Anatomical study of meandering and functions of human intralaryngeal artery

The thyroid foramen: a systematic review and meta-analysis

PURPOSE

To systematically review published studies on the prevalence of the thyroid foramen (TF), perform a meta-analysis to generate pooled prevalence estimates, and identify factors associated with its presence.

METHODS

A systematic literature search was conducted in Google Scholar, PubMed, and Journal Storage databases. Studies reporting the prevalence of the thyroid foramen were included without language or date restrictions. Quality assessment was performed using AQUA tool. A random-effects meta-analysis was performed with subgroup analyses. Heterogeneity was assessed using Higgins' I2 statistics, and publication bias was evaluated using funnel plots and Egger's test.

RESULTS

Out of 271 entries, 38 studies met the inclusion criteria, comprising 3,030 subjects from various continents. The overall TF prevalence was 24.5% (95% CI: 19.2-29.8%, I2 = 93.44%), with unilateral TF present in 16.9% and bilateral TF in 6.2%. Prevalence was highest in North America (31.4%,) and lowest in Africa (12.3%). No significant prevalence difference was found between adults and younger populations (p = 0.15). Publication bias, or the small-study effect, was detected (p < 0.01).

CONCLUSION

This meta-analysis reveals a 24.5% overall prevalence of TF, with significant heterogeneity primarily explained by geographical differences. The TF's clinical relevance necessitates awareness among surgeons and radiologists to avoid complications during laryngeal surgeries and prevent misdiagnosis in imaging studies.

Inside-Out Surgical Anatomy of Superior Laryngeal Artery Endoscopic Dissection and Proposal for Nomenclature of Branches

Objectives

To describe the inside out surgical anatomy of the superior laryngeal artery and to resolve the ambiguities in the nomenclature of its main branches.

Study Design

Endoscopic dissection of the superior laryngeal artery in the paraglottic space of larynges of fresh frozen cadavers and a review of the literature.

Setting

A center for anatomy encompassing facilities for latex injection into the cervical arteries of human donor bodies and a laryngeal dissection station equipped with a video-guided endoscope and a 3-dimensional camera.

Methods

Video-guided endoscopic dissection of 12 hemilarynges in fresh frozen cadavers whose cervical arteries were injected with red latex. Description of the inside-out surgical anatomy of the superior laryngeal artery and its main branches. Review of the previous reports describing the anatomy of the superior laryngeal artery.

Results

From inside the larynx, the artery was exposed upon its entry through the thyrohyoid membrane or through the foramen thyroideum. It was traced ventrocaudally in the paraglottic space exposing its branches to the epiglottis, the arytenoid, and the laryngeal muscles and mucosa. Its terminal branch was followed until it left the larynx through the cricothyroid membrane. Branches of the artery, previously described under different names, appeared to supply the same anatomical domains.

Conclusion

Mastering the inside out anatomy of the superior laryngeal artery is mandatory to control any intraoperative or postoperative hemorrhage during transoral laryngeal microsurgery or during transoral robotic surgery. Naming the artery's main branches according to their domain of supply would resolve the ambiguities resulting from various nomenclatures.

Open Partial Horizontal Laryngectomies for T3⁻T4 Laryngeal Cancer: Prognostic Impact of Anterior vs. Posterior Laryngeal Compartmentalization

Open partial horizontal laryngectomies (OPHLs) are well-established and oncologically safe procedures for intermediate–advanced laryngeal cancers (LC). T–N categories are well-known prognosticators: herein we tested if “anterior” vs. “posterior” tumor location (as defined in respect to the paraglottic space divided according to a plane passing through the arytenoid vocal process, perpendicular to the ipsilateral thyroid lamina) may represent an additional prognostic factor. We analyzed a retrospective cohort of 85 T3–4a glottic LCs, treated by Type II or III OPHL (according to the European Laryngological Society classification) from 2005 to 2017 at two academic institutions. Five-year overall survival (OS), disease-specific survivals (DSS), and recurrence-free survivals (RFS) were compared according to tumor location and pT category. Anterior and posterior tumors were 43.5% and 56.5%, respectively, 78.8% of lesions were T3 and 21.2% were T4a. Five-year OS, DSS, and RFS for T3 were 74.1%, 80.5%, and 63.4%, respectively, and for T4a 71.8%, 71.8%, and 43%, respectively (p not significant). In relation to tumor location, the survival outcomes were 91%, 94.1%, and 72.6%, respectively, for anterior tumors, and 60.3%, 66.3%, and 49.1%, respectively, for posterior lesions (statistically significant differences). These data provide evidence that laryngeal compartmentalization is a valid prognosticator, even more powerful than the pT category.

Anatomical Cadaver Study of Endolaryngeal Vascularization: Focus on the Glottis, Supraglottis, and Subglottis From the Transoral Microsurgical Point of View

Introduction

Carbon dioxide laser coagulation during transoral laser microsurgery (TLM) for laryngeal cancer allows control of bleeding from vessels smaller than 0.5 mm. Therefore, larger arteries and veins must be carefully managed by clipping and/or monopolar cautery. The aim of this paper is to detail endolaryngeal vascular anatomy and identify areas of possible bleeding during TLM.

Methods

We performed an anatomical study on a series of 11 fresh-frozen human cadavers. After injection of a bicomponent red silicone into the innominate, left common carotid, and left subclavian arteries, 22 hemilarynges were dissected, the course of the supraglottic, glottic, and subglottic vessels were traced after microdissection of the intervening structures, and their size measured at specific landmark points where such vessels are more frequently encountered during TLM.

Results

Three vessels arising from the superior laryngeal artery were identified after its entry point at the level of the thyro-hyoid membrane: (1) the epiglottic artery (EA), documented in 100% of cases, a common trunk dividing into two main vessels (2) the postero-inferior artery (PIA), present in 100% of the specimens, running downward and dividing in a posterior (pPIA), and anterior (aPIA) branches (3) the antero-inferior artery (AIA), present in 95% of our specimens, running downward to the anterior commissure (AC). Two transverse anastomotic networks (TANs) connected the AIA and PIA, both parallel to the vocal muscle, one lateral (present in 100% of cases), and another medial (91% of specimens). Finally, a fourth vessel supplying the glottic plane was found to be the endolaryngeal paracommissural branch of the crico–thyroid artery (PCA), arising from the inferior laryngeal artery and emerging just below the AC, through the crico–thyroid membrane (reported in 100% of the specimens). This vessel anastomosed in 91% of cases with the AIA, through one or both of the TANs.

Conclusion

The course of the endolaryngeal arteries, their relationships with adjacent structures, and size at specific landmark points have been herein described in order to provide surgeons with a map to guide them during the steep learning curve of transoral surgery of the larynx, with special emphasis given to TLM.

Variations in the origin of superior laryngeal artery

The superior laryngeal artery is the principal artery supplying the laryngeal mucosa, musculature, and glands. Knowledge of variations in the origin of superior laryngeal artery could prove to be very useful during reconstructive surgeries of the larynx, partial laryngectomy, laryngeal transplantation, and also during procedures like super-selective intra-arterial chemotherapy for laryngeal and hypolaryngeal cancers. However, relatively few studies have been done on the superior laryngeal artery in comparison to its clinical importance. The present study was aimed at documenting the prevalence of variable origin of the superior laryngeal artery within the carotid triangle. Sixty hemi-necks obtained from 30 South Indian cadavers were dissected and studied for variations in the origin of superior laryngeal artery. It was observed that the superior laryngeal artery took origin from superior thyroid in 91.7% cases. Variable origin from the external carotid artery was noted in 5% cases. The superior laryngeal artery was found to arise from the lingual artery in one case alone (1.7%). In addition to the above findings, a very rare variation of superior laryngeal artery arising from the ascending pharyngeal (1.7%) was also observed in the hemi-neck of one cadaver. All the variations that were observed were unilateral and on the left side. These findings may help provide further insight to the anatomists, radiologists and surgeons and can help improve performances during surgical manipulations of the larynx.

Proposal of landmarks for clamping neurovascular elements during endoscopic surgery of the supraglottic region

BACKGROUND

Bleeding within the supraglottic region can be a lethal complication after CO(2) laser microsurgery. Our aim was to propose endoluminal anatomical landmarks to locate the superior laryngeal vessels resulting in a safer microsurgery.

METHODS

Endoluminal dissections were made in 22 larynges without laryngeal disease.

RESULTS

The neurovascular structures were in the superior third of a triangle defined by the vocal process, the anterior commissure, and the epiglottic attachment of the aryepiglottic fold. They overlapped in 4 different ways: pattern I (70.4%): superior laryngeal vein (SLV), superior laryngeal artery (SLA), and internal laryngeal nerve (ILN); pattern II (13.6%): SLA, SLV, ILN; pattern III (4.6%): SLV, ILN, and SLA; pattern IV (4.6%): SLA, ILN, and SLV.

CONCLUSION

Microsurgery in the supraglottic region may be safer if surgeons are aware of the superior third of the above-defined triangle, "danger area", where the vascular elements of this region are located.

Altered position of the medial lingual nutritional foramina at different stages of alveolar ridge atrophy

To determine the altered location of the medial lingual nutritional foramina in different stages of bone resorption, 55 cadaveric mandibles were selected for this study from a total of 1532. Prevalence, location of the foramen (lingual, cranial, labial), application of Atwood classification (grades 1-6), and macroanatomic dissections were tools of this examination. An increasing grade of atrophy leads to a shift in position of the medial lingual nutritional foramen.