Descending musculospinal branch of the ascending pharyngeal artery as a feeder of carotid body tumors: Angio-architecture and embryological consideration

Carotid body tumors-epidemiology and surgical resection

Carotid body tumor originates from paraganglion cells of the carotid body and is a hypervascular tumor with multiple feeding arteries and uniquely located at the carotid bifurcation. Recently, it has been revealed that various types of gene alterations exist mainly in the succinate dehydrogenase (SDH) gene family. Although resection is a radical therapy for this tumor, complete resection is challenging. On the other hand, radiotherapy for carotid body tumors is insufficient as a radical therapy concerning the response rate. Here, we reviewed articles reporting carotid body tumor treatment and surgical resection focusing on choice of treatment, surgical difficulties, and preoperative embolization of feeding arteries. The effectiveness of preoperative embolization remains controversial due to the varied situations performing surgical resection among the institutions.

Angiographical Investigation of Vagal and Carotid Body Paragangliomas

Objective

Although vagal paragangliomas (VPs) and carotid body paragangliomas (CBPs) are both neck paragangliomas, they have different surgical risks and clinical courses. In this report, we investigated the feeding arteries of VPs compared with CBPs, with an aim to better differentiate these tumors and improve our understanding of their angioarchitecture.

Methods

We conducted a retrospective analysis of angiography data from 3 cases of VPs and 10 tumors from 9 cases of CBP. For each case, we evaluated the level of the vertebral body corresponding to the upper margin of the tumor, the tumor size, the arterial supply of the tumor, the topological relationship between the external carotid artery and internal carotid artery and the tumor, the details of preoperative embolization, and the incidence of postoperative neurological deficits.

Results

In all 3 cases of VPs, the blood supply originated from the occipital, vertebral, and ascending pharyngeal arteries. By contrast, among the 10 CBP tumors, 3 were supplied by the occipital artery, 1 was supplied by the vertebral artery, and all 10 were fed by the ascending pharyngeal artery. VPs, when compared to CBPs, exhibited larger tumor sizes, a higher positioning of the upper margin of the tumor, and a lack of splaying of the internal and external carotid arteries, compressing both forward. Additionally, preoperative embolization was frequently performed in cases of VPs. Furthermore, the postoperative occurrence of complications such as hoarseness and vocal cord paralysis was also higher.

Conclusion

VPs originate from the inferior ganglion of the vagus nerve, which is chiefly nourished by the vertebral artery. This original arterial distribution may explain the angioarchitecture observed in this study. This study may facilitate the better understanding of the VP angioarchitecture and safe and efficient embolization for them.

Unilateral Variation of the Left Ascending Pharyngeal Artery: A Case Report

During routine cadaveric dissection of a 77-year-old male, a series of unique arterial variations were observed within the left anterior cervical region. Firstly, the ascending pharyngeal artery (APA) was observed branching from the common carotid artery (CCA), between the internal (ICA) and external carotid (ECA) arteries. The APA continued superiorly without branching, as is typical for APA. Secondly, a common arterial trunk was observed emerging from the posterior cervical segment of the left ICA. As the common trunk continued superiorly, it bifurcated into two distinct branches. The first branch terminated as several muscular branches (MB) feeding the salpingopharyngeus and superior constrictor muscles. The second branch, a suspected neuromeningeal trunk (NMT), continued superiorly and terminated within the jugular foramen. We believe this individual presented with atypical branching of the APA system. The course of both the muscular branch and the neuromeningeal trunk were novel in that they both originated from a common trunk off the ICA. Both variations could have pathologic and clinical implications.

Prevalence, characteristics, evaluation, and management of carotid body tumors: Systematic analysis based on available evidence

OBJECTIVE

Although carotid body tumors (CBTs) are rare, they attract particular attention because of their propensity for malignant transformation and the high surgical risk. Because data are scarce and as it is difficult to achieve a large sample size, no study has yet comprehensively analyzed the characteristics, management, or operative complications of CBTs. Therefore, we collected and analyzed all currently available information on CBTs and used the pooled data to derive quantitative information on disease characteristics and management.

METHODS

We systematically searched PubMed, Embase, the Cochrane Library, and the Web of Science up to December 1, 2022, for studies that investigated the characteristics and management of CBTs. The primary objective was to identify the prevalence of the various characteristics and the incidence of complications. The secondary objective was to compare patients who underwent preoperative embolization (PE) and those who did not (non-PE), as well as to compare patients with different Shamblin grades and those with and without succinate dehydrogenase (SDH) mutations in terms of CBT characteristics and complications. Two reviewers selected studies for inclusion and independently extracted data. All statistical analyses were performed using the standard statistical procedures of Review Manager 5.2 and Stata 12.0.

RESULTS

A total of 155 studies with 9291 patients and 9862 tumors were identified. The pooled results indicated that the median age of patients with CBT was 45.72 years, and 65% were female. The proportion of patients with bilateral lesions was 13%. In addition, 16% of patients had relevant family histories, and the proportion of those with SDH gene mutations was 36%. Sixteen percent of patients experienced multiple paragangliomas, and 12% of CBTs had catecholamine function. The incidence of cranial nerve injury (CNI) was 27%, and 14% of patients suffered from permanent CNI. The incidence rates of operative mortality and stroke were both 1%, and 4% of patients developed transient ischemic attacks. Of all CBTs, 6% were malignant or associated with metastases or recurrences. The most common metastatic locations were the lymph nodes (3%) and bone (3%), followed by the lungs (2%). Compared with non-PE, PE reduced the estimated blood loss (standardized mean difference, -0.95; 95% confidence interval [CI], -1.70 to -0.20) and the operation time (standardized mean difference, -0.56; 95% CI, -1.03 to -0.09), but it increased the incidence of stroke (odds ratio, 2.44; 95% CI, 1.04-5.73). Higher Shamblin grade tumors were associated with more operative complications. Patients who were SDH gene mutation-positive were more likely to have a relevant family history and had more symptoms.

CONCLUSIONS

CBT was most common in middle-aged females, and early surgical resection was feasible; there was a low incidence of serious operative complications. Routine PE is not recommended because this may increase the incidence of stroke, although PE somewhat reduced the estimated blood loss and operation time. Higher Shamblin grade tumors increased the incidence of operative complications. Patients who were SDH gene mutation-positive had the most relevant family histories and symptoms.

Current management of carotid body tumors

Carotid body tumors (CBTs) are neoplasms that occur at the bifurcation of the carotid artery and are pathologically classified as paragangliomas. In the 4th edition of the WHO classification, paragangliomas are categorized as neoplasms with malignant potential. Clinically, about 5% of CBTs present with malignant features such as metastasis. Currently, it is challenging to distinguish between tumors with benign courses and those that present malignantly. Recent advances in genetic testing have elucidated the genetic characteristics of paragangliomas, including carotid body tumors. Over 20 genes have been identified as being involved in tumor development. Particularly in head and neck paragangliomas, abnormalities in genes related to succinate dehydrogenase are frequently observed. Research is ongoing to understand the mechanisms by which these genes contribute to tumor development. The definitive treatment for CBTs is surgical resection. These tumors are prone to bleeding and often adhere firmly to the carotid artery, making intraoperative bleeding control challenging. The risk of lower cranial nerve paralysis is relatively high, and there is a risk of stroke because of manipulation of the carotid artery. Preoperative evaluation with angiography is essential, and a multi-disciplinary surgical team approach is necessary. In cases where the tumor is difficult to resect or has metastasized, radiation therapy or chemotherapy are employed. Clinical trials involving targeted molecular therapies and radiopharmaceuticals have recently been conducted, with some applied clinically. The development of various new treatments is anticipated, providing hope for therapeutic options in refractory cases.

An analysis from the CAPACITY database of outcomes of preoperative embolization before carotid body tumor surgery compared with resection alone

OBJECTIVE

There is no definitive consensus on the impact of preoperative embolization on carotid body tumor (CBT) treatment. The objective of this study was to compare surgical outcomes of patients who underwent preoperative embolization before CBT resection vs patients who underwent resection alone.

METHODS

The CAPACITY registry included 1432 patients with CBT from 11 medical centers in four different countries. The group of patients undergoing CBT resection with preoperative embolization was matched in a 1:6 ratio from a pool of patients from the CAPACITY database, using a generated propensity score with patients who did not underwent preoperative embolization.

RESULTS

A total of 553 patients were included for analysis. Mean patient age was 56.23 ± 12.22 years. Patients were mostly female (n = 469; 84.8%). Bilateral CBT was registered in 60 patients (10.8%). Seventy-nine patients (14.3%) underwent preoperative embolization. Embolized patients had larger CBT sizes than non-embolized patients (33.8 mm vs 18.4 mm; P = .0001). Operative blood loss was lower in the embolized group compared with the non-embolized group (200 mL vs 250 mL; P = .031). Hematomas were more frequent in the non-embolized group (0% vs 2.7%; P = .044). Operative time, rates of stroke, cranial nerve injuries, and death were not statistically significant between groups.

CONCLUSIONS

Embolization before CBT resection was associated with significantly lower blood loss and lower neck hematomas than patients who underwent resection alone. Operative time, stroke, cranial nerve injuries, and death were similar between groups.

Transcatheter arterial embolization for traumatic injury to the pharyngeal branch of the ascending pharyngeal artery: Two case reports

BACKGROUND

The ascending pharyngeal artery (APhA) comprises the pharyngeal trunk (PT) and neuromeningeal trunk. The PT feeds the nasopharynx and adjacent tissue, which potentially connects with the sphenopalatine artery (SPA), branched from the internal maxillary artery (IMA). Due to its location deep inside the body, the PT is rarely injured by trauma. Here, we present two cases that underwent transcatheter arterial embolization (TAE) of the PT of the APhA due to trauma and iatrogenic procedure.

CASE SUMMARY

Case 1 is a 49-year-old Japanese woman who underwent transoral endoscopy under sedation for a medical check-up. The nasal airway was inserted as glossoptosis occurred during sedation. Bleeding from the nasopharynx was observed during the endoscopic procedure. As the bleeding continued, the patient was referred to our hospital for further treatment. Contrast-enhanced computed tomography (CT) demonstrated extravasation in the nasopharynx originating from the right Rosenmuller fossa. TAE was performed and the extravasation disappeared after embolization. Case 2 is a 28-year-old Japanese woman who fell from the sixth floor of a building and was transported to our hospital. Contrast-enhanced CT demonstrated a complex facial fracture accompanying extravasation in the left pterygopalatine fossa to the nasopharynx. Angiography demonstrated an irregular third portion of the IMA. As angiography after TAE of the IMA demonstrated extravasation from the PT of the APhA, additional TAE to the artery was performed. The bleeding stopped after the procedure.

CONCLUSION

Radiologists should be aware that the PT of the APhA can be a bleeding source, which has a potential connection with the SPA.

[Modern conceptions on neck paragangliomas]

Neck paragangliomas are orphan diseases with incidence 1:30 000-1:100 000. Life expectancy is poor in patients with distant metastasis (5-year overall survival 11.8%), whereas 5-year overall survival in patients with regional metastasis is 76.8-82.4%. Meanwhile, there is still no any reliable tool for prediction of malignant potential of paraganglioma. Above-mentioned data indicate an importance of early diagnosis and timely treatment of neck paragangliomas. Total resection of tumor in ablastic conditions is a gold standard of treatment. However, surgery is associated with a high risk of neurovascular complications and requires multidisciplinary approach. Nevertheless, new knowledge dedicated to different aspects of pathogenesis of neck paraganglioma, diagnosis and treatment arise every year. This review is devoted to modern data on neck paragangliomas.