Surgical Anatomy of the Jugular Foramen

Jugular Foramen Paragangliomas

Paragangliomas are the most common tumors at jugular foramen and pose a great surgical challenge. Careful clinical history and physical examination must be performed to adequately evaluate neurological deficits and its chronologic evolution, also to delineate an overview of the patient performance status. Complete imaging evaluation including MRI and CT scans should be performed, and angiography is a must to depict tumor blood supply and sigmoid sinus/internal jugular vein patency. Screening for multifocal paragangliomas is advisable, with a whole-body imaging. Laboratory investigation of endocrine function of the tumor is necessary, and adrenergic tumors may be associated with synchronous lesions. Preoperative prepare with alpha-blockage is advisable in norepinephrine/epinephrine-secreting tumors; however, it is not advisable in exclusively dopamine-secreting neoplasms. Best surgical candidates are young otherwise healthy patients with smaller lesions; however, treatment should be individualized each case. Variations of infratemporal fossa approach are employed depending on extensions of the mass. Regarding facial nerve management, we avoid to expose or reroute it if there is preoperative function preservation and prefer to work around facial canal in way of a fallopian bridge technique. If there is preoperative facial nerve compromise, the mastoid segment of the nerve is exposed, and it may be grafted if invaded or just decompressed. A key point is to preserve the anteromedial wall of internal jugular vein if there is preoperative preservation of lower cranial nerves. Careful multilayer closure is essential to avoid at most cerebrospinal fluid leakage. Residual tumors may be reoperated if growing and presenting mass effect or be candidate for adjuvant stereotactic radiosurgery.

Modern Management of Complex Tympanojugular Paragangliomas: Systematic Review and Meta-Analysis

OBJECTIVE

Tympanojugular paragangliomas (TJPs) are slow-growing tumors arising within the middle ear or jugular foramen. The development of modified skull base approaches and the increasing use of stereotactic radiosurgery have provided more modern techniques in the management of TJPs. Several factors dictating approach selection, and resulting clinical outcomes have been inconsistently described.

METHODS

A systematic review of the literature describing modern management of complex TJPs was performed and summarized. A random-effects meta-analysis was performed to describe the rate of tumor control, complications, and symptom improvement in patients undergoing radiosurgery or surgical resection.

RESULTS

Nineteen studies were identified with a total of 852 TJP patients. A minority (153 patients) underwent radiosurgery while 699 underwent surgery. On meta-analysis, there was a 3.5% (95% confidence interval [CI]: 0.5%-6.4%) tumor growth rate following radiosurgery and 3.9% (95% confidence interval [CI]: 1.8%-6.0%) recurrence rate in surgical resection, with no significant moderator effect between the 2 groups (P = 0.9046). Complication rate for radiosurgery was 7.6% (95% CI: 2.8%-12.4%), differing significantly from surgical complication rates of 29.6% (95% CI: 17.1-42.0%, P = 0.0418).

CONCLUSIONS

Stereotactic radiosurgery and surgical resection for TJPs have similar rates of tumor recurrence. Radiation is associated with less risk and lower morbidity, yet there is comparably modest reduction of the tumor size. In sum, the data suggest that radiosurgery is a reasonable management option for patients with minimal symptoms who are high risk for surgery. Microsurgical resection should be reserved for patients with lower cranial neuropathies or those who have failed radiation treatment.

Anatomical study of jugular foramen in the neck

Introduction

The anatomical complexity of the jugular foramen makes surgical procedures in this region delicate and difficult. Due to the advances in surgical techniques, approaches to the jugular foramen became more frequent, requiring improvement of the knowledge of this region anatomy.

Objective

To study the anatomy of the jugular foramen, internal jugular vein and glossopharyngeal, vagus and accessory nerves, and to identify the anatomical relationships among these structures in the jugular foramen region and lateral-pharyngeal space.

Methods

A total of 60 sides of 30 non-embalmed cadavers were examined few hours after death. The diameters of the jugular foramen and its anatomical relationships were analyzed.

Results

The diameters of the jugular foramen and internal jugular vein were greater on the right side in most studied specimens. The inferior petrosal sinus ended in the internal jugular vein up to 40 mm below the jugular foramen; in 5% of cases. The glossopharyngeal nerve exhibited an intimate anatomical relationship with the styloglossus muscle after exiting the skull, and the vagal nerve had a similar relationship with the hypoglossal nerve. The accessory nerve passed around the internal jugular vein via its anterior wall in 71.7% of cadavers.

Conclusion

Anatomical variations were found in the dimensions of the jugular foramen and the internal jugular vein, which were larger in size on the right side of most studied bodies; variations also occurred in the trajectory and anatomical relationships of the nerves. The petrosal sinus can join the internal jugular vein below the foramen.

Meningeal Architecture of the Jugular Foramen: An Anatomic Study Using Plastinated Histologic Sections

OBJECTIVE

This 3-dimensional histologic study aimed to provide a precise description of the meningeal structures in the jugular foramen.

METHODS

22 posterior skull base tissue blocks containing the jugular foramen region were obtained from 11 human cadaveric heads. These blocks were plastinated and cut into serial sections. After staining, these sections were examined under an optical microscope and used to reconstruct a 3-dimensional visualization model.

RESULTS

At the intracranial orifice of the jugular foramen, the meningeal dura formed 2 separate dural perforations: the glossopharyngeal meatus and the vagal meatus. The arachnoid extended into 2 dural meatuses and terminated at the inferior ganglion of the glossopharyngeal nerve in the glossopharyngeal meatus and the superior ganglion of the vagus nerve in the vagal meatus. At the intraforaminal part of the jugular foramen, the meningeal dura encased the glossopharyngeal nerve to form a dural sheath while encasing the vagus and accessory nerves to form a dural network. At the extracranial orifice of the jugular foramen, the dural wall of the jugular bulb extended downward to form a dense connective tissue sheath. The initial end of the internal jugular vein invaginated into this sheath and fused with the jugular bulb.

CONCLUSIONS

Knowledge of the anatomy of the meningeal architecture of the jugular foramen can be helpful in avoiding surgical complications of the lower cranial nerves when this complex area is approached.

The interperiosteodural concept applied to the jugular foramen and its compartmentalization

OBJECTIVE

The dura mater is made of 2 layers: the endosteal layer (outer layer), which is firmly attached to the bone, and the meningeal layer (inner layer), which directly covers the brain and spinal cord. These 2 dural layers join together in most parts of the skull base and cranial convexity, and separate into the orbital and perisellar compartments or into the spinal epidural space to form the extradural neural axis compartment (EDNAC). The EDNAC contains fat and/or venous blood. The aim of this dissection study was to anatomically verify the concept of the EDNAC by focusing on the dural layers surrounding the jugular foramen area.

METHODS

The authors injected 10 cadaveric heads (20 jugular foramina) with colored latex and fixed them in formalin. The brainstem and cerebellum of 7 specimens were cautiously removed to allow a superior approach to the jugular foramen. Special attention was paid to the meningeal architecture of the jugular foramen, the petrosal inferior sinus and its venous confluence with the sigmoid sinus, and the glossopharyngeal, vagus, and accessory nerves. The 3 remaining heads were bleached with a 20% hydrogen peroxide solution. This procedure produced softening of the bone without modifying the fixed soft tissues, thus permitting coronal and axial dissections.

RESULTS

The EDNAC of the jugular foramen was limited by the endosteal and meningeal layers and contained venous blood. These 2 dural layers joined together at the level of the petrous and occipital bones and separated at the inferior petrosal sinus and the sigmoid sinus, and around the lower cranial nerves, to form the EDNAC. Study of the dural sheaths allowed the authors to describe an original compartmentalization of the jugular foramen in 3 parts: 2 neural compartments—glossopharyngeal and vagal—and the interperiosteodural compartment.

CONCLUSIONS

In this dissection study, the existence of the EDNAC concept in the jugular foramen was demonstrated, leading to the proposal of a novel 3-part compartmentalization, challenging the classical 2-part compartmentalization, of the jugular foramen.

[Approach to the jugular foramen and related structures - an analysis of the surgical technique based on cadaver simulation]

This study presents consecutive stages of the approach to the jugular foramen and related structures. Eleven simulations of the approach were performed on non-fixed human cadavers without any known pathologies in the head and neck. The consecutive stages of the procedure were documented with photographs and schematic diagrams. The starting point for the discussed approach is removal of the mastoid and petrosal parts of the temporal bone, as well as the jugular process and the jugular tuberculum. It allows penetration of the jugular foramen from the back. Widening of the approach enables penetration of the jugular foramen from above and the front. Approach to the jugular foramen is a reproducible technique, which provides surgical penetration of this foramen and related structures. This approach is particularly useful in the surgical treatment of tumours expanding in the petrous pyramid, surroundings of the petrosal part of the internal carotid artery, cerebellopontine angle, subtemporal fossa and nervous-vascular bundle of the neck.

The chemical neuroanatomy of vagus nerve stimulation

In this short overview a reappraisal of the anatomical connections of vagal afferents is reported. The manuscript moves from classic neuroanatomy to review details of vagus nerve anatomy which are now becoming more and more relevant for clinical outcomes (i.e. the therapeutic use of vagus nerve stimulation). In drawing such an updated odology of central vagal connections the anatomical basis subserving the neurochemical effects of vagal stimulation are addressed. In detail, apart from the thalamic projection of central vagal afferents, the monoaminergic systems appear to play a pivotal role. Stemming from the chemical neuroanatomy of monoamines such as serotonin and norepinephrine the widespread effects of vagal stimulation on cerebral cortical activity are better elucidated. This refers both to the antiepileptic effects and most recently to the beneficial effects of vagal stimulation in mood and cognitive disorders.

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.

Morphology and compartmentation of the jugular foramen in adult Indian skulls

PURPOSE

Knowledge of the complex anatomy of the jugular foramen is vital for a favorable surgical outcome in technically challenging operations of this region. Various reports about the compartmentation of this foramen and the contents passing through them have come up with conflicting observations.

METHOD

As many as 116 dry, adult skulls were utilized to study the morphology and the compartmentation of the jugular foramen.

RESULTS

The study demonstrates and describes the precise location and frequency of occurrence of processes bridging the foramen and clarifies the existing ambiguity and confusion regarding the compartmentation and the contents passing through. A comprehensive classification for the bridging pattern and compartmentation of the jugular foramen is suggested.

CONCLUSION

This information will be of help to the clinicians for understanding clinical presentations and progression of the lesions of the jugular foramen region and planning for the operations.