Minimally invasive surgical exposure of the extreme high cervical internal carotid artery: anatomical study

Lower Four Cranial Nerves in the Management of Glomus Jugulare: Anatomical Study

Introduction  The surgical management that achieves minimal morbidity and mortality for patients with glomus and non-glomus tumors involving the jugular foramen (JF) region requires a comprehensive understanding of the complex anatomy, anatomic variability, and pathological anatomy of this region. Objective  The aim of this study is to propose a rational guideline to expose and preserve the lower cranial nerves (CNs) in the lateral approach of the JF. Methods  The technique utilized is the gross and microdissection of 4 fixed cadaveric heads to revise the JF's surgical anatomy and high part of the carotid sheath compared with surgical cases to understand and preserve the integrity of lower CNs. The method involves radical mastoidectomy, microdissection of the JF, facial nerve, and high neck just below the carotid canal and the JF. The CNs IX, X, XI, and XII are microscopically dissected and kept in sight up to the JF. Results  This study realized well the surgical and applied anatomy of the lower CNs with relation to the facial nerve and JF. Conclusions  The JF anatomy is complicated, and the key to safely operate on it and preserving the lower CNs is to find the posterior belly of the digastric muscle, to skeletonize the facial nerve, to remove the mastoid tip preserving the stylomastoid foramen, to skeletonize the sigmoid sinus and posterior fossa dura not only anterior but also posteroinferior to reach and drill the jugular tubercle.

The Posterior Belly of Digastric Muscle as the Landmark in Facial Nerve Anastomosis Surgery: Anatomical Study and Case Illustration

OBJECTIVE

To establish a new method for fast exposure of the facial nerve and hypoglossal nerve during facial nerve anastomosis surgery.

METHODS

Dissection of 12 formalin-fixed cadaveric specimens was performed to explore the positional relationship between the posterior belly of digastric muscle (PBD) and the facial nerve and hypoglossal nerve. We retrospectively reviewed patients who underwent facial nerve reconstruction surgery between 2015 and 2020 at Xuanwu Hospital, Capital Medical University, and the optimized surgical strategy based on the PBD was proposed.

RESULTS

The trunk of the hypoglossal nerve runs across the external carotid artery after giving off the descendens hypoglossi located within the 1-cm scope deep to the junction of the tendon and belly of the PBD. The mean depth difference between the hypoglossal nerve and the junction of the tendon and belly of the PBD was 5.48 ± 2.24 mm (range, 1.88-9.27 mm). The stylomastoid foramen segment of the facial nerve was revealed after the parotid gland was dissected within the angle between the anterior margin of the mastoid tip and the inferior margin of the cartilage of the external acoustic meatus.

CONCLUSIONS

The facial nerve and hypoglossal nerve can be rapidly identified using the PBD as an anatomical landmark. The end-to-end facial-descendens hypoglossi anastomosis is a reliable facial nerve reconstruction method for patients whose facial nerve was damaged during operation.

Surgical access to the distal cervical segment of the internal carotid artery and to a high carotid bifurcation – integrative literature review and protocol proposal

Abstract Several different maneuvers have been described for obtaining access to the distal cervical segment of the internal carotid artery or to a high carotid bifurcation. However there are different approaches to systematization of these techniques. The objective of this study is to review the techniques described and propose a practical protocol to support selection of the most appropriate technique for each case. The review is based on the results of database searches on PubMed Central, the Virtual Health Library (BVSalud), and SciELO for articles on the subject published in English or Portuguese from 1980 to 2021. Among the different maneuvers described, it appears reasonable that the first two steps should be to obtain access at the sternocleidomastoid muscle, followed by section or retraction of the digastric muscle posterior belly. If needed, temporary unilateral mandibular subluxation is an additional resource that is preferable to division of the styloid apparatus process, because of its lesser potential for morbidity. Even wider exposure can be obtained using mandibular osteotomies.

Acesso cirúrgico ao segmento cervical distal da artéria carótida interna e à bifurcação carotídea alta – revisão integrativa da literatura e proposta de protocolo

Several different maneuvers have been described for obtaining access to the distal cervical segment of the internal carotid artery or to a high carotid bifurcation. However there are different approaches to systematization of these techniques. The objective of this study is to review the techniques described and propose a practical protocol to support selection of the most appropriate technique for each case. The review is based on the results of database searches on PubMed Central, the Virtual Health Library (BVSalud), and SciELO for articles on the subject published in English or Portuguese from 1980 to 2021. Among the different maneuvers described, it appears reasonable that the first two steps should be to obtain access at the sternocleidomastoid muscle, followed by section or retraction of the digastric muscle posterior belly. If needed, temporary unilateral mandibular subluxation is an additional resource that is preferable to division of the styloid apparatus process, because of its lesser potential for morbidity. Even wider exposure can be obtained using mandibular osteotomies.

Preauricular retromandibular trans tympanic plate and styloid process keyhole approach to parapharyngeal lesions: a laboratory study

BACKGROUND

The surgical removal of the infratemporal parapharyngeal lesions (IPL) is challenging due to its anatomical complexity. Previous surgical approaches have often been too invasive and necessitated sacrifice of normal function and anatomical structures, particularly in the retromandibular nerve region. Therefore, we sought to identify an approach corridor to this area that requires less sacrifice and report an innovative approach through a retromandibular fossa route to the IPL.

METHODS

Five cadaveric specimens were dissected bilaterally with a trans-tympanic plate and styloid process approach. These specimens were investigated microanatomically and morphometrically to examine the extent of the approach in the parapharyngeal space. The clinical application of this approach was compared to previous approaches to the IPL used in our clinical series of 20 cases.

RESULTS

Using this novel approach, the inferior alveolar nerve was identified in all specimens, while the chorda tympani and lingual nerve were identified in 6 (60%) and 4 (40%) dissections, respectively. In all specimens, the petrous portion of the internal carotid artery and the exit of the lower cranial nerve were identified. The average length of the exposed lower cranial nerves was 16.6 ± 3.8 mm (range: 11-25 mm).

CONCLUSIONS

The described approach is feasible for accessing the IPL at the retromandibular nerve and is less invasive than conventionally used approaches.

Clinical utility and versatility of the petrous segment of the internal carotid artery in revascularization

Direct approaches to high cervical lesions, including tumors and aneurysms, carry significant risks. This renders alternative approaches desirable, with vascular disease amenable to exclusion and revascularization to the intracranial circulation, including the petrous or supraclinoid segments of the internal carotid artery (ICA). The cervicopetrous ICA bypass via saphenous venous grafting has proven an effective strategy for treating and excluding these lesions. In current practice, this is performed via an extradural subtemporal approach to access the petrous segment of the ICA and a cervical incision for access to the cervical ICA. The venous graft is alternately tunneled subcutaneously or in situ through the cervical ICA, with the latter eschewing external compression, kinking, and torsion, which increases risk of graft thrombosis with the former. Maxillary or middle meningeal arteries may also serve as donors to the petrous ICA. Moreover, the petrous ICA may be used as a donor in revascularization procedures, to the supraclinoid segment of the ICA and the middle cerebral artery, with petrous supraclinoid and petrous-MCA bypasses described. Clinical utility and operative approaches bypassing to or from the petrous ICA in revascularization procedures are reviewed and discussed.

Tracking the glossopharyngeal nerve pathway through anatomical references in cross-sectional imaging techniques: a pictorial review

Abstract

The glossopharyngeal nerve (GPN) is a rarely considered cranial nerve in imaging interpretation, mainly because clinical signs may remain unnoticed, but also due to its complex anatomy and inconspicuousness in conventional cross-sectional imaging. In this pictorial review, we aim to conduct a comprehensive review of the GPN anatomy from its origin in the central nervous system to peripheral target organs. Because the nerve cannot be visualised with conventional imaging examinations for most of its course, we will focus on the most relevant anatomical references along the entire GPN pathway, which will be divided into the brain stem, cisternal, cranial base (to which we will add the parasympathetic pathway leaving the main trunk of the GPN at the cranial base) and cervical segments. For that purpose, we will take advantage of cadaveric slices and dissections, our own developed drawings and schemes, and computed tomography (CT) and magnetic resonance imaging (MRI) cross-sectional images from our hospital’s radiological information system and picture and archiving communication system.

Teaching Points

• The glossopharyngeal nerve is one of the most hidden cranial nerves.

• It conveys sensory, visceral, taste, parasympathetic and motor information.

• Radiologists’ knowledge must go beyond the limitations of conventional imaging techniques.

• The nerve’s pathway involves the brain stem, cisternal, skull base and cervical segments.

• Systematising anatomical references will help with nerve pathway tracking.

Retromandibular Fossa Approach to the High Cervical Internal Carotid Artery: An Anatomic Study

Objective:

Access to the high cervical internal carotid artery (ICA) is technically challenging for the treatment of lesions in and around this region. The aims of this study were to analyze the efficacy of approaching the high cervical ICA through the retromandibular fossa and to compare preauricular and postauricular incisions. In addition, the relevant neural and vascular structures of this region are demonstrated in cadaveric dissections.

Methods:

The retromandibular fossa approach was performed in four arterial and venous latex-injected cadaveric heads and necks (eight sides) via preauricular and postauricular incisions. This approach included three steps: 1) sternocleidomastoid muscle dissection; 2) transparotid dissection; and 3) removal of the styloid apparatus and opening of the retromandibular fossa to expose the cervical ICA with the internal jugular vein along with Cranial Nerves X, XI, and XII.

Results:

The posterior belly of the digastric muscle and the styloid muscles were the main obstacles to reaching the high cervical ICA. The high cervical ICA was successfully exposed through the retromandibular fossa in all specimens. In all specimens, the cervical ICA exhibited an S-shaped curve in the retromandibular fossa. The external carotid artery was located more superficially than the ICA in all specimens. The average length of the ICA in the retromandibular fossa was 6.8 cm.

Conclusion:

The entire cervical ICA can be exposed via the retromandibular fossa approach without neural and vascular injury by use of meticulous dissection and good anatomic knowledge. Mandibulotomy is not necessary for adequate visualization of the high cervical ICA.

Petrous carotid artery's in situ bypass: anatomic study

The purpose of our study was to reveal the possibility of cervical-to-petrous carotid artery in situ bypass with maximum preservation of cranial nerves. Four human cadavers prepared in formalin were investigated. Eight surgical approaches were used (bilateral exposure on each cadaver). The skin incision started from the level of the temporomandibular joint. The VII, IX, X, and XII cranial nerves, starting from the stylomastoid angle, were maximally preserved. Resection of the styloid process, subluxation of the mandibular joint, and milling of tympanic bone revealed the petrous carotid artery. Exposure of the carotid bifurcation was performed with a mini-skin incision. After dividing the petrous internal carotid artery (ICA) and the cervical ICA, the cervical ICA was dilated using a Fogarty catheter to simulate aneurysmal dilatation. The patient's saphenous vein after stripping was utilized for the bypass. The vein was passed into the lumen of the dilated cervical ICA, and a cervical-to-petrous carotid bypass was performed. In each case, the described technique made it possible to expose the intrapetrous carotid artery adequately. In two cases it was impossible to make a luxation, and therefore the mandibular branch was resected. The vertical segment's mean length was 12 mm (range 10-15 mm). In all cases, the VII, IX, X, and XII cranial nerves were preserved maximally. The main points of the approach are luxation of the mandibular articulation and milling of the tympanic bone. Our study in cadavers suggests the possibility of petrous carotid artery bypass without exposing the cervical ICA.