Jugulotympanic paragangliomas

Single-cell RNA-Seq reveals the heterogeneity of fibroblasts within the tympanojugular paraganglioma microenvironment

Tympanojugular paragangliomas (TJP) originate from the parasympathetic ganglia in the lateral base of the skull. Although the cellular composition and oncogenic mechanisms of paragangliomas have been evaluated, a comprehensive transcriptomic atlas specific to TJP remains to be established to facilitate further investigations. In this study, single-cell RNA sequencing and whole-exome sequencing were conducted on six surgically excised TJP samples to determine their cellular composition and intratumoral heterogeneity. Fibroblasts were sub-classified into two distinct groups: myofibroblasts and fibroblasts associated with bone remodeling. Additionally, an elaborate regulatory and cell-cell communication network was determined, highlighting the multifaceted role of fibroblasts, which varies depending on expression transitions. The Kit receptor (KIT) signaling pathway mediated interactions between fibroblasts and mast cells, whereas robust connections with endothelial and Schwann cell-like cells were facilitated through the platelet-derived growth factor signaling pathway. These findings establish a foundation for studying the mechanisms underlying protumor angiogenesis and the specific contributions of fibroblasts within the TJP microenvironment. IL6 signaling pathway of fibroblasts interacting with macrophages and endothelial cells may be involved in tumor regrowth. These results enhance our understanding of fibroblast functionality and provide a resource for future therapeutic targeting of TJP.

Anatomical Variations of the Ascending Pharyngeal Artery: Implications for Endoscopic Surgery in the Parapharyngeal Space

Objectives: The ascending pharyngeal artery (APA) travels with the parapharyngeal internal carotid artery (pICA) in the parapharyngeal space (PPS). This study aimed to investigate the anatomical variations of the APA, and to explore their implications for endoscopic surgery in the PPS. Methods: Dissection of the APA in the PPS was performed on 10 cadaveric specimens (20 sides). The relationship between APA and PPS tumors was retrospectively reviewed in 20 patients, attempting to ascertain the APA during the resection of 10 pre-styloid and 10 retro-styloid PPS tumors. Results: During the cadaveric dissections, the APA was identified at the medial, posteromedial, or bilateral aspects of the pICA in 12 (60%) and 4 (20%) sides, respectively. In the remaining 4 sides (20%), the APA branched into several subcategory arteries lying at the medial and lateral aspects of the pICA. Branches of the APA were observed in 13/20 sides (65%). Two branches were found in 9/13 sides and 3 branches in 4/13, respectively. The APA was only identifiable in 1/10 (10%) of pre-styloid tumors, a patient with basal cell adenoma. In contrast, the APA was encountered surrounding the pICA in 8/10 (80%) of patients with retro-styloid tumors, all of which were schwannomas. No inadvertent injury of the APA or the pICA occurred in this cohort. Conclusions: With identification of the ascending pharyngeal artery on preoperative magnetic resonance imaging, it may serve as an additional landmark during the endoscopic extirpation of tumors arising in the PPS.

Comprehensive Genetic Study of Malignant Cervical Paraganglioma

Malignant middle ear paraganglioma (MEPGL) is an exceedingly rare tumor of the neuroendocrine system. In general, MEPGLs represent as slow growing and hypervascularized benign neoplasms. The genetic basis of MEPGL tumorigenesis has been poorly investigated. We report a case of malignant MEPGL accompanied by the comprehensive genetic analysis of the primary tumor and metastasis. Based on whole-exome sequencing data, the germline pathogenic mutation p.R230H in the SDHB gene, encoding for subunit B of mitochondrial complex II, was found in a patient. Analysis of somatic mutation spectra revealed five novel variants in different genes, including a potentially deleterious variant in UNC13C that was common for the tumor and metastasis. Identified somatic variants clustered into SBS1 and SBS5 mutational signatures. Of note, the primary tumor was characterized by Ki-67 4% and had an elevated mutational load (1.4/Mb); the metastasis' mutational load was about 4.5 times higher (6.4/Mb). In addition, we revealed somatic loss of the wild-type SDHB allele, as well as loss of heterozygosity (LOH) at the 11p locus. Thus, germline mutation in SDHB combined with somatic LOH seem to be drivers that lead to the tumor's initiation and progression. Other somatic changes identified can be additional disease-causing factors. Obtained results expand our understanding of molecular genetic mechanisms associated with the development of this rare tumor.

Surgery of the ear and the lateral skull base: pitfalls and complications

Surgery of the ear and the lateral skull base is a fascinating, yet challenging field in otorhinolaryngology. A thorough knowledge of the associated complications and pitfalls is indispensable for the surgeon, not only to provide the best possible care to his patients, but also to further improve his surgical skills. Following a summary about general aspects in pre-, intra-and postoperative care of patients with disorders of the ear/lateral skull base, this article covers the most common pitfalls and complications in stapes surgery, cochlear implantation and surgery of vestibular schwannomas and jugulotympanal paragangliomas. Based on these exemplary procedures, basic "dos and don'ts" of skull base surgery are explained, which the reader can easily transfer to other disorders. Special emphasis is laid on functional aspects, such as hearing, balance and facial nerve function. Furthermore, the topics of infection, bleeding, skull base defects, quality of life and indication for revision surgery are discussed. An open communication about complications and pitfalls in ear/lateral skull base surgery among surgeons is a prerequisite for the further advancement of this fascinating field in ENT surgery. This article is meant to be a contribution to this process.

Rehabilitation after treatment for jugular foramen lesions

Swallowing problems following jugular foramen surgery are more common than is often acknowledged and affect up to a third of our patients. They have a significant effect on quality of life. We have become more proactive in this respect and anticipate these problems before they become established. In this article we present our management protocol that has evolved over the past 30 years as a result of our experience treating 134 glomus jugulare tumors. Our current protocol involves a thorough preoperative assessment of swallowing. After jugular foramen surgery, patients undergo further evaluation using fiberoptic endoscopic evaluation of swallowing (FEES), videofluoroscopy, and manometry. Those with prolonged or poorly compensated dysphagia are offered rehabilitation surgery. We describe this technique, which has proved beneficial to our patients. Guidelines for management are proposed.

The glossopharyngeal, vagus and spinal accessory nerves

The glossopharyngeal, vagus and spinal accessory nerves are closely related anatomically, and to a certain extent, functionally. We present an overview of their anatomy, highlighting the important clinical and imaging implications. The main pathologic lesions arising from these nerves are also discussed and the imaging features reviewed.

The ascending pharyngeal artery and its relevance for neurosurgical and endovascular procedures

OBJECTIVE

The ascending pharyngeal artery (APA), a branch of the external carotid artery (ECA), supplies the lower cranial nerves, superior cervical ganglion, and nasopharyngeal structures. The APA can also supply blood to various intracranial lesions. We studied the anatomy of the APA in the context of its neurosurgical and endovascular relevance.

METHODS

The cervical origin, branching pattern, and course of the APA were studied in 20 human cadaveric craniocervical sides. The diameter of the APA, the extension of its main trunk, and the distance of its origin from the common carotid artery bifurcation were measured. The relationships between the APA and surrounding structures were also observed.

RESULTS

In 80% of the specimens, the APA originated from the ECA. It originated from its medial wall in 56% and from the posterior wall in 44%. The APA originated from the internal carotid artery, common carotid artery bifurcation, occipital artery, and a trunk common to the lingual and facial arteries in 5% each. The APA was usually the third branch of the ECA (40%). The mean distance from the origin of the APA to the common carotid artery bifurcation was 15.3 mm (range, 0-32; standard deviation, +/- 8.3 mm). The APA was frequently the second smallest branch of the ECA (caliber, 1.54 mm; range, 1.1-2.1; standard deviation, +/- 0.25 mm).

CONCLUSION

The APA is an important channel for supplying neural structures of the posterior fossa. Knowledge of its anatomy, variants, and anastomotic channels is essential in the treatment of lesions supplied by its branches and to avoid complications related to its inadvertent injury.

Vascular Lesions of the Skull Base: Endovascular Prospective for the Otolaryngologist

With continual advances being made in endovascular equipment and techniques, the role that these image-guided, minimally invasive therapies play in the multidisciplinary management of vascular lesions of the skull base will probably continue to expand. The introduction of emerging technologies, including the development and implementation of implantable bioactive devices such as drug-eluting stents, bioactive embolic coils, and bioactive particulate embolic materials, will provide an increasing array of options for these patients. This article has reviewed the basic concepts of embolization and revascularization for vascular lesions of the skull base encountered by the practicing otolaryngologist. These concepts can provide a framework for collaboration between the otolaryngologist and neuroendovascular operator in a cooperative approach to these patients. The importance of detailed knowledge of the vascular anatomy of the skull base when dealing with these lesions, the concept of dangerous anastomoses, several clinically useful classification schemes for these lesions, and basic endovascular techniques of embolization and revascularization have been highlighted.

Paraganglioma presenting as chronic otitis media with cholesteatoma: pitfalls and strategies

The coexistence of paraganglioma with cholesteatoma is a very rare clinical disorder. The clinical presentations are nonspecific. There may be radiological characteristics of either cholesteatoma or paraganglioma in the middle ear area, but the diagnosis of the coexistence of the 2 is usually made only postoperatively. Here is such a case that is made more interesting not only because it initially presented with conductive hearing loss but also because the clinical picture mimicked chronic otitis media. The patient underwent postauricular tympanomastoidectomy with extended facial recess approach to remove the tumor. No evidence of recurrence and complications were noted.

Cerebellopontine angle paraganglioma

BACKGROUND

Acoustic neuroma account for 80% of cerebellopontine angle tumors. Paraganglioma is a rare tumor in this region.

OBJECTIVE

The authors report a case of cerebellopontine angle paraganglioma arising from the anterior inferior cerebellar artery.

RESULTS

The clinical and radiologic features were indistinguishable from those of a neuroma, and only the intraoperative view showed a vascular tumor. Definitive diagnosis was made by histopathologic methods.

CONCLUSIONS

This unique paraganglioma location may be explained by existing embryologic data. The minimal retrosigmoid approach, assisted by endoscopy, allows safe and complete removal of the tumor.