Single-cell transcriptome analysis reveals tumoral microenvironment heterogenicity and hypervascularization in human carotid body tumor

Carotid body tumor (CBT) is a rare neck tumor located at the adventitia of the common carotid artery bifurcation. The prominent pathological features of CBT are high vascularization and abnormal proliferation. However, single-cell transcriptome analysis of the microenvironment composition and molecular complexity in CBT has yet to be performed. In this study, we performed single-cell RNA sequencing (scRNA-seq) analysis on human CBT to define the cells that contribute to hypervascularization and chronic hyperplasia. Unbiased clustering analysis of transcriptional profiles identified 16 distinct cell populations including endothelial cells (ECs), smooth muscle cells (SMCs), neuron cells, macrophage cells, neutrophil cells, and T cells. Within the ECs population, we defined subsets with angiogenic capacity plus clear signs of later endothelial progenitor cells (EPCs) to normal ECs. Two populations of macrophages were detectable in CBT, macrophage1 showed enrichment in hypoxia-inducible factor-1 (HIF-1) and as well as an early EPCs cell-like population expressing CD14 and vascular endothelial growth factor. In addition to HIF-1-related transcriptional protein expression, macrophages1 also display a neovasculogenesis-promoting phenotype. SMCs included three populations showing platelet-derived growth factor receptor beta and vimentin expression, indicative of a cancer-associated fibroblast phenotype. Finally, we identified three types of neuronal cells, including chief cells and sustentacular cells, and elucidated their distinct roles in the pathogenesis of CBT and abnormal proliferation of tumors. Overall, our study provided the first comprehensive characterization of the transcriptional landscape of CBT at scRNA-seq profiles, providing novel insights into the mechanisms underlying its formation.

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

INTRODUCTION

Although the ascending pharyngeal artery (APhA) is known as a main feeder of carotid body tumors (CBTs), its detailed architecture and embryological consideration have not been described. The objective of this study was to describe the architecture of a descending feeder of the APhA and to consider its origin embryologically through a review of our CBT embolizations.

METHODS

We retrospectively analyzed data from patients with CBTs who underwent transarterial embolization or angiographic examination-only between July 2010 and February 2017. The arterial supply of the tumors, the number of feeder pedicles, the mean tumor size, embolization materials, complication of embolization, and extent of tumor removal were assessed. The embryological origin of feeding artery was considered based on the literature.

RESULTS

Eighteen patients with 20 CBTs underwent preoperative embolization or angiographic examination. The number of feeder pedicles was significantly related to the size of the CBT (P = 0.0002). The main feeding artery was the descending branch of APhA, which was hypertrophied and tortuous (18/20, 90%). Embryologically, this artery originated from the musculospinal branch and is termed the "descending musculospinal branch".

CONCLUSION

The main feeder of the CBTs was the "descending musculospinal branch" of the APhA and needs special consideration such as dangerous anastomosis for embolization.

Carotid Body Tumor Resection: Just as Safe without Preoperative Embolization

BACKGROUND

Carotid body tumors (CBTs) are rare entities for which surgical resection remains the gold standard. Given their hypervascularity, preoperative embolization is often used; however, controversy exists over whether a benefit is associated. Proponents of embolization argue that it minimizes blood loss and complications. Critics argue that cost and stroke outweigh benefits. This study aimed to investigate the impact of embolization on outcomes following CBT resection.

METHODS

Patients undergoing CBT resection were identified using the Healthcare Cost and Utilization Project State Inpatient Database for 5 states between 2006 and 2013. Patients were divided into 2 groups: carotid body tumor resection alone (CBTR) and carotid body tumor resection with preoperative arterial embolization (CBETR). Descriptive statistics were calculated using arithmetic means with standard deviations for continuous variables and proportions for categorical variables. Patients were propensity score matched on the basis of sex, age, race, insurance, and comorbidity prior to analysis. Risk-adjusted odds of mortality, stroke, nerve injury, blood loss, and length of stay (LOS) were calculated using mixed-effects regression models with fixed effects for age, race, sex, and comorbidities.

RESULTS

A total of 547 patients were identified. Of these, 472 patients underwent CBTR and 75 underwent CBETR. Mean age was 54.7 ± 16 years. Mean number of days between embolization and resection was 0.65 ± 0.72 days (range 0-3). When compared with CBTR, there were no significant differences in mortality for CBETR (1.35% vs. 0%, P = 0.316), cranial nerve injury (2.7% vs. 0%, P = 0.48), and blood loss (2.7% vs. 6.8%, P = 0.245). Following risk adjustment, CBETR increased the odds of prolonged LOS (odds ratio 5.3, 95% confidence interval 2.1-13.3).

CONCLUSIONS

CBT resection is a relatively rare procedure. The utility of preoperative tumor embolization has been questioned. This study demonstrates no benefit of preoperative tumor embolization.

Effective Bleeding Control during Resection of Giant Carotid Body Tumor

Carotid body tumor is a rare neoplasm located at the carotid bifurcation. Ligation and excision of the external carotid artery together with the tumor is preferred in patients with transmural tumor invasion. In those without transmural tumor invasion, temporary occlusion of the external carotid artery at the bifurcation allows trouble-free tumor excision and keeps the external carotid artery intact.

[Experience of surgical treatment of carotid body tumor after preoperative embolization of feeding vessels]

OBJECTIVE

To evaluate the effect of preoperative embolization of the feeding vessels of carotid body tumor in the treatment thereof.

METHODS

33 patients with carotid body tumors not less than 3 cm in diameter were examined by color Doppler ultrasound. Polyvinyl alcohol particle 250-1000 microm in diameter were suspended in meglumine diatrizoate or Ultravist and then injected via microcatheter into the feeding vessels until detainment or reflux was seen. Operation was performed 1 day later on 23 patients and 4 days later on 10 patients. External carotid artery to internal carotid artery bypass was performed on 1 case, anastomosis of common carotid to internal carotid artery with auto-saphenous vein interposition on 3 cases, and repair of internal carotid artery on 1 case.

RESULTS

One-stage resection was completed on all tumors. One case suffered contralateral hemiplegia two times in the operative day, on the next day the contralateral lower limb could move, but the patient could not speak clearly and his tongue was not in right position, after 3 months he was completely recovered and MRI illustrated cranial infarction.

CONCLUSION

An important adjunct in treating large carotid body tumor, preoperative embolization makes the surgical exploration proceed much smoother, blood loss become less, and morbidity lower.

A novel mutation in the SDHD gene responsible for familial paraganglioma. Medical and psychological implications

Familial paragangliomas/pheochromocytomas are dominantly inherited disorders characterized by the development of highly vascularized tumors of the head and neck, derived from non-chromaffin cells of the extra-adrenal paraganglia, and tumors with endocrine activity, derived from chromaffin cells, usually located in the adrenal medulla and pre- and para-vertebral thoracoabdominal regions. Germline inactivating heterozygous mutations in one of the genes encoding for succinate dehydrogenase subunits B, C or D (SDHB, SDHC or SDHD) are responsible for hereditary paragangliomas (PGLs), accounting for nearly 70% of familial cases. Particularly in the SDHD gene, different types of mutations have been found, nevertheless, alterations other than point mutations and deletion leading to missense/nonsense/splicing mutations are extremely rare. Here we report a family with multiple cases of PGL which co-segregates with a novel SDHD gene mutation predictable to give rise to an abnormal gene product (CybS). The identification of the molecular event responsible for PGL in our family made genetic counseling particularly useful for younger first degree relatives at risk to develop this late-onset disease.

Synchronous bilateral carotid body tumor and vagal paraganglioma: a case report and review of literature

We present a case of synchronous bilateral carotid body tumor and vagal paraganglioma in a 49-year-old man who presented with 3 months history of tenderness and palpable neck masses bilaterally. An encapsulated mass which was thought to be a carotid body tumor and an incidental 3 cm x 2 cm, 5 cm x 1 cm, 5 cm mass which seemed to be originated from vagus nerve were dissected from the left side. Pathology revealed carotid body tumor and vagal paraganglioma. Six months after the first operation, the carotid body tumor on the right side was totally excised. A discussion of this case is followed by a review of the literature surrounding this rare clinic and pathological entity.

Stroke from delayed embolization of polymerized glue following percutaneous direct injection of a carotid body tumor

A 52-year-old male with right carotid body tumor underwent direct percutaneous glue (n-butylcyanoacrylate [NBCA]) embolization. Several hours later, he developed left hemiparesis from embolization of the polymerized glue cast. Migration of glue during percutaneous tumor embolization is presumed to occur only in the liquid state, which may lead to stroke or cranial nerve deficits. To the best of our knowledge, this is the first report of delayed glue embolization from a treated hypervascular tumor of the head and neck.

Carotid Body Tumor Resection: Does the Need for Vascular Reconstruction Worsen Outcome?

We evaluated outcomes after carotid body tumor resection (CBR) requiring vascular reconstruction. Patients undergoing CBR at an academic medical center between 1990 and 2005 were identified. Medical records were retrospectively reviewed for clinical data, operative details, Shamblin's classification, tumor pathology, complications, and mortality. Comparisons were performed between those undergoing CBR alone and CBR requiring vascular reconstruction (CBR-VASC). Of the 71 CBRs performed in 62 patients, 16 required vascular reconstruction (23%). Although there was no difference in mean tumor size (CBR 29.1 +/- 11.9 mm, CBR-VASC 32.5 +/- 9.9 mm; p = 0.133), carotid body tumors were more commonly Shamblin's I when CBR was performed alone (CBR 53% vs. CBR-VASC 25%, p = 0.045) and Shamblin's II/III when vascular reconstruction was required (CBR 47% vs. CBR-VASC 75%, p = 0.045). There was also a significant difference in malignant tumor pathology when vascular reconstruction was required (CBR 4.4% vs. CBR-VASC 25%, p = 0.034). Cranial nerve dysfunction was higher in patients requiring vascular repair (CBR 27% vs. CBR-VASC 63%, p = 0.012), but there was no difference in baroreflex failure (CBR 7.27% vs. CBR-VASC 0%, p = 0.351), Horner's syndrome (CBR 5.5% vs. CBR-VASC 6.25%, p = 0.783), or first bite syndrome (CBR 7.27% vs. CBR-VASC 12.5%, p = 0.877). There were no perioperative strokes in either group, and one death was unrelated to operation. When required, carotid artery reconstruction at the time of CBR can be performed safely. Although cranial nerve dysfunction is more common when vascular repair is required, this is more likely related to locally advanced disease and tumor pathology rather than operative techniques.

Management of cervical paragangliomas: review of a 15-year experience

BACKGROUND AND AIMS

Cervical paragangliomas are highly vascular neoplasms and should be considered in the evaluation of all lateral neck masses. The aim of this study is to review an institutional experience in the management of these tumors.

MATERIALS AND METHODS

Thirteen patients with 14 paragangliomas were treated in our institution during a period of 15 years. There were eight women (61.5%) and five men (38.5%) with a mean age of 41.3+/-15 years. A painless lateral neck mass was the main finding in 69.2% of patients. There was no evidence of a functional tumor. Carotid angiography was performed in all patients to define the vascular anatomy of the lesion. The 78.6% of paragangliomas underwent selective embolization of the major feeding arteries. Surgical resection followed within the next 48 h.

RESULTS

The majority of the lesions were paragangliomas of the carotid bifurcation (85.7%), while one patient was diagnosed with a jugular and one with a vagal paraganglioma. In one patient, bilateral paragangliomas in the carotid bifurcation were detected. There was no evidence of malignancy in any case. Preoperative embolization has proven successful in reducing tumor vascularity. Vascular reconstruction was necessary in one patient. The main postoperative complication was transient cranial nerve deficit in seven (53.8%) patients, and a permanent Horner's syndrome was documented in one patient. No stroke occurred. The jugular paraganglioma was treated with irradiation due to skull base extension with significant symptomatic relief.

CONCLUSION

Combined therapeutic approach with preoperative selective embolization followed by surgical resection by an experienced team offers a safe and effective method for complete excision of the tumors with a reduced morbidity rate.

Large Symptomatic Carotid Body Tumor Resection Aided by Preoperative Embolization and Mandibular Subluxation

Carotid body tumors (CBT) are rare and usually benign neoplasms (60%-90%), originating from the mesoderm and neural ectoderm. In view of the extensive and unrelenting growth of unresected CBT, encasing vital neurovascular structures, and the significant incidence of malignancy (> or = 10%), surgical excision is the standard treatment of choice. Despite progress in CBT imaging and surgical technique, cranial nerve deficit, stroke, and death continue to affect 10% to 40% of patients undergoing curative surgical resection, particularly in large tumors proximal to the skull base. In such cases, CBT shrinkage by preoperative embolization, improved surgical access utilizing mandibular subluxation, and electroencephalographic monitoring combined with meticulous surgical technique may enable curative tumor resection, without prohibitive morbidity. In light of associated disability, preoperative acknowledgment of the ever-present substantial risk of cranial nerve injury cannot be overemphasized. We report on a patient with a large symptomatic CBT treated surgically with the aid of mandibular subluxation and preoperative embolization.

Intratumoral injection of cyanoacrylate glue in head and neck paragangliomas

BACKGROUND AND PURPOSE

Substantial intraoperative bleeding during surgical removal of head and neck paragangliomas may be a major problem in the management of these highly vascularized tumors. Traditional preoperative embolization via a transarterial approach has proved beneficial but is often limited by complex vascular anatomy and unfavorable locations. We report our experience with the preoperative devascularization of head and neck paragangliomas by using direct puncture and an intralesional injection of cyanoacrylate.

METHODS

We retrospectively analyzed nine consecutive patients with head and neck paragangliomas who were referred for preoperative devascularization. Three patients were treated for carotid-body tumors; two for vagal lesions; and four, for jugular paragangliomas. Direct puncture of the lesion was performed by using roadmap fluoroscopic guidance. Acrylic glue was injected by using continuous biplane fluoroscopy. All patients underwent postembolization control angiography and immediate postoperative CT scanning.

RESULTS

Angiograms showed that complete devascularization was achieved in all cervical glomus tumors, whereas subtotal devascularization was achieved in jugular paragangliomas. In this latter location, the injection of acrylic glue was limited by the potential risk of reflux into normal brain territory via feeders from the internal carotid or vertebral artery. The tumors were surgically removed and histologically examined. No technical or clinical complications related to the embolization procedure occurred.

CONCLUSION

Percutaneous puncture of paragangliomas in the head and neck region and their preoperative devascularization by intralesional injection of acrylic glue is a feasible, safe, and effective technique.

New approach to preoperative vascular exclusion for carotid body tumor

We report a new approach to preoperative vascular exclusion of a carotid body tumor. Before surgery, covered stents were placed in the external carotid artery, resulting in vascular exclusion of the tumor. Subsequent surgical excision was uneventful, with operative blood loss less than 200 mL and no neurologic complications postoperatively. This technique deserves further consideration as a reasonable alternative to conventional embolization.

[Carotid body tumors - diagnosis and treatment]

Carotid body tumors are rare, with a tendency of slow but progressive growth, giving rise to external compression and/or involvement of the carotid arteries, craniofacial nerves and other neighbouring structures. They are adequately vascularized, with surgery being the treatment of choice. Localization and vascularity require comprehensive understanding of the anatomy, and most likely, vascular surgeons with carotid experience and neurosurgeons would make the best teams. In certain cases the participation of craniofacial surgeon is likewise needed. Over the period 1989 through 1999, in the Department of Vascular Surgery, six patients presenting carotid body tumor are treated. There is not a single case with bilateral involvement, and all have negative family history for carotid body tumor. Two of them are subjected to explorative surgery elsewhere. Two patients only are asymptomatic. In 3 patients CT of the neck, and in one--MRI are used as diagnostic modalities. Five patients undergo carotid artery ultrasonography, and three--angiography. Internal carotid clamping is necessitated in one case only, undergoing explorative surgery at another hospital and presenting a big tumor, stage III (Shamblin). Postoperatively, the patients complain of slight deviation of the tongue and slurred speech. The check-up carotid ultrasound shows hemodynamically relevant stenosis of the internal carotid artery, 1 cm distally to the carotid bifurcation, without flow into the external carotid being detected. On follow-up, all patients are alive and free of local recurrences or metastases.

Evaluation of paragangliomas presenting as a cervical mass on color-coded Doppler sonography

OBJECTIVES

To assess the potential of color Doppler sonography to identify cervical mass lesions as paragangliomas.

STUDY DESIGN

Prospective evaluation.

METHODS

Fifteen patients with 18 paragangliomas (13 carotid body tumors, 3 vagal and 2 temporal) presenting as a mass in the neck were investigated using color Doppler sonography.

RESULTS

All paragangliomas presented in B-mode sonography as solid, well-defined, and hypoechoic tumors. Color Doppler imaging revealed hypervascularity in 15 (82%) tumors. No flow signal was detected in 3 carotid body tumors at standard velocity encoding (30 cm/s). Only carotid body tumors could be assessed in their full extent. Temporal and vagal paragangliomas were only partially visible. Carotid body tumors showed a splaying of the carotid bifurcation with displacement of the external carotid anteriorly and both the internal carotid and the internal jugular vein posteriorly. Anterior displacement of both carotid arteries and posterior displacement of the internal jugular vein was found in the 3 vagal paragangliomas. The caudal tumor extension of the 2 temporal paragangliomas was recognized within the expanded lumen of the internal jugular vein. According to the direction of tumor growth and vascular supply, the intratumoral flow signal was predominantly directed upward in carotid body tumors and downward in vagal and temporal paragangliomas.

CONCLUSIONS

Based on the appearance in the B-mode, the hypervascularity, the relationship toward the carotid arteries and the internal jugular vein, and the intratumoral flow direction, color Doppler sonography was able to establish the diagnosis and type of a paraganglioma.

Carotid body tumors: the role of preoperative embolization

Resection of carotid body tumors (neck paragangliomas) carries inherent risks of injury to the cranial nerves and other structures as well excessive blood loss. Preoperative embolization has been used to lessen the morbidity in tumors that are larger than 2 cm in diameter. Two female patients presented for treatment with large asymptomatic carotid body tumors-one 4 cm and one 5 cm in diameter. Both patients had preoperative angiography the day before surgery that revealed the feeding arterial vessels so that successful embolization could be accomplished with gel. Success was judged by diminution of the angiographic blush. Both patients had an uneventful surgical excision the following day with the carotid body tumors being able to be resected periadventitially without damage to either the external or internal carotid artery. The cranial nerves were preserved in both patients and blood loss was only 200 cc in both cases. We conclude that preoperative embolization is an important adjunct in treating patients with large carotid body tumors. The surgical exploration proceeds much smoother, the blood loss is minimal, and patients have minimal morbidity.

[Carotid body tumors: contribution of the various imaging techniques. A report of six cases]

INTRODUCTION

Carotid body tumors are rare hypervascular lesions arising from neural crest paraganglion cells.

MATERIALS AND METHODS

We retrospectively analyzed the imaging features of six patients with carotid body tumors to precise their imaging characteristics in order to find specific signs and elaborate a strategy for diagnosis.

RESULTS

Imaging features detect the vascular nature of these tumors of the carotid space causing characteristic widening of the carotid bifurcation. Two patients had multiple (two or more) localizations and one had a family history of glomus tumor.

CONCLUSION

MRI with MRA is considered as the gold standard imaging technique for the evaluation of glomus tumors as it allows a multiplanar approach which is important in the preoperative study.

Power Doppler scanning in the diagnosis of carotid body tumors

The aim of this work was to show contribution of power Doppler imaging in the diagnosis of the carotid body tumors. Six patients with a nontender mass beneath the mandibular angle were evaluated with gray scale and power Doppler sonography. Well-defined, solid, weakly hyperechoic masses were noted on gray scale sonography in the carotid bifurcation. Power Doppler sonography showed abundant flow, characterized as an intense blush, throughout the entire tumor in all patients. We believe that invasive and expensive diagnostic modalities are not necessary to evaluate carotid body tumors. Gray scale sonography and power Doppler imaging are sufficient for primary diagnosis of carotid body tumors.

Diagnostic and therapeutic approaches to carotid body tumours: report of three cases and review of the literature

BACKGROUND

Carotid body tumour is a rare neoplasm of the carotid body. Three cases of carotid body tumour presenting as a painless progressive mass in the neck region are reported here. A review of the relevant literature regarding carotid body tumours is also presented.

METHODS

Angiographic features were diagnostic of carotid body tumour and complete surgical excision was done.

RESULTS

There was no mortality and minimum morbidity. There were no malignant tumours. All three patients belong to the high-altitude area of Himachal Pradesh.

CONCLUSIONS

A high degree of clinical suspicion of upper posterior triangle neck masses and an accurate diagnostic work-up are needed for operative planning.

Color Doppler imaging of paragangliomas in the neck

PURPOSE

In this study, we describe the color Doppler imaging findings in carotid body tumors and vagal body tumors.

METHODS

B-mode and color Doppler imaging were performed on 17 patients who had a total of 25 previously diagnosed paragangliomas (14 carotid body tumors and 11 vagal body tumors).

RESULTS

Nineteen of 25 tumors were depicted. Five small vagal body tumors in the region of the nodose ganglion and 1 carotid body tumor could not be depicted. With B-mode imaging, paragangliomas appeared as well-defined, solid, hypoechoic masses. With color Doppler imaging, hypervascularity with a low-resistance flow pattern was demonstrated in all but 1 of the 19 tumors.

CONCLUSIONS

The use of color Doppler imaging in the workup of an ambiguous neck mass is advocated.

Magnetic resonance angiography in neck masses

Carotid MR angiography has primarily been used to evaluate for stenotic lesions. We performed 2D time of flight MR angiography in 25 patients with palpable neck masses. There were 23 masses confirmed histologically. Two of the masses represented abnormal carotid arteries. Carotid deviation was seen in 23 of 25 (92%) of patients. Widening of the carotid bifurcation was identified in seven patients, including four carotid body tumors, one inflammatory mass, one benign salivary gland tumor, and one schwannoma. Increased vascularity was identified in one carotid body tumor and in one metastatic papillary carcinoma of the thyroid. MR angiography may be useful to demonstrate flow within vessels and represents a familiar imaging display for surgical planning. Splaying of the carotid bifurcation is useful in demonstrating carotid space lesions.

[The role of color duplex ultrasound in diagnosis and differential diagnosis of carotid body tumors]

BACKGROUND

Currently the diagnosis of tumorous lesions of the carotid bifurcation is the domain of magnetic resonance imaging (MRI) and digital subtraction angiography (DSA). So far, colour Doppler imaging (CDI) has not been playing an important part in this field. The aim of this study was to define the diagnostic value of CDI in the evaluation of these tumours related to the big arteries and to compare the different imaging techniques.

PATIENTS AND METHODS

6 female patients with suspected tumours of the carotid bifurcation were examined with CDI. Additionally 5 MRI examinations and 3 preoperative diagnostic DSA examinations were performed in the same patients. Pathologically, there were 4 typical carotid body tumours, 1 neuroma of the sympathetic trunk and 1 multifocal paraganglioma of the neck.

RESULTS

In carotid body tumours we found a characteristic broadening of the bifurcation with shifting of the internal carotid artery posteriorly and laterally and of the external carotid artery anteriorly and medially. The highly vascularized tumour is surrounded by the arteries. This combination of ultrasound findings was absent in cases of sympathetic neuroma and multifocal paraganglioma. No additional information was achieved with MRI and DSA.

CONCLUSION

CDI and MRI evaluation revealed the same diagnostic value in cases of vascularised tumours of the carotid bifurcation. CDI proved to be as accurate as DSA in the imaging of the big arteries and their relationship to the tumour, as well as of the small tumour feeding vessels. Therefore DSA may be omitted as an invasive diagnostic tool in the diagnosis of carotid body tumours.

[Usefulness of three-dimensional CT angiography for cervical tumor]

In this study, the usefulness of three-dimensional angiographic imagings from helical scanning computed tomography (CT) enhanced by contrast media were evaluated based on results from three patients with a cervical mass, e.g. thyroid cancer and carotid body tumor. Three-dimensional CT (3D-CT) angiographic imagings in these cases clearly demonstrated secondary dislocation or distortion of the major cervical vessels caused by the tumor or metastatic lymph nodes. It was remarkable that in the highly vascularized tumor in case 3, all features of the tumor were delineated by 3D-CT angiography. Our results indicate that 3D-CT angiographic imagings are especially useful for preoperative evaluation of the relationship of the cervical mass to major cervical vessels as well as in the observation of tumors rich in vasculature.

[Rare neck tumors: neurogenic tumors and carotid glomus tumors]

Among the rare tumors of the neck, neurogenic tumors and paraganglioma of the carotid body are discussed. Special emphasis is placed on a preoperative diagnosis of the carotid paraganglioma.

[Lateral neck paraganglioma: diagnostic imaging and preoperative embolization]

Sixteen paragangliomas of the neck were reviewed. Lesions were found in the carotid body (n = 12), vagal nerve (n = 3) and larynx (n = 1). While paragangliomas were often misdiagnosed clinically, CT scanning defined the extent of the disease. MR was able to accurately characterize the tumors as highly vascular. Multiplanar imaging, exquisite tissue contrast and anatomic detail allowed better display of the relationship between these neoplasms and surrounding carotid sheath vessels and intracranial structures. MR constitutes the imaging modality of choice in carotid body tumor. Arteriography is necessary for definite diagnosis and presurgical embolization.

Carotid body tumor: flow sensitive pulse sequences and MR angiography

The magnetic resonance (MR) appearance of carotid body tumors has been previously described. Classically, these lesions are well circumscribed and highly vascular and cause a characteristic separation of the external and internal carotid arteries. Hypointense foci within these tumors are seen on T1-weighted images. The T2-weighted images snow a "salt and pepper" pattern. We report a carotid bifurcation glomus tumor that exhibited the above features on conventional MR. Multiplanar gadolinium enhanced MR as well as flow-sensitive MR techniques including small flip angle gradient refocused images and MR angiography were performed. Magnetic resonance angiography demonstrated the abnormal morphology of the carotid bifurcation. Axial gradient refocused images revealed evidence of flow within the lesion. The findings were then correlated with postcontrast CT, arterial digital subtraction angiography, and histopathology.

Surgical treatment of carotid paragangliomas presenting unusual technical difficulties. The value of preoperative embolization

Although the application of reconstructive vascular surgical procedures to the treatment of carotid paragangliomas has made their resection the method of choice and has produced excellent cure rates, it has not obviated some of the technical problems presented by excessively vascular, adherent, or bulky lesions. Our experience with preoperative trans-catheter embolization for the reduction of the vascularity in six cases of this group of lesions is presented and the conclusion is made that preoperative embolization greatly reduced operative technical difficulties.

Carotid body tumors: a subject review and suggested surgical approach

Carotid body tumors are a rare but potentially difficult surgical entity. Their pathology, physiology, and natural history are reviewed along with surgical results reported in the literature. A surgical approach for removal of these tumors is presented which differs significantly from the recommended techniques in that emphasis is placed on intraoperative monitoring of cerebral blood flow, the the selective use of shunts, a tumor-adventitial plane of dissection, preservation of the carotid artery complex, and mobilization of the parotid gland. Thirteen cases using these techniques are reviewed. The mortality rate and the incidence of cerebrovascular sequelae were both 0%. The major morbidity consisted of injury to the lower cranial nerves in five patients (39%) with tumors larger than 5 cm in length.

Vascular problems associated with carotid body tumors

In the last 25 years at the University of Toronto, 27 patients with carotid body tumors were encountered. All patient problems appeared to be related to delay in treatment, size of the tumor, and previous operations. To minimize hazard in this procedure, one should avoid operating on elderly and unfit patients, and otherwise operate early to avoid the problem of a bulky tumor, using a simple subadventitial approach while reserving complete carotid excision and vascular replacement for complicated adherent lesions. Preoperative angiography is mandatory for definitive diagnosis, which permits proper planning of available operating room time, blood replacement, and availability of workers with expertise in vascular surgery. Adequate surgery is effective in tumor clearance, preventing malignant transformation and the lethal effects of local growth.