Medial orbital wall landmarks in three different North American populations

A review of the ethmoidal foramina and their clinical application

The ethmoidal foramina (EF), located on the medial orbital wall along the frontoethmoidal sutures, are critical anatomical landmarks for surgeries involving the medial orbital wall. This review aimed to review the surgical anatomy of the EF, including their embryology and radiology. Although the frontoethmoidal sutures mostly have two foramina passing through them, there are reports of single foramen or multiple, up to six foramina. These foramina provide a passage for the ethmoidal arteries and nerves, branches of ophthalmic arteries and nerves. The surgical guideline "24-12-6" is based on the approximate distance between the anterior lacrimal crest, the anterior and posterior ethmoidal arteries, and the optic canal, commonly used to navigate this area. However, some studies from various populations defined different ratios. Embryologically, the EF were formed by the union of intramembranous ossified frontal bones and endochondral ossified ethmoid bones. EF and neurovascular structures can be identified in computed tomography even in the 3 mm sectional intervals. A comprehensive anatomical understanding of EF will help clinicians improve surgical guidelines and ultimately reduce the risk of complications.

A Systematic and Critical Review on the Anatomy of the Ethmoidal Foramina

PURPOSE

The osteologic anatomy of the orbit is still a field of intense research, particularly as far as vascular channels are concerned. Among them, ethmoidal foraminas (EFs) are certainly those that have more clinical importance and indeed have been deeply investigated. Unfortunately, the vast production of articles, far from clarifying their anatomy, generated a certain degree of confusion.

METHODS

A search on Pubmed and Scopus databases updated up to December 31, 2023, has been carried out with the keyword "ethmoidal foramen" yielding a list of 357 items. With a careful screening process, 31 articles were enlisted to be included in the present review.

RESULTS

A critical review process confirmed that many results published over the years appear inconsistent, particularly as far as EFs topography is concerned. The possible reasons for this lack of consistency can be traced back to inter-ethnical differences, uncertainty on the anterior bony landmarks employed in the investigations, and lack of a general consensus over EFs classification. A novel approach, based on the normalization of the distance of the anterior landmarks relative to the length of the orbit (relative depth index), should overcome some of the major problems encountered so far.

CONCLUSIONS

Novel and clear guidelines to classify EFs and to locate them on the medial wall are required. Determining the relative depth index of EFs may be an interesting approach to solve the matter. Other methods can be also devised. However, direct measurements from bony landmarks, without any further analysis seem inadequate and possibly misleading.

Position of the anterior ethmoidal foramen and trauma to the cranial base during transconjunctival medial orbital decompression: a systematic literature review

PURPOSE

To review the literature on the location of the anterior ethmoidal foramen (AEF) and trauma during transconjunctival medial wall decompression.

METHODS

A comprehensive literature search was conducted using the PubMed, Embase, and Scopus databases, combining the terms "olfactory fossa" and "fovea ethmoidalis" with "trauma," "cerebrospinal fluid leak," "pneumocephalus," "orbital decompression," and "anterior ethmoidal artery" (AEA). All cases of cranial base trauma during medial orbital decompression and the anatomical studies on the location of the AEF and the course of the AEA were reviewed.

RESULTS

Ninety-four articles were identified, of which 37 were related to the AEF, 41 reported the course of the AEA, and 16 to reported cases of cranial base trauma. Out of these cases, 10 were related to transconjunctival medial orbital decompression, affecting 11 patients. Most AEFs are situated at the frontoethmoidal suture, but up to 38.15% of AEFs are located above the suture on the frontal bone. Most AEFs are adjacent to the roof of the ethmoidal sinus. The distance of the AEF to the cranial base increases in the presence of supraorbital ethmoidal cells (SOEC).

CONCLUSIONS

The position of the AEF is variable and should not be considered a safe landmark for all patients.

Cycle Performance of Aerated Lightweight Concrete Windowed and Windowless Wall Panel from the Perspective of Lightweight Deep Learning

This paper aims to explore the seismic mechanical properties of newly developed fabricated aerated lightweight concrete (ALC) wall panels to clarify the interaction mechanism between wall panels and structures. It first introduces the lightweight deep learning object detection algorithm and constructs a network model with faster operation speed based on the convolutional neural network. Secondly, combined with the deep learning object detection algorithm, the quasi-static loading system is adopted to conduct the repeated loading test on two fabricated ALC wall panels. Finally, the hysteresis load-displacement curve of each test is recorded. The experimental results show that the proposed deep learning algorithm greatly improves the operation speed and compresses the model size without reducing the accuracy. The lightweight deep learning algorithm is applied to the study of the slip performance of the wall plate. The pretightening force of the connecting screw characterizes the slip performance between the wall plate and the structural beam, thereby affecting the deformation response of the wall plate when the interstory displacement increases. The hysteresis curve of the ALC wall panel has obvious squeezing effect, indicating that the slip of the connector can unload part of the external load and delay the damage of the wall panel. The skeleton curve suggests that the fabricated windowless ALC wall panel has higher positive and negative initial stiffness and bearing capacity than the fabricated windowed wall panel. However, the degradation analysis of the stiffness curve reveals that the lateral stiffness deviation of the fabricated windowless ALC wall panel is more obvious. It confirms that the proposed connection method based on the lightweight deep learning model can improve the seismic performance of ALC wall panels and provide reference for the structural analysis of embedding fabricated ALC wall panels. This work shows the important practical value for exploring the application effect of embedded ALC wall panels.

A cadaveric study investigating the anatomy of the medial orbital wall

The purpose of this study is to investigate the applicability of the current surgical guideline, known as ‘24-12-6’ surgical guideline, in the Hispanic and European populations. This guideline is used during numerous orbital surgeries and states that the distance between the anterior lacrimal crest (ALC) to the anterior ethmoidal foramen (AEF) (24 mm), the AEF to the posterior ethmoidal foramen (PEF) (12 mm), and the PEF to the optic canal (OC) (6 mm) follows a Rule of Halves. Previous studies suggest this surgical guideline is not applicable for all ethnicities; however, to our knowledge, no data has been published regarding the accuracy of this guideline pertaining to the Hispanic population. An experimental study was performed on 79 orbits (52 cadavers) donated to the Human Anatomy Program at UT Health San Antonio. The ALC, AEF, posterior ethmoidal foramen, and OC were identified; the orbit was enucleated and all remaining soft tissue removed. The distance between each landmark was recorded using a digital caliper. For all cadavers studied, the distances between the ALC, AEF, posterior ethmoidal foramen, and OC were 24.76 mm, 13.89 mm, and 7.61 mm, respectively. Thus, the ‘24-12-6’ surgical guideline was not applicable to the sample studied. Based on ethnicity data, these relationships were also not true for the European or the Hispanic populations. Therefore, significant anatomical variations exist in the current surgical guideline. Clinicians may need to adjust their methodology during surgical procedures in order to optimize patient care.

Porous orbital implant after enucleation in retinoblastoma patients: indications and complications

This study aims to identify risk factors associated with complications in retinoblastoma patients following primary and secondary enucleations with porous implant placement. A retrospective case-control study was performed between 2010 and 2015. Data pertaining to subjects' demographics, medical history, clinical, and pathological findings, implant characteristics and complications were collected. The analysis included 103 eyes of 101 patients age 27.8 ± 21.9 months undergoing enucleation for retinoblastoma. Postoperatively, 19/103 (18%) eyes developed exposure, extrusion, or hematoma requiring subsequent surgery. Exposure was the most common postoperative complication (12/19, 63%). Age at enucleation 24 months or younger, Hispanic ethnicity, female gender, and intravenous chemotherapy prior to enucleation were associated with increased odds of implant complications. In contrast, patients who were given intravitreal melphalan (IM), subtenons carboplatin (SC), or external beam radiation therapy (EBRT) did not demonstrate an increased risk of complications. In this cohort of retinoblastoma patients undergoing primary or secondary enucleation with porous implants, implant exposure was the most common postoperative complication. Our findings suggest that female gender, Hispanic ethnicity, age at enucleation 24 months or younger, and intravenous chemotherapy prior to enucleation may increase the risk of complications.

Clinical and surgical implications regarding morphometric variations of the medial wall of the orbit in relation to age and gender

The ethmoidal foramens are located on the medial wall of the orbit and are key reference points for intraoperative orientation. Detailed knowledge of the anatomy, bony landmarks and morphometric characteristics of the medial wall of the orbit is essential for various surgical procedures. The aim of this study was to determine the morphometric variations in the medial wall of the orbit and establish significant variations regarding age and gender. A total of 110 orbits were analyzed and subdivided by age (over or under 40 years) and gender. The distances of the medial wall of the orbit between the anterior lacrimal crest, the ethmoidal foramen, the optic canal and the interforamina were determined. Safe surgical areas were sought. Statistical tests were used to determine the differences between groups. In men, there is a safe surgical area proximal to the anterior and posterior ethmoidal foramen. In women, this area is in the posterior third of the medial wall of the orbit between the posterior ethmoidal foramen and the optic canal. Regarding variation according to age, the results of this study suggested that the anteroposterior diameter of the medial wall increases with age. This study showed that the anteroposterior total length of the medial orbit wall is similar between genders of similar age, increases with age, and has significant variations in the distances between the various structures that make up the medial orbit wall with regard to gender and age.