Meningo-orbital Foramen Research Articles

Transpalpebral transorbital endoscopic lateral approach to the middle cranial fossa: anatomical study in cadaver

Transorbital expanded endoscopic approaches allow different areas of the skull base to be approached. The aim of our study is to analyse the main anatomical bone and neurovascular structures of the middle cranial fossa by means of a transpalpebral transorbital lateral endoscopic approach (TTLEA). An anatomical study was performed on 12 orbital cavities corresponding to 6 cadaver heads. All specimens were previously injected with colored latex through both carotid systems. The mean distance from the orbital rim to the zygomatic-facial foramen and to the zygomatic-temporal foramen was 11 mm and 16 mm respectively. In all cases the meningo-orbital foramen was found at a mean distance from the orbital rim of 34 mm. The superior orbital fissure (SOF) was located posterior to the meningo-orbital foramen at 39 mm. The foramen rotundum and foramen ovale were located separated from each other by 10 mm on average. Anterior to the foramen ovale a bony prominence was observed in all cases. In 11 cases (92%) the entrance of the accessory meningeal artery into the foramen ovale was evident and in one case an accessory foramen was observed. The middle meningeal artery was located in all dissections within the foramen spinosum. The TTLEA offers a wide and direct exposure of the middle cranial fossa. It should be considered as an alternative to transcranial approaches in certain lesions invading the lateral region of the middle cranial fossa, the lateral wall of the cavernous sinus or the infratemporal fossa.

Cribra Orbitalia is Vascular in Nature and is Dependent on the Meningo‐Orbital Foramen

The etiology of cribra orbitalia is obscure; however, a recent study has proposed that this anatomical variation is of a vascular nature. This study assessed the relationship between cribra orbitalia and vascular variation by determining the presence of meningo-orbital foramina and cribra orbitalia. Of the 150 human orbits in this study, cribra orbitalia was found in 35:150 (23.3%) with 32:35 (91.4%) having a concurrent finding of the meningo-orbital foramen. Further, 3:76 (2.0%) orbits with cribra orbitalia had an absence of the meningo-orbital foramen. A Fisher's exact test was performed to determine the statistical significance and found that the two anatomical variants are dependent (p=0.0002). This study demonstrates a predisposition for cribra orbitalia in the presence of a meningo-orbital foramen and provides further evidence of the vascular nature of cribra orbitalia. Clinically, a surgeon should be aware of vascular anastomoses in individuals with cribra orbitalia.

Clinical Implications in Orbital and Pterional Flap Surgeries as Well as Radioimaging Studies to Determine Topographical Prevalence and Characterization of Meningo-Orbital Foramen in Orbits of the Indian Population

Clinical Implications in Orbital and Pterional Flap Surgeries as Well as Radioimaging Studies to Determine Topographical Prevalence and Characterization of Meningo-Orbital Foramen in Orbits of the Indian Population

Cidence of Meningo Orbital Foramen in Dry South Indian Skulls and its clinical significance

cidence of Meningo Orbital Foramen in Dry South Indian Skulls and its clinical significance

Meningo-Orbital Foramen in South Gujarat population

Abstract Background & Aims: Meningo-orbital foramen is provides a route for an anastomosis between the meningo-orbital branch of the middle meningeal artery and recurrent meningeal branch of ophthalmic artery. Practical importance is emphasized when the middle meningeal artery has abnormal origin, in the cases of subtemporal epidural hematoma, tumors, vascular malformations and in the cases when the foramen spinosum is absent. Present study was undertaken in order to explore the frequency and positional anatomy of this foramen in ninety dry adult human skulls of south Gujarat population. Material & Method: This study was conducted on 90 dry skulls of human origin. Different parameters were noted. Result: Meningo-orbital foramen was absent bilaterally in 35[38.88%] of the skulls studied .The presence of the Meningo-orbital foramen was detected in the 55[61.11%] cases. It was present unilaterally in 30[33.33%] cases [10 on the right and 20 on the left side], and bilaterally in 25[27.77%] cases. Triple MOF were in 2 skulls on right orbit only. Largest variability was noted for distance from the lateral end of the superior orbital fissure. Conclusion: Knowledge of presence and variation in meningo-orbital foramen's anatomical parameter can be crucial for ophthalmologists and neurosurgeons.

A Study of Occurrence and Morphometric Analysis on Meningo Orbital Foramen

Aim and Objective: To study the occurrence and morphometric analysis on meningo-orbital foramen. Background: Foramen meningo-orbital is present in the greater wing of sphenoid bone close to superior orbital fissure.It is a site of anastomoses between the orbital branch of middle meningeal artery and recurrent meningeal branch of ophthalmic artery. It was stated that it is a rare occurrence. But nowadays there is frequent incidence of this foramen. Reason: This study is conducted to improve our knowledge about the occurrence of the meningo-orbital foramen in the skull which may be of surgical significance to ophthalmologist, neurosurgeons and radiologists.

Morphology and Morphometry of the Meningo-Orbital Foramen as a Result of Plastic Responses to the Ambient Temperature and Its Clinical Relevance

The meningo-orbital foramen (FMO) is an osteal opening, containing vessels providing an accessory blood supply to the orbit, situated close to the superior orbital fissure. Recent studies show FMO to be ubiquitous, with localization and occurrence varying, depending on a population, what may be due to environmental conditions (ie, temperature). It is often located near the operating area in surgeries in the orbital cavity, and its accurate localization allows avoiding unexpected bleeding during intervention. Because there is a lack of clarity in the literature concerning the morphology and the morphometry of the FMO, this study aimed to clarify the issue with clinical relevance. We studied dry adult human skulls (50 men and 33 women). The morphology and minimal distances between the FMO and standard anthropologic landmarks (nasion, frontomalare orbitale, supraorbital foramen, and zygomaticomaxillary suture) were measured, using MicroScribe G2L, a three-dimensional contact scanner. We compared the result with results of previous studies on populations from various climate zones. The FMO was present in 69.88% of the skulls (56.02% of orbits): in 60.34% of the skulls, the FMO was bilateral; and in 39.66%, unilateral. We observed 74 single, 10 double, and 2 triple foramina. The FMO was present mostly on the sphenoid and the frontal bone. There was no difference in minimal distances between the FMO and the anthropologic landmarks, depending on sex, except the distance to the nasion (shorter in women). The occurrence of the FMO in the population differed from that of other populations. The results show that it is possible that the morphology and the morphometry of the FMO depend on the climate zone or ambient temperature during growth, which should be considered before performing surgery in the orbital cavity.

Branching of the foramen rotundum. A rare variation of the sphenoid.

The human orbit communicates with the middle cranial fossa through several canals and openings. Some of them (optic canal, superior orbital fissure) are constant, others (meningo-orbital foramen, Warwick's foramen, metoptic canal) are less frequent. Here we report a rare variation of the foramen rotundum which, opening into the orbit with a branching canal, represented a further connecting pathway between the orbit and the middle cranial fossa. Such variation was detected in about 1.06% of individuals and it was almost always located on the right side. Only in one cases it could be found left-sided and in another skull it was spotted bilaterally. The vari- ation consisted of the branching of a 5 mm long canal from the lateral wall of the foramen rotun- dum that opened into the orbit. In general the diameter of the canal was comprised between 0.5 and 0.6 mm but it could be as large as 1 mm or as thin as 0.2 mm. The canal, straight and directed slightly superolaterally, likely transmitted the zygomatic nerve and/or part of the infraorbital nerve. To our knowledge, an independent entrance through a dedicated canal of such nerves has never been reported. The surgeons operating in this region, either neurosurgeons or ophthalmologists, should be aware of the possible variation in the course of these nerves.

Multi–Detector-Row Computed Tomography Imaging of Variant Skull Base Foramina

Several inconstant skull base foramina can be observed on multi-detector-row computed tomographic studies. These include the meningo-orbital foramen, foramen of Vesalius, canaliculus innominatus, palatovaginal canal, persistent craniopharyngeal canal, transsphenoidal canal, canalis basilaris medianus, and fossa navicularis. Although many of these foramina are simply incidental findings, there may be associated anomalies and important clinical implications. The multi-detector-row computed tomographic features of variant skull base foramina are depicted and discussed in this article.

Absence of foramen spinosum and abnormal middle meningeal artery in cranial series

In comparative and evolutionary aspects in humans, the middle meningeal artery enters the cranium through the foramen spinosum, whereas in great apes the middle meningeal artery can enter the cranium through foramen spinosum, through foramen ovale or through petrosphenoid fissure. Generally, in nonhuman primates the anterior meningeal system is associated with the ophthalmic branch of the internal carotid artery. The vessels joining the two systems pass through the additional channels: the superior orbital fissure or through the cranio-orbital foramen. In anatomically modern humans, the absence of foramen spinosum involves abnormal development and course of the middle meningeal artery and it is usually accompanied with replacement of the conventional middle meningeal artery with such, arising from the ophthalmic artery system. In these cases the middle meningeal artery most often enters the middle cranial fossa through the superior orbital fissure and rarely through the meningo-orbital foramen. All skulls, investigated in the present study, belonged to adult individuals of both sexes, conditionally grouped into three cranial series--contemporary male, medieval male, and medieval female series. The absence of foramen spinosum was established only among the medieval male and female series--in 1 (0.70%) male and in 1 (0.72%) female skull on the right side and in 3 (2.13%) female skulls on the left side. In 1 (0.72%) female skull, a small atypically located foramen spinosum was established on the right side. In all of the described cases, the intracranial meningeal grooves started from the lateral edge of the superior orbital fissure and probably reflect the ophthalmic origin of the middle meningeal artery.

Refined and Simplified Surgical Landmarks for the MacCarty Keyhole and Orbitozygomatic Craniotomy

Precise placement of the MacCarty keyhole, a burr hole simultaneously exposing the anterior cranial fossa floor and orbit, provides accurate, efficient entry for orbitozygomatic and supraorbital craniotomies. To locate the optimal keyhole site, previous studies have used superficial landmarks that, in our experience, are not always visible or consistent on older crania. Therefore, we present a technique for accurate keyhole placement using landmarks that are easily visible across age ranges. From inside the cranium, 1-mm burr holes were placed along the anterior junction of the floor and lateral wall of the anterior cranial fossa in 50 adult skulls (100 sides, with calvaria removed). Additionally, from inside the orbit, 1-mm burr holes were placed into the lateral orbital roof. Exit sites of intracranial and intraorbital burr holes were referenced to the frontozygomatic suture. The center of the site between the exiting intracranial and intraorbital holes was deemed the best location for the keyhole. The keyhole center was 6.8 mm (mean) superior and 4.5 mm (mean) posterior to the frontozygomatic suture, which was easily identified on all specimens. Although this keyhole center was slightly more superior on right sides than left, this was not statistically significant. In a minority of specimens, the keyhole was located near the meningo-orbital foramen (22%) and the lateral extent of the frontal sinus (2%). We defined an alternative method for locating the MacCarty keyhole, based on a reliable external landmark, approximately 7 mm superior and 5 mm posterior to the frontozygomatic suture.

The meningo‐orbital foramen in a Scottish population

The meningo-orbital foramen is a small opening in the orbit lateral to the lateral end of the superior orbital fissure. It is widely reported to contain an orbital branch of the middle meningeal artery. The foramen may be single or multiple and may occur in the posterosuperior part of the lateral orbital wall or in the posterolateral part of the orbital roof. There is a lack of clarity in the literature as to whether foramina occurring in the orbital roof are the same entity as those occurring in the lateral wall. The disposition of the lesser wing of the sphenoid at the anterior limit of the middle cranial fossa makes it difficult to see how a foramen communicating with the anterior cranial fossa could transmit a branch of the middle meningeal artery. Our study contained 16 meningo-orbital foramina in the orbital roof that would transmit a fine probe. Fourteen of these passed into canals that tracked posteriorly in the bone to open into the middle cranial fossa close to the lateral extremity of the superior orbital fissure. The other two of these foramina communicated with the anterior cranial fossa and both were associated with a more posterior foramen that communicated with the middle cranial fossa. We hope this study clarifies an issue with relevance to surgery in the anterior cranial fossa.

Importance of the Anatomic Features of the Lacrimal Artery for Orbital Approaches

Knowledge of variations in the possible patterns of origin, course, and distribution of the lacrimal artery are necessary for the diagnosis and important for the treatment of orbital disorders. The vascularization of 38 lacrimal glands was studied by orbital dissection subsequent to injection of the arterial bed with red-dyed latex. The origin, calibration, and branches of the lacrimal artery and its topographic relations were investigated. In all subjects, arteria lacrimalis originated from ophthalmic artery. On the right, the lacrimal artery sprang from the angle of the ophthalmic artery in 63.15% of the cases, from the curve of the ophthalmic artery in 26.31%, and from the first part the ophthalmic artery in 5.26%. The outer diameter of the lacrimal artery was measured as 1.02 +/- 0.17 mm on the right and 1.03 +/- 0.16 mm on the left. In 68.42 of the cases on the right and in 52.63 of the cases on the left, the lacrimal artery was present, and the lacrimal nerve was seen in a superolateral position with respect to the origin of the artery. Variability of the glandular branch in its course toward lacrimal gland was observed. Recurrent meningeal branch was seen in six cases on the right and in five on the left. On the right, of the six cases, two passed through meningoorbital foramen, and four passed through superior orbital fissure and entered middle cranial fossa. On the left, of the five cases, two passed through meningoorbital foramen, and three passed through superior orbital fissure and entered middle cranial fossa. In this case, the lacrimal gland is the site of an intraorbital anastomosis between internal and external carotid systems. This article confirms the well-known variability of the lacrimal arterial branches and their relation to the lacrimal gland. These variations have been discussed and described with respect to the embryonic development. A better understanding of the vascular anatomy of the lacrimal gland should allow modification of surgical techniques to reduce bleeding during biopsy or excision of the lacrimal gland.

Classification of the ophthalmic artery that arises from the middle meningeal artery in Japanese adults.

In a study of Japanese adults, we found that the orbital branch (OB) passing through the superior orbital fissure frequently anastomosed with the lacrimal artery or the ophthalmic artery (12/20). However, the OB passing through the meningo-orbital foramen (mof) only associationaly anastomosed with branches of the ophthalmic artery (4/79). Furthermore, the OB in the orbit, excluding the lacrimal gland as previously reported. We examined 116 cases in which the OB passed through the mof in 129 adult Japanese cadavers (45.0% in 258 sides). The OB passing through the mof was always distributed to the periorbital region and the area that it supplied was limited to the periorbita in about half of those cases. In another half of the cases (58/116), the area supplied included the lacrimal gland.

Association of a Parasagittal Meningioma, supplied by the Middle Meningeal Artery of Ophthalmic Origin, with an Aneurysm

A 56-year-old female was admitted because of repeated focal fits, weakness, and sensory disturbance of the left foot and leg. Computed tomography (CT) scan showed a high density mass in the right frontoparietal parasagittal region, and perifocal edema. Right internal carotid angiography revealed an unusual middle meningeal artery, which originated from the ophthalmic artery and supplied the vascular tumor. A saccular aneurysm was noted at the internal carotid-posterior communicating artery junction. Right external carotid angiography showed no conventional middle meningeal artery. Plain skull roentgenogram and bone window CT scan verified the presence of the right meningoorbital foramen (Hyrtl's canal) and the absence of the right foramen spinosum. The tumor was almost totally removed. The histological diagnosis was meningioma. Six weeks later the aneurysm was clipped. The ophthalmic artery occasionally provides most or part of the blood supply of the middle meningeal artery through anastomosis between the recurrent meningeal branch of the ophthalmic artery and the orbital branch of the middle meningeal artery. Twenty-nine such cases are analysed and the clinical significance of this vascular channel is discussed.