Diagnosis and Operative Management of Carotid Endarterectomy in Patients with Twisted Carotid Bifurcation

Carotid Endarterectomy for a Case with an Extremely Twisted Internal Carotid Artery

The internal carotid artery (ICA) typically runs posterolaterally to the external carotid artery (ECA) at the level of the common carotid artery (CCA) bifurcation in the neck. The "twisted ICA" is an anatomical variation, wherein the ICA is medial to the ECA. Several studies on the twisted ICA have discussed its anatomical definition, incidence, clinical features, and surgical results in patients with luminal stenosis. Computed tomography angiography (CTA)-based analyses of surgically treated cohorts documented a twist angle, reaching up to 95°. Carotid endarterectomy (CEA) was successfully performed for these patients. This study reports a case of a significantly twisted ICA with severe luminal stenosis that was successfully treated with CEA. An 81-year-old male was incidentally diagnosed with asymptomatic right ICA stenosis based on magnetic resonance (MR) angiography. Three-dimensional (3D)-CTA showed that the ICA revealed 74% stenosis of the ICA, based on the North American Symptomatic Carotid Endarterectomy Trial criteria. The 3D-CTA showed the ICA medial to the ipsilateral ECA at the level of the CCA bifurcation in the neck. It extended proximally to the pharynx, and the twist angle was 102°. Black-blood MR of the carotid plaque exhibited a high intensity on T1-weighted imaging, indicating vulnerability. Intraoperatively, the position of the ICA was corrected using multiple hooks instead of a surgical retractor. He showed no permanent deficits, such as an ipsilateral cerebral infarction, although transient postoperative hoarseness was observed. This case report documented a significantly twisted ICA with luminal stenosis, successfully treated via CEA, by correcting the carotid position using multiple hooks with gentle manipulation.

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.

Older age, carotid artery stenosis, and female sex as factors correlated with twisted carotid bifurcation based on 457 angiographic studies

BACKGROUND

Twisted carotid bifurcation (TCB) is a well-known anatomical variation of the carotid bifurcation in patients undergoing carotid endarterectomy. However, few investigations of TCB have focused on patients without internal carotid artery (ICA) stenosis. This study was performed to analyze the characteristics of TCB in patients with ICA stenosis and other diverse pathologies.

METHODS

All conventional cerebral angiographies performed in our institute for any reason from January 2012 to December 2018 were reviewed. The patients were divided into two groups, the TCB group and the anatomically normal non-TCB group, and the basic characteristics of the groups were analyzed.

RESULTS

Both sides of the carotid bifurcation were clearly visualized in 457 patients. TCB was found in 89 of 457 patients (19.5%); among these 89 patients, 74 (83.1%) had TCB only on the right side, 8 (9.0%) only on the left side, and 7 (7.9%) bilaterally. TCB was found more frequently on the right than left [81 (17.7%) and 15 (3.3%), respectively, on each of the 457 sides (p < 0.0001)]. TCB was significantly more frequent in older patients (p = 0.02), female patients (p < 0.001), and patients with ICA stenosis or occlusion at the bifurcation (p = 0.005). The prevalence of TCB was 19.5%, and 84.4% of cases were on the right side in patients with diverse pathologies.

CONCLUSIONS

Older patients, female patients, and patients with ICA stenosis or occlusion are more prone to have TCB.

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.

Carotid Endarterectomy Requiring Removal of the Superior Horn of Thyroid Cartilage: Case Report and Literature Review

Carotid endarterectomy (CEA) is an established surgical procedure for carotid stenosis. We present the case of a 74-year-old man who underwent CEA for symptomatic internal carotid artery (ICA) stenosis. During the operation, we found that the hyoid bone (HB) and the superior horn of the thyroid cartilage covered the carotid sheath, preventing adequate visualization. Since this was anticipated based on preoperative examinations, the superior horn of thyroid cartilage was removed with the help of an otorhinolaryngologist. The HB was preserved because it could be retracted, and thereafter we performed CEA. Although CEA is a common procedure, the HB and thyroid cartilage are rarely involved in the operation. We present a case report including literature review of acute cerebrovascular syndrome (ACVS) due to HB and thyroid cartilage obstruction.

Comparison of Single and Dual Monitoring during Carotid Endarterectomy

We compared the rate of selective shunt and pattern of monitoring change between single and dual monitoring in patients undergoing carotid endarterectomy (CEA). A total of 121 patients underwent 128 consecutive CEA procedures. Excluding five procedures using internal shunts in a premeditated manner, we classified patients according to the monitoring: Group A (n = 72), patients with single somatosensory evoked potential (SSEP) monitoring; and Group B (n = 51), patients with dual SSEP and motor evoked potential (MEP). Among the 123 CEAs, an internal shunt was inserted in 12 procedures (9.8%) due to significant changes in monitoring (Group A 5.6%, Group B 15.7%, p = 0.07). The rate of shunt use was significantly higher in patients with the absence of contralateral proximal anterior cerebral artery (A1) on magnetic resonance angiography (MRA) than in patients with other types of MRA (p <0.001). Significant monitor changes were seen in 16 (12.5%) in both groups. In four of nine patients in Group B, SSEP and MEP changes were synchronized, and in the remaining five patients, a time lag was evident between SSEP and MEP changes. In conclusion, the rate of internal shunt use tended to be more frequent in patients with dual monitoring than in patients with single SSEP monitoring, but the difference was not significant. Contralateral A1 absence may predict the need for a shunt and care should be taken to monitor changes throughout the entire CEA procedure. Use of dual monitoring can capture ischemic changes due to the complementary relationship, and may reduce the rate of false-negative monitor changes during CEA.

Surgical Technique for Carotid Endarterectomy: Current Methods and Problems

Over the last 60 years, many reports have investigated carotid endarterectomy (CEA) and techniques have thus changed and improved. In this paper, we review the recent literature regarding operational maneuvers for CEA and discuss future problems for CEA. Longitudinal skin incision is common, but the transverse incision has been reported to offer minimal invasiveness and better cosmetic effects for CEA. Most surgeons currently use microscopy for dissection of the artery and plaque. Although no monitoring technique during CEA has been proven superior, multiple monitors offer better sensitivity for predicting postoperative neurological deficit. To date, data are lacking regarding whether routine shunt or selective shunt is better. Individual surgeons thus need to select the method with which they are more comfortable. Many surgical techniques have been reported to obtain distal control of the internal carotid artery in patients with high cervical carotid bifurcation or high plaque, and minimally invasive techniques should be considered. Multiple studies have shown that patch angioplasty reduces the risks of stroke and restenosis compared with primary closure, but few surgeons in Japan have been performing patch angioplasty. Most surgeons thus experience only a small volume of CEAs in Japan, so training programs and development of in vivo training models are important.