifurcates into the left gastric (LGA), common hepatic (CHA) and splenic (SA) arteries. Additional branches of the CT are scarcely reported in the literature. Less than ten reports were found presenting patterns of pentafurcation of the CT (pCT), all being resulted after anatomic dissections. METHOD: We hereby report such a rare pCT, which was found on the computed tomography angiograms of a 71-year-old female patient. RESULTS: From that pCT were branching off three collateral branches, two ascending and one descending, and two terminal branches. The ascending ones were the left inferior phrenic artery and a secondary hepatogastric trunk, further divided into a replaced left hepatic artery and the left gastric artery. The dorsal pancreatic artery was the descending collateral branch of the pCT. The pCT ended by dividing into the CHA and SA. The CHA reached the anterior side of the portal vein to divide into the gastroduodenal and right hepatic arteries. An accessory right hepatic artery left the superior mesenteric artery (SMA) and ascended posterior to the portal vein. CONCLUSIONS: To the authors' knowledge, the combination of a pCT and a hepatic branch from the SMA, which raises to three the main arteries of the liver, was not reported previously. Additional branches of the CT should be carefully documented by computed tomography prior to surgical or interventional approaches of the aorta in the celiac region.

Quadrifurcation Variants of the Celiac Trunk.

BACKGROUND: The celiac trunk (CT) commonly trifurcates into the left gastric artery, common hepatic artery (CHA), and splenic artery (SA). The CHA then sends off the proper hepatic artery and gastroduodenal artery (GDA). The arcades of the head of the pancreas are celiacomesenteric anastomoses between branches of the GDA and the superior mesenteric artery. A quadrifurcation of the CT commonly occurs when a different branch is added to the 3 normal ones. An uncommon quadrifurcation of the CT occurs when only one or 2 of the normal branches of the CT participate. METHODS: The CT quadrifurcations were documented on 112 computed tomography angiograms. RESULTS: Five different types of CT quadrifurcation-3 uncommon (types 1-3) and 2 common (types 4-5)-were found in 15/112 cases (13.39%). A marginal significant association was found between the presence of quadrifurcations and male gender (P = 0.05; Fisher's exact test). Type 1 showed a hepatogastric trunk+SA + right hepatic artery+GDA pattern, type 2 had an HGT + right inferior phrenic artery + CHA + SA pattern, type 3 had a gastrophrenic trunk + left inferior phrenic artery+CHA + SA pattern, type 4 showed an left gastric artery + CHA + SA + left inferior phrenic artery combination, and type 5 had an additional common inferior phrenic trunk. One of the type 4 cases showed a buildup of a mesentericomesenteric anastomotic pancreatic arcade between the inferior pancreaticoduodenal arteries, rather than a celiacomesenteric one. CONCLUSIONS: Anatomic variation of the celiacomesenteric axis is important during hepatobiliary and duodenopancreatic approaches. Therefore, preoperative evaluation is essential because theoretical anatomic possibilities could be real arterial variants.